TY - JOUR
T1 - Geographic variation in morphology of Alaska-breeding Bar-tailed Godwits is not maintained on their nonbreeding grounds in New Zealand
AU - Conklin, J.R.
AU - Battley, Phil F.
AU - Potter, Murray A.
AU - Ruthrauff, D.R.
PY - 2011
Y1 - 2011
N2 - Among scolopacid shorebirds, Bar-tailed Godwits (Limosa lapponica) have unusually high intra- and intersexual differences in size and breeding plumage. Despite historical evidence for population structure among Alaska-breeding Bar-tailed Godwits (L. l. baueri), no thorough analysis, or comparison with the population’s nonbreeding distribution, has been undertaken. We used live captures, field photography, museum specimens, and individuals tracked from New Zealand to describe geographic variation in size and plumage within the Alaska breeding range. We found a north–south cline in body size in Alaska, in which the smallest individuals of each sex occurred at the highest latitudes. Extent of male breeding plumage (proportion of nonbreeding contour feathers replaced) also increased with latitude, but female breeding plumage was most extensive at mid-latitudes. This population structure was not maintained in the nonbreeding season: morphometrics of captured birds and timing of migratory departures indicated that individuals from a wide range of breeding latitudes occur in each region and site in New Zealand. Links among morphology, phenology,and breeding location suggest the possibility of distinct Alaska breeding populations that mix freely in the nonbreeding season, and also imply that the strongest selection for size occurs in the breeding season.
AB - Among scolopacid shorebirds, Bar-tailed Godwits (Limosa lapponica) have unusually high intra- and intersexual differences in size and breeding plumage. Despite historical evidence for population structure among Alaska-breeding Bar-tailed Godwits (L. l. baueri), no thorough analysis, or comparison with the population’s nonbreeding distribution, has been undertaken. We used live captures, field photography, museum specimens, and individuals tracked from New Zealand to describe geographic variation in size and plumage within the Alaska breeding range. We found a north–south cline in body size in Alaska, in which the smallest individuals of each sex occurred at the highest latitudes. Extent of male breeding plumage (proportion of nonbreeding contour feathers replaced) also increased with latitude, but female breeding plumage was most extensive at mid-latitudes. This population structure was not maintained in the nonbreeding season: morphometrics of captured birds and timing of migratory departures indicated that individuals from a wide range of breeding latitudes occur in each region and site in New Zealand. Links among morphology, phenology,and breeding location suggest the possibility of distinct Alaska breeding populations that mix freely in the nonbreeding season, and also imply that the strongest selection for size occurs in the breeding season.
U2 - 10.1525/auk.2011.10231
DO - 10.1525/auk.2011.10231
M3 - Article
SN - 0004-8038
VL - 128
SP - 363
EP - 373
JO - The Auk
JF - The Auk
IS - 2
ER -