"State of the Birds" Report; and Is Climate Change Shrinking Avians?

By Andrew Moseman | March 12, 2010 11:09 am

albatrossThis week the federal government released its 2010 report, “The State of the Birds,” examining the health of the United States’ native fowl. According to Interior Secretary Ken Salazar, the state of our union’s birds is precarious.

The 2010 report focused on climate in particular. In it, scientists reviewed data for 800 species nationwide, and ranked their sensitivity to climate change based on factors including how many young they produce each year, how able they are to move to new habitats, and how unique their food and nesting needs are [San Jose Mercury News]. Each of the 800 then received a designation of low, medium, or high vulnerability. You can see the methods for scoring here.

Birds that rely on coastal areas are in the most threatened position, Salazar says. Seabirds tend to have low reproductive potential and often nest on islands that can be inundated by rising sea levels, changes in water chemistry and other disruptions to the marine ecosystem [AP]. Hawaii birds are especially troubled, as they many are already under the gun by invasive species and disease, the report says. All 67 species of ocean-reliant seabirds ranked with a medium or high level of vulnerability. Birds native to forests or to arid regions, however, showed less climate vulnerability.

Kenneth Rosenberg of Cornell University’s Lab of Ornithology, a contributor to the report, says, “Birds are excellent indicators of the health of our environment, and right now they are telling us an important story about climate change. Many species of conservation concern will face heightened threats, giving us an increased sense of urgency to protect and conserve vital bird habitat” [AFP]. Scientists from the U.S. Geological Survey, Forest Service, and other organizations compiled the 2010 report (the full list at the bottom of the press release).

Meanwhile, a separate study published in the journal Oikos found a different but interesting effect on American birds. In biology, there is a general rule of thumb that animals tend to become smaller in warmer climates: an idea known as Bergmann’s Rule [BBC News]. Biologists aren’t totally settled on why Bergmann’s Rule should be so, but Josh Van Buskirk and colleagues wanted to see if that was happening in the United States over the past decades, as global warming has gradually increased temperatures. Luckily, the Carnegie Museum of Natural History in Rector, Pennsylvania, has kept measurements of hundreds of thousands of birds, coming from more than 100 different species, that migrated through the area since 1961.

Van Buskirk found birds getting slightly smaller no matter their migratory season: 60 of 83 spring migrating species, 66 of 75 for autumn, 51 of 65 for summer, and 20 of 26 for winter. In a spot of good news, though, the study says that the populations of these birds aren’t in decline, and are perhaps adapting to their changing world. “So many of these species are apparently doing just fine, but the individual birds are becoming gradually smaller nonetheless,” says Dr Buskirk [BBC News].

Related Content:
80beats: Tiny Tern Makes World-Record 44,000-Mile Migration
80beats: The Birds’ Sixth Sense: How They See Magnetic Fields
80beats: Like a Wool Sweater, Scottish Sheep Shrink As Climate Heats Up
80beats: Will All Animals Shrink Under a Warmer Climate
DISCOVER: Works in Progress: How do migrating birds know where to go?

Image: flickr / Wili_hybrid

  • Tometheus

    OK, one thing about climate change often confuses me. It seems people forget the earth was warmer in geologic ages past.

    Let me shift the perspective: Dinosaurs = really big in warmer climate. Modern dinosaurs (birds) = small in a cooler climate.

    I’m having a hard time buying Bergmann’s Rule.

  • Steven Douglas

    I can appreciate the desire for warmists to get another loveable animal poster child mascot, now that polar bears and other species have been debunked from climate change hysteria, but come on. Birds? Smaller in just FIFTY YEARS as a result of climate change? I have a better theory, one FAR more plausible: In a word, CATS.

    A senior scientist at Audubon estimates that over a billion birds are killed by domestic cats alone each year in the US. That alone (which is an anthropogenic influence on the environment) could account for observed (2% on average, not much) decrease in average size (in SOME species), given that larger birds would have a more difficult time avoiding predators than smaller birds, leaving more of the smaller birds alive to continue breeding.

    But no, somehow a small change anywhere is presumed to be caused by climate change everywhere. I would seriously like to knock on the doors of some of the more vacuous heads making these leaps and ask, “Is anybody home, or are you just enjoying your grant money?”

  • RealTH

    WInd farms in Spain are causing high mortality rates in large birds of prey like vultures and eagles which are slow to reproduce. So “climate change” may indeed be having an effect;just not the one the warmists may think.

  • m


    clearly this was funded by the taxpayers…THIS is the kind of economic stimulous we are spending our money on???

    it is obvious to me….

    1) Canadian Geese were excluded from the study – they are bigger, fatter, meaner and thousands more of them.
    2) Seagulls were excluded. See item 1
    3) Anyone seen a pigeon in a city lately? Some of them are so fat they cant fly. Great youtube video of these cats catching pigeons that are too fat to fly.
    4) Turkey Vultures are a serious problem now. And these are predatory birds!

    what a crock – all one has to do to debunk this *ahem* study (i feel so dirty calling it that) is look up in the sky.

  • m


    leafing through the report…try as I may, I could only find references to specific speacies whose populations are “natrually” low (when compared to – uh – more scientific data provided by you know – actual researchers).

    it seems that the author had a conclusion first, then went to prove it.

  • Antiquated Tory

    Jesus wept.


Discover's Newsletter

Sign up to get the latest science news delivered weekly right to your inbox!


80beats is DISCOVER's news aggregator, weaving together the choicest tidbits from the best articles covering the day's most compelling topics.

See More

Collapse bottom bar