Hopefulness Despite 2.9 Billion Lost Birds

Guest Post by Jim Steele

What’s Natural

In 2019 bird researchers published Rosenberg et al “Decline of the North American Avifauna”, reporting a decline in 57% of the bird species. They estimated a net loss of nearly 2.9 billion birds since 1970, and urged us to remedy the threats, claiming all were “exacerbated by climate change”, and we must stave off the “potential collapse of the continental avifauna.” Months before publication the researchers had organize and extensive media campaign. Typical doomsday media like the New York Times piled on with “Birds Are Vanishing From North America” and Scientific American wrote, “Silent Skies: Billions of North American Birds Have Vanished.”

As I have now been sheltering in place, I finally had ample time to thoroughly peruse Rosenberg’s study. I had a very personal interest in it, having professionally studied bird populations for over 20 years and had worked to restore their habitat. I also had conducted 20 years of surveys which were part of the study’s database. Carefully looking at their data, a far more optimistic perspective is needed. So here I join a chorus of other ecologists, as reported in Slate, that “There Is No Impending Bird Apocalypse”. As one ecologist wrote, it’s “not what’s really happening. I think it hurts the credibility of scientists.”

First consider since 1970 many species previously considered endangered such as pelicans, bald eagle, peregrine falcon, trumpeter swan, and whooping crane have been increasing due to enlightened management. Despite being hunted, ducks and geese increased by 54%. Secondly, just 12 of the 303 declining species account for the loss of 1.4 billion birds, and counterintuitively their decline is not worrisome.

Three introduced species – house sparrows, starlings and pigeons – account for nearly one half billion lost birds. These birds were pre-adapted to human habitat and are considered pests that carry disease and tarnish buildings and cars with their droppings. Across America, companies like Bird-B-Gone are hired to remove these foreign bird pests. Furthermore, starlings compete with native birds like bluebirds and flickers for nesting cavities, contributing to native bird declines. The removal of starlings is not an omen of an “avifauna collapse”, but good news for native birds.

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When European colonists cleared forests to create pastures and farmland or provide wood for heating, open-habitat species “unnaturally” increased. Previously confined to the Great Plains, brown‑headed cowbirds quickly invaded the newly opened habitat. Unfortunately, cowbirds parasitize other species by laying its eggs in their nests. A cowbird hatchling then pushes out all other nestlings, killing the parasitized species’ next generation. The loss of 40 million cowbirds only benefits our “continental avifauna”.

Several bird species had evolved to colonize forest openings naturally produced by fire, or floods or high winds. Those species “unnaturally” boomed when 50% to 80% of northeastern United States became de-forested by 1900. Still, eastern trees will reclaim a forest opening within 20 years, so open habitat species require a constant supply of forest openings. However as marginal farms and pastures were abandoned, fires were suppressed and logging reduced, forests increasingly reclaimed those openings. With a 50% decline in forest openings, their bird species also declined; now approaching pre-colonial numbers. Accordingly, birds of the expanding forest interior like woodpeckers are now increasing.

White-throated Sparrows and Dark-eyed Juncos quickly colonize forest openings but then disappear within a few years as the forest recovers. Those 2 species alone accounted for the loss of another quarter of a billion birds; not because of an ecosystem collapse, but because forests were reclaiming human altered habitat. Nonetheless those species are still 400 million strong, and juncos remain abundant in the open habitat maintained by suburban back yards. If environmentalists want to reclaim the abundance of their boom years, they must manage forest openings with logging or prescribed burns.

Insect outbreaks also create forest openings. For hundreds of years forests across Canada and northeastern US have been decimated every few decades by spruce bud worm eruptions. So, forest managers now spray to limit further outbreaks. Today there are an estimated 111 million living Tennessee Warblers that have specialized to feed on spruce bud worms. But the warbler’s numbers have declined by 80 million because insect outbreaks are more controlled. Still they have never been threatened with extinction. Conservationists must determine what is a reasonable warbler abundance while still protecting forests from devastating insect infestations.

The grassland biome accounted for the greatest declines, about 700 million birds. Indeed, natural grasslands had been greatly reduced by centuries of expanding agriculture and grazing. But in recent times more efficient agriculture has allowed more land to revert to “natural” states. However fossil fuel fears reversed that trend. In 2005 federal fuel policies began instituting subsidies to encourage biofuel production. As a result, 17 million more acres of grassland have been converted to corn fields for ethanol since 2006.

Although still very abundant, just 3 species account for the loss of 400 million grassland birds: Horned Larks, Savannah Sparrows and Grasshopper Sparrows. Horned Larks alone accounted for 182 million fewer birds due to a loss of very short grass habitats with some bare ground. To increase their numbers, studies show more grazing, mowing or burning will increase their preferred habitat.

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It must be emphasized that the reported cumulative loss of 2.9 billion birds since 1970, does not signify ecosystem collapses. But there are some legitimate concerns such as maintaining wetlands. And there are some serious human-caused problems we need to remedy to increase struggling bird populations. It is estimated that cats kill between 1 to 3 billion birds each year. Up to 1 billion birds each year die by crashing into the illusions created by window reflections. Collisions with cars and trucks likely kill 89 to 350 million birds a year. Instead of fearmongering ecosystem collapse, our avifauna would best be served by addressing those problems.

Questioning Bird Models

Population estimates for most land birds are based on data from the US Geological Surveys Breeding Bird Surveys (BBS). I conducted 2 BBS surveys on the Tahoe National Forest for 20 years. Each survey route consists of 50 stops, each a half‑mile apart. At each stop for a period of just 3 minutes, I would record all observed birds, the overwhelming majority of which are heard but not seen. Many birds can be missed in such a short time, but the BBS designers decided a 3-minute observation time allowed the day’s survey to cover more habitat. Each year on about the same date, the BBS survey was repeated.

Each BBS route surveys perhaps 1% the region’s landscape. To estimate each species’ population for the whole region, the survey’s observations are extrapolated and modeled. However, models rely on several assumptions and adjustments, and those assumptions that can inflate final estimates. For example, in 2004 researchers estimated there were 6,500,000 Rufous Hummingbirds. By 2017, researchers estimated there were now 21,690,000. But that larger population cannot be deemed a conservation success. That tripling of abundance was mostly due to new adjustments.

Because singing males account for most observations, the number of observed birds is doubled to account for an unobserved female that is most likely nearby. Furthermore, it is assumed different species are more readily detected than others. The models assume that each stop will account for all the birds within a 400‑meter radius. Because a crow is readily detected over that distance, no adjustments are made to the number of observed crows. But hummingbirds are not so easily detected. The earlier surveys assumed a hummingbird could only be detected if it was within an 80‑meter radius. So, to standardize the observations to an area with a 400‑meter radius, observations were multiplied by 25. Recent survey models now assume hummingbirds can only be detected within 50 meters, so their observations are now adjusted by multiplying by 64.

Thus, depending on their detection adjustments, one real observation could generate 50 or 128 virtual hummingbirds. That number is further scaled up to account for the time‑of‑day effects and the likely number of birds in the region’s un-surveyed landscapes.

Setting aside assumptions about the regional homogeneity of birds’ habitat, one very real problem with these adjustments that has yet to be addressed. If one bird is no longer observed at a roadside stop, the model assumes that the other 127 virtual birds also died.

Survey routes are done along roadsides and up to 340 million birds are killed by vehicles each year. Many sparrows and warblers are ground nesters and will fly low to the ground. Many seed eating birds like finches will congregate along a roadside to ingest the small gravel needed to internally grind their seeds. Every year I watched a small flock of Evening Grosbeaks ingesting gravel from the shoulder of a country road, get picked off one by one by passing cars. Roadside vegetation often differs from off-road vegetation. Roads initially create openings that are suitable for one species but are gradually grown over during the lifetime of a survey to become unsuitable habitat. So, it should never be assumed that the loss of roadside observations represents a decline for the whole region.

The larger the models’ detectability adjustments are for a given species, the greater the probability that any declining trend in roadside observations will exaggerate a species population loss for the region. The greatest population losses were modeled for warblers and sparrows and most warbler and sparrow data are adjusted for detectability by multiplying actual observations 4 to 10-fold. It is worth reporting good news from recent studies in National Parks that used a much greater density of observation points and were not confined to roadsides. Their observation points were also much closer together and thus required fewer assumptions and adjustments. Of the 50 species they observed, all but 3 populations were stable.

Pushing a fake crisis, Rosenberg et al argued that declining numbers within a species that is still still very abundant doesn’t mean they are not threatened with a quick collapse. He highlighted the Passenger Pigeon was once one of the most abundant birds in North America and they quickly went extinct by 1914. That doomsday scenario was often repeated by the media. But comparison to the Passenger Pigeon’s demise is a false equivalency. Passenger Pigeons were hunted for food when people were suffering from much greater food insecurity.

Rosenberg et al summarized their study with one sentence: “Cumulative loss of nearly three billion birds since 1970, across most North American biomes, signals a pervasive and ongoing avifaunal crisis.” But it signals no such thing. Wise management will continue. With better accounting of the natural causes of each species declines, plus more accurate modeling, it will be seen that Rosenberg’s “crisis” was just another misleading apocalyptic story that further erodes public trust in us honest environmental scientists.

Jim Steele is director emeritus of the Sierra Nevada Field Campus, SFSU and authored Landscapes and Cycles: An Environmentalist’s Journey to Climate Skepticism.

Contact: naturalclimatechange@earthlink.net

140 thoughts on “Hopefulness Despite 2.9 Billion Lost Birds

  1. Thank you for a most insightful look into a subject I knew almost nothing about.

    Excellent.

    • So you’re saying we must induce a man-made alteration to the ‘climate’ (ie forest management) to get the bird population back to where it once was when man had no real ability to ‘change’ Mother Nature as she did ‘her’ thing (ie forest management via fire)…hmmm interesting hypothesis

      One could call this a win-win – bird-ophiles see increases they desire; the economy gets more lumber (and the green beanies still have their ‘carbon’ sequestered – as if that has any importance)

  2. You forget to add the millions killed by the Bird Choppers aka Wind-Farms…..good article on yet another faux crisis.

  3. To save the birds, we must stop the climate change and to do so, we must build thousands of wind farms !

    /s

    More seriously, very informative. Thanks.

    • I didnt tweet that title

      but I did tweet “Hopefulness Despite 2.9 Billion Lost Birds”.

      9 others including WUWT tweeted my title. But I am surprised to see none of those tweets got a like or retweet except 2 likes for WUWT.

      Do twitter users not care about the birds?

      • Using a similar type of methodology for counting birds, we could measure 1 percent of the oceans and estimate 99 percent to get the global average ocean temperature.

  4. Only the other day I posted on another forum ( in regard to UK bees and flower meadows) that few people understand how much of the ‘natural’ environment is actually the result of human management over 100s, even 1000s of years, and often the declines people are fretting about is just nature restoring the status quo after an unnatural explosion.

  5. Great posting by Jim Steele, who again demonstrates an accurate, observational, truthful approach to reporting natural phenomena. As usual, the truth is a mixture of good and bad, set against the larger background of natural variation. Day 41 of quarantine, protocol changed yesterday so went shopping at supermarket, what a great adventure! Stay sane and safe.

  6. “They estimated a net loss of nearly 2.9 billion birds since 1970, and urged us to remedy the threats, claiming all were “exacerbated by climate change””

    Right on! Great article. I get so tired of seeing ignorant people who want to get their writing published- blame some problem on climate change. Here in Massachusetts- the hysterical climate change crowd want to stop all forestry work because they say it contributes to climate change. When I try to find out if they actually know anything about forestry- and ask them questions- then never respond because they know nothing about the subject- but they have bills filed in the state legislature and they’ve found many legislators supporting them in this ultra politically correct state. No legislator here wants to not support a bill that will help save the climate!

  7. “Three introduced species – house sparrows, starlings and pigeons – account for nearly one half billion lost birds.”

    Coincidentally they were rife in Australia too until the Indian Myna took over-
    https://www.mynabird.com.au/all-about-myna-birds-in-australia
    The pigeons seemed to have fared the best but the spoggies and starlings have virtually disappeared with survival of the fittest invading species.

  8. Jim, as always, you add the needed background granularity re habitat and behavior of individual species to bulk ecological studies, or studies of preselected sites that are presented to be representative of a broader region for a given species (such as your critique of the ‘activist’ Edith Checkerspot (?)butterfly study methodology several years ago). Thank you so much.

    I have long thought that biology has been pretty thoroughly corrupted by anti-human activists since prior to the doomsday books published by practitioners in the1960s -70s. It’s a relief to me that there are the likes of you and Susan Crockford out there battling to keep the science straight. Both of you also do this in such calm civilized class.

  9. Loss of birds? Where?
    They came back on time from their southern vacation spots and ended up at my feeding station, which is simply the railing on my front deck. Two female red-bellied woodpeckers, for starters, then lots of redwinged blackbirds – male & female both, so I’d have to assume mated pairs – and cardinals, juncos, and a few vireos, and grackles, that annoying bird that squawks and hogs the food spots. Since it’s been so chilly here and the bugs weren’t out on time, I have no qualms about putting out food for them, and I don’t care if it’s house sparrows (aka English sparrows), or goldfinches tucking into the sunflower seeds. All I care about is that they’re back and I will have a great spring and summer with my camera – again.

  10. Amateur NYC ornithologist Eugene Schieffelin has a lot for which to answer. He’s the culprit who, in a misguided effort to introduce all birds mentioned by Shakespeare, released 100 starlings in Central Park around 1890. Now they infest the whole country.

    Eurasian collared doves escaped captivity in the Bahamas in 1974, flew to Florida, thence to most of the rest of the US. The first time I heard its loud, obnoxious call, I wondered what an owl was doing out in the daytime.

    The first natural historian to observe that it is cuckoo hatchlings, not their parents, who eject eggs and other hatchlings from the invaded nest was Dr. Edward Jenner, whose cowpox vaccine saved untold millions of lives. He wasn’t believed until avian artist Jemima Blackburn noted the same behavior, prompting Darwin to correct later editions of the Origin.

    • One good thing about the collared dove is that it’s delicious, but I have witnessed their numbers increase in middle America in the last 10 years.

      • True. If my hometown is ever under siege, we won’t starve. Same goes for the flying rats here in Valparaiso.

        Starlings however are entirely redeeming feature-free.

  11. Heard those kind of comments about the spotted owl in the northeast. Timbering was decimating the population. Put millions out of work and years later turned out to be a different predator

      • I think she or he does, Mr. Zorzin.

        In 1996 I wrote a research report for a Portland, Oregon law firm dealing with this issue. My study area was the Columbia River Gorge, including thousands of acres of private and federal forestlands along both Oregon and Washington sides. ***

        There is no demonstrated correlation between owl populations and artificial designations of “critical habitat” zoning. These areas appear far more critical for the survival of agency biologists and ecologists than for owls of any stripe or spot. Predator-prey relationships seem to have much more to do with owl populations than forest structure … .

        (Source: Dr. Bob Zybach, Ph.D., Program Manager, http://www.ORWW.org June 19, 2013

        https://forestpolicypub.com/2013/06/19/spotted-owls-the-spotty-sciences-that-spawned-them-5-questions-2/ )

        And it matters. A lot. As I type this, I can still feel anger welling up inside me. (Yes, I realize that I need to forgive…)

        Efforts to stabilize or increase spotted owls numbers have:

        — cost American taxpayers tens of billions of dollars,
        — been partly responsible for unprecedented numbers of catastrophic wildfires,
        — caused the loss of tens of thousands tax-producing jobs for western US families,
        — created economic hardships for hundreds of rural counties, towns,
        and industries, and
        –indirectly resulted in the deaths of millions of native plants and animals.

        Ibid (readability punctuation added by me).

  12. An ornithologist told me that 10:1 variation in a given species was the norm, not the exception. A cold winter will kill nearly all the wrens for example.

    I found a dead ringed bird once. I phoned it in “Did a cat get it” “No” “Do you have cats?” “Yes” “Are you surea cat didn’t get it?” “Yes. It was just dead with no apparent injuries”

    She didn’t believe me.

    A pigeon fell out of the sky at my feet once. It died.

    A simple calculation will tell you that for most small bird species if 90% didn’t die before nesting and pairing the world would be awash with little birds. Some of these will be brought home by cats as presents.

    What people believe about birds and the reality of birds are two different things…

    There’s one slowly dying in my chimney right now. Where I can’t reach it. If they fall down the open fire flues I can let them out but this is above a woodburner and there is a baffle in the way.

    It will die of thirst in another day and get dried, smoked and burnt next winter.

    • Leo ==> Cats primarily kill birds by eating the young in the nests of ground- and low-nesting birds — they gobble up the hatchlings like kids eat gummy-bears. It is this aspect that is the most damaging to bird populations.

      Really good hunters (we had one that was a champion) will catch the occasional full-grown bird — but generally they are not very efficient at it. If they were, Cat Lovers wouldn’t have to feed feral cats kitty-nibbles.

      • Beautifully expressed essay, thank you Jim Steele.
        From Memory Lane in Australia, one of our cats would bring us half-dead snakes, but did not trouble the birds. In the summertime, one snake every 4-7 days. Not harmless little playthings, but really adult, healthy, deadly venomous types that he would taunt, daring them to strike so he could jump out of the way. Then turn his back on them and smile. At his peak, he would bring them indoors so we had to watch they did not revive a little and be a danger to our young sons. These sons became quite fond of birds as they got older and we used to encourage them to bring them indoors. Geoff S

  13. Thank you very much for this very interesting read.
    I added the paper to my list of questionable climate impact studies with link to this wuwt post.

  14. Wonderful article. I know the media will not update their Original alarmist stories with a more rational analysis so a interested readers could actually inform themselves. Still, I wonder what price doEs Rosenberg, et. al., pay for a shoddy piece of work in their professional circles?

  15. Thanks, that’s a good summary. I’m a wildlife biologist and am appalled at the low level of expertise the profession has sunk to. Way too much activism and model schmodel. As an aside to your analysis, I’d like to look at bird biomass. For example, the explosion of geese, especially Canada geese, suggests to me that bird biomass is much increased from the not so distant past.

  16. Sorry, it’s OT, but a nice finding concerning global temp.:
    Meridional Distributions of Historical Zonal Averages and Their Use to Quantify the Global and Spheroidal Mean Near-Surface Temperature of the Terrestrial Atmosphere by Gerhard Kramm, Martina Berger, Ralph Dlugi, Nicole Mölders

    The zonal averages of temperature (the so-called normal temperatures) for numerous parallels of latitude published between 1852 and 1913 by Dove, Forbes, Ferrel, Spitaler, Batchelder, Arrhenius, von Bezold, Hopfner, von Hann, and Börnstein were used to quantify the global (spherical) and spheroidal mean near-surface temperature of the terrestrial atmosphere. Only the datasets of Dove and Forbes published in the 1850s provided global averages below ⟨T⟩=14˚C,mainly due to the poor coverage of the Southern Hemisphere by observations during that time. The global averages derived from the distributions of normal temperatures published between 1877 and 1913 ranged from ⟨T⟩=14.0˚C (Batchelder) to ⟨T⟩=15.1˚C (Ferrel). The differences between the global and the spheroidal mean near- surface air temperature are marginal. To examine the uncertainty due to interannual variability and different years considered in the historic zonal mean temperature distributions, the historical normal temperatures were perturbed within ±2σ to obtain ensembles of 50 realizations for each dataset. Numerical integrations of the perturbed distributions indicate uncertainties in the global averages in the range of ±0.3˚C to ±0.6˚C and depended on the number of available normal temperatures. Compared to our results, the global mean temperature of ⟨T⟩=15.0˚C published by von Hann in 1897 and von Bezold in 1901 and 1906 is notably too high, while ⟨T⟩=14.4˚C published by von Hann in 1908 seems to be more adequate within the range of uncertainty. The HadCRUT4 record provided ⟨T⟩≅13.7˚C for 1851-1880 and ⟨T⟩=13.6˚C for 1881-1910. The Berkeley record provided ⟨T⟩=13.6˚C and ⟨T⟩≅13.5˚C for these periods, respectively. The NASA GISS record yielded ⟨T⟩=13.6˚C for 1881-1910 as well. These results are notably lower than those based on the historic zonal means. For 1991-2018, the HadCRUT4, Berkeley, and NASA GISS records provided ⟨T⟩=14.4˚C,⟨T⟩=14.5˚C,and ⟨T⟩=14.5˚C,respectively. The comparison of the 1991-2018 globally averaged near-surface temperature with those derived from distributions of zonal temperature averages for numerous parallels of latitude suggests no change for the past 100 years

    I think, a worth read, or a subject for an article ?

  17. Climate change for sure-
    https://www.msn.com/en-au/news/australia/mysterious-virus-causing-lorikeets-to-drop-out-of-the-sky-across-south-east-queensland/ar-BB13snWP
    Clearly affecting their sense of social distancing and they need to flatten the curve.

    How do you like the headline lead in and then you get to read about weather-
    https://www.abc.net.au/news/2020-05-01/bom-says-april-fifth-warmest-on-record-south-east-cold-snap/12206638
    The doomsters never give up.

    • Yup. It’s the coldest ‘warmest ever’ ever!

      Going to get down to 12C at night here in the tropics. Of course, it’s only weather. Everywhere else is sweltering, except where it’s not (which seems to be most places).

  18. I had begun noticing a loss of bird and small animals around my house. First, no robins attempted to build a nest on one of my window sills. Then I saw feathers and a robin’s wing under a big fir in my back yard.

    An unrecognized shrill call of a bird pierced the air. This was the first time I noticed the cause. Two medium sized hawks visit my yard daily now. Often I see them with bits of small birds or rabbits in their clutches. I don’t miss the rabbits whatsoever.

    • We noticed a big drop in bird sounds after a flock of crows moved into a belt of trees along the waterfront. This spring the crows have moved to greener pastures (someone across the bay is feeding them), and the little birds are back.

    • We have a pair of wedge-tailed eagles on our property. They like the hill we have because they can get a good swoop down to give them time to lift (they are slow to rise from low down), and our house & shed rooves provide excellent thermals.

      I wouldn’t let a kitten out with them there, probably a full grown cat is a risk. Luckily our cat earns her keep at night. They even dive bomb our German Shepherd, they are that big. It really annoys her, too!

  19. I conducted 2 BBS surveys on the Tahoe National Forest for 20 years. Each survey route consists of 50 stops, each a half‑mile apart. At each stop for a period of just 3 minutes…

    Hmm. A 25 mile hike over variable terrain, plus 2 1/2 hours of observation. Hope you got time and a half for everything over 8 hours…
    : >)

      • If you got a late start did apply the appropriate TOB adjustment!
        Do I need this /sarc?

        As always, learned something new, thanks.

    • If you read more carefully, you’ll note that the observations are taken along the roadside. I’d speculate that Jim was getting around via car.

      • When I first read the stories of impending doom, I wondered about the sources of the data. Thank you for a very enlightening explanation.

  20. For our region here in Germany around Mainz/Wiesbaden near river Rhine, I cant’t sign a loss of birds, just the opposite.
    Neckband Parakeet (Psittacula krameri) numbers are incresing aswell as Alexander Parakeets (Psittacula eupatria), around 1.500 krameri now and 500 eupatria. The letter is the tall brother of the first one.

    Egyptian goose we have a lot here on the Rhine since some years, also increasing, aswell as cormorant, storks
    and grey herons.

  21. Jim, “Marra and his colleagues extrapolated findings from 21 studies in the U.S. and Europe to come up with an estimate of 30 million to 80 million “unowned” cats and 84 million “owned” cats in the U.S., their kill rates, and other factors leading to bird predation.” this study is just as flawed as so many extrapolated studies. It assumes and even distribution of cat colonies over all the continent that is equivalent to cat colonies from the regions where the 21 studies were done. However that assumption is incorrect. For example cat colonies can not survive in Canada without some humans nearby providing heat and food in winter. We have feral cat colonies in Canada but there is no way they exist in a uniform distribution over the entire prairie. Also individual cats tend to be specialists in what works and is available. Many cats exclusively kill rodents and don’t kill birds. Some well fed cats that are pets of humans do not hunt and they might kill one or two birds in an entire year. The assumption that all cats outside kill X amount of birds/day is just wrong and studies since that 2003 article have show this.

  22. Extremely thoughtful and well presented article. Thank you!

    I am of particular interest in the 3 min surveys. Given the vastness of the area and the current resources, I get the time limit, however what was that 3 minutes based upon?

    For example, survey of sea lions off surfers cove in Santa Cruz, CA–as an undergrad we were told that observations and counts were to be taken no less than 3 days and a period of at least 2 hours per day per student. There were 6 students assigned to that cove to cover (theoretically) 12 hours over 4 days, giving a better observational account of species at surfers cove. That time frame was put into the model to extrapolate as an uncertainty–this was a modeling and population survey exercise to basically hone in how freaking difficult it is. LOL. –Caveat, there were 3 groups at the time, each assigned to an area of observation approximately 2 miles apart.

    Fast forward a few years and during sea turtle beach nesting survey time, we were to locate the actual eggs of every 5th nest. Those nests would be marked, once hatched the nest would be dug up, eggs counted, stragglers rounded up for their free trip to the Sargasso Sea and the numbers recorded in the database for the federal government. Keep in mind this was for 1 species (there were 3 on the beach, although the other 2 species were the outliers of their normal nesting locations). The model run on those numbers from the NBNS was again based upon the sample size and that size of every 5th nest used as an uncertainty.

    Funny how real science takes into consideration utilizing the teaching of statistics and methods of modeling to extrapolate population sampling observed in the field. In both cases the models utilized did indeed give an interesting view into the populations sampled, but absolutely no conclusions were drawn based entirely on the models. In fact, it was pounded into our heads that models are simply a tool for further inquiry, not absolutes.

  23. Thanks Jim, Your analysis just supports what I have seen in Environmental Modeling dating back to my first involvement in the 1970’s. Simply put there are some systems that we have more than adequate data for numerical modeling. Adjustments are not needed to calibrate the model to observations. Case in point is modeling of surface water flows in a watershed. I have used those models for very accurate predictions of flows in rivers and streams. Those models pretty much nail the observed hydrographs of streams in a watershed. Great for planning storm water management. Plenty of hood data to feed the model. Now, move to modeling hydrogeologic modeling and the systems we are attempting to model are several orders of magnitude more complex and buried underground; very difficult to accurately characterize and monitor. Although we have gotten pretty good at using groundwater models for certain applications we really can’t count on them to routinely simulate those real world systems, even though we thoroughly understand the hydrodynamics of flow through geologic media. We just can’t “see” the complexity of what is down there. So we use them as order-of-magnitude estimates. We still do not use FUDGE factors to adjust our model estimates. That would be useless.

    The Bird system the USGS is trying to characterize is probably more complex and you really can’t take those estimates for more than they are: crude estimates. Applying FUDGE factors to those estimates and calling them “reality” is simply absurd. I would just call it junk science.

  24. Thank you for this educational post. WUWT keeps me learning well into retirement.

  25. “If one bird is no longer observed at a roadside stop, the model assumes that the other 127 virtual birds also died.”

    More models with no real verification done. Sounds a lot like some GAT projections.

    Blaming an amorphous “climate change” with no science to back it up is not science it is religion. Do eggs not hatch because it’s too hot or too cold? Do birds die because temps have risen or fallen too far? Will their metabolisms not support different temps? What temperature ranges do each bird species need to reproduce? How do local temps compare? Have birds moved to better climates?

  26. Of 100 references, I only found four pre-2000, earliest 1985 about radar. One (1997) is about “ecological services.” Doesn’t prove much but part of a group of negative papers that don’t seem to have much history unless their references do. Not knowing much about birds I have long hung around some who do in the northwestern Gulf of Mexico and have been interested in finding information about their relationship to marine and estuarine critters. There is a lot on ocean cold water fisheries and birds but apparently not here having to do with their impact and interaction with fisheries. Although there are some interesting papers (herding, using lures and a few other subjects), clearly the focus is heavy on conservation. A sign on the Port Aransas beach threatens fines and jail for driving through a bird flock. Lots of flocks are laughing gulls, probably more run off or killed by hurricane, doesn’t seem to be much research on natural morality.

    The main success story is brown pelican, eat lots of fish, hard to find data. Like some gulls, also beggars. Our pest bird is white ibis, call them street birds, forage in lawns, prey uncertain, but apparently also kill and eat small birds.

  27. “Despite being hunted, ducks and geese increased by 54%.”
    You mean “Because”, not “Despite”. Hunters and their conservation efforts always end in the species being replenished. Just look at the North American Whitetail for evidence.

    • Jeff Wallace – May 1, 2020 at 7:38 am

      Hunters and their conservation efforts always end in the species being replenished.

      Just look at the North American Whitetail for evidence.

      Sure, go ahead and look, …… but you won’t find very many examples of “species replenishment” by hunters, …… especially WT deer.

      Even by local DNR employees …….. even though they will charge you a “replacement fee” for an illegal kill, ….. although they have never been known to “replace” one.

      Lots of Clubs stock Ring-neck pheasants, ….. usually the week before season “opens” so they get 1st shot at them.

      One might claim that the DNR “replaces” (stocks) trout, …. but they only do that to entice one into purchasing a fishing license and a trout “stamp”. And it’s a big fine if one is caught fishing in a trout stream without a fishing license and stamp.

      • I disagree Sam Ducks Unlimited have played a large role in increasing wetlands. They contributed to our watershed restoration. In eastern USA hunters have been working to improve Bobwhite habitat by creating more open habitat

        • Jim, now I really don’t want to get into a “peeing contest” with you, but tell me, ….. how has Ducks Unlimited been increasing wetlands?

          By building dikes, lakes, levees, dams and/or releasing pairs of beavers.

          It takes really deep pockets to accomplish any of the above, ….. except for “beaver releasing”. And “donations” funded organizations really don’t like to spend “big money” on the “cause” that they solicit the money for.

          And Jim, it takes a lot more than just “open habitat” to support a covey of Bobwhite quail.

          In the 1950’s there were quite a few Bobwhite quail in central WV because I would often “flush” a covey when I was out hunting, especially around or near abandoned or no-longer working farms. Grown-up fields and meadows, thickets, brushland, scrubland, …… ya never knew when you were going to “flush” up a covey. But that was then, ….. this is now, which I can attest to, …. to wit:

          Habitat degradation has likely contributed to the northern bobwhite population in eastern North America declining by roughly 85% from 1966–2014.
          https://en.wikipedia.org/wiki/Northern_bobwhite

    • Yes it should have read “had organized an extensive ” I corrected it for my post on my blog but only after I submitted it also to WUWT

  28. Jim Steele, great “fact based” article. I enjoyed reading it.

    To define the causes of the “rise n’ fall” of the bird populations in North America I will use the history of West Virginia (western Virginia) to do so.

    During the “colonial years” WV was pretty much completely covered with virgin forests, a condition not conducive to the health and well being of most bird species, therefore birds were extremely limited in numbers. But as the pioneers began crossing over the Alleghenies and clearing the land to build their homestead, ….. and raise their garden and crops to feed themselves and their livestock, ….. the birds migrated in to the newly cleared land which provided nesting sites and an abundance of food. And thus, the birds migrated across the landscape right behind the pioneers.

    By 1869, West Virginia had 40,000 farms totaling 8.6 million acres. ……………. By 1900 there were nearly 100,000 farms in West Virginia, occupying more than 8.9 million acres.

    At the end of the 19th century West Virginia farmers grew 1.2 million acres of corn and wheat.

    The number of farms peaked at 105,000 in 1935, and dropped steadily thereafter.

    In 2010, West Virginia had 23,000 farms, ….. according to the U.S. Department of Agriculture. The average size of the farm was 159 acres. The total farmland in West Virginia fell to 3.65 million acres.

    Most West Virginia farmland produces grass. Nearly one third of the 3.7 million acres of farmland in the state is devoted to permanent pastures.
    https://www.wvencyclopedia.org/articles/166

    1869, … 40,000 farms, … 8.6 million acres.
    1935, … 105,000 farms ….
    2010, … 23,000 farms, …3.65 million acres

    2020, … most of the 3.65 million acres of farmland produces only grass.

    2020, … nearly 1/3 of the 3.65 million acres is devoted to permanent pastures

    Current bird populations in WV are down considerably from the 1950’s, …… primarily because homeowners have stopped “growing gardens” ……and most bird species don’t eat ‘grass’ for survival.

    • Samual Cogar, almost all pics of the US Appalachian regions in the 1930s showed denuded/clear-cut mountains. Those slopes have long since reforested. Of course, the flatter areas are often still pastured, but my county in west MD, for example, is ~85% forested as it has little flat areas. The county just to the north in PA has more flatter land and agriculture is its greatest economic activity, tho still over 50% forested.

      There’s no shortage of birds….. Awaiting the return of hummingbirds, but they’re prb’ly delayed due to chilly weather.

      • After the civil war, Pennsylvania was clear cut from east to west.
        The people that did it were veterans of the civil war who had had the job of working ahead of the advancing armies.
        By the end of the war, the people doing it could clear a forest and use the materials obtained to made a corduroy road as fast as the army could march.
        Since all the trees were cut, huge floods ensued on the early 20th century.
        There were massive replanting efforts, and there were no trees for decades, so there was no logging industry in PA.
        By the late 20th century, PA had one of the largest stands of temperate hardwood trees in the world.
        And the deer which had reproduced out of control began to starve to death in large numbers every winter when activists had hunting banned in much of the state.
        This article does not mention the aspect of the postbellum clearcutting, but I
        wrote an essay about it many years ago.
        https://www.pghcitypaper.com/pittsburgh/a-century-ago-pennsylvania-stood-almost-entirely-stripped-of-trees/Content?oid=1848219

        • Thanks, Nicholas, very interesting article. PA of course has suburb forests, and also some of the world’s best/most productive farmlands.

        • Nicholas McGinley – May 1, 2020 at 11:20 am

          By the late 20th century, PA had one of the largest stands of temperate hardwood trees in the world.
          And the deer which had reproduced out of control began to starve to death in large numbers every winter when activists had hunting banned in much of the state.

          Nicholas, me thinks you should really clarify your above statement.

          It infers that …… “the stands of hardwood trees” …… was responsible for ……. “the deer reproducing out of control”, …… whereas it should have stated that …… “during the re-growth period of the hardwood trees, …… there was nothing controlling deer reproduction”.

          Deer are “browsers”, ……. and they can’t browse on leaves of trees if greater than 10 feet in height.

          And Pennsylvania had a more recent problem of “overabundance of deer” which was caused by the “unwillingness” of teenagers to be the ‘killers’ of Bambi. Social pressure from the “bleeding heart” liberals convinced them it was wrong to shoot any animal and thus License revenue has dropped like a rock.

      • beng135 – May 1, 2020 at 9:51 am

        Samual Cogar, almost all pics of the US Appalachian regions in the 1930s showed denuded/clear-cut mountains. Those slopes have long since reforested.

        Shur nuff, ….. beng135, ….. but there is a big difference in the “virgin’ forests of the pre-1900 era and the “second” or “third” regrowth woodlots of the post-1930 era. There were several migratory bird species that passed thru Appalachia to and from their summer feeding areas. Most were aquatic except for the Passenger Pigeon.

        Beng, do you have any of these birds in your neighborhood: Gray Jay, Boreal Chickadee, Spruce Grouse, Black Backed Woodpecker, Three-Toed Woodpecker and Palm Warbler?

        Of course you don’t because they are all “forest living” birds and don’t habitat cities, suburbs, farmland or woodlots.
        Read more @ https://www.fws.gov/refuge/Umbagog/wildlife_and_habitat/northernforestbirds.html

        There’s no shortage of birds…..

        Beng, I hate to hafta pull rank (age) on you but I have been an avid “student of (WV) nature” for at least the past 75 years, And during my adolescent/teen years in central WV during the late 40’s and the 50’s, I can assure you that the local bird population was greater then, …. than it is now. And that was because most everyone had a garden, berry vines, etc., ….as well as 2 or 3 fruit trees.

        So tell me, Beng, …… do you and your neighbors produce enough food on your properties for the birds to survive on. And ps, the modern habit of keeping your lawns mowed is what attracts Robins to nest nearby.

        • do you and your neighbors produce enough food on your properties for the birds to survive on

          Samuel, most of the people around me do indeed have gardens, fruit trees, berry vines, etc (I’m out in the country & so do I). So the answer to your question is — yes indeed.

  29. Jim ==> Excellent. I like birds — I like cats. Cats should be confined to their owners property, like dogs and other pet animals.

    It is societal madness to let the little vicious pet predators roam free through our neighborhoods and to fail to eliminate any and all feral cats.

    Where is the public movement to pass laws to confine cats to their homes? To license and tag and regulate and to sweep up the lost and feral animals?

    • Kip Hansen – May 1, 2020 at 8:39 am

      It is societal madness to let the little vicious pet predators roam free through our neighborhoods and to fail to eliminate any and all feral cats.

      Of course it is “societal madness”, ….. but society would not enact Laws to prevent said even if those “pet predators” (cats) became “carriers” of the Covoid-19 virus and began infecting humans.

      So, don’t mess with those cats, feral or otherwise, because if you are caught harming one, your fate will be worse than if you had beat up a 3 year old with baseball bat and sexually molested him/her “to boot”.

      • Samuel C Cogar ==> I have had occasion here to write about feral cats before — and there are few special interest groups more rabid (pun intended) than the Cat Lovers who are nearly as vicious as the feral cats they feel compelled to “protect” from the likes of me. All I said was that they should all be rounded up and euthanized (the feral cats, not the Cat Lovers)….which I still believe and am happy to promote.

        Now, your pet cat I think should be licensed, collared, wear a registration tag and a vaccination tag and required to remain in your home or on your own property — and if not, collect up by animal control and returned to you if your pay a hefty fine — and it not, join its feral brothers and sisters in the feral cat solution.

        • Now, your pet cat …….

          Kip, not my pet cat because I hate all “domesticated” cats, feral or otherwise.

          And I agree with your “solution” except for the ‘wearing of a registration tag’, …… which I think should be an implanted microchip, ….. which would prevent pet owners from just removing the registration tag and then dumping them out of a car late at night when they no longer wanted them .

        • “Now, your pet cat I think should be licensed, collared, wear a registration tag and a vaccination tag and required to remain in your home or on your own property — and if not, collect up by animal control and returned to you if your pay a hefty fine — and it not, join its feral brothers and sisters in the feral cat solution.”

          Totally agree, Kip. I’ve had pet cats and dogs for decades, none of them run loose, unless it’s by accident. Those who let their cats (and dogs) out loose are selfish and irresponsible.

  30. Thank you very much for more of your well stated your common sense and integrity – both very lacking in much of the environmental propaganda.

    • Look like Common Grackles. Tail is relatively too long to be a crow. Grackles benefitted from human habitat much the same way House Sparrows and Starlings did. Rosenberg et al estimate Grackles declined by 83 million probably due to pest control as they are getting out of hand in many places

    • It’s actually harder to tell than you would think, because some look like crows and some look like grackles. Likely they’re all just grackles given the location, time of year, and there are no CAWS in the audio that I can hear.

    • Looks like a flock of grackles we saw years ago overwhelming an HEB parking lot in Uvalde, Texas. After a while they left. Lots of grackles in S Texas.

  31. Jim:
    Where did you get the estimate that 1 to 3 billion birds are killed by feral cats each year?

    This reads like the junk science article published by two Smithsonian bird specialists several years ago who claimed that feral AND domestic cats killed billions upon multiple billions of birds and (I believe they said) 45 billion small animals each year. Absolute garbage!

  32. Kenneth V, Rosenberg, et al., (2019) was published in Science 366(6461), 120-124; doi: 10.1126/science.aaw1313.

    The editorial blurb over the abstract starts this way:

    Staggering decline of bird populations

    Because birds are conspicuous and easy to identify and count, reliable records of their occurrence have been gathered over many decades in many parts of the world. ….

    Contrast, Science’s “birds are conspicuous and easy to identify and count” with Jim Steele’s “Many birds can be missed in [the 50 3-minute stops of the US Geological Surveys Breeding Bird Surveys (BBS)] … Each BBS route surveys perhaps 1% of the region’s landscape.

    To estimate each species’ population for the whole region, the survey’s observations are extrapolated and modeled. However, models rely on several assumptions and adjustments, and those assumptions that can [alter] final estimates.

    So, the editors of Science began their alarmist commentary with a facilitating double — what? Their opening sentence either evidences a duplex of incompetence or a knowing lie.

  33. reporting a decline in 57% of the bird species. They estimated a net loss of nearly 2.9 billion birds since 1970

    Just like in regard to the ChiCom virus, numbers are the first thing the marxists corrupt/manipulate. Any number(s) from them can be assumed a LIE.

  34. I offten wonder how much the reintroduction of West Nile have on the bird population. Add in the late spring snows also.

    • Not all birds develop disease from WNV infection, but crows and jays do. Also sage hens, which might mean that other grouse or even galliforms in general might be as well. Few are the avian families and orders without antibodies these days.

  35. Does anyone really think that us puny mortals can change the Earths climate?

    Why oh why are people obsessed with dreams?

  36. You might want to look into the source of the data used to make the ridiculous extrapolation of birds killed by cats.
    They never documented a single bird death, or counted cats across the country.
    I have extensively and completely debunked this hogwash numerous times.

    • NIcholas I did not examine the claims regards cats killing birds so I do not know how valid there numbers are. Perhaps you have a link to your debunking? I should dig into that issue more.

      However I do know cats can be a problem. I removed my bird feeder in part due to window crashes and in part because neighbor cats had learned to wait in ambush. As a kid I watched our cat kill many birds.

      Theoretically feral cats that are being fed by people are a problem. If a cat overhunts, its food becomes scarce to its detriment. But people often bring food to parks to feed the cats. Such food subsidies remove the natural negative feedbacks allowing cats to survive and breed better than they would naturally. There are many parks where this is happening that feral cat sterilization programs were initiated to assuage bird people with out offending the cat people

    • Nicholas McGinley ==> Your assertion: “They never documented a single bird death” is simply false. Where in the world did you get such an idea?

      There have been a series of “KittyCam” projects carried out over the years and these record, in gruesome details, the activities of domestic cats — including the eating of nestlings, chipmunks, baby rabbits, insects, amphibians and grown birds of varying types. Using Google Scholar to search for “KittyCam” studies will turn up the results.

      The extrapolation of “national” numbers from such samples is always controversial — but the fact of the impact is not.

      • When I say they, I am talking about the people who did these projections.
        Yes, there are kitty cam studies and you tube videos of cats going about the daily life of being a cat.
        I am talking about a scientific survey with documentation.
        Not random cats outfitted with kitty cams.
        Do you know the number of cams on kitties?
        Average number of birds killed per cat per day, week or year during each of the changing seasons in every part of the country?
        Of course not, because none of those kitty cam things was even pretending to do science.
        There was survey done in a village in England which was extrapolated out to the rest of the country and ultimately the world based on zero actual argued rationale for thinking this was anything like valid.
        In fact they had a few cameras and they wanted to make it interesting so they asked for people with cats that wander far and who have cats that bring home prey to volunteer.
        It was not random.
        It was not representative, and it was in one village in one country and a small number of cats.
        How many songbirds in Wisconsin between October and April?

  37. Behind most surveys of things like wild birds or feral cats, there is almost always an activist with a cause and plenty of bias and all the reasons in the world of activism to fudge the numbers.
    Typically birders count birds in places where many birds can be observed, then estimates are made of the range of the species, and then oftentimes ridiculous projections are made based on that number counted extending to the whole range.
    This is what was done with feral cats killing birds as well, only even more ridiculous.
    Counted cats in a large feral colony in an urban area where dozens of cat lovers feed them 365 days a year.
    Looked at the number in a square mile, or a fraction of a square mile more likely, and projected that out to the entire country based on acreage, without even subtracting mountains, water, deserts, crop fields, or made any allowance for the actual ability of habitat to support a predator.
    Cats do poorly outside of human habitation areas.
    They are utterly unable to survive across vast percentages of the US.
    Most places round up feral cats whenever they can catch them.
    And now we have had years of capture, neuter/spay, and release.
    Plus most places have made it illegal for pet stores to sell farmed cats and dogs, which has greatly decreased the number of abandoned animals at the same time it has increased demand for adoption.
    It is very hard for a cat to catch a bird.
    For many reasons.
    The same sorts of nonsense applies to estimates of cats killed by electric wires, buildings, and vehicles.
    All one needs to do is some math a little thought and logic, and it is immediately apparent the numbers are nonsensical, even without knowing they were derived by someone who must have been deliberately making up the highest number they could find a way to do.
    Birds are smart and fast and have excellent vision and field of view, and they are not active at night (with a few exceptions that are more likely to eat cats than be eaten), and they nest up high in hidden locations.

    • Sorry, estimates of birds k!lled by electric lines, buildings, and vehicles.
      These things happen, but the projections are over the top.
      Mostly what one will find when looking for the source of such assertions, is a long chain of people citing one single estimate that somehow took on a life of it’s own, and which has little support even in that study.

  38. Boy does that grid survey and extrapolation method sound familiar. One has to wonder how in their wisdom, the climate modelers account for “NOAA Satellite records second largest 2-month temperature drop in history” (today on WUWT); or the epidemiological models for the currently rampaging Black Swan.

  39. At several places in the article, it is noted that when new habitat became available, birds were able to move into these areas and colonize them and increase in number with astounding rapidity.
    And one takes a look at the multiplication rates of many birds, it becomes apparent how they manage to do this.
    A pair of songbirds can fledge three or more clutches of eggs a year, and each clutch has numerous eggs, sometimes as many as 10.
    And each bird lives on average about 10-12 years, although smaller ones generally live less long and larger ones can live considerably more.
    Some large birds might live as long as 80 years!
    That is for a parrot in Australia kept inside.
    Albatross are documented to live nearly 40 years, and Canada Geese have been kept as pets and lived over 30 years.

    I was just reading how it has been discovered that some migratory songbirds fly over three time faster than previous thought.
    Some birds in PA were fitted with some device that recorded location data, and it has been found that some of them have flown over 300 (actually 311 miles, or 500 km) miles a day when returning to the US from Brazil in the Spring.
    I wonder how fast they can go when they are not lugging around tracking devices?

    https://www.sciencedaily.com/releases/2009/02/090212141152.htm

  40. Jim

    This is in no way a criticism of you or what you have written. I very much appreciate your contrarian views of things that are usually taken for granted.

    As is so often the case when considering problems associated with the impact of Man, there are unstated assumptions that lean heavily towards blaming humans, even before a study is conducted. What I’m suggesting is that there is a tendency to have a myopic view of the situation and focus on one aspect, in this case, the impact of cats on birds, and to ignore the bigger picture. To whit, feral cats and strays often become food for larger predators such as foxes, coyotes, owls, and eagles; cats become alternative food for competitors. At the same time, cats reduce the availability of food for the larger predators. In the absence of cats, one could expect that the smaller birds, rodents, and reptiles would increase, providing more food for foxes, bobcats, hawks, and coyotes. With more food, their offspring will have higher survival rates, and put more pressure on small prey. It is a dynamic system in which various predators can fill the role of others. That is, I haven’t seen evidence that if cats were removed from the picture that the same number of birds wouldn’t be killed by the ‘natural’ predators that pre-dated the introduction of domesticated cats. The question becomes, are feral cats more efficient predators than native predators? If yes, then they are having a negative impact on birds. If the predation efficiency of cats is comparable to other similar-sized predators, then it is problematic that they are having an excessive impact. To the extent that cats are reducing the population of small prey, and hence food for competitors, then they are also reducing the population of competitors. Clearly, cats have an impact on the balance between prey and predators. However, it becomes a value judgement as to whether a weasel or skunk has higher ‘value’ than a common cat. Nature is pretty good at balancing out things. If cats were the deadly killers they are made out to be, by those who place high value on birds, then Europe and Asia would long ago have seen extinctions of those birds that were common prey of Felis sylvestris.

    The house mouse is thought to have originated in Asia. It then almost certainly was introduced to the New World by explorers and immigrants from Europe. It is a major food source for feral and domesticated cats. Would we eliminate cats and ignore the non-native mice, rats, starlings and other small prey? Pandora’s Box was opened by early Man. I think it a fools errand to try to put everything back in.

    • Consider this aspect, Clyde: A pair of songbirds lays between four and ten eggs per clutch, occasionally more, and has three to four clutches per year in many locales.
      Then each of those start breeding after not too long.
      But for the number of songbirds to remain stable, exactly two birds from each pair, and all of the descendants thereof, have to survive the original pair, which may live ten to twelve years or more.
      That is a lot of offspring, the overwhelming majority of which will necessarily die or the populations will explode.
      Two more than that number surviving per year will cause a population to double every year.

      • NIcholas, Most migratory warblers only produce one clutch and typically lay about 4 eggs on average. Some resident sparrows like the juncos often have 2 and maybe 3 clutches, but that depends on the local climate Again they lay about 4 eggs.

        Ducks and quails will lay up to 10 eggs, but 10 is unheard of more virtuallhy every songbird.

        • Hey Jim,
          I confess I have never gone up any trees to check, but I have double checked sources from my library to Wikipedia, that detail hole nesting species like tits commonly laying as many as 12 per clutch, and sometimes way more than that.

          These numbers always surprise me too, and I have studied birds since I was in grade school.

          “Most tree-nesting tits excavate their nests, and clutch sizes are generally large for altricial birds, ranging from usually two eggs in the rufous-vented tit of the Himalayas to as many as 10 to 14 in the blue tit of Europe. In favourable conditions, this species had laid as many as 19 eggs, which is the largest clutch of any altricial bird. Most tits are multibrooded, a necessary strategy to cope with either the harsh winters in which they reside in the Holarctic or the extremely erratic conditions of tropical Africa”

          Corvids are listed as having between 3 and 10 per clutch:

          “Corvids can lay between 3 and 10 eggs, typically ranging between 4 and 7. The eggs are usually greenish in colour with brown blotches. Once hatched, the young remain in the nests for up to 6–10 weeks depending on the species”

          I may be imprecise to use the term songbird to describe basically any small birds that come and feed at bird feeders.

          I never make stuff up, and if I am guessing, I do my best to always remember to say so.
          But when it comes to something like this, where I am refuting something in no uncertain terms, I always make sure I only say anything in a declarative way if I believe it is beyond contention.
          Large clutch sizes may be uncommon, but from everything I have been able to gather about these kind of birds, they are mostly only food and daylight limited when it comes to breeding.
          So if there is predation, more food will be available, more eggs can be laid by well fed females, more chicks fledged by prosperous parents.
          I am not sure how soon after fledging various sorts of birds might have young or their own, but given the lifespan and the numerous clutches and the large number…even if it is four fledglings twice a year, that number will lead to a lot of birds from just two after a few years.

          If I post links to the Wikipedia articles, the comment will go to moderation, but I did look at the references for these numbers, knew it to begin with from books right here on my shelves, and looked at other sites as well.
          Hey, check out this video I came across today…a bird in Australia that imitates construction sounds…chain saw, hammer, drill, screw gun…and even the guy working the tools talking and laughing:

          https://youtu.be/C0ZffIh0-NA

          • Nicholas, I am not saying you are “making up stuff”, I am saying I believe you are overstating the number of eggs and clutches that MOST birds produce. I confess not knowing anything about the European Great Tit and I was totally unaware of how many eggs they lay, although I do wonder if the high counts are due to brood parasitism. But Great Tits are an extreme exception for song birds.

            Most migratory birds have only one clutch will re-nest under very favorable conditions or to replace a depredated nest. On average most song birds lay only 4 eggs. Some warblers that specialize on spruce bud worms will have larger clutches to take advantage of an insect outbreak, and I suspect the range of eggs laid by most species will depend on the amount of available food each year. I have done many nest searches but perhaps I am biased by Sierra Nevada birds but many of those species are widespread and I have yet to find a songbird with more than 6 eggs in a nest. Our song bird surveys also determined ratios of young birds to adults, and the data typically suggested on average about two surviving young for each breeding pair. No indication of large clutches producing greater ratios of young

          • Nick
            I was once hiking in a tributary canyon of the Grand Canyon and heard what I was sure was a dog barking. Wondering why there was a dog there, I followed the sound and, to my utter surprise found that it was a raven imitating a dog!

    • Clyde, I am not trying to suggest cats are inherently evil. I encouraged my workers to bring their cats to my field station to help alleviate our rodent problems (we were over run by deer mice- Peromyscus). But the cats did noticeably reduce other animals. And I do not see a bird’s death be it via a weasel or a cat as anything unnatural.

      But I do worry that when people feed feral cats they are subsidizing their killing in a way that is now unnatural. A weasel’s survival will be limited by its hunting success, but a cat being fed by humans is not.

      I do advocate eradicating introduced cats on islands ( as I advocate for foxes or mongooses) where their introductions have undeniably taken a toll and endangered many species that had not evolved a behavior to avoid land predators. But elsewhere I would take a local regional approach to determine if cats were helpful (eliminating rodents) or harmful.

    • Clyde ==> “If cats were the deadly killers they are made out to be, by those who place high value on birds, then Europe and Asia would long ago have seen extinctions of those birds that were common prey of Felis sylvestris.”

      Can’t agree with you on that …

      1) we don’t know that some species haven’t been driven to extinction by the domestic cat — it is certain that many ISLAND species have been wiped out by the combined pressure of domestic cats, pigs and dogs.

      2) many bird species can far out breed the ability of cats to kill them. Not all birds are at risk from cats. Birds that nest in urban and suburban areas, and near human habitations with cats, on the ground or low in bushes and trees are the most adversely affected as the cats take the nestlings.

      3) There is no doubt that cats kill birds — and there are some good studies on how many and which ones.

      Cats, like all of our pets, should be confined to our homes or at least to our private property. We have no business allowing them to roam free in the environment.

      • Kip
        I think that you missed the main point of my comment. Predators of similar size and similar diets are largely interchangeable in the ecosystem. Eliminating a particular predator, such as a cat, when there are many species of predators, means more food for the remaining competitors, and they will prosper, and eat the prey that the cats would have otherwise eaten. You are fooling yourself to think eliminating just one species will benefit the prey. There will always be a balance between the available food, albeit it that it might be cyclical. Jim makes an important point that feeding feral cats gives them an advantage over other predators and should not be done.

        Certainly, the introduction of predators to islands that had never known mammalian predators will take a heavy toll on the defenseless prey. It is an entirely different situation disturbing an ecosystem with predators where there had been none. If I remember correctly, the breeding grounds of albatross are being impacted by rats that have made their way onto the island(s).

        I would question the claim of “good studies” unless a complete inventory was done of ALL predators and the impact each has on the prey population. That would also include the cats being taken by larger predators, which then don’t have to turn to smaller prey that the cats would normally take.

        I don’t imagine that most cats would be any happier with ‘lockdowns’ than most humans are these days. I once had a tomcat that had been hit by a car and lost an eye. I tried to keep him in so that he wouldn’t get injured in fights with other cats, or be taken by a dog. Despite having a litter box in the house, which he had always used faithfully, one day he urinated in an empty shoe box in my closet. I figured that he was expressing his displeasure with his confinement. I gave in and let him out. That was the only time he ever urinated in the house outside his litter box. Animals are intelligent and complex creatures. They need more than food and water and a place to sleep.

        • In many parts of the US, there are almost no small predators.
          Without predation, populations outstrip the available resources.
          Predation also generally eliminates the unfit, sick, old, stupid, and when there are just too many of something.
          Anyone who has spent significant time observing cats and birds knows the circumstances wherein a cat might catch a bird. It is not healthy adults.
          Unless perhaps someone sets up a situation that lures birds into an ambush.
          But even then, the other birds will see what is happening and learn.
          Even small songbirds can recognize a particular person who has acted in a threatening way, years later.
          A study at a New England University demonstrated that certain corvids can not only recognize a particular person who was a threat, but can somehow communicate a particular face to individuals that never saw the person, who will then recognize the threat.
          Cats are fast, but birds are faster, at least as smart, and they can fly.

          But say that somehow cat haters succeeding in getting approval to round up all cats they did not feel like keeping and killed every last one of them.
          What happens to vermin populations when all the cats are rounded up and slaughtered?
          Why, in the minds of some individuals, are the lives of those animals to be counted for nothing unless they are detained as pets that must always be confined?

          Even this study showed that back yard birds are not the ones declining…if anyone really knows one way or the other.
          One thing I know…every place I have ever been in the eastern US, you walk outside in the morning, and birds are flying hither and yon and huge numbers.
          Another thing I know is, cats are living beings, not toys or disposable plaything.

    • Clyde, yes, I was going to mention that for every bird I find that my 3 cats has killed (only rarely find a bird), I find 100 others, mostly mice & voles & an occasional mole, rat, rabbit & squirrel.

  41. To all the cat lovers who take exception to the one reference to cats as a threat to birds. The article I referenced was based on the study Loss (2012) “The impact of free-ranging domestic cats
    on wildlife of the United States”

    found at https://www.nature.com/articles/ncomms2380.pdf

    It was a meta-analysis.

    They calculated there are about 1 billion owned cats and about 1.8 billion feral cats for a total of nearly 3 billion cats. If I assume that humans and cats displaced a substantial number of natural predators and not all cats are good hunters, I would estimate that there are about 1 billion cats exerting above natural pressure on bird abundance. I would suspect the more vulnerable birds are the ground nesters such as Juncos in the suburbs or meadowlarks around farmland. If we trust the BBS data, both species have declined significantly. If each of the 1 billion cats kills just 1 bird, then the low end estimate of a total loss of 1 billion birds due to cats is reasonable. I have not thoroughly perused the paper, nor checked the papers that they used to support their estimations. I will do so, and I suggest others do so as well.

    • Jim ==> You are spot on about free-roaming cats. It is just plain weird that our country ( USA) has strict laws about pet dogs and NONE about pet cats. I think people should have pet house cats — they make nice companions — particularly for old folks. People could be allowed to have outdoor cats if they owned enough property (so that the cats remain on their private land) or if they could keep the cats confined to their yard (not easy to do).

      There should be no free-roaming cats in urban and suburban areas.

      There might be an exception for “working cats” — such as those that live in and near dairy barns.

      Feral cats — un-owned, free-roaming — should be rounded up and dealt with humanely — euthanized.

      (I have a strong opinion on this, but have dialed it back for public consumption.)

      • We have a diabolical cat problem in Australia, both feral and domestic. We also have marsupial equivalents which are listed as threatened species (quolls).

        Fewer cats and more quolls should make sense. However, cat ownership is simple and ubiquitous. Keeping a pet quoll is downright dangerous, it would seem, given the restrictions placed on this species in captivity reduces that possibility to a mere pipe dream.

        Even a child rescuing frog’s eggs from a drying puddle and removing them to a garden pond for their own protection is strictly illegal. How this ‘saves’ a species is quite beyond me.

      • Kip
        You remark, “It is just plain weird that our country ( USA) has strict laws about pet dogs and NONE about pet cats.” I think that there are two important distinctions. Dogs are more likely than cats to get rabies if they are not vaccinated, and dogs are more likely to bite people than are cats, if they are not confined or supervised.

        You also opine, “There should be no free-roaming cats in urban and suburban areas.” I think that this betrays your bias. There are few if any ground-nesting birds in urban areas, and even manicured suburban areas provide poor habitat for birds that would be at risk from cats. Urban areas often attract rats, and would benefit from cats whether feral or domesticated. I don’t think that you are being objective about this, despite claiming to like cats.

        • I love birds and cats.
          Rodents, roaches…not so much.
          Cats kill hundreds of rodents and roaches for every bird they might get ahold of.
          Typically it is when a nestling falls from a nest, or a nest is poorly located like in a rain gutter or a low branch.
          I would not be surprised if raccoons kill more birds than cats.
          And crows.

          Owls and hawks typically clear out every songbird from the site of a bird feeder once or twice a year. Takes about a month for any of them to come back.
          Cats mostly wish they could catch a bird.

      • “Feral cats — un-owned, free-roaming — should be rounded up and dealt with humanely — euthanized.”
        This is appalling.
        Truly.
        Luckily we have laws to severely punish lunatics’ who try to murder small animals.

  42. Anyone with a real interest in ecology must surely see that species rise and fall in response to a wide range of events, including many natural and/or cyclical events.

    However, there is one sure method to find that a species is threatened by decline.

    Don’t look for it.

    Here, in Victoria, Australia, we have a cute threatened aboreal marsupial as a state emblem. Some environmental activists have defied Covid movement restrictions to search forests soon to be harvested, where they have found the cute millionaire possums (Leadbeaters), in residence, leading to an immediate logging ban (but, naturally, no findings leading to fines or convictions for breaking the law, largely as these locals and foreign visitors were all, like the cute possum itself, totally homeless)!

    One may reasonably ask if it is so easy to find this cute endangered species in logging coups on demand, is it not possible to find them elsewhere?

    These are surely “millionaire” possums, as the state government has effectively protected at least a million trees for each known individual of this cute small-framed nocturnal mammal species, which is clearly one or two more than they really need.

    Whilst it is perfectly sensible to support legislation for the protection of an endangered species, the critical foundation of this must be sound population studying of said species. Too often, the protection comes first and the sound population studying comes never, even for famously cute state emblems.

    For the record, I have followed current best practices by referring to the species as “cute” as often as I reasonably could. And then some. One couldn’t call oneself a conservationist if one didn’t.

    .

  43. I want to know how they counted those 2.9 billion birds. Armies of volunteers with clickers scouring the trees for birds? What’s that? They didn’t actually count all 2.9 billion, you say? Huh. Never mind. Nothing to see here. Moving on to the next imaginary apocalypse…

    • I was also wondering what proportion of total bird population this number represents?
      In any case, most small and medium birds have numerous eggs, and many have more than one clutch per year.

  44. Some thoughts on cats and one on birds:

    -Cats do kill birds but I’ve only ever known one that was good at it and you would regularly see him hunting and catching healthy adult birds. Outside of that one cat I’ve seen a lot of cats try and fail, can’t say anything about how many nests they raid. While our house cats brought us all sorts of mice so we knew they were doing their job, they’ve only managed to bring us a couple of birds in decades worth of mouse gifts.

    -There’s no way in hell you’ll be able to catch and euthanize all the feral cats and likely not even put much of a dent in their population. I grew up on a farm with a lot of feral cats, we didn’t hunt them as they helped with the uncounted number of mice/rats we had. Here’s the issue, they darn near breed like rabbits in the wild. They also had a high fatality rate, we never saw any one feral cat for years on end like you do a house cats. Disease and predation cull their numbers on a regular basis. Not only did we have feral cats but we had hawks, coyotes, foxes, dogs and non predators that would kill a cat if provoked. I pity the cat that decides a baby neutria is edible if one of the parents are anywhere nearby assuming the baby didn’t kill it first.

    -You can’t license/chip/tag cats and keep them on your property like we do dogs. Cats are master of going under, through and over barriers so the only way you can have a cat outside and stay in your yard is to keep it in a cage or on a leash/chain. Do either of those and the ASCPA (and other animal rights groups) will be suing you for animal abuse. Doubt me? Look what they’ve done to change laws for keeping dogs.

    -This one is on birds and because of the conversation on nesting habits. We had a pair of barn swallows that nested on the side of the house and returned every year to their nest. They would have 3 batches of babies with 3-4 eggs per batch. Almost 100% survival rate when they flew south for the winter. It’s species dependent on how many batches, eggs and survival rate you get. FYI, get a long term couple like these were and they damn near become domesticated, cat even treated them as part of the family and wouldn’t touch a baby that fell out of the nest. Parents would come screaming to us until we went to see what the problem was, they knew we would put the baby back up in their nest. The only real issue is they though it was perfectly OK to fly into the house, sit on the pictures, talk to us and crap all over the place (we had no AC so door/windows were always open during the summer). On the plus side they kept the fly and mosquito population in check so it’s all about trade offs.

    • Darrin ==> “-Cats do kill birds but I’ve only ever known one that was good at it and you would regularly see him hunting and catching healthy adult birds. ”
      The threat of domestic cats to birds is MOSTLY to nestlings — see any of the KittyCam studies.

      Feral Cats — It WOULD be difficult to totally eliminate feral cats — but not that difficult. It has been done wth dogs very successfully — and cats tend to clump together. The first step it to eliminate feral cat colonies.

      Keeping cats in — Those who don’t wish to keep their cats indoors will simply have to forego cat ownership. There is a unending list of animals that we would not let people keep as pets if they chose to let them run free in the environment. Cats should be on that list. Re: Laws on dogs — it is illegal nearly everywhere in the USA to let your pet dog run free in the environment — it should be so for cats as well.

      Working cats — there is a place for the working cat — which are mostly known as Barn Cats — barn cats generally not roam the environment but stay in their place and do their jobs where they have plenty of food (both human provided and through hunting barn pests).

      The cat questioin requires rationality — and a proper solution is inhibited by the misguided emotionality attached to cats.

      • My impression is that there are two sides to the calculation. Many birds caught by cats exist because human activity creates food, such as earthworms in lawns – robins like those, and berry bushes.

        Note also that some people say that barn cats are not effective unless they are fed some food. Dunno why, surprising.

  45. Thankyou for information.

    A negative mentality where I live likes to claim there are no more songbirds in the city.

    Yet I see robins on lawns in the sun after a rain, eating earthworms.

    One error is assuming the birds not only show up when the claimant is out and about, but also sing for them.
    In reality birds utter whatever they do for a reason, when it is present. Perhaps happiness in some cases, but definitely to attract a mate (rock doves, aka pigeons, coo), to remind a mate where the nest is when their mate is out foraging, and as a warning (a harsh sound from rock doves). And to communicate to others abut danger – crows are quite loud, or maybe a good source of food.

    (Behaviour will vary with species. Orcas for example were cavorting near Seattle last year when there was much of their favourite source of food – large salmon, which has not been as plentiful as they want. But the supposedly intelligent creatures limit themselves culturally whereas their itinerant cousins eat other things too. Yes, some humans are also Darwin Candidates, like those who suffer from lack of iron and vitamin B12 because of the diet they choose.)

    And in the Victoria BC area there’s the misleading bird count at Christmas, which I say is not accurate because birds take shelter in poor weather or windy weather, birds vary location, watchers may not choose the best place to look, watchers may not stay out a s long or may stay home when weather is bad, smaller birds are less easily spotted, larger birds may be counted twice as they move away from a gawker.

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