Two years ago, it was “Study says global warming shrinks birds” now thanks to impressive further study, they’ve discovered it’s “Bigger birds in central California, courtesy of global climate change.“
Can’t they get their story straight? Why don’t they ask Jim Henson Hansen?
From San Francisco State University
Bigger birds in central California, courtesy of global climate change
SAN FRANCISCO — Birds are getting bigger in central California, and that was a big surprise for Rae Goodman and her colleagues.
Goodman uncovered the trend while working as a graduate student for San Francisco State University biologist Gretchen LeBuhn, analyzing data from thousands of birds caught and released each year at two sites near San Francisco Bay and the Point Reyes National Seashore.
The SF State scientists, working with researchers from PRBO Conservation Science and the San Francisco Bay Bird Observatory who collected the data, found that birds’ wings have grown longer and birds are increasing in mass over the last 27 to 40 years.
What’s making the birds bigger? The researchers think that the trend is due to climate change, but their findings put a twist in the usual thinking about climate change and body size. A well-known ecological rule, called Bergmann’s Rule, states that animals tend to be larger at higher latitudes. One reason for this rule might be that larger animals conserve body heat better, allowing them to thrive in the generally colder climate of higher latitudes.
Under this reasoning, some scientists have predicted that animals would get smaller as the Earth has warmed up over the past 100 years. But the study, published in the journal Global Change Biology, suggests that the connection may not be so simple.
Climate change may affect body size in a variety of ways, they note in their paper. For instance, birds might get bigger as they store more fat to ride out severe weather events, which are expected to be more common under global climate change. Climate change could also alter a region’s plant growth, which may eventually lead to changes in a bird’s diet that affect its size.
LeBuhn, an assistant professor of biology, said she was “completely surprised” to find that the central California birds were growing larger over time. “It’s one of those moments where you ask, ‘what’s happening here?'” The results were so unexpected, she said, that the findings made them take a step back and look more closely at how climate change could influence body size.
The bird data come from two long-term “banding stations” in central California, where a wide variety of birds are captured, banded about the leg with an identification tag, and weighed and measured before being released. Many of the same birds were captured each year, allowing the researchers at the sites to build up a unique database that could be used to track changes among the birds over several decades.
The researchers used data from 14,735 individual birds collected from 1971 to 2010 at the Palomarin Field Station, near the southern end of the Point Reyes National Seashore, by researchers from PRBO Conservation Science. Their study also included data on 18,052 birds collected between 1983 and 2009, from the Coyote Creek Field Station at the southern end of the San Francisco Bay by the San Francisco Bay Bird Observatory.
“At the time I started my research, a few studies had looked at body size changes in a few species in Europe and the Middle East, but no one had examined bird body size changes in North America,” said Goodman, who now teaches Biology and Environmental Science at San Francisco’s Jewish Community High School of the Bay.
“We had the good fortune to find an unexpected result — a gem in research science,” she added. “But we were then left with the puzzle of figuring out what was going on.”
After testing and discarding a number of other explanations, Goodman and her colleagues were confident that climate change was behind the longer wings and bigger bodies in most of the birds. The birds may be responding to climate-related changes in plant growth or increased climate variability in central California, the researchers suggest in the paper.
“The fingerprint of climate change is showing up in many of our ecosystems,” explains Nat Seavy, research director for the Central Coast at PRBO Conservation Science. “The challenge is to use the long-term data we’ve been collecting to understand how, where and why these changes are occurring.”
The findings offer a glimpse at the potent effects of climate change across a wide range of species, LeBuhn said. “Even over a pretty short period of time, we’ve documented changes in important traits like body size, where we don’t expect to see much flexibility.”
“But in some ways,” she added, “it gave me a little more hope that these birds are able to respond — hopefully in time — to changes in climate.”
“Although it is encouraging that species are changing in response to climate change,” said Seavy, “it is also troubling that environmental stressors are pushing and pulling on species in diverse ways…What will happen to our ecosystems as some species get larger and others get smaller? We need long-term monitoring to help us understand the impact of these changes.”
“Avian body size changes and climate change: warming or increasing variability?” appeared online Oct. 12, 2011, published by Global Change Biology. http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2486.2011.02538.x/full
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Right. The birds anticipate the more frequent severe weather events that have yet to materialize, because that is how evolution works. Of course, if we lived in harmony with Nature, just like the birds do, then we would just know, too, what climate change will bring, and there would be no more pesky bickering and [snip].
But weren’t frogs getting samller just last week?
“We need long-term monitoring to help us understand the impact of these changes”
Translation; “We need more dollars!!”
To borrow from Twain, “Wholesale return of conjecture for such a trifling investment of fact.”
As I read the article, due to MMGW, birds will get bigger when they don’t get smalle if they don’t stay the same, but some may get bigger and smaller. And they were surprised by this result!
In the UK great tits adjust their weight depending on how many predators (mainly sparrowhawks) are around. My guess is that all the fast falcons and hawks in LaLa… sorry, California are being mashed by the windmills and the larger chicks, clumsier and slower flyers when just fledged and thus normally gobbled up, are now growing to adult size.
Or something.
JF
Just use your imagination guys — and get a grip, please.
Birds have wings so that they may travel to their preferred climate, mostly following their food sources.
It is called migration.
The birds will be fine, as long as they find enough to eat.
This is all bird-brained. There is no discussion of statistical significance. Maybe its in the detailed paper. But in any case, why jump immediately to climate change as the cause?
I guess it could be possible that some birds grow larger as they age and with more food and good conditions, living longer equals larger birds. Of course, I am not qualified to make such wild speculation:-)
John Phillips:
Climate Change causes everything.
Potholes in the road, increases in taxation, degredation of roofing tiles, everything.
I liked the part about how they looked at several potential causes and discarded them …
… leaving “It’s climate change.” as the obvious answer. I also noticed the same thing Michael Plamer did – the amazing ability of birds to anticipate events and start to compensate for them before they arrive. Gives a whole new meaning to the term bird brained.
All they needed to do was read:
http://green.blogs.nytimes.com/2011/10/16/climate-change-is-shrinking-species-research-suggests/
We all know that climate change makes things hotter, and colder…bigger, and smaller. Climate change also explains conflicting studies and theories.
It has been my impression that almost all global warming studies are either models attempting to prove that yes the earth is heating up and man is responsible or yes the earth is heating up and this is how it will damage, change or eliminate life as we know it.
Wouldn’t it make sense to state clearly and unequivocally that these strategies are not acceptable and prove nothing. So if the above methods aren’t cutting it what kind of study would? The key thought here is what would work, what would convince the majority of skeptics. Has anyone said this is the only style of study that would really prove once and for all that global warming is catastrophic and yes man is responsible. Why wouldn’t it make sense to challenge the best of the best on the other side tell them here are the parameters, show your work and let’s talk.
Bob
diet is the biggest decider of what size the bird will become.
Different diets favor different gut sizes, a change in the types of crops grown will impose a selection pressure on the species.
With some diets small birds do well and others, larger ones.
In the last 50 years I have gone from 130 pounds to 230 because my “climate’ changed. Why can’t the birds?
“After testing and discarding a number of other
explanationsgrant applications, Goodman and her colleagues were confident thatclimate change wasAGW grant applications were behind the longer wings and bigger bodies in most of the birds. The birds may be responding toclimategrant-related changes inplantAGW grant growth or increasedclimate variabilitygrant variability in central California, the researchers suggest in the paper.”“The fingerprint of
climate changeAGW grants is showing up in many of our ecosystems,” explains Nat Seavy, research director for the Central Coast at PRBO Conservation Science. “The challenge is to use the long-termdatagrants we’ve been collecting to understand how, where and why these changes are occurring.”Its a reminder that despite everything that has happened the AGW funding bucket is still large and well filled and there are still plenty of people looking to get their snouts in it . There should actual be award for research that makes the silliest link to AGW, as there would be quite a few contenders for this ‘honor’ .
I wonder if the changes in the food crops being planted that have taken place in the past 27 to 40 years may have something to do with the noted changes, better grains, more resistant to disease, more nutritious, more abundantly found, could not possibly i guess result in bigger birds, more birds, bigger rats, mice, voles and other prey animals for the carnivorous birds to eat … Nah, it is impossible that could explain this phenomenon even in part.
There is a Medieval look to the approach that wants everything to be explained via global warming. Like the vapours that were responsible for all ills in the Middle Ages. It is not science, but it is kind of cute. Everyone can join the conversation and be an expert.
Julian Flood said ;
“La La… sorry, California”
La La Land. Very good. Excellent in fact.
I’d love to see a good statistician get ahold of this one – McKitrick maybe? While 14,735 birds sounds like a LOT of birds, once you divide by 39 years over which they were caught, that’s all of 377 birds per year – of many different species. The 18K birds over 29 years is a bit better – maybe.
So, how many birds of each species were caught each year? Can they tell if the bird isn’t fully mature and may not have reached it’s full size yet, both in terms of wingspan and separately weight? If yes, were those not fully mature for both aspects eliminated from the count? If no, were enough of each species caught to be able to statistically overcome the issue of immature birds being counted? Next, how did they account for natural variation in levels of food available for each species? Most animals have a cycle where for some years the species flourishes, then for some years they don’t – all of which has a knock on effect on anything that the species either preys on, or is preyed on by – and vice versa.
So it sure would be interesting to know just how well they actually accounted for various factors such as these – and to have a really good statistician then evaluate the whole thing as broken down by someone who knows those various factors, and see if there was actually enough to provide statistical significance. (I sure wish research papers weren’t paywalled, so it was easy to at least take a quick look at basic scientific methods issues associated with the research. Ah well, so it goes.)
What a big step in evolution!
Frogs getting smaller, so they can hide better from bigger birds!
Why don’t those $&%#* “scientists” simply say, “We need more $$$ funding!”?
Global warming isn’t causing birds to grow, it’s causing rulers to shrink.
We’re doooomed!!!
Now we have “obese” birds. That does it. We’ll have to shut down all the fast food joint in California.
I just can’t believe the crap that passes as science these days. AGW has polluted a lot of scientists minds. Evolutionary biology was my study at university, specifically phylogenetics. There is NO WAY these guys can know what the selection pressures are. There are thousands of factors, let alone human caused selection pressures. Did the Galapagos 30 year study not have any impact on these scientists? CHANGE HAPPENS!!! Geeze.
“What’s making the birds bigger?”
Standing a lot closer will make them bigger.