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Temporal and spatial shifts in habitat use by Black Brant immediately following flightless molt

Wilson Journal of Ornithology

By:
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DOI: 10.1676/09-114.1

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Abstract

Each year thousands of Pacific Black Brant (Branta bernicla nigricans) undergo flightless wing molt in the Teshekpuk Lake Special Area (TLSA), Alaska, in two distinct habitats: inland, freshwater lakes and coastal, brackish wetlands. Brant lose body mass during wing molt and likely must add reserves upon regaining flight to help fuel their 2,500 km migration to autumn staging areas. We characterized movements and habitat use by Brant during post-molt (the period immediately following the recovery of flight) by (1) marking individual Brant with GPS (global positioning system) transmitters, and (2) conducting a series of replicate aerial surveys. Individuals molting in inland habitats promptly abandoned their molt wetland during the post-molt and moved into coastal habitats. Consequently, inland habitats were nearly deserted by early August when Brant had regained flight, a decrease of >5,000 individuals from the flightless period of early July. Conversely, coastal molting Brant largely remained in coastal habitats during the post-molt and many coastal wetlands were occupied by large flocks (>1,000 birds). Our results indicate that inland, freshwater wetlands were less suitable post-molt habitats for Brant, while coastal wetlands were preferred as they transitioned from flightless molt. The immediacy with which Brant vacated inland habitats upon regaining flight suggests that food may be limiting during molt and they are not selecting inland molt sites strictly for food resources, but rather a balance of factors including predator avoidance and acquisition of protein for feather growth. Our data clearly demonstrate that patterns of habitat use by Brant in the TLSA change over the course of the molt season, an important consideration for management of future resource development activities in this area.

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Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Temporal and spatial shifts in habitat use by Black Brant immediately following flightless molt
Series title:
Wilson Journal of Ornithology
DOI:
10.1676/09-114.1
Volume
122
Issue:
3
Year Published:
2010
Language:
English
Publisher:
The Wilson Ornithological Society
Publisher location:
Lawrence, KS
Contributing office(s):
Alaska Science Center
Description:
10 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Wilson Journal of Ornithology
First page:
484
Last page:
493
Country:
United States
State:
Alaska
Other Geospatial:
Teshekpuk Lake Special Area