Wood trush, grasshopper sparrow. Photos by Scott Whittle
By PATRICIA HEGLUND
When I was a young biologist, more than 30 years ago, I was stationed on Adak Naval Air Station at Aleutian Islands National Wildlife Refuge (now part of Alaska Maritime National Wildlife Refuge). Out in the Aleutians, the weather was always changing. It could be dead calm one minute and gale force winds in another. Rain squalls would blast from above, pelting your face with millions of icy needles for a few minutes and then the sun would break through. Heavy fog could roll by on 50-knot winds for days on end, and then skies would suddenly clear. The weather was so variable that the Nightly Navy News weather report was called, “Today’s Weather Was…” The unpredictability of the Aleutian weather was, well, predictable and thus, something we were well-prepared for.
Today, climate change is throwing an increasing number and magnitude of unexpected extreme weather events at wildlife and land managers. Our uncertainty about the impacts of such change is something managers need to get a hold of so that we can prepare for and respond to such change. In 2011, the Service partnered with NASA’s Ecological Forecasting Program and the University of Wisconsin-Madison to look at the potential impacts of climate change and extreme weather on bird populations on national wildlife refuges in the continental United States.
Birds, and all wildlife, are now experiencing a higher frequency of extreme events, such as droughts or heavy rains, in some places where extreme events were once rare. When combined with higher temperatures, an extreme event can affect the availability of critical resources and be more than a species can bear. As a result, wildlife may move to more suitable areas, abandon breeding attempts or even die. In a recent paper, Dr. Sebastian Martinuzzi and others reported that droughts are expected to become more frequent on some wildlife refuges, particularly in the Southwest, where increasing temperature may already be pushing the limits of some species, so we know we will need strong management there.
Current suitable climate space vs. projected suitable climate space for breeding wood thrush.
Even in other areas, drought may have a profound effect on birds. Drs. Brooke Bateman and Andrew Allstadt developed models suggesting that drought and precipitation are particularly important in shaping the suitable climate range for breeding wood thrush. The projected increase in drought conditions in the southern United States may influence the loss of the region’s suitability as future breeding habitat for the wood thrush by the end of the century. Suitable climate conditions, however, are projected to expand north and east.
Current suitable climate space vs. projected suitable climate space for breeding grasshopper sparrow.
The grasshopper sparrow needs a more even combination of temperature and precipitation conditions, although it appears to favor wetter conditions like those projected for the Midwest in the future. So while its suitable climate range is projected to shrink in the south and west, it is also projected to expand north and east.
Armed with projections like these, we are better able to think about alternative actions the Service can take in response to climate change.
Even in the face of an uncertain climate future, knowing the potential magnitude of change allows the Service to better prepare and act with intention.
Contributing: Anna Pidgeo, Volker Radleoff, Steve Vavrus, Brooke Bateman, Andy Allstadt and Sebastian Martinuzzi, all from the University of Wisconsin-Madison; Wayne Thogmartin, U.S. Geological Survey; Tom Albright, University of Nevada-Reno; and Resit Akcakaya, Stony Brooke University
PATRICIA HEGLUND, Division of Biological Resources and Regional Refuge Biologist, Midwest Region
|This article appeared in the fall issue of Fish & Wildlife News, our quarterly magazine.|