Migratory Connectivity of a Widely Distributed Songbird, the American Redstart (Setophaga Ruticilla)

From Pubwiki

[edit] Author(s)

• Norris, D. R.
• Marra, P. P.
• Bowen, G. J.
• Ratcliffe, L. M.
• Royle, J.A.
• Kyser, T. K.

[edit] Journal

Ornithological Monographs 61 (2006): 14-28.

[edit] Abstract

Determining the degree of connectivity between breeding and wintering populations is critical for understanding the ecology and evolution of migratory systems. We analyzed stable hydrogen isotopic compositions in tail feathers (δDw) collected from 26 sites in 11 countries throughout the wintering range of the American Redstart (Setophaga ruticilla), a Nearctic– Neotropical migratory passerine bird. Feathers were assumed to have molted on the breeding grounds, and δDw was used to estimate breeding origin. Values of δDw were highly correlated with longitude of sampling location, indicating that breeding populations were generally distributed along the east–west axis of the wintering grounds. Within the Caribbean region, Florida, and Bahamas, δDw values were negatively correlated with winter latitude, which suggests that American Redstarts exhibit a pa� ern of chain migration in which individuals wintering at northern latitudes are also the most northern breeders. To identify the most probable breeding regions, we used a likelihood-assignment test incorporated with a prior probability of breeding abundance using Bayes’s rule. Expected δD values of feathers from fi ve breeding regions were based on interpolated δD values from a model of continent-wide growing-season δD values in precipitation (δDp) and were adjusted to account for a discrimination factor between precipitation and feathers. At most wintering locations, breeding assignments were signifi cantly diff erent from expected frequencies based on relative breeding abundance. Birds wintering in eastern and western Mexico had a high probability of breeding in northwest and midwest North America, whereas birds in the Greater and Lesser Antilles were likely to have originated from breeding regions in the northeast and southeast, respectively. Migratory connectivity, such as we report here, implies that the dynamics of breeding and nonbreeding populations may be linked at a regional scale. These results provide a key opportunity for studying the year-round ecology and evolution of spatially connected populations in a migratory species.

[edit] Complete Publication (PDF; password required)

If you would like to join MIGRATE to get access to this publication, please email us!