Numbers of Black Brant (Branta bernicla nigricans) have declined dramatically in at least one important breeding area in the Western Canadian Arctic (WCA) and the regional population is small and widely scattered. The overall Pacific Flyway Population, to which the WCA Brant belong, has declined historically as well, probably in part due to high rates of harvest and low rates of survival during the 1960s and 1970s. To better understand how changes in survival rates may have influenced WCA Brant, band recoveries and recaptures were used to estimate historical (1962-67 and 1975-79), and more recent (1991-2001) survival rates. On the mainland WCA, adult survival rates (derived from band recoveries) averaged 0.719 ± SE 0.045 and 0.693 ± 0.082 in the 1960s and 1970s, respectively but increased significantly (P < 0.05) to 0.884 ± 0.052 (based on band recoveries of both sexes) or 0.886 ± 0.025 (based on recaptured females) during 1991-2001. Comparable survival rates for juvenile Brant, derived from band recoveries only, were 0.216 ± 0.051, 0.460 ± 0.112, and 0.694 ± 0.205, and increased significantly over time. On Banks Island, located 250 km northeast of our mainland study site, adult survival rates averaged 0.945 ± 0.037 during 1992-94. The harvest of Pacific Flyway Brant has declined substantially since the 1960s which possibly explains much of the observed increase in survival estimates in WCA Brant. The most recent survival estimates for WCA Brant are as high as, or higher than, those for other areas in arctic North America or Eurasia. Managing harvest to maintain current levels of survival, and maintaining or increasing current levels of productivity (known to have declined in at least one important breeding area) may be required to maintain WCA Brant at present population levels.
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Vol. 31 • No. 2