Irrigated Agriculture - Important for Long-billed Curlews
Petaluma, CA – Despite the recent rainfall, California is still in a drought (snowpack 32% of average), so not only are water supplies limited, but demand for water is increasing from a variety of uses. In a recent study published by Point Blue Conservation Science (Point Blue) and Audubon California in the journal Western Birds, scientists document the importance of irrigated agricultural crops in California’s Central Valley to a conspicuous shorebird.
Crops like alfalfa provide critical habitat for the Long-billed Curlew, the largest shorebird in North America and a species of continental conservation concern. As the drought continues, mirroring conditions that are projected to be more common in the future, scientists say the need for allocating water reliably to wetlands and flooded agricultural lands will only grow stronger for wetland-dependent birds.
"Curlews can’t survive in the Central Valley without irrigated agriculture, given the loss of most of their historic shallow-water habitats in summer and fall,” says Dave Shuford, Point Blue ecologist and lead author of the publication.
The Central Valley’s protected wetlands (federal wildlife refuges, state wildlife areas, and private lands) and certain types of agriculture (e.g. rice, alfalfa), provide nearly all of the habitat used by millions of ducks, geese, shorebirds, and other waterbirds every fall, winter, and spring. In early fall—the driest time of year in the Valley—it is especially important that these birds can find flooded fields and wetlands for their survival. In the study, Point Blue scientists, Audubon California, and a host of volunteers studied the curlews for three years. Observers recorded over 20,000 curlews: about 93% were in the central and southern portions of the Central Valley, concentrating in areas extensively flood irrigated for alfalfa and irrigated pasture.
“Millions of migratory birds rely on the flooded agricultural fields each year. Conservation and agricultural groups can work together to benefit birds and people,” says Meghan Hertel, Audubon Working Lands Director.
In the future, irrigated agriculture will face increased water costs driven by competing needs of an increasing human population and probably drier conditions under a changing climate. These threats might be offset if a program of economic incentives can be devised for farmers to maintain flooding of crops, such as alfalfa and irrigated pasture, to the benefit of both farmers and curlews.
To view Long-billed Curlews in the SF Bay area, you can visit:
Bolinas Lagoon: July thru March.
Dixon area: fields east of Hwy 113 and south of town (best July-Sep).
San Francisco Bay NWR: July thru March.
Study citation: Shuford, W. D., G. W. Page, G. M. Langham, and C. M. Hickey. 2013. The importance of agriculture to Long-billed Curlews in California’s Central Valley in fall. Western Birds 44:196-205.