Winter movement dynamics of black brant

Journal of Wildlife Management
By: , and 

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Abstract

Although North American geese are managed based on their breeding distributions, the dynamics of those breeding populations may be affected by events that occur during the winter. Birth rates of capital breeding geese may be influenced by wintering conditions, mortality may be influenced by timing of migration and wintering distribution, and immigration and emigration among breeding populations may depend on winter movement and timing of pair formation. We examined factors affecting movements of black brant (Branta bernicla nigricans) among their primary wintering sites in Mexico and southern California, USA, (Mar 1998–Mar 2000) using capture–recapture models. Although brant exhibited high probability (>0.85) of monthly and annual fidelity to the wintering sites we sampled, we observed movements among all wintering sites. Movement probabilities both within and among winters were negatively related to distance between sites. We observed a higher probability both of southward movement between winters (Mar to Dec) and northward movement between months within winters. Between-winter movements were probably most strongly affected by spatial and temporal variation in habitat quality as we saw movement patterns consistent with contrasting environmental conditions (e.g., La Niña and El Niño southern oscillation cycles). Month-to-month movements were related to migration patterns and may also have been affected by differences in habitat conditions among sites. Patterns of winter movements indicate that a network of wintering sites may be necessary for effective conservation of brant.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Winter movement dynamics of black brant
Series title Journal of Wildlife Management
DOI 10.2193/2006-051
Volume 71
Issue 2
Year Published 2007
Language English
Publisher The Wildlife Society
Contributing office(s) Alaska Science Center Biology WTEB, Alaska Science Center
Description 7 p.
First page 534
Last page 540
Country Mexico, United States
State Baja California, California