Migratory birds shrinking as climate warms, new analysis of four-decade record shows

News Release 4-Dec-2019

Migratory birds shrinking as climate warms, new analysis of four-decade record shows

University of Michigan

University of Michigan evolutionary biologist Benjamin Winger with some of the migratory songbirds used in a large study of avian responses to climate warming.  Credit: Roger Hart/University of Michigan Photography.

University of Michigan evolutionary biologist Benjamin Winger with some of the migratory songbirds used in a large study of avian responses to climate warming. Credit: Roger Hart/University of Michigan Photography.

ANN ARBOR–North American migratory birds have been getting smaller over the past four decades, and their wings have gotten a bit longer. Both changes appear to be responses to a warming climate.

Those are the main findings from a new University of Michigan-led analysis of a dataset of some 70,000 North American migratory birds from 52 species that died when they collided with buildings in Chicago.

Since 1978, Field Museum personnel and volunteers have retrieved dead birds that collided with Chicago buildings during spring and fall migrations. For each specimen, multiple body measurements are made.

The research team analyzed this remarkably detailed dataset to look for trends in body size and shape. The biologists found that, from 1978 through 2016, body size decreased in all 52 species, with statistically significant declines in 49 species.

Over the same period, wing length increased significantly in 40 species. The findings are scheduled for publication Dec. 4 in the journal Ecology Letters.

“We had good reason to expect that increasing temperatures would lead to reductions in body size, based on previous studies. The thing that was shocking was how consistent it was. I was incredibly surprised that all of these species are responding in such similar ways,” said study lead author Brian Weeks, an assistant professor at the U-M School for Environment and Sustainability.

The senior author is Benjamin Winger of the U-M Department of Ecology and Evolutionary Biology and the Museum of Zoology. Weeks worked on the project as a postdoctoral researcher in Winger’s lab. Co-authors include David E. Willard, the Field Museum ornithologist and collections manager emeritus who measured all 70,716 birds analyzed in the study.

The new study is the largest specimen-based analysis of body-size responses to recent warming, and it shows the most consistent large-scale responses for a diverse group of birds, Weeks said.

Several lines of evidence suggest a causal relationship between warming temperatures and the observed declines in avian body size, according to the researchers. The strongest evidence is that–embedded within the long-term trends of declining body size and increasing temperature–there are numerous short-term fluctuations in body size and temperature that appear to be synchronized.

“Periods of rapid warming are followed really closely by periods of decline in body size, and vice versa,” Weeks said. “Being able to show that kind of detail in a morphological study is unique to our paper, as far as I know, and it’s entirely due to the quality of the dataset that David Willard generated.”

“It’s really been a herculean effort on the part of Dave and others at the Field Museum, including co-author Mary Hennen, to get such valuable data from birds that might otherwise have been discarded after they died from building collisions,” Winger said.

Within animal species, individuals tend to be smaller in warmer parts of their range, a pattern known as Bergmann’s rule. And while the possibility of body size reduction in response to present-day global warming has been suggested for decades, evidence supporting the idea remains mixed.

The uncertainty is likely due, in part, to the scarcity of datasets like the Field Museum trove.

For each bird, Willard measured the length of a lower leg bone called the tarsus, bill length, wing length, and body mass. In birds, tarsus length is considered the most precise single measure of within-species variation in body size.

The data analysis revealed that:

  • Three measures of body size–tarsus length, body mass and PC1, a common measure of overall body size that combines several key body-part measurements–showed statistically significant declines. Tarsus length declined 2.4% across species.
  • Wing length showed a mean increase of 1.3%. Species with the fastest declines in tarsus length also showed the most rapid gains in wing length.
  • Mean summer temperature was significantly negatively associated with bird body size–meaning that body size decreased significantly as temperatures warmed. Temperatures at the birds’ summer breeding grounds north of Chicago increased roughly 1 degree Celsius (1.8 degrees Fahrenheit) over the course of the study.

Studies of plant and animal response to climate change often focus on shifts in the geographical range of a species or the timing of events such as springtime flowering and migration. The consistency of the body-size declines reported in the new study suggests that such changes should be added to the list of challenges facing wildlife in a rapidly warming world, Weeks said.

“It’s clear that there’s a third component–changes in body size and shape–that’s probably going to interact with changes in range and changes in timing to determine how effectively a species can respond to climate change,” he said.

Long-distance bird migration is one of the most impressive feats in the animal kingdom. The extreme energetic demands of flying thousands of miles have shaped the morphology of migrating birds–their form and structure–for efficient flight.

The authors of the Ecology Letters paper suggest that the body-size reductions are a response to climate warming and that increased wing length may help offset the body-mass losses.

The researchers plan to test that idea in a follow-up project, which will again make use of the Field Museum dataset. They’ll also look further into the mechanism behind the body size and shape changes and whether they are the result of a process called developmental plasticity, the ability of an individual to modify its development in response to changing environmental conditions.

The birds analyzed in the study are small-bodied songbirds that breed north of Chicago in the summer and migrate through the region in high numbers. Several species of sparrow, warbler and thrush make up the majority of the dataset, with thousands of individuals of each species documented as lethal collisions.

The observed changes in avian body size and shape are subtle–at most a couple grams’ difference in body mass and a few millimeters in wing length–and are not detectable with the naked eye. The Field Museum bird collision dataset highlights the value of natural history museum specimen collections, which help scientists understand how nature changes through time, the authors note.

“When we began collecting the data analyzed in this study, we were addressing a few simple questions about year-to-year and season-to-season variations in birds,” said the Field Museum’s Willard. “The phrase ‘climate change’ as a modern phenomenon was barely on the horizon. The results from this study highlight how essential long-term data sets are for identifying and analyzing trends caused by changes in our environment.”

###

The authors of the Ecology Letters paper, in addition to Weeks, Winger, Willard and Hennen, are Marketa Zimova of the Institute for Global Change Biology at the U-M School for Environment and Sustainability, former U-M undergraduate Aspen A. Ellis, and Max L. Witynski of the Field Museum.

Funding for the study was provided by the Field Museum and the University of Michigan’s Department of Ecology and Evolutionary, Museum of Zoology, and Institute for Global Change Biology.

More information: April 2019 Michigan News release about nocturnal flight calls and building collisions.

Image link: https://drive.google.com/drive/folders/1u6DxrzXGE7bk48Vi_DefaX_W2eBkwxvs

From EurekAlert!

175 thoughts on “Migratory birds shrinking as climate warms, new analysis of four-decade record shows

  1. Perhaps the hevier birds have been chopped down in numbers due to accelerating numbers of man made wind turbine parks? 😉

    • Heavier/bigger is storing energy to migrate….

      Planet greening means more food is available…they can be smaller/lighter and still migrate…

      The opposite would also hold….less food would select for the bigger birds..smaller birds would have less energy stored

      • Isn’t nature marvelous! How organisms are able to evolve with changing environmental conditions! A true marvel!! Why the glum faces?

          • Nature has certain laws that govern all creatures and plant life. One of them is that warm weather makes everything easier–more plants grow, more seeds set, longer growing season, more food for birds and animals. Birds and animals adapt to these kinds of minor, incremental changes seamlessly and automatically. Especially when they enhance the conditions of life. Human civilization follows exactly the same patterns historically.

            I believe the alarmist hysteria is at a fever pitch right now because:

            (1) We are at the beginning of a solar minimum, slated to bring a 30-year cooling cycle; this junk crystal-ball “science” will become harder to sell with each cooler year.

            (2) It’s all the desperate global-socialist elites in the Democratic Party have–trying to spook the populace into some kind of stampede to their side via scary stories of doom.
            Might fool teens raised on “dystopian” novels; adults over 40 not so much.

            Most of this crap can be debunked in 5 minutes online–for instance, the Victoria Falls were this dry on February 1, 1950! (Credit–Steve Milloy)

          • Possibly the second best movie line of all time next to “All those moments will be lost in time, like tears in rain. Time to die.”

      • For warm-bloodied species, homeotherms, as with birds, colder temperatures mean more calories spent on maintaining and thus less growth. Things grow larger when they spend less on maintenance.

        With cold blooded species, poikilotherms, lower temperatures means more calories spent on growth, which is why the fish on the Grand Banks grow so large.

        Most mallard ducks migrate south for the winter. Those that do are visibly larger than those who spend the winter in the north living off what they can find or from humans. There are clearly tow different populations defined by size.

          • The species not the individuals. Mallards are a migratory species but some individuals may not migrate. Same thing happens with many other species (e.g. Canada geese).

          • Migratory birds that do not migrate are almost a separate sub-species. In 50 years of living here and observing the nearest city park lake and the nearest power plant cooling lake, where there is always a population of ducks and geese that don’t migrate, I don’t remember ever seeing any newly hatched ducks or geese from the static population. Those individuals in the static populations obviously have such a low instinctual drive to breed and migrate that they truly are a separate sub-species.

      • I don’t see any way of knowing how old these birds were when their particular window collision occurred. Could it be that recent years have been quite successful for urban bird populations, and more 1st year adults are hitting windows?

        • The great increase in number of people feeding birds has definitely had an impact. Feeder bird populations have increased, birth rates and survival are up, and some birds have enough food they’ve stopped migrating. At least according to the Cornell ornithology folks.

          Of course if warming is to blame for a 40 year decline in bird size, how is that possible when nearly 20 years of that were “The Pause” when temperatures flatlined?

        • “Smaller bodies, longer wings, fly easier.”

          An albatross has a very long wing span compared to its body. Ever see one take off?

          Long wings are good for soaring the way a buzzard does. Not so good for evading prey like a sparrow does.

    • Conversely it may be that during the Little Ice Age which ended in the late 1800s that bird species had increased body mass and decreased wing span to combat the cold.

      This study could equally have proposed that.

      The LIA was 2C and more colder than normal, making 1850 as an LIA year a very convenient date for the IPCC to choose to demonstrate ” global warmjng”, hard not to find warming as earth recovers from a very cold period – quite naturally.

      • yep…..less food along the way selects for birds with larger body mass…which selects for shorter stubbier wings to get their fat a$$es off the ground faster…they still have to move fast enough to escape predators, move fast enough to catch bugs, etc

        conversely….smaller and longer wings is more energy efficient for long migrations…but they don’t have as big a reserve to draw on…so they have to be able to find more food along the way

        …what they are really saying is evolution happens a lot faster than what they want to believe..and global warming is not the big threat they try to make it out to be

          • “Why would short wings be adequate for a fat ass?

            Wouldn’t you need larger, more powerful wings?”

            Ask someone who hunts upland game birds if they have large, powerful wings or shorter, powerful wings. The wings on a quail are small compared to the whole body, same for pheasant. Both of these bird species have explosive takeoffs, rising quickly to 15′ to 20′. Ever see a buzzard take off from the ground? Or a red-tailed hawk? Or a barn owl?

          • 10-4 Tim G, Watch how slow a Heron or a Loon gains speed and altitude taking flight and you’ll see why small wings powered by big muscles rule birdland.
            It’s why shooting ducks on a pond is way easier than quail in a meadow.

    • The first point is that US temperatures have been cooling these past 90 years. The 1940s are the warmest period in the US.

    • Oh my God, they are melting in the unrelenting heat! As their bodies melt their wings seem longer. The horror of it all, will nothing in nature stay constant as Gaia intended?

  2. hmm, Migratory birds are in decline for many reasons – of course climate change is thrown in for funding etc.

    “General factors underlying declines of migratory taxa include land-use change, barriers to migration, overexploitation and climate change”

    Safe to say that those that do survive probably dictate that smaller and with longer wings survive better.

    Darwin’s book, Origin of Species, page 83 onwards illustrated how quickly species change when the environment changes. I don’t think he mentions climate change.

        • Is climate change being confused with UHI??? Last time I checked, Chicago is a UHI and these birds obviously spend time in Chicago. Need to run some controls using dead birds outside of a UHI. Way too many variables here to conclude climate change.

      • My take….

        Greening of the planet mean more bird food….they don’t have to be as large to store body weight/reserve..to migrate..there’s more food available

        • I have a nice, useful book on my shelves, title “Climategate – The Crutape Letters.” Published 2010. Written by Thomas W Fuller and a guy called Steven Mosher.
          I don’t think Steve was ever a sceptic, let alone a nasty ‘denier’. But he did seem to think honesty was important.

          Now, any cocamanie hypothesis deserves his full support.

          What went wrong, Steve? Has Mike Mann got some embarrassing photos?

          I don”t know about unicorns, perhaps that’s your schtick.

          But perhaps it was the same (alleged) one degree temperature rise that changed you?

          Or maybe it is, after all, those naughty witches. The hypothesis that witches changed little song birds’ inside leg measurements by a millimetre or so, is every bit as plausible as a 40 year temperature rise.

          Sad, really.

          • So far as I know, Steven is still in academia.

            In academia, one must believe in Catastrophic Anthropogenic Global Warming, Orange Man Bad, Fifty Seven Genders, Capitalism Evil, Israel Is the New Reich, and a whole host of other tenets. One must prove this belief by constant and fervent declarations.

      • Since natural selection is the main driver of evolution, was the question “What about a slight temperature increase would select for these changes?”

        The obvious assumption is that bird strikes are a completley random event. Is that true? Could it be instead that something about a smaller body and increased wing length increases the chance of hitting a building?

        What about the number of birds striking the buildings? The ages of the birds? Weather conditions?

        So many questions that apparently were never asked, because hey — climate change!

      • Steven Mosher, a scientific study demands that there be some mechanism to control variables, that is, to isolate the variable under research from other variables. How were the variables controlled in this bird study? They weren’t. These types of studies are thought pieces at best, and maybe some scientific person will undertake an actual scientific study, with control of the variables. For example, my identical twin brother and I were control in adopted and separated twins studies, because we were adopted and not separated (thanks mom and dad). Additional control was by virtual twins, that is, two totally genetically separate babies adopted at birth and raised in the same environment. Where is the equivalent control in this bird study?

        • Yes. What temperature dataset was used? If it was a global average, then all you have is an ambiguous correlation. If it was the actual temperatures where the birds were living at both ends of their migratory routes, then you have some suggestion that more than correlation is going on.

          And this is a somewhat peculiar population — only birds that hit buildings in Chicago. Interesting, but hardly definitive. The results very well may be informative, but they need confirmation. And even after that, it’s good to know bird populations are adaptable. Now if they only could improve their radar.

      • there are many reasons why a species change- “land-use change, barriers to migration, overexploitation ”

        the climate change meme has become rather tedious.

        “Humans and animals are constantly evolving — shedding less-favorable characteristics for features that maximize the odds of survival [source: ABC Science]. This process began with the very first living creatures and will continue until there’s no life left. What makes modern evolution so fascinating is that in some cases, it’s occurring at an accelerated rate. It’s often so fast that humans can see the changes in just a few generations”

      • “Steven Mosher December 8, 2019 at 4:17 am
        decline in SIZE
        this is simple. It was predicted. Now observed.”

        Mosher goes on record declaring support for Confirmation Bias.

        “Several lines of evidence suggest a causal relationship between warming temperatures”

        N.B. The researchers did not establish causal relationship!

        That was their operating theme going into the study. And unsurprisingly, their conclusions at the end of the study; with waffle words for caveats.

        “Three measures of body size
        …Tarsus length declined 2.4% across species.
        …Wing length showed a mean increase of 1.3%.

        Mean summer temperature was significantly negatively associated with bird body size–meaning that body size decreased significantly as temperatures warmed.
        Temperatures at the birds’ summer breeding grounds north of Chicago increased roughly 1 degree Celsius (1.8 degrees Fahrenheit) over the course of the study.”

        A) N.B. temperatures are roughly measured… One must be curious how a particular breeding ground is substantially warmer than climate tracking?

        B) No mention whether all birds whether birds were ‘harvested’ at the identical stage of development, seasons of the year, before during or after breeding, natural foods or sustained by human supplemental feedings, feather maturity, etc. etc…

        Length and breadth measurements well within measurement errors are described as statistically significant. Small sample size and statistics failure.

        Yet the researchers can immediately assume their ingoing “confirmation bias” belief is valid and Mosher jumps in to support and defend them.
        right…

      • Steven: Yeah, but is this good or bad? Your confreres leave this question out in all these types of studies. The code has become that “change in anything is bad and it is all human’s fault” so you guys don’t have to say more.

        I’m suspicious for a scientific reason on the the “fact” of the data matching the temperature wiggles: were these birds all the same age? Were none of the birds who died in 1978 born during the early 70s when we had “The ice age cometh” bitterly cold years? Did the the changes stop from 1997 to the present?

        I’m a geologist trained to the forensics of giving meaning to things that happened up to billions of years ago. I must say that most biologists I’ve known or read are basically “describers” of static things and tend to lack the curiosity of deeper meanings. In this static world, change is scary, right?

      • Steven Mosher wrote:
        “decline in SIZE
        this is simple. It was predicted. Now observed.”

        My elderly neighbor complains that his privy member is getting smaller – he also blames global warming/climate change. 🙂

        Correlation is NOT causation.

      • Au contraire. Predicted? Usually individuals in the warmer end of the range are lankier and lower body weight and those in the colder range are stockier/heavier to preserve body heat. An association well known among naturalists. OTOH- individuals in shrinking habitats are often smaller- cf populations confined to islands compared to their mainland counterparts….Anyone familiar with the change in land use of Chicagoland over the last half century knows that there is very little natural habitat left within a 100 mile radius of The Loop. Midway & O’Hare airports(call letters ORD for apple ORcharD) were located well out in the hinterland when they were built 85 & 70 y/a respectively, and were still surrounded by farmland 40 yrs ago. Now they’re surrounded by megalopolis. Not many bugs left for the birdie or places for their nests in that range. BTW- the change in body size is also highly correlated with the number of HRs hit in the National League over that time span.

      • This was predicted? So was every single weather event that was extraordinary in the last decade, by the all-inclusive climate change theory. Any theory that predicts everything actually predicts nothing.

    • Lead-in sentence – posted article:

      ANN ARBOR– North American migratory birds have been getting smaller over the past four decades, and their wings have gotten a bit longer. Both changes appear to be responses to a warming climate.

      WHOA, ……. stop right there, ….. the intent of the above “study” is obviously to “push” the CAGW junk science.

      “DUH”, …… all migratory birds “respond” to a warming climate, ….. and likewise, …… all migratory birds “respond” to a cooling climate. A seasonal warming/cooling of the higher latitudes of the NH.

      When the climate begins to “warm” in the Spring, they head “north” to the higher latitudes of their choice. When the climate begins to “cool” in the Fall, they head back “south” to the lower latitudes of their choice.

      All migratory birds spend far more days of their lives (+- 7 months) in the much warmer lower latitudes of their choice, ……. while spending far less days of their lives (+- 5 months) in the much cooler higher latitudes of their choice.

      Me thinks maybe one might claim “lack of food” as the cause of “smaller” size over the past four decades.

      “DUH”, iffen they hadn’t flown into a building and killed themselves, they would have probably starved to death in Chicago. Starlings, pigeons and English Sparrows are the “city slickers” of the Aves.

  3. So, no other factors – eg habitat loss – could have caused these changes?
    Hmmm, let’s see. A typical avian summer migrant to southern Scotland has to pass over southern England in the spring and reverse that journey in the late summer or early autumn. The distance is around 400 miles and birds typically take a few days over it. People shuttling by plane between Gatwick and Glasgow airports do similar – in an hour.
    Fact- while the average difference is around 1.5C to 2C in Gatwick’s favour, temperature differentials of 10C are not rare.
    So, even within Britain, a bird can undergo warming or cooling of the order of 1,000 plus years of the supposed anthropogenic result in a matter of days. Yet, they survive and have done for a multitude of climate cycles.
    We are to be told that AGW – happening at a microscopic snail’s pace compared to what they experience regularly -is causing these birds to change size. Sorry, just don’t buy it. Doesn’t add up.

    • “So, no other factors – eg habitat loss – could have caused these changes?”

      it could have been UNICORNS!

      here is how science works

      “Within animal species, individuals tend to be smaller in warmer parts of their range, a pattern known as Bergmann’s rule. And while the possibility of body size reduction in response to present-day global warming has been suggested for decades, evidence supporting the idea remains mixed.”

      Hypothesis: warming will lead to a reduction in size.
      Test it? Collect birds for 40 years.
      Result? Hypothesis CONFIRMED.

      Now, you may SUGGEST that it might be something else. perhaps X caused it.
      perhaps, perhaps perhaps.

      Now it’s YOUR job to SPECIFY an exact cause and test your SUPPOSITION.

      In short the very structure of scientific explanation is such that we never know
      ALL the causes. It could ALWAYS be “something else” Even when variable
      Y is totally explained by variable X, we can still posit that it MIGHT BE something
      else. Your job as the proponent of “something else” is to specify and test your
      something else.

      “habitat loss?” easy to test. Go get the database. Look at all the species test your supposition
      that is it habitat loss. Perhaps it plays a role, but HOW EXACTLY does habitat loss create a smaller
      bird? and longer wingspan? AND why is the weight loss CONISTENT across many species?
      Did they all magically lose the same amount of habitat?

      it could be unicorns!!! they have magical properties and can explain everything that global warming
      explains.

      Or it could be that the thermometers are corrrect!! imagine THAT! OMG

      Those dang thermometers say its warming. Reconstructions of weather using pressure measurements
      only ( no thermometers) ALSO suggest its warming.
      glaciers on the whole are shrinking. Consistent with warming.
      ice shets are melting. Conistent with warming.
      Plant ranges are changing. Consistent with warming
      Borehole measurements are consistent with warming.
      Sea level rise continues, consistent with warming
      Satellite records show warming, consistent with the thermometer record.
      Blooming dates are changing, consistent with warming

      Now it could be that ALL these alternative indicators are wrong as well as thermometers being wrong
      It could all be wrong. However, we have no evidence that any of it is wrong.
      Its getting warmer. There was an LIA. Folks expected to see smaller birds. Now they do.

      Another bit of evidence. as it piles up remember this. you will ALWAYS be able to say
      “it could be something else” that is NOT a scientific objection. It is merely a comment
      about the epistemic chracter of scientific explanation: always contingent, always incomplete.
      Its why science doesnt stop.

      • Climate change and habit change are entirely collinear. Could have just as easily said that habit change was causal and come to the same conclusion. In Northern Michigan alone there are 3 primary migratory paths that have become urbanized over the last 50 years. A large proportion of of the UofM sample comes from those migratory paths. As birds are forced to fly across / around urbanized areas there is ample support for the notion that more efficient mechanics prevail, hence lighter, (smaller), bodies and relatively longer wings.

      • Actually, science is asking “could it be something else”. If I or anyone can propose any scenario that could account for the observation, then it is up to the researcher to control for those factors before insisting on any link. The fact that an observation fits a pre-conceived expectation is interesting, but not compelling.
        As Popper asserted, it is easy to find confirmations of any theory–if we look for confirmations. The true test of a theory is to test what that theory prohibits.
        Is there anything that the CAGW hypothesis prohibits?

      • Hypothesis: warming will lead to a reduction in size.
        Test it? Collect birds for 40 years.
        Result? Hypothesis CONFIRMED.
        ===
        Hypothesis: less food selects for larger migratory birds

        result?….it’s true

        • Yup. It’s the high school-level approach to science, leading to the person to thinking that the causal mechanism is thus explained. Just like the global warmers saying CO2 must make it warm, it has warmed, therefore it woz CO2 wot dun it.

      • Personally, I think this is all BS. Studying small migratory birds actually tells you nothing about the impact on *migratory* birds of all kinds. I’ve hunted ducks, geese, and mourning doves for 55 years. In fact the geese and mourning doves harvested this year were visibly larger and heavier than in many of the past years, especially the mourning doves. I noticed no differences in the ducks I harvested. These species migrate vast distances compared to most smaller species. If climate change were to affect migratory birds you would expect it to affect the larger species that cover vast differences to exhibit changes to lower body weights first.

        All this study has done is to show a correlation, it does not lay out any kind of causal link. There *are* all other kinds of confounding factors. First, longer wings require *more* muscle mass to push against the extra loading from the longer wings. Having longer wings and lower body mass is just totally counter-intuitive. Longer wings and lower body mass would be more indicative of a species evolving more to becoming a soaring species similar to buzzards and eagles. Again, this is counter-intuitive for smaller species since it wold make them much more susceptible to predatory species like falcons and hawks. Smaller species normally tend toward short, quick flights (i.e. larger body mass compared to wing area) with abrupt turns to avoid predators. Longer wings and smaller body mass are simply not conducive to this.

        My guess is that the actual causal link will be found with food supply and habitat, not with climate change.

        • There’s also the possibility that tall buildings have been darwinning a certain body type, leading to selection for a different type that live around (and fly into) tall buildings.

      • “Mosher”

        From your citation as premise (emphasis added):

        And while the possibility of body size reduction in response to present-day global warming has been suggested for decades, evidence supporting the idea remains mixed.

        To your conclusion (emphasis added):

        Hypothesis: warming will lead to a reduction in size.
        Test it? Collect birds for 40 years.
        Result? Hypothesis CONFIRMED.

        Why do you do it? It’s getting worse you know.

      • No while what you described would be science that’s not what they did.

        It would be more accurate to say,

        Hypothesis: we’ll find something valuable if we store all these dead bird measurements
        Test: collect birds for 40 years
        Result: we found something that correlates with the cause du jour! Hypothesis proven that storing dead birds is valuable.

        Actual science has to predict something, not merely observe it, and good science explains why that will occur. Does that often start by observing something in nature that needs explaining? Of course. Is this an interesting area to research based on their historical data? Absolutely. Was this science? Nope, because it wasn’t able to predict anything we didn’t already know.

        Could this be turned into a scientific study? Absolutely, and I hope it does. But they won’t be able to do it this way because as others have pointed out already it would be just as accurate to say that buildings cause birds to grow larger wings and lose mass. Science has to differentiate between these.

      • It’s amusing watching an English Lit grad trying to explain science.

        Science 101 a hypothesis should not be confused with a theory and you always need to consider the NULL hypothesis. The problem above also needs reflection on a law vs a theory.

        A scientific law or rule is the description of an observed phenomenon it offers no explanation of the problem. So our first problem is Bergmann’s rule in a strict science sense is nothing more than junk or a rule of thumb, it is like Moore’s Law or even Murphys Law. You have a set of observations that sort of follow a pattern except for the countless exceptions to the rule that must exist 🙂

        Science laws always have countless exceptions because at there very best they are an approximation of some underlying theory. You can talk about how good a science law is but at it’s heart it’s always wrong it is just a matter of how bad.

        So now in our case above we cast a hypothesis to a something akin to Murphy’s law that heat will make animals smaller and we set out and measure it. Now when we have our results we got a statistically significant variation on 49 out of 52 species. A real scientist would be interested with the 3 fails because either the hypothesis is wrong (needs adjustment), you have data errors or you have exceptions to law/rule. The reason this is important is because if we want to convert our law to a theory we must have no exceptions, it must cover ALL OBSERVATIONS.

        So now we come to the fun part what does the study actually mean. The scientific answer is not very much Bergmann’s rule is not much better than Murphy’s law and your result seems to show that. You certainly can not extend the above result to a theory because it has failures.

      • @ Steve Mosher.

        According to the World Obesity Federation a third of the world is now obese , increasing in size and numbers, this is happening in every country. The human race is evolving into a race of fatties.

        Obviously this is happening due to climate change as the world is greening and producing more food.

      • Jeez, Steven, are you the Anti-Popper? The Anti-Feynman?

        Hypothesis: warming will lead to a reduction in size.
        Test it? Collect birds for 40 years.
        Result? Hypothesis CONFIRMED.

        A hypothesis cannot be “confirmed”. They can only be “not falsified.”

        Now it’s YOUR job to SPECIFY an exact cause and test your SUPPOSITION.

        ” …if you’re doing an experiment, you should report everything that you think might make it invalid — not only what you think is right about it; other causes that could possibly explain your results; and things you thought of that you’ve eliminated by some other experiment, and how they worked — to make sure the other fellow can tell they have been eliminated.

        “Details that could throw doubt on your interpretation must be given, if you know them. You must do the best you can — if you know anything at all wrong, or possibly wrong — to explain it. If you make a theory, for example, and advertise it, or put it out, then you must also put down all the facts that disagree with it, as well as those that agree with it. There is also a more subtle problem. When you have put a lot of ideas together to make an elaborate theory, you want to make sure, when explaining what it fits, that those things it fits are not just the things that gave you the idea for the theory; but that the finished theory makes something else come out right, in addition.

        In summary, the idea is to try to give all of the information to help others to judge the value of your contribution; not just the information that leads to judgement in one particular direction or another. ” — Richard Feynman

      • Steven Mosher – December 8, 2019 at 4:34 am

        Your job as the proponent of “something else” is to specify and test your
        something else.

        “habitat loss?” easy to test. Go get the database. Look at all the species test your supposition
        that is it habitat loss. Perhaps it plays a role, but HOW EXACTLY does habitat loss create a smaller
        bird? and longer wingspan?

        Elementary, my dear Mosher, …… elementary.

        They are talking migratory birds ….. which engage in a “yearly” northernly migration to a chosen feeding/nesting ground (habitat) ….. and if that habitat is lost they will have to migrate farther north where the food supply is less abundant. Thus, “survival of the fittest”, …… smaller birds with longer wingspans.

        AND why is the weight loss CONISTENT across many species?
        Did they all magically lose the same amount of habitat?

        The number of different species matters not, …… and the study area was the City of Chicago so there was no loss of habitat …… but there was surely a loss food resources for all species during those 38 years, resulting in an average “weight loss”. Birds (Aves) are one of the original “hunter-gather” species …. and when their “gathering” of food diminishes, so does their body mass.

        it could be unicorns!!! they have magical properties and can explain everything that global warming explains.

        But, but, ….. the Flying Spaghetti Monster has more horse sense than any silly unicorn.

        • And I got to thinking about Mosher’s question of, to wit:

          “AND why is the weight loss CONISTENT across many species?

          And these two excerpted statements from above published article:

          For each bird, (all 70,716) Willard measured the length of a lower leg bone called the tarsus, bill length, wing length, and body mass.

          The observed changes in avian body size and shape are subtle–at most a couple grams’ difference in body mass and a few millimeters in wing length–

          WHOA, ….. measuring the “body mass” of 70,716 dead birds and using said “body mass or weight loss” results as an input parameter of a scientific study is a waste of time and energy because there is no way of knowing how long each bird had been dead ….. or anything about the environment in which the dead bird was found.

      • The evidence shows that large buildings kill lots of birds which have evolved larger wings to fly over the buildings. These larger wings and the energy required to drive them increases CO2 exhalation which causes temperatures to increase. Science!

      • The world famous Harvard Nurses Study aimed to prove FAT was bad for humans and achieved that result. Millions of people changed their diets based on that study and diabetes is skyrocketing due to that fact. Now we all know the study was BS because they didn’t control for total calorie intake, carbohydrate intake etc. etc. etc. Example: Eat a doughnut that has almost no nutritional value and it is the fat from the frying that will kill you, not the refined flower and sugar coating that spikes your bodies insulin response. What is the term, confirmation bias?

        So when you INTEND to prove something and your phony study does “PROVE” your intended result your study is SCIENCE even though you have not taken ANYTHING ELSE into consideration.

        Way to go Steve. Science looses again.

      • Smaller bird bigger wingspan: reduced food is a logical possibility possibility, the latter the need to fly around more daily, increased competition?

        • “Smaller bird bigger wingspan: reduced food is a logical possibility possibility, the latter the need to fly around more daily, increased competition?”

          Smaller birds generally live in denser vegetation for protection against predators. Longer wingspans would make this much more difficult, an evolutionary no-no. Watch a sparrow or quail take off from the ground sometime and then compare that with a hawk or buzzard that have long wingspans. Compare the wingspan of a barn swallow with that of a gull. One lives with short flights and lots of agility. The other lives with long, soaring flights and not much in-air agility.

      • Total nonsense from Steve.
        He suggests we prove that habitat loss can be a factor while overlooking that this pseudo-study did NOT eliminate any other factors. they just NAMED climate change as a cause. A REAL scientist would have done the work. Self declared expert Steve now tries to pin it on the reader. Not acceptable.
        In order to prove this “theory” they should also have shown that cooling causes an increase in weight and shorter wings.
        As one of the commenters asked “What temperature data was used?”
        Note that Tony Heller has shown that maximum temperatures have been decreasing in the USA since the 1930’s.

      • None of those observations evidence that it is warming. They only show that it has warmed over a specific period. It may actual cool in the future or it may actually have cooled over a longer period of time which proxy evidence suggests. Nothing there but a non-linear trend that is not a predictor of the future. Nothing indicates if the trend will continue or, if it does, for how long.
        In the past, cooling has always followed warming and warming has always followed cooling. It is probable that history will repeat but there is no certainty of even that for any specific time period.

      • They are just rewording bergmann’s rule with climate change. I learned this rule in my evolutionary biology class when I was working on my PhD in zoology.

        However a recent paper questions this hypothesis and it has some very interesting conclusions. No general relationship between mass and temperature in endothermic species
        Kristina Riemer,1 Robert P Guralnick,2 and Ethan P White1,3. Its on PubMed

        Abstract
        Bergmann’s rule is a widely-accepted biogeographic rule stating that individuals within a species are smaller in warmer environments. While there are many single-species studies and integrative reviews documenting this pattern, a data-intensive approach has not been used yet to determine the generality of this pattern. We assessed the strength and direction of the intraspecific relationship between temperature and individual mass for 952 bird and mammal species. For eighty-seven percent of species, temperature explained less than 10% of variation in mass, and for 79% of species the correlation was not statistically significant. These results suggest that Bergmann’s rule is not general and temperature is not a dominant driver of biogeographic variation in mass. Further understanding of size variation will require integrating multiple processes that influence size. The lack of dominant temperature forcing weakens the justification for the hypothesis that global warming could result in widespread decreases in body size.

      • Steve Mosher wrote, “here is how science works… ‘Within animal species, individuals tend to be smaller in warmer parts of their range, a pattern known as Bergmann’s rule…’
        Hypothesis: warming will lead to a reduction in size.
        Test it? Collect birds for 40 years.
        Result? Hypothesis CONFIRMED.”

        “If you can’t quantify it, you don’t understand it.”
        – Peter Drucker

        Ian is right, Steve.

        Science, that is, the Scientific Method, makes measurable predictions, and then tests them. If, instead, you notice a slight change, and then fish around for some way that Global Warming could explain it, you’re not doing science.

        “Hmmm… the dead birds seem to have gotten slightly smaller, and have slightly shorter legs and slightly longer wings. How could climate change explain those things?”

        Allen’s Rule: body form or shape is more linear in warm climates and more rounded and compact in cold climates.
        Nope, that can’t be it. The legs shouldn’t be getting shorter.

        Bergmann’s rule: animals in cold habitats will be larger than those in warm habitats.
        Ah ha, that’s it! Publish!!

        That’s not science.

        If you want to do science, than you need to quantify your predictions, so that you can test them properly.

        How would you do that? Well, we know that Bergmann’s rule doesn’t work with all species, and it is only noticeable over long distances and large climate variations. So you would start by seeing which species exhibit a detectable variation in size over their ranges which is consistent with Bergmann’s rule, and then you would quantify how much change in size they exhibit per degree of temperature change. Then you would calculate how much size variation to expect from the actual temperature variation over that 40 years. Then you would measure the actual size variations seen, and compare them with those predictions, species by species.

        Oh, and you can’t just report the results for selected species “which work,” and ignore the others:
        https://www.sealevel.info/Bonferroni-blue_by_Hilda_Bastian_used_by_permission_CC_BY-NC-ND_4.0.html

        I skimmed the paper, and found no reference to the authors having made any attempt to quantify the amount of change expected in each species from a one degree temperature change, nor even to identify which species follow Bergmann’s rule.

        The temperature change in Illinois over the last 40 years has been so slight…
        https://www.isws.illinois.edu/statecli/climate-change/iltrend-temp.png
        …and the predicted size variations in birds will be so minuscule, and the random variations in individual bird sizes are so large, that I’m confident you cannot make a quantified prediction based on Bergmann’s rule which can be confirmed by a statistically significant measured change in bird size.

    • Insect holocaust is what is causing it:
      Scientists have long been speculating about the potential reasons for the declining number of insects and the birds that depend on these critters for their survival, with new research potentially shedding some light on this problem.

      An insect apocalypse with a massive decline in the number of arthropods is underway due to the prevalence of artificial light at night, also known as light pollution, a new study published in the journal Biological Conservation claims.

      Scientists from Tufts University in Massachusetts reviewed the results of more than 200 independent studies to conclude that it is artificial light at night (ALAN) that could be a significant factor driving the so-called insect apocalypse due to its influence on reproductive success, hiding from predators, and the search for food by various insect species, potentially contributing to the loss of about 40% of all species in the next few decades.

      “Artificial light at night impacts nocturnal and diurnal insects through effects on development, movement, foraging, reproduction, and predation risk”, the paper claims.
      “We also emphasise that artificial light at night is not merely a subcategory of urbanisation. The ecological consequences of light pollution are not limited to urban and suburban centres, but widespread along roadways and around protected areas”, researchers added.

      In an Oct. 7, 2015, photo, a bucket of crickets are seen in the Detroit Zoo’s cricket breeding area in Royal Oak, Mich.
      © AP PHOTO / CARLOS OSORIO
      Insects Are Dying Off in Europe in Apocalyptic Wildlife Omen, New Study Suggests
      The declining number of insects, in turn, leads to disruptions in the food chain and global ecosystem by causing a significant reduction in the number of birds. So, researchers believe that the loss of around 3 billion birds in the US and Canada in the last 50 years is likely to be directly related to the declining number of insects.
      The study concludes by saying that this problem is still relatively easy to address in comparison to other anthropogenic problems, by, for example, reducing our reliance on artificial light or shielding outdoor illumination.

      • So there’s a large increase in insect death during a full moon? I’m calling B.S. The vast majority of the Earth’s surface isn’t artificially lighted at night.

        Come to Alabama and go camping with me. Then come home with me. If you don’t wear insect repellent you will get eaten up in both locations.

  4. Less payload and bigger wings ? What it takes to keep altitude and maneuver out of harm from wind turbines.

  5. While they seem to imply that climate change was a modern phenomenon (at least the phrase), they stopped short of invoking CAGW!

    I wonder what the trend was for the hundred years prior to 1978?

  6. If you already know the problem is climate change, it is easy to find evidence of such. But, these birds are MIGRATORY, which means they live through MANY climates. They move to where the climate is more suitable, since they don’t build houses and streets.
    Attempting to pin bird size changes on climate change is ridiculous, in the extreme. How about the invasive species, like the starlings, which travel in massive flocks and eat all manner of food – insects and seeds and fruit – that native species thrive on. Their FOOD supply is under attack, yet these idiots claim that the change from 1970’s (a cool period) to now, (a warmer period) is the CAUSE of the bird size changes. Isn’t bird size related to food availability? What kind of researchers would leave that very obvious problem out of their prognostications about climate change and bird size.

  7. And the birds in the photo may have smaller bodies and longer wings but they are all dead! Why is he smiling?

    • Good question. Drawers of dead birds is a rather disturbing site. Did they die of natural causes? If not, what killed them? Inquiring minds want to know.

    • Perhaps the body size is smaller in order to fit into the drawers.

      Bigger drawers, bigger birds.

      Send funding for further study.

  8. My bullshit detector just went haywire.

    The tiny variations (a couple of grams) over 40 years?

    And the natural variation of temperature over a day, over a month, over a year is how much?

    Do they predict how long it will take for these little birds to be weightless?

    Or like the legendary Oozlum bird, will they fly round in ever decreasing circles until they disappear up their own arses in a puff of smoke?

    Enquiring minds want to know.

    Send more Grant Money.

    • These birds all were collected after smacking into a building. That suggests that the evolutionary transformation also affected decision making skills along with increased wingspan and others.
      Evolution simply means change and takes many different paths to find one that works. The ones that don’t work, don’t survive.

    • Mark Twain had something to say about extrapolation.

      In the space of one hundred and seventy-six years the Lower Mississippi has shortened itself two hundred and forty-two miles. That is an average of a trifle over one mile and a third per year. Therefore, any calm person, who is not blind or idiotic, can see that in the Old Oolitic Silurian Period, just a million years ago next November, the Lower Mississippi River was upwards of one million three hundred thousand miles long, and stuck out over the Gulf of Mexico like a fishing-rod. And by the same token any person can see that seven hundred and forty-two years from now the Lower Mississippi will be only a mile and three-quarters long, and Cairo and New Orleans will have joined their streets together, and be plodding comfortably along under a single mayor and a mutual board of aldermen. There is something fascinating about science. One gets such wholesale returns of conjecture out of such a trifling investment of fact. link

  9. “The authors of the Ecology Letters paper suggest that the body-size reductions are a response to climate warming and that increased wing length may help offset the body-mass losses.”

    Increased wing length to offset reduced body mass? Oh, really?

    In other news, this study undermines the trope that climate change portends mass extinctions.
    Instead, if their attributions for body changes are correct, the study shows (again,) that species adapt very quickly to incremental environmental changes and therefore, those changes pose less of an existential threat.

    • New species aren’t being formed here…just (very minor) species variations are being selectively expressed for reasons hypothesized but still unknown. It will take a lot more funding $$ than it’s worth to titrate the MAIN factor out of possibly many SIMULTANEOUS factors in the selection of species attributes that are favored in changing circumstances…when more than 1 environmental factor and probably more than 10 environmental factors are changing (amount of food available, types of food available, quality of the food available, numbers of species competing for the food, new species entering regions that compete for food, the amount of “flock mixing” that “mixes” genes within different migratory groups during mating, local rainfall affecting food and growth and food rotting rates, amounts of molds and fungi affecting foods, wind speed averages during migration that greatly affect energy requirements, just how random the “sample bird” selection is – smaller birds might get caught more often) in other words JUST LIKE THE CLIMATE, IT’S TOO COMPLICATED to make simple claims and get confident answers WITHOUT A WHOLE LOT OF EFFORT that requires time and money. Obviously more $$ than it could ever be worth to find out why an average bird weighs 1.3 g more and has a wingspan 6mm wider than it used to.

      I’d need to study the statistics involved in this study to put a grade on their claims. Lots of interlocking variables are obviously involved here…the main one OBVIOUSLY being the need to find anything that could possibly be caused by 1/3 of a degree warming over several decades for species that migrate through regions that typically differ by 10’s of degrees.

      In other words…this is mostly wasting my $$ to provide another climare propaganda story.

    • “Increased wing length to offset reduced body mass? Oh, really?”

      Indeed! I suspect that the researchers don’t know much about aerodynamics.

  10. “liked” cos it made me laugh
    lighter weight due to less bugs and how many that hit windows would be juvelines over wiser adults I wonder?
    understand limited area confined changes happening soonish die to environment
    but not in a spot where their options for breeding and habitat are fairly wide
    bloody sparrows getting smaller? aerial vermin like them never go without a feed!
    and the ones the feral cats never catch are them and starlings!
    near impossible to skittle em while driving as well.

  11. https://www.discovermagazine.com/planet-earth/climate-change-could-be-making-birds-smaller
    From a volunteer collector–
    “I’m a better data generator than I am a data analyzer,” adds Willard. “And the changes were small enough that it’s not like we could see them……The scientists found that the species with the fastest decline in body size also had the speediest gains in wingspan over the 40-year timeframe.” Percentage, variation, changes by date, etc.?
    https://onlinelibrary.wiley.com/doi/abs/10.1111/ele.13434

    Accord to the Ecology Letters website it took only two days to accept the paper. Paywall, abstract not clear, but if all birds were collected from buildings, maybe other possibilities exist. “It’ll be up to people’s imaginations to use this dataset in ways that we haven’t even thought of yet.” What where the results from body mass? They have a reasonable hypothesis, what are others? Their percentages of changes are very small, therefore easily suspect.

    Did not know that you could measure to that precision, but then I just saw a weather forecast with wind speeds to two decimal places. Be careful what you advertise. Mortality numbers of migratory birds crossing the Gulf of Mexico is probably unknown, but significant. They land on oil platforms, boats, even show up in shark stomachs.

    • I was wrong, it was fog visibility, maybe a clerical error, makes sense less than mile, but not more. I got to thinking that while favoring hypotheses is nothing new, I ran across this paper not long ago about HARKING, Hypothesis after results known. In this case, it was perhaps before. Authors maybe never had their term paper title crossed out. Common, long ago warned error about confusing statistical with biological significance. Never measured birds, but lots of marine animals, even had the device they showed to measure small bones, not for the decimals, but more accurate. Such apparently claimed precision detracts from what might be a good study.

  12. Notice he used percentages instead of measurements.

    Those birds with 10 cm wing spans increasing 1.3\% etc.
    1.3 millimeters, but he found it, what utter bollocks.

    • Very far afield for me, but bird wings have flexible joints and the feathers ‘feather out’. I wonder how the measuring protocol can be standardized to less than mm?

  13. More junk science: the findings come from a dataset of some 70,000 birds that died when they collided with buildings, to be truly representative they also need to have 70,000 birds that didn’t collide with buildings.

    Q:
    Are the dead ones a mutation & hitting buildings because the wings are too long ?
    Or are they malnourished leading to poor eyesight ?
    or, Is it survival of the fittest ? read Darwin.
    Which direction were they flying when they died – from hot to cold or vice-versa ?**

    “Both changes appear to be responses to a warming climate.”
    **In 1847 Carl Bergmann, a German biologist knew that Birds and mammals in cold regions were observed to be bulkier than individuals of the same species in warm regions.

    I’m an engineer not a biologist & I knew that !!!

    • You hit on their underlying assumption. Why did they assume that the collection of dead birds which collided with buildings in Chicago is a representative sample of a species? They never considered the hypothesis that lighter birds with larger wings could be more likely to collide with buildings. They claim statistical significance but what is the standard deviation of their data? What is their measurement error?

    • Christmas is coming, the geese are getting fat,
      Please to put a penny in an old man’s hat;
      If you haven’t got a penny a ha’penny* will do,
      If you haven’t got a ha’penny, God bless you.

  14. Many things have changed around Chicago in the last 40 years. To reach the conclusions that global warming shrinks bird weights, increases bird wing lengths, and decreases bird leg lengths, requires some assumptions:

    ● that the downtown Chicago location is a typical bird habitat

    ● that the Chicago area hasn’t changed in 40 years in any way which could affect birds

    ● that 40 years of having bird populations culled by flying into windows hasn’t exerted any evolutionary pressure on them

    There’s no clear causal mechanism which would lead us to predict that global warming would shrink bird weights, increases bird wing lengths, and decreases bird leg lengths. So to credibly attribute those changes in birds which flew into a particular building in a particular city, to global warming, requires ruling out other factors which could, just as credibly, affect birds. Obviously that wasn’t done.

    The amount of global warming which has occurred is minute: 1 °C is equivalent to a change in latitude of perhaps 60 miles. Are the birds 60 miles south of where you live smaller than the birds in your yard? Do they have longer wings, and shorter legs?

    Many, many things have changed in 40 years. Nearby trees have grown, or died. The Field Museum has probably switched to LED lighting, as have other surrounding (“competing”) buildings, and streetlights. The mix of crops grown in surrounding rural Illinois has probably changed, as have the pesticides used on them, and the tilling practices. Air pollution has been abated. Airplane traffic has changed.

    Any of those things are at least as plausible as “global warming,” as candidates for attribution of the minuscule changes observed.

    The attribution of any and every observed change, in just about anything you can imagine, to manmade climate change, is one of the most strikingly unscientific aspects of climate hysteria.

    • Good comments … these authors obviously set out to blame global warming for whatever change they discovered over what is a very short period of time (40 years) in evolutionary timeframes. They ignored dozens if not hundreds of other potential “causes” of changes in avian physiology over time.

      Besides, are birds happier with smaller bodies and longer wings, or vice versa? Sounds like we should empanel a group of expert avian psychologists and avian sociologists.

    • Dave, what has changed is more CO2…..greening….more food

      Migratory birds can be smaller, find more food along the way and when they get there, don’t need to store as much energy, and can have longer wings to glide better

      • Perhaps the average size of birds killing themselves by collision with museum windows is smaller now because bigger birds fly higher, and some of the larger birds are being killed by wind turbines.

        Perhaps the adoption of low-till & no-till agricultural practices has made it harder for bird species that eat bugs turned up in fields to get enough to eat.

        Perhaps the use of Roundup-Ready crops and glyphosate, or of increasing acreage devoted to corn ethanol production (to “fight climate change”), has reduced the availability of weed seeds eaten by some bird species, resulting in leaner birds.

        Perhaps the population of “outdoor cats” (feral and non-feral) has changed, with resulting changes in bird populations.

        Perhaps the spread of invasive mussels in Lake Michigan has changed the food chain in that region in ways that have affected bird diets.

        Perhaps the pressure on bat populations, due to the spread of “white-nose syndrome” disease, has had secondary effects on insect and bird populations.

        https://www.youtube.com/watch?v=iSd6-EvBgN4

        We could come up with such “perhapses” all day.

        • Too true Dave.

          One wonders whether these geniuses checked with dead birds hitting buildings in New York, perhaps.

          Or maybe cast the net a little wider.
          Spanish and Italian hunters love to shoot migrating song birds. And eat them. Tasty morsels.
          Have they been grousing that their favourite snacks seem a little, err, diminished?

          And that’s yet another ‘perhaps’.

          (I guess every regular on here could dream up a dozen ‘perhapses’ in five minutes – despite these geniuses only thinking of the one in their heads when they started.)

          Perhaps the ‘volunteer corpse collectors’ just trousered the plumper specimens…

  15. This just such BS.

    The idea that a 1 degree rise in globally averaged temperatures precipitates a noticeable evolutionary change in just 4 decades is ridiculous.

    • Indeed. What were the various climate changes for all the habitats through which they migrated and lived? some places could have been cooler. But, of course, they said “climate change”, which could be literally anything.

      • Indeed. These bird species all survived multiple glaciation and deglaciation cycles, which saw the site of the Field Museum (and the rest of Chicago) alternately buried beneath a mile or so of ice, and then uncovered again, repeatedly.

        We also know from ice core isotope analyses that over the last 100,000 years the Earth has experienced dozens of natural “Dansgaard-Oeschger events” in which temperatures changed at rates as rapid as several degrees per decade.

        EXCERPTS FROM THE LATTER SOURCE:

        “…a jump in Greenland’s air temperatures of 10-15 degrees (C) in just a few decades beginning about 14,700 years ago.” …
        [and] “… about 12,800 years ago … abrupt cooling of some 5-9 degrees (C), also over a matter of decades.”
        (Caveat: Greenland’s temperature changes tend, in general, to be at least twice as rapid as the global average trend, due to “Arctic amplification.”)

        Those temperature changes were much, much larger and more rapid than anything caused by mankind, and they often persisted for thousands of years — and nobody knows with certainty why they occurred. (Fortunately, mankind, corals, polar bears, and nearly every other existing species of animal and plant, including all those bird species, survived all those large, abrupt temperature changes, so there’s no reason to fear that the current slight warming trend will be catastrophic for them.)

  16. How does anyone know that the specimens which were used as “controls” were normal-sized in their day? Seems likely to me that the museum would collect the “best” specimens, and those frequently are perceived to be the largest ones.

  17. I observe that in temperate zones migratory individuals are smaller than resident individuals of the same species.

    Can I get a grant?

  18. Well, it’s a good thing they weren’t after the goldfinches in my sunflowers last summer. Making pigs of themselves, they were, while they were changing from the yellow (male) feathers to the green seasonal travel pattern.
    If the measurements are as small as the article indicates, did it NOT occur to these people that maybe the birds that slammed into Chicago’s skyscrapers were not fully-grown adult birds? No, I guess not. Smaller body size may only mean less stored fat for migration, and there is no indication in that article that the time of body-slamming a building was noted. That does make a difference.

    Since the sparrows stick around all winter (I feed them, so I have my own bird count), I see fat little birds that may or may not be fully mature adults, ready for a few more seasons. I see the newly-fledged youngsters show up with a parent bird at my feeding station and their wings are longer than their bodies because they are now flying, even if they are not fully mature. The birds’ age has something to do with that, which it seems those people at the Field Museum failed to take into account.

    Flawed study, and the guy in the photo looks a bit too smug to me. Also, since there’s no recorded age on these critters (yeah, how would they do that, anyway, when they don’t observe fledglings and parents?), the real data that they came up with is flawed, in my view, because they are sitting at desks, measuring dead birds instead of observing the live critters the way the rest of us birders do.

  19. I see these are dead birds due to collisions with buildings. I missed that in my earlier comment as to why are they dead. So, these are the stupid birds…..

    This study started BEFORE climate change was a cash cow. I would imagine the early reason for the study was simply study of migratory birds and their changes. Decades ago, I watched a special on birds in the Galapagos and how their beak size changed as seed size changed. It was a special supporting Darwin. Now, all specials and study do NOT support Darwin but instead claim something unnatural is occurring and we, either made by God or aliens from another planet, are causing it. We CANNOT be part of evolution under that scenario or we would not be unnatural. It is interesting what climate science necessitated as reality and how they killed Darwin so effectively.

  20. Several points here:

    1) Correlation is not causation.

    2) The data set is of birds killed by flying into buildings … not all birds .. the authors did nothing to discuss how the birds that are more likely to be killed by flying into buildings might have different characteristics that actually amount to causation.

    3) The authors are merely ASSERTING a climate causation.

    4) The authors did not postulate how a warming climate might result in changes in avian body sizes .. i.e., what actual physical manipulation of the body results from warmer temperatures.

    5) The authors fail to mention that when the climate was much warmer than it is today, birds were also much bigger. They were called “dinosaurs” – today’s birds are successors to dinosaurs, the only major difference, aside from smaller size (???????) being that today’s birds are warm blooded, and therefore natural selection favored them over cold blooded creatures in a cooling climate.

    Etc. etc. etc.

    Very poor study – typical climate alarmist BS, by the way. A bit of data, and a huge amount of assertion and false claims of causality.

    • Indeed. If you want to know how 1°C of warming affects birds of a particular species, then you could simply compare the birds at two locations which have a 1°C difference between their average temperatures (typically about 60 miles apart).

      Of course that would be silly because everybody knows there’s no measurable difference between bird populations of a single species that near to each other. But it is no more silly than this “study.”

      The Audubon Society has a page about Cardinals, here:
      https://www.audubon.org/field-guide/bird/northern-cardinal
      Note the map, showing their range: from southern Canada to the middle of Mexico.

      Here’s a gardeners’ growing zone chart, where you can see that that corresponds to a climate difference of at least 50°F = 28°C:

      https://sealevel.info/zones-2015_700x420.png

      Now, seriously, given that kind of range, how can anyone think that 1°C of warming could be a problem for those birds?

  21. Smaller body, larger wingspan – looks like adaptations to fly fast, change direction quickly, hunt insects in flight. Cf. swifts and swallows. Might be an adaptation to the urban habitat.

  22. cientists have long been speculating about the potential reasons for the declining number of insects and the birds that depend on these critters for their survival, with new research potentially shedding some light on this problem.

    An insect apocalypse with a massive decline in the number of arthropods is underway due to the prevalence of artificial light at night, also known as light pollution, a new study published in the journal Biological Conservation claims.

    Scientists from Tufts University in Massachusetts reviewed the results of more than 200 independent studies to conclude that it is artificial light at night (ALAN) that could be a significant factor driving the so-called insect apocalypse due to its influence on reproductive success, hiding from predators, and the search for food by various insect species, potentially contributing to the loss of about 40% of all species in the next few decades.

    “Artificial light at night impacts nocturnal and diurnal insects through effects on development, movement, foraging, reproduction, and predation risk”, the paper claims.
    “We also emphasise that artificial light at night is not merely a subcategory of urbanisation. The ecological consequences of light pollution are not limited to urban and suburban centres, but widespread along roadways and around protected areas”, researchers added.

    In an Oct. 7, 2015, photo, a bucket of crickets are seen in the Detroit Zoo’s cricket breeding area in Royal Oak, Mich.
    © AP PHOTO / CARLOS OSORIO
    Insects Are Dying Off in Europe in Apocalyptic Wildlife Omen, New Study Suggests
    The declining number of insects, in turn, leads to disruptions in the food chain and global ecosystem by causing a significant reduction in the number of birds. So, researchers believe that the loss of around 3 billion birds in the US and Canada in the last 50 years is likely to be directly related to the declining number of insects.
    The study concludes by saying that this problem is still relatively easy to address in comparison to other anthropogenic problems, by, for example, reducing our reliance on artificial light or shielding outdoor illumination.

  23. Very far afield for me, but bird wings have flexible joints and the feathers ‘feather out’. I wonder how the measuring protocol can be standardized to less than mm?

    Were all measurements made at the time of collection across all the years, or were they made prior to writing the paper? What are the effects of laying around in drawers for extended time periods.

    Existence of evidence of potential is not existence of evidence of outcome. Or Causality.

  24. This has to be as silly as david Attenborough lying about walruses jumping of cliffs because of “climate change” or polar bears hunting whales, due to “climate change” 😐 Or how about a small part of victoria falls which dries up every year and has done so for many years, suddenly its “climate change” 😐 I’ve learnt from this site alone the mass lying the greens are doing, especially the Imaq ice melt….. The “We need 28 Billion Dollars Asap” U.N. is pure cancer, It seems they didn’t like traveling in non first class seats, and the 5pm Diplomats Bar closing time is interfering with them saving the planet (again) 😐

  25. It’s 9 degrees here in Massachusetts at 9am on Sunday. But of course it’s warming everywhere else but where we are.

  26. Has nothing to do with “warming”.

    When you want a given technology of slow aircraft to fly farther on less fuel at a higher altitude you narrow the body and lengthen the wing.

    The U-2 is a great example.

    Basically the birds have had to fly progressively longer stretches between feedings on their migration path because of monoculture farming and urbanization. It has ZERO to do with a degree of warming.

  27. If those that measured the birds knew the year each specimen died then the study is not valid due the potential for bias in measurements. How many measurers were there and were they calibrated with each other?

  28. Take this study at face value. It’s data starts in 1978(New ice Age in the 70’s) to now( the hottest decade ever).
    What does this have to do with CO2?

  29. OK WAIT…

    Had my coffee now.

    So their “sample” was specifically birds that did not have the aerodynamic/neurological properties necessary to avoid or survive striking a building. This sounds more like a mechanical engineering and/or toxicity study than anything to do with temperature.

    Any 12 year old or Janitor would have refused to publish the paper.

    100% of their sample is ANECDOTAL in nature and literally taken out-of-context.

  30. I could make the same claim around the teeth in large cats. None have had teeth as large as the sabertooth cat, therefore, I’m a warming world their teeth will continue to shrink.

  31. Shorter, lighter body, longer wings = improved flight adaptation; but instead of celebrating this as a demonstration that natural selection can continue to improve the adaptability of species, we are told this is a climate catastrophe. Another example of how the politicization of university research has destroy science.

  32. A couple of observations:
    1. Lower body mass and larger wing area are an adaptation to lower air density from warmer air. Simple evolution, not necessarily a bad thing, or
    2. Since we don’t have a representative sampling of birds that didn’t fly into buildings and die, we can’t assume
    that it’s just a demonstration that dumber birds are flying into buildings. Dumber and smaller birds.

  33. Let’s do some math. 70,000 birds/52 species is 1346 samples/species over 38 years equals 35 data points per year per species on average. (I realize this is a couple of crude assumption. This is a thought experiment.) Now according to Wikipedia the common starling “The common starling is 19–23 cm (7.5–9.1 in) long, with a wingspan of 31–44 cm (12–17 in).” So we have a 4 cm variation for length and 13cm variation in wingspan. They are claiming 1-2% change. That’s a difference millimetres.

    Was there anything like an error bar? I have to wonder how is a 1.3% change can be statistically significant over that range? How much error range in their method of measurement do they get? Did they blind the researcher to make sure the researcher didn’t know what side of the data the birds were on? Did they have the same researcher measure all the birds over all 38 years? Did they control for desiccation over the years if they did?

    There is one good thing about this study. This is a superb paper for ensuring more funding while eager volunteers feel they are actually doing something. I’ll give them that.

  34. Bayesian thinking hypothesizes migratory birds showing increasing wing length and decreasing body mass die by hitting buildings in Chicago and that this must be due to a warming environment.

    Karl Popper would have a field day with this one.

  35. “… from 52 species that died when they collided with buildings in Chicago”

    Strewth. As if that’s a properly representative sample of the whole population. Perhaps there’s just more smaller birds in Chicago because humans have created an environment where smaller specimens get to live longer.

    Or perhaps the birds have got more stupid by chattering to climate scientists obsessed with global warming. So stupid that they’re less competent at avoiding large obstacles in their flight path.

  36. So, when temperatures were much warmer millions of years ago- most birds must have been tiny, right?

  37. Amazing-

    Cities can be up to 20 degrees hotter than the surrounding country side and in this hotter micro-climate

    How Wild Animals Are Hacking Life in the City
    Search domain http://www.nationalgeographic.com/news/2016/04/160418-animals-urban-cities-wildlife-science-coyotes/https://www.nationalgeographic.com/news/2016/04/160418-animals-urban-cities-wildlife-science-coyotes/
    Apr 18, 2016″The bird seems to be adapting to urban spaces, and it indicates we can do conservation in cities.”

    wow- species adapt!

  38. As has been pointed out this is a very superficial study at best, and even if the findings are correct- so what? To jump to “climate change ” is sheer stupidity from a science viewpoint- so it’s clearly a study designed to grab funding for the cause of the day

  39. “Since 1978, Field Museum personnel and volunteers have retrieved dead birds that collided with Chicago buildings during spring and fall migrations. For each specimen, multiple body measurements are made.”

    Could it be that the buildings simply acted to filter out the smaller / weaker / young individuals within the populations. With the larger/stronger/older individuals avoiding collisions and thereby not being represented in the measured population?

  40. The changes may be statistically significant, but they aren’t very significant. Less than 2 percent change over 40 years and 1 degree temp change indicates , even if the temps increase 1 1/2 degrees by 2021, the changes in the birds sizes will still be insignificant. No mention of the typical variation in sizes for individuals Meaningless articl, overall

  41. Decline in size would imply a lack of food for growth, which is not shown in warming climates. A greening/warming climate would show an increase in size. Maybe just the dumb birds run in to buildings. Why are we depending on birds that run into buildings and die to be the reflective sample to make a scientific claim?

  42. Oh, here we go. The meat of the story:

    “We had good reason to expect that increasing temperatures would lead to reductions in body size, based on previous studies. The thing that was shocking was how consistent it was. I was incredibly surprised that all of these species are responding in such similar ways,” said study lead author Brian Weeks, an assistant professor at the U-M School for Environment and Sustainability.

    >I was completely surprised our study reflected exactly what we wanted to claim.<

  43. Lots of very negative comments here. Mostly not justified IMHO.

    The study presents new data, and generating and publishing new data is the most important thing that natural sciences can do (and, of course as we know well, the conspicuous absence of new data is what characterises most publications in climate science world, where model output substitutes for data. And where data itself becomes malleable so it can be used in support of pet hypotheses).

    They have a hypothesis based on a correlation of changes in body dimensions with changes in temperature – that warmer climate leads to smaller bodies and longer wings. Natural selection in action. Or could it be epigenetics? I used to make snide comments about epigenetics as just being a 21st century revival of lysenkoism, but it turns out to be a real field of study about how variations in environmental conditions lead to variations in gene expression, which lead to physical variations in the phenotype. Or (as they say) it could be “developmental plasticity” which is a new one on me.

    They also quote “Bergmann’s rule” that birds tend to be smaller in the warmer parts of their habitat. So perhaps their hypothesis should be that “a warmer climate may have caused their entire migratory ranges to move north by an as yet undetermined amount, so birds collected in later years come from warmer parts of those migratory ranges”. Chicago being fixed in space but not necessarily fixed in relation to avian habitat ranges. That alternative hypothesis could be tested by gathering field data (perhaps it has been tested and rejected)

    • Most of the negative comments have to do with the actual failings of studies like this, which are becoming more and more common in science. Mere presentation of the data would have been a great service. Trying to tie it to climate change with no actual causal link and no direct analysis of confounding factors is a *disservice* to science.

      Even Bergmann’s Rule is misapplied. Bergmann’s Rule applies to populations *living* in different temperatures. This simply doesn’t apply to migratory species. You don’t have cold weather geese vs warm weather geese. You don’t have cold weather ducks vs warm weather ducks. And so on.

    • The entire paper is going to be published and all of the details are not available but there was no mention of what should be a standard of any study claiming to be statistically significant such mean, standard deviation, confidence level. That teeny tiny result reported in percentage on what obviously has a large range just screams out for further justification. I once had the audacity to ask on a proclimate change website about where are the error bars on that graph and I got called foul names, accused of being in the pay of big oil and summarily banned from the website. I am thus a little sensitive about small stuff like this.

  44. “Since 1978, Field Museum personnel and volunteers have retrieved dead birds that collided with Chicago buildings during spring and fall migrations. For each specimen, multiple body measurements are made…”

    Well if this is science, it should be equally valid to draw conclusions about all Tesla drivers based on a sample obtained exclusively from those that collided with stationary objects.

  45. The study could just as easily been about the changes in human beings who fell off ladders and concluded that because the size of humans were larger by a barely measurable amount that barely measure able increase in size was due to global warming. I am not a scientist in any way but I suspect that all species if studied closely enough to measure changes so subtle as to not be observable to the naked eye would involve a whole range of reasons why such changes may exist. Perhaps evolution, perhaps random chance, perhaps changes to the gene pool. I am sure that humans are larger than previous generations by a measurable amount yet I can’t imagine that anyone in their right mind would conclude that climate change was the cause ( or even a dominant cause).
    I would need more info to be convinced that such a link may exists.

  46. According to NOAA, since 1901, the average surface temperature across the contiguous 48 states has risen at an average rate of 0.14°F per decade, which equates to 0.014°F per year.

    Songbirds don’t have very long lifespans. The average lifespan of a Red-winged blackbird is 2 years. The average lifespan of an American Robin is 2 years. Some songbirds live slightly longer lives, but if we use 2 years as a reasonable average, then in the course of the bird’s life it experiences an increase in the average temperature of 3 one-hundredths of a degree Fahrenheit. (0.03°F)

    We are being asked to believe that 3 one-hundredths of a degree Fahrenheit average over a 2 year period creates enough biological stress to drive evolutionary processes. Or, that the stress is perhaps not driving evolutionary processes, but instead limiting and diminishing the ability of the birds to grow to full potential.

    No evidence is offered to support why this extremely small change in body size is harmful. If might be harmful or beneficial or completely unimportant. All we get is a linkage to “a warming world” – and we already “know” that all claimed anthropogenic climate change can only lead to negative consequences. Actually, all consequences are not just negative, but catastrophic. Not one – even by lucky chance – is claimed to be beneficial for any lifeform, large or small.

    Furthermore, these songbirds didn’t just appear recently. They have existed for at least several glacial-interglacial cycles. The species have dealt with 100kyr long glacial cycles that were at least 12°F colder in their current range. During the last glacial period, there were at least 25 Dansgaard-Oeschger events where the temperatures increased by more than 10°F in a decade or two. These songbirds also experienced and survived interglacials of 10k-20kyrs that were more than 5°F warmer than today in their current ranges. Climate reconstructions also show that these songbirds experienced warmer periods than today over the past 2k years.

    The conclusion: we have measurements of 70k dead birds, no causal link to anything, no claims as to whether the changes are beneficial or detrimental, and that all too familiar bitter aftertaste from tax-payer funded studies that allow misanthropes to link human activity to a diminished world.

    • The conclusion reached by the authors of this paper is ridiculous. All they have come up with is a very unscientific, leap-of-faith hypothesis. The slight decrease in body weight and increase in wing length, if its real, screams of natural selection alone. Migratory birds with lighter bodies and longer wings will travel much more efficiently for the energy expended, and are thus the best adapted among the whole species population to survive. This is all the authors are seeing in the data.

  47. And where is the discussion on the massive displacement of native flora/fauna with many invasive species.

    Company I worked for took the 40 acres in front of the office plant and training center and planted native grass and flowers as recommended by the university agriculture department. Took over three years to displace all of the invasive plants. When fully restored it was obvious that the fauna numbers had increased. It is clearly obvious that this area is different than the other acerage. When the seeds and the insects attracted by the native plants that birds eat are now longer growing they need to find something else.

  48. Wing length is usually closely connected with migration distance, so the most likely explanation is that the birds are either breeding further north, or wintering further south than before.
    Which could be due to either climate change or changes in land use (e g deforestation in the breeding areas and/or wintering areas).

  49. The problem is not the study, the observations, or necessarily the conclusions (e.g. frame of reference, including period). The problem is the imputed negative connotation to “climate change” forced by sociopolitical adventurism, including: sociopolitical exemptions to favored industries, calls for redistributive change, extrajudicial stalking, legal harassment, bigotry, etc. People are, with cause, progressively skeptical of methods and motives.

  50. It appears that birds are only adapting to adjusted data. When I go to Tony Hellers site and look at temperature data I don’t find any correlation.

    Conclusion: Quit adjusting the data and birds will adapt to the new data record.

  51. This could be another polar bear: correct observation(s), wrong conclusions. The use of correlation can lead to false conclusions in a chaotic (e.g. evolutionary) system. Combined with sociopolitical adventurism, and the responses will become progressively skeptical, even dismissive.

  52. The University of Michigan could probably have found an even bigger and more representative selection of specimens to study, by looking around the bases of Wind-Turbines and under concentrating solar stations. The birds that hit buildings in Chicago, may have been a selection of sillier birds who were not looking where they were going. Those under the renewable choppers were completely taken by surprise.

  53. The birds that moult all feathers in their 1st year essentially end up as adults with the same wing length. It is birds that do not fully moult in their first year & keep some of their immature plumage that have end up with lengthier wings as adults.

    1st winter birds (juveniles) of the same kind that are larger tend to be males. Those males as adults end up larger than their contemporary adult females.

    Point being: I am not sure if the original post’s cited report controlled for variables such as whether comparing the same kind 1st year & 2nd year birds, or whether the same kind if bird comparison accounted for male & female variability.

  54. Bird population decline is based on a variety of factors. How many were chopped up by the installation of 350,000 wind turbines globally over the last four decades? We don’t know because only Hawaii requires bird and bat mortality reporting and any attempt to determine that number will result in wind industry lawsuits to avoid divulging it. We could collect a larger sample size by collecting under the turbines but the wind industry will not allow it. For a discussion of these issues read Kenn Kaufman’s book “A Season on the Wind.”

  55. Sounds like migratory birds can now be the new proxy for earth temperature measurements. When will Michael Mann come out with his latest earth temperature reconstruction?

  56. From the article: “ANN ARBOR–North American migratory birds have been getting smaller over the past four decades, and their wings have gotten a bit longer. Both changes appear to be responses to a warming climate.”

    Well, that can’t be possible because the climate warmed during the 1930’s right up to the same level of warmth as today, and the birds didn’t shrink back then, so it must be something else that is affecting these birds. Perhaps these are adaptions by the birds to dodging windmill blades. 🙂

  57. If the climate is getting warmer then the birds that used to migrate due to cold weather don’t have to migrate. These “scientists” need to ask more outside the CLIMATE CHANGE box

  58. With a million possible causes for a nearly imperceptible change in suicidal Chicago inner city bird BMI, I’ll bet they never seriously considered anything other than globe-a-warmin’.

    • “I’ll bet they never seriously considered anything other than globe-a-warmin’.”

      That’s where the money’s at.

  59. There are a lot more tall buildings in Chicago now than there were a half century ago. Ya think maybe that the fat birds with stubby wings might have gotten killed off from running into them early on?

  60. This is the most ridiculous fear mongering I have yet to see. I monitored bird populations for over 20 years, measurring weights, wing lengths and tarsi lengths. An average sparrow’s tarsus lengths such as a Song Sparrow’s measures about 26 mm. It varies with subspecies. There about 9 subspecies breeding in California alone. According to this bogus report, birds are “shrinking” based on on a 2.4% reduction in the tarsus length. 2.4% 0f 26 mm is about 0.6 mm, typically a measurement that is beyond the precision of the tools employed. The accuracy in measurements of tarsi can easily vary by 1 to 2 mm. Furthermore there is no reason to believe that a bird’s tarsus length would be affected by climate or such a change means bias are shrinking. But the media loves such BS. Much more likely is the fact that subspecies tarsus lengths vary and the reduction determined by averaging many species is an artifact of avearging many species and subspecies migrating through Chicago.

    • Good points. Climate alarmists use temperatures with a +/- 0.5 degC error interval and average them to come up with temperatures supposedly accurate to the hundredth or thousandths of a deg. This is the same idiocy you point out, ” typically a measurement that is beyond the precision of the tools employed.”.

      It makes one wonder exactly what is being taught to students today!

  61. I’ve a bunch of wild birds who accept food from my hand. They thrive, and tend to be larger than other completely wild members of their species.

    The other variable is nesting sites.

    If nesting sites and abundant food are available you get lots of big wild birds.

    So if ‘global warming’ occurs (which so far it seems not to have, at least this century) then birds should do OK. More food. Except that people are taking their nesting sites and building great big fly swats called ‘wind turbines’.

  62. Oh, the buzzards in the sky get so dizzy they can’t fly just from sniffin’ that good old mountain dew.

    Canada geese, snow geese, gray geese, teal, mallard, Ruddy, canvasback, coots, blue heron, Sandhill cranes, and, get this, Whooping cranes. I see them all during the great migration of avian species escaping, fleeing, none other than cold weather. The warm is gone, the seasons change, cold forces action. You take flight, a warmer place is the place to be. Thirty below zero has a direct effect on your chances of survival. believe it or not.

    Whooping cranes fly directly above where I am in late September. Less than 500 feet right above my head. They’re out in the creek at times resting up for the next leg of the migratory flight. This year, the number of whoopers observed was twelve, probably were some more, just didn’t see them. They migrate with the Sandhill cranes, both can fly more than a mile high, you’ll see them if you can spot them that far up in the sky. Incredibly smart birds, Whooping cranes and Sandhills both.

    They’ll all be moving on, south is the destination, anywhere away from the cold. It is a natural phenomena, seek warmth, you have to do what keeps you alive. Cold can be a killer. Nunavut is no place to be in January, just the way it is.

    A shortage of western meadowlarks, not that many, but I do hear them during the summer months, they’re not gone. Habitat is going to determine where they go. Urban spaces are not a place for meadowlarks. The word ‘meadow’ is the key word here.

    Upland game, they’re out there, but you can’t hunt them, the numbers are dwindling. Stopped hunting grouse about forty years ago, shot one back in 1980, last one. In the mid-sixties, partridge were everywhere, shooting ducks in a pond. No more, hunted to a threatened population. Doves seem to survive okay. Pheasant numbers remain strong. Don’t hunt them though, could, but don’t. Pigeons are there and can be harvested if I want one or two. Too many hunters, not enough upland game, it will take a toll. The Passenger pigeon wasn’t so lucky.

    Owls are around, bald eagles, red-tail hawks, falcons, kites, gulls, orioles, sparrow, finches, barn swallows, robins, blue jays, all out there. The doggone woodpeckers don’t stop when they are rattling away of some cottonwood branch. Depends upon the time of year. Hummingbirds, check. Usually, hummingbirds and bald eagles hunt in tandem. Just kidding.

    A bird population estimated at 20 billion for the North American continent alone, the estimated number, anyhow. Got to have hatched chicks, you’ll lose a lot of birds if there are no eggs to hatch, doesn’t matter the species.

    All hatched birds will die, don’t need to be chopped out of the sky by some predatory wind turbine. It is not right, an outrage.

    May the Bird of Paradise fly up your nose.

  63. I have a different hypothesis. I think they’ve gotten smaller because of the number of television screens per household, which has exploded since 1979.

  64. It would be interesting to see if the samples from a cold decade (say the 1970s) were any larger than the warmer decades before and after. Bergman’s Law on average size versus average temperature seems to be kicking in awfully fast given the rather marginal change in temps. The pressure to find a climate-related angle on so many scientists makes me a tad skeptical of a significant 2% change when anything less would probably not be publishable.
    Small migratory birds (e.g. warblers) are mostly insectivores. Changes in pesticide use over time make for better feeding and so smaller ( presumably weaker) birds can survive and thus lower the average size.
    There is also the issue of collection uniformity. I saw a report of a similar study comparing carcasses of modern birds to 19th-century museum bird specimens in which the more robust samples were likely selected. Birds who collapse, make navigation errors etc are likely to include sicklier members. If instead, the scientists hit a migrating flock at the same time every year with a random shotgun blast….(not advocating, just saying).

  65. If this is already almost a law in the warmer areas of their habitat, I’m not sure this is any revelation at all.

  66. The assumption that the birds collected after hitting windows in Chicago represent a random sampling of the entire migratory bird population is the major assumption that needs to be tested and tested and tested. As always, lets look at the data, including things like location of collection and the local architecture/geography. Did the numbers suddenly shift when one building was torn down and a new building put up? Have prevailing winds been from a different direction for a few critical years blowing different sized birds off course than in subsequent years? Have changes in windows reflectivity had an affect. I am not an ornithologist, and this took me 15 seconds to come up with. Science is all about trying to destroy your own hypothesis, and being pleasantly surprised, from time to time, when one survives all your attempts to kill it off.

  67. They are just rewording bergmann’s rule with climate change. I learned this rule in my evolutionary biology class when I was working on my PhD in zoology. A recent paper questions this hypothesis and it has some very interesting conclusions. No general relationship between mass and temperature in endothermic species
    Kristina Riemer,1 Robert P Guralnick,2 and Ethan P White1,3. Its on PubMed

    Abstract
    Bergmann’s rule is a widely-accepted biogeographic rule stating that individuals within a species are smaller in warmer environments. While there are many single-species studies and integrative reviews documenting this pattern, a data-intensive approach has not been used yet to determine the generality of this pattern. We assessed the strength and direction of the intraspecific relationship between temperature and individual mass for 952 bird and mammal species. For eighty-seven percent of species, temperature explained less than 10% of variation in mass, and for 79% of species the correlation was not statistically significant. These results suggest that Bergmann’s rule is not general and temperature is not a dominant driver of biogeographic variation in mass. Further understanding of size variation will require integrating multiple processes that influence size. The lack of dominant temperature forcing weakens the justification for the hypothesis that global warming could result in widespread decreases in body size.

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