CLIMATE CHANGE AND BIRD MIGRATION REDUX

TWO COMPLEMENTARY STUDIES

A month ago I posted about the Audubon Society’s report on the northward shift of ranges for North American birds because of global warming. Now a study just published in Public Library of Science One by the US Geological Service reports similar findings. As one news article reporting the study puts it, by 2075 the birds in your backyard may be quite different. Really? And what about the Tualatin River National Wildlife Refuge?

The interesting thing about the USGS study is that they added land-use and land cover data (farming, forest cutting, growing cities and suburbs, industry) and topographic data to climate data to refine their model for predicting what ranges will be for 50 bird species for the conterminous United States in the next several decades. This is, after all, the federal geology agency, so they’ve got land data. They claim combining land-use and land-condition (LULC) data with temperature forecast information produces significantly better results than either alone.

CHANGING MIGRATION

Like the Audubon report, this study says birds likely will be shifting northward. Warming winters in Canada and Alaska means migratory birds won’t need to migrate so far south, and potential summer breeding areas will likely be farther north too. Of course, satisfactory range also depends on the availability of appropriate food, nesting areas, and the presence of predators.

A recent article in Environmental Health News about the changing migration habits of the Pacific black brant  provides a good example of how ranges are already shifting . They used to migrate in winter from the Izembek National Wildlife Refuge in the Aleutians Islands to Baja California, 3,500 miles away. Now that Alaska is warmer many brants no longer make the trek. Staying put has advantages for the geese, but a cold snap can endanger them. Just days ago, remnants of Typhoon Nuri , one of the most virulent storms in a long time, swept across the Aleutians. We’ll have to wait and see what the impact at the INWR is.

The thing is, global warming is not a linear, gradual increase; it’s an erratic, nonlinear trend with a lot of inherent unpredictability.  I’m curious about the long-term outcomes, for sure, but all the perturbations and consequences of climate change will be sorting themselves out for a long time after I’m gone.

LET’S GET THE DATA

An interesting feature of both studies is the use of data about current bird locations from “citizen scientists.” The Audubon study used annual bird surveys. The USGS uses eBird data. eBird is an app from the Cornell Laboratory of Ornithology for iPhone and Android that enables birders to create bird identification reports with accompanying GPS data in the field. The reports are then uploaded to the eBird worldwide database .

I have eBird on my phone, but I have to admit that I don’t use it often. Frankly, field trips with school children are way too hectic to enter information even by smartphone. That’s a situation I think might be remedied by organizing volunteer naturalist or birder teams with a commitment to recording more consistent data while on the refuge. Or, perhaps it could be something we work with teachers and kids on. This could be a lesson about real data collection and real science. The predictions of changes to bird ranges are from computer models, but wouldn’t it be exciting to collect data over time that validates or challenges these studies? I think so.

Twenty of the 50 birds the USGS studied are on the Tualatin River National Wildlife Service Watchable Wildlife list. Will we see fewer migratory birds from the far north in future years on the refuge, or will we begin to see more birds usually associated with California? Interesting questions only time will answer.

 

 

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