Most waterfowl that use the Pacific flyway in western North America are dependent on the series of lakes and wetlands that dot the landscape. These waterways cover a large area within the Great Basin region, which is sensitive to changes in climate that might impact water within it.
New research on water in the Great Basin region makes one of the first links between climate change and population responses of migratory waterfowl. Using data from the Breeding Bird Survey spanning almost 50 years, the study looks at waterfowl abundances at lakes and wetlands across the Great Basin region and compares them to climate trends over the past 100 years. Changes in climate have important implications across the entire annual cycle of the waterfowl, since multiple life stages depend on these bodies of water.
The analysis shows that both the quantity and quality of water in the region has changed in the past several decades. Higher temperatures have led to higher evapotranspiration rates, which lead to smaller, drier water sources. These higher temperatures also lead to earlier snow melt, which results in an earlier water peak in the spring.
As a result of less water, many lakes and wetlands have higher salinity. This is fine up to a point, since saline waters support desired invertebrate prey. But at too high salinity, prey species start to suffer and waterfowl are impacted. In addition, chicks, which have trouble processing high levels of salt, are dependent on freshwater reserves, which are shrinking or disappearing under higher temperatures.
The main message is that climate change is undoubtedly impacting water quality and quantity in the Great Basin region, and this is impacting waterfowl populations, mostly in a negative way. This trend is compounded by anthropogenic changes that alter or limit waterways, such as the diversion of water for cities or farming. The end result is wetlands and lakes that are becoming fewer and farther between.
With poorer quality water and lowered connectivity throughout the landscape, the Great Basin region is under threat as an effective flyway for waterfowl. Management decisions that consider the potential impact of climate change across the broader migratory network might better maintain connectivity between critical wetlands in the face of these water issues. Conservation actions that look at the landscape as a whole can more effectively support waterfowl species across their entire life cycle.
Haig, S.M., Murphy, S.P., Matthews, J.H., Arismendi, I. and Safeeq, M. 2019. Climate-altered wetlands challenge waterbird use and migratory connectivity in arid landscapes. Scientific Reports 9(1): 4666.