Molt ecology and age determination of Rusty Blackbird (Euphagus carolinus) in southern Yukon

The Rusty Blackbird (Euphagus carolinus) breeds in boreal forest wetlands across North America, and winters in the southeastern USA. This species is listed under Canada’s Species at Risk Act as Special Concern due to population declines. For the study, 1220 Rusty Blackbirds were captured in spring and fall from 2005-2010 at three sites in southern Yukon Territory (Whitehorse, Teslin, Watson Lake) in order to investigate timing of migration, stopover and molt, and to develop methods for age determination. We recorded sex, weight, wing length, fat, body molt, molt of primary and secondary wing feathers, eye colour, and extent of skull ossification. We photographed each bird (head, underwing, upperparts), and collected a primary feather (P1) for stable isotope analysis in order to determine breeding origin. Each bird was fitted with an aluminium band and a single colour band to indicate banding site. This dataset includes 717 individual Rusty Blackbirds captured at the Whitehorse Landfill site (60.751° -135.157°) by Canadian Wildlife Service personnel, plus 63 recaptures involving 57 of those 717 individuals. The other birds in the study (not included here) were captured in Teslin and Watson Lake, YT, by the Society of Yukon Bird Observatories http://www.yukonbirdobservatories.org/ . Basic banding data for all banded birds are also held by the Bird Banding Lab of Canadian Wildlife Service in Ottawa https://www.canada.ca/en/environment-climate-change/services/bird-banding.html