Weekend Birdery: State of the Birds

March 14, 2010

This is the inaugural edition of a new, occasional feature about birds.

This week, the U.S. Department of the Interior released its 2010 State of the Birds report. Woohoo! The theme of the report is how climate change is affecting populations and habitats of the roughly 800 species of bird in America. The report finds that birds in every category of habitat are threatened by climate change, as the graph below illustrates, but particularly vulnerable are the 67 ocean-going species (like albatrosses and petrels) and others that breed on low-lying islands imperiled by rising sea levels.

Relative Vulnerability of U.S. Bird Species by Habitat
Red = high vulnerability; Yellow = medium vulnerability; Green = low vulnerability

Warming trends are amplifying and adding to existing ecosystem stressors. Coastal and island birds face erosion of habitat and disruption of food supply from the increased frequency and severity of storms caused by increasing sea temperatures. Warming can tip the ecological balance towards birds’ predators, invasive species, or disease. (E.g., mosquito-borne avian malaria and pox spread easily through bird populations on islands like Hawaii, where the native species have little natural resistance. And as average temperatures rise and creep up to higher elevations, mosquitos and malaria creep with them.)

One notable and measurable effect of warming has been a northward shift in the wintering ranges of many if the most widespread species in the northern states.

Although many factors are known to drive range changes, results from the Christmas Bird Count (CBC) show that the warmer winters in recent decades have played an important role in shifting winter bird ranges to the north. CBC data from the mid-1960s through 2006 show that 170 (56%) of the 305 most widespread, regularly occurring species have shifted their ranges to the north, whereas only 71 species (23%) have shifted to the south and 64 species (21%) have not shifted significantly north or south.

State of the State of the Birds Report Report

Overall I think the report is nicely presented, and I think the idea of integrating disparate surveys, studies, and data sources is great. I presume the effort provides a helpful backdrop for setting and funding research agendas and for articulating the basis for conservation efforts.

But I must say I’m a little disappointed in this year’s State of the Birds report. For one thing, it lacks a comprehensive overview of, you know, what’s going on with birds in America. I’d like to see some population estimates, lists of endangered and threatened species1, data trends, and such. And while the layout and pretty pictures (bird porn) are nice, the report has an unforgivable paucity of informative charts. (Sorta just kidding about the unforgivable part. But the charts are paltry. Besides the two above, there are some basically pointless pie charts and not a table in sight.)

Altogether it comes off like a promotional brochure, lacking a certain analytical heft—though I have no doubt that it represents serious scientific work product. (See the report in pdf here.)

So: geek that thing up next year, guys! A statistical appendix, maybe. Or at least post some tables and lists on the website.

  1. There was a table of endangered species in the 2009 report. [↩]
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