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

Abstract

Abstract 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.

Keywords

• augmentation
• Cervus elaphus
• elk
• harvest
• survival
• translocation