Effects of drought on the abundance and distribution of non-breeding shorebirds in central California, USA

• Published in: PloS one 2020-10, Vol.15 (10), p.e0240931-e0240931
• Main Authors: Barbaree, Blake A, Reiter, Matthew E, Hickey, Catherine M, Strum, Khara M, Isola, Jennifer E, Jennings, Scott, Tarjan, L Max, Strong, Cheryl M, Stenzel, Lynne E, Shuford, W David
• Format: Article
• Language: English
• Subjects: Abundance; Agricultural land; Agricultural management; Animal Migration; Animals; Aquatic birds; Availability; Biology and Life Sciences; Bird migration; Birds; Breeding; California; Charadriiformes - growth & development; Charadriiformes - physiology; Climatic extremes; Coastal ecology; Coastal zone; Coasts; Conservation; Conservation of Natural Resources - methods; Distribution; Drought; Droughts; Earth Sciences; Ecology and Environmental Sciences; Environmental aspects; Environmental protection; Extreme drought; Extreme weather; Floods; Fresh water; Freshwater resources; Geographical distribution; Habitat availability; Habitats; Long-term effects; Migratory birds; Migratory species; People and places; Precipitation; Research and Analysis Methods; Rice; Seasons; Shorebirds; Surface water; United States; Valleys; Water shortages; Wetland agriculture; Wetland management; Wetlands; Wildlife; Wildlife conservation; Wildlife habitats; Wildlife management; Wireless networks
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0240931

Conservation of migratory species requires anticipating the potential impacts of extreme climatic events, such as extreme drought. During drought, reduced habitat availability for shorebirds creates the potential for changes in their abundance and distribution, in part because many species are highly mobile and rely on networks of interior and coastal habitats. Understanding how shorebirds responded to a recent drought cycle that peaked from 2013 to 2015 in central California, USA, will help optimize management of wetlands and fresh water for wildlife. In the Central Valley, a vast interior region that is characterized by a mosaic of wetlands and agricultural lands, we found 22% and 29% decreases in the annual abundance of shorebirds during periods of 3-year drought (2013-2015) and 2-year extreme drought (2014-2015), respectively, when compared to non-drought years. Lower abundance of shorebirds coincided with significant decreases in the mean proportion flooded of survey units (7% and 9%, respectively) that were reliant on fresh water. Drought was associated with lower abundance within both the interior Central Valley and coastal San Francisco Bay for greater and lesser yellowlegs (Tringa melanoleuca and T. flavipes) and long- and short-billed dowitchers (Limnodromus scolopaceus and L. griseus). Only dunlins (Calidris alpina) had patterns of abundance that suggested substantial shifts in distribution between the Central Valley and coastal regions of San Francisco Bay and Point Reyes. Our results indicate that drought has the potential to reduce, at least temporally, shorebird populations and flooded habitat in the Central Valley, and the ability to respond to drought by taking advantage of nearby coastal habitats may limit the long-term effects of drought on some species. Successful conservation strategies must balance the impacts of reduced habitat availability at interior sites with the ability of some migratory shorebirds to adapt rapidly to shifting distributions of resources.