Implications of Prebasic and a Previously Undescribed Prealternate Molt for Aging Rusty Blackbirds
Aging birds often relies on differences in plumage between immatures and adults, and understanding these patterns can improve our ability to discern demographic patterns within populations. We investigated patterns of prebasic molt of the Rusty Blackbird (Euphagus carolinus) in fall at Whitehorse, Y...
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ftbioone:10.1525/cond.2010.100150 2024-05-12T08:12:19+00:00 Implications of Prebasic and a Previously Undescribed Prealternate Molt for Aging Rusty Blackbirds Claudia Mettke-Hofmann Pamela H. Sinclair Paul B. Hamel Russell Greenberg Claudia Mettke-Hofmann Pamela H. Sinclair Paul B. Hamel Russell Greenberg world 2010-11-01 text/HTML https://doi.org/10.1525/cond.2010.100150 en eng American Ornithological Society doi:10.1525/cond.2010.100150 All rights reserved. https://doi.org/10.1525/cond.2010.100150 Text 2010 ftbioone https://doi.org/10.1525/cond.2010.100150 2024-04-16T02:08:44Z Aging birds often relies on differences in plumage between immatures and adults, and understanding these patterns can improve our ability to discern demographic patterns within populations. We investigated patterns of prebasic molt of the Rusty Blackbird (Euphagus carolinus) in fall at Whitehorse, Yukon Territory, and developed a new technique for aging based on characteristics of the head plumage acquired during prebasic molt. Furthermore, we investigated the possibility of a prealternate molt among wintering Rusty Blackbirds on the basis of captures in Mississippi and museum specimens from across the species' winter range. Finally, we examined how a prealternate molt might affect the aging of winter birds by plumage. Rusty Blackbirds completed their prebasic molt by the end of September, and immature birds had a more prominent eye ring and a paler chin than adults, allowing a reliable age determination. Previously, the Rusty Blackbird was thought to attain its breeding plumage through feather wear exclusively, but we discovered a partial prealternate molt in our examinations of live captures (76% molting) and museum specimens (59% molting). The prealternate molt was observed in all age and sex classes, was concentrated along the feather tracts of the head, and peaked in occurrence from mid-February to mid-March, when nearly 90% of birds were molting. Between mid-December and mid-February, the prealternate molt did not appear to interfere with aging birds in the hand by the pattern of the eye ring and chin in basic plumage. Age determination later in the spring, however, remains to be investigated. Text Whitehorse Yukon BioOne Online Journals Yukon The Condor 112 4 854 861 |
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English |
description |
Aging birds often relies on differences in plumage between immatures and adults, and understanding these patterns can improve our ability to discern demographic patterns within populations. We investigated patterns of prebasic molt of the Rusty Blackbird (Euphagus carolinus) in fall at Whitehorse, Yukon Territory, and developed a new technique for aging based on characteristics of the head plumage acquired during prebasic molt. Furthermore, we investigated the possibility of a prealternate molt among wintering Rusty Blackbirds on the basis of captures in Mississippi and museum specimens from across the species' winter range. Finally, we examined how a prealternate molt might affect the aging of winter birds by plumage. Rusty Blackbirds completed their prebasic molt by the end of September, and immature birds had a more prominent eye ring and a paler chin than adults, allowing a reliable age determination. Previously, the Rusty Blackbird was thought to attain its breeding plumage through feather wear exclusively, but we discovered a partial prealternate molt in our examinations of live captures (76% molting) and museum specimens (59% molting). The prealternate molt was observed in all age and sex classes, was concentrated along the feather tracts of the head, and peaked in occurrence from mid-February to mid-March, when nearly 90% of birds were molting. Between mid-December and mid-February, the prealternate molt did not appear to interfere with aging birds in the hand by the pattern of the eye ring and chin in basic plumage. Age determination later in the spring, however, remains to be investigated. |
author2 |
Claudia Mettke-Hofmann Pamela H. Sinclair Paul B. Hamel Russell Greenberg |
format |
Text |
author |
Claudia Mettke-Hofmann Pamela H. Sinclair Paul B. Hamel Russell Greenberg |
spellingShingle |
Claudia Mettke-Hofmann Pamela H. Sinclair Paul B. Hamel Russell Greenberg Implications of Prebasic and a Previously Undescribed Prealternate Molt for Aging Rusty Blackbirds |
author_facet |
Claudia Mettke-Hofmann Pamela H. Sinclair Paul B. Hamel Russell Greenberg |
author_sort |
Claudia Mettke-Hofmann |
title |
Implications of Prebasic and a Previously Undescribed Prealternate Molt for Aging Rusty Blackbirds |
title_short |
Implications of Prebasic and a Previously Undescribed Prealternate Molt for Aging Rusty Blackbirds |
title_full |
Implications of Prebasic and a Previously Undescribed Prealternate Molt for Aging Rusty Blackbirds |
title_fullStr |
Implications of Prebasic and a Previously Undescribed Prealternate Molt for Aging Rusty Blackbirds |
title_full_unstemmed |
Implications of Prebasic and a Previously Undescribed Prealternate Molt for Aging Rusty Blackbirds |
title_sort |
implications of prebasic and a previously undescribed prealternate molt for aging rusty blackbirds |
publisher |
American Ornithological Society |
publishDate |
2010 |
url |
https://doi.org/10.1525/cond.2010.100150 |
op_coverage |
world |
geographic |
Yukon |
geographic_facet |
Yukon |
genre |
Whitehorse Yukon |
genre_facet |
Whitehorse Yukon |
op_source |
https://doi.org/10.1525/cond.2010.100150 |
op_relation |
doi:10.1525/cond.2010.100150 |
op_rights |
All rights reserved. |
op_doi |
https://doi.org/10.1525/cond.2010.100150 |
container_title |
The Condor |
container_volume |
112 |
container_issue |
4 |
container_start_page |
854 |
op_container_end_page |
861 |
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1798834650872807424 |