Morphological variation in spring migrant and wintering American Golden-Plovers Pluvialis dominica
128 – 134
1 September 15
Joop Jukema, John B. Dunning, Jr., Piet Vlas, Lauren Brierley, Paul Brooks
Department of Forestry and Natural Resources, Purdue University, 195 Marsteler Street, West Lafayette, Indiana 47907, USA
Seasonal variation in morphology may reflect the selective pressures experienced by migrating birds, especially for long-distance migrants such as shorebirds. We quantified variation in linear measurements, plumage scores, and body mass among sex and age classes in the American Golden-Plover Pluvialis dominica at different points in the nonbreeding period, from November to May. Most previously reported samples of morphological variation in this species were taken on the breeding grounds. Using birds caught in Uruguay and Indiana (USA), we show that there is little sexual dimorphism in size in samples from the wintering and migration seasons. First-year birds had shorter wings than adults on the wintering grounds, as previously found in the Pacific Golden-Plover P. fulva and Eurasian Golden-Plover P. apricaria. Molting American Golden-Plovers at a spring stopover site were not heavier than non-molting birds. We compared patterns of seasonal morphological variation in the American Golden-Plover to that of the Pacific and Eurasian Golden-Plovers and relate the differences and similarities of this variation to the migration strategies of these closely related species.