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Survival of native and autumn-translocated elk in a recovering western Washington population


  • Associate Editor: Rominger


We documented survival of elk (Cervus elaphus) in the Nooksack herd of Northwest Washington, USA, 2000–2008, following a temporary harvest moratorium. To increase Nooksack elk abundance, 77 adult female elk were radiocollared and translocated from the Mt. St. Helens Wildlife Area (MSHWA) during October 2003 (n = 38) and October 2005 (n = 39). We used known-fate models to explore survival among radiocollared native adult females (n = 26), translocated adult females (n = 77), and native branch-antlered males (n = 24) in the Nooksack herd using 16 candidate models. The best model assumed similar survival for native and translocated female elk, except for a 1-year reduction in survival for the 2003 translocation cohort. The best model assumed that survival for branch-antlered Nooksack males differed during the harvest moratorium (pre-2007) and after limited permit-controlled hunting resumed in 2007. Under the best model, we estimated that annual survival for all adult female elk was 0.93 (95% CI = 0.90–0.95), except that 2003 MSHWA-translocated elk survival was 0.68 (95% CI = 0.51–0.82) during the first year post-translocation. We estimated male survival was 0.92 (95% CI = 0.76–0.99) prior to 2007 and was 0.68 (95% CI = 0.50–0.82) during 2007–2008. We did not detect a difference in mean body fat between translocated elk that died during the first year after translocation and those that survived (P = 0.39), although there were proportionally more very lean elk among those that died in the first post-translocation year. Elk that died in their first post-translocation year had marginally higher body temperatures at handling than those that survived (105.3°F ± 0.6° [SE; 40.7° C ± 0.3°] and 104.2° ± 0.2° [40.1° C ± 0.1°], respectively; P = 0.07). Despite the lower first-year survival of elk translocated in 2003, we concluded that the 2 translocations contributed substantively to Nooksack elk restoration. We discuss strategic aspects of autumn translocation that appeared to promote success. © 2013 The Wildlife Society.

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