Satellites reveal divergent migration habits among Long-billed Curlews

3/6/2014 | 1

Long-billed Curlew at Fort De Soto County Park, Tierra Verde, Florida, by geopix.

Long-billed Curlew at Fort De Soto County Park, Tierra Verde, Florida, by geopix.

Cinnamon-brown above, buff below, and large, Long-billed Curlew is always a welcome sight. Its ringing call is the quintessential sound of spring and summer on many midwestern and western grasslands.

Yet the bird’s population is small, its breeding range has shrunk, and many aspects of its biology remain unknown, leading it to be categorized as a species of high conservation concern in the United States, Mexico, and Canada.

Curlew conservation

Fellows, S. D., and S. L. Jones. 2009. Status assessment and conservation action plan for the Long-billed Curlew (Numenius americanus). U.S. Department of Interior, Fish and Wildlife Service, Biological Technical Publication, FWS/BTP-R6012-2009, Washington, D.C. (PDF)

To shed light on its migration patterns, Gary W. Page of Point Blue Conservation Science, Nils Warnock of Audubon Alaska, and other researchers recently netted over two dozen curlews at three widely separated breeding sites, outfitted them with satellite transmitters, and then tracked their movements over four years. The birds were captured in north-central Oregon, northeastern Nevada, and north-central Montana.

The Oregon birds flew straight south to agricultural regions of California’s Central Valley, while the Nevada birds traveled either to the Central Valley or to the northern Gulf of California or the west coast of Baja California.

The Montana breeders, by contrast, migrated more than twice as far, they stopped more often and longer, and they wintered across a broader range than the birds from the other areas.

The Montana curlews navigated along the east slope of the Rocky Mountains to the Texas panhandle or northeastern New Mexico. Then, after a lengthy stopover, they continued southeast to the Gulf coast, to Laguna Madre in South Texas and the northeastern state of Tamaulipas in Mexico, or veered southwest to destinations on the Mexican Plateau.

“None of the Montana curlews migrated to the wintering areas of Oregon or Nevada birds, even though that course could have shortened their migration routes,” write the researchers. “Possibly the risk of crossing over the precipitous Rocky and Sierra mountain ranges is too high.”

The birds’ stopovers on the southern High Plains or northern Mexican Plateau lasted from one to three months. “These layovers seemed much longer than necessary to accumulate reserves for subsequent flights of only 400–1100 km farther south, and may instead have been made by birds undergoing prebasic molt, an energetically costly process.”

Page and his team published their findings in The Condor: Ornithological Applications, the journal of the Cooper Ornithological Society.

Read the abstract

Gary W. Page, Nils Warnock, T. Lee Tibbitts, Dennis Jorgensen, C. Alex Hartman, and Lynne E. Stenzel (2014) Annual migratory patterns of Long-billed Curlews in the American West. The Condor: February 2014, Vol. 116, No. 1, pp. 50-61. Abstract.

A version of this article appeared in “Birding Briefs” in the April 2014 issue of BirdWatching. Subscribe.