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1 August 2011 Recent Trends in First-Year Survival for Black Brant Breeding in Southwestern Alaska
James S. Sedinger, Christopher A. Nicolai
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We estimated first-year and adult survival of Black Brant (Branta bernicla nigricans) from the Yukon—Kuskokwim Delta, Alaska, to assess (1) the role that first-year survival plays in declining recruitment and in the local breeding population's decline since the early 1980s and (2) the potential role of subsistence harvest in declining first-year survival. We used band-recovery models in program Mark to estimate band-recovery rates and annual survival from 1986 to 2007. The only models of band recoveries that received support contained annual variation and an additive effect of sex on band-recovery rates. The two best-supported models of annual survival differentiated between first-year and older Black Brant. The best-supported model (Akaike weight = 0.69) included a linear trend in first-year survival, while the second best-supported model (Akaike weight = 0.20) included an effect of mean gosling mass on first-year survival. Band-recovery rates corresponded to harvest rates of ∼1%, indicating that during the study period harvest was not demographically important. Adult survival was comparable (0.87) to that from other studies of this population, while first-year survival declined from 0.46 in 1986 to 0.24 in 2007. The trend of decline in first-year survival represented the effects of variation in conditions for goslings' growth in the breeding area combined with unknown effects on migration and in the wintering areas. Declining first-year survival is an important contributor to decline in the local breeding population of Black Brant.

© 2011 by The Cooper Ornithological Society. All rights reserved. Please direct all requests for permission to photocopy or reproduce article content through the University of California Press's Rights and Permissions website, reprintInfo.asp.
James S. Sedinger and Christopher A. Nicolai "Recent Trends in First-Year Survival for Black Brant Breeding in Southwestern Alaska," The Condor 113(3), 511-517, (1 August 2011).
Published: 1 August 2011

Black Brant
Branta bernicla nigricans
population dynamics
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