Variation in timing, behaviour, and plumage of spring migrant Bar-tailed Godwits on the Yukon-Kuskokwim delta, Alaska
179 – 185
1 December 10
Brian J. McCaffery, Robert E. Gill Jr, David Melville, Adrian Riegen, Pavel Tomkovich, Maksim Dementyev, Matthew Sexson, Rob Schuckard, Sarah Lovibond
Brian J. McCaffery
US Fish and Wildlife Service, Yukon Delta National Wildlife Refuge, PO Box 346, Bethel, Alaska 99559, USA.
We summarize 19 site-years of data on the spring migration of Bar-tailed Godwits Limosa lapponica baueri on the Yukon-Kuskokwim Delta of Alaska. Two distinct waves of godwits arrive on the Delta each spring. The first wave appears in early May and consists of local breeders arriving and dispersing into breeding habitat. The second wave appears in the third week of May. These later flocks are larger than those of the first wave, tend to be headed north, and include significant numbers of males that have brighter and more extensive ventral breeding plumage than do the local breeders. Godwits of this second wave apparently depart from the Delta by the end of the first week of June en route to breeding grounds farther north in Alaska.