ESTIMATES OF CALF SURVIVAL AND FACTORS INFLUENCING MORTALITY IN NORTHWESTERN CALIFORNIA.
Erin M. Nigon; Humboldt State University/CDFW; 2908 Loop Road, Fortuna, CA, 95540; (218) 343-3321; emn213@humboldt.edu; Richard Brown, Carrington Hilson, Micaela Szykman-Gunther, Tim Bean
Juvenile survival of ungulates is known to be highly variable, yet it is fundamental to understand the dynamics and trends of wildlife populations. Factors influencing calf survival are poorly understood in northwestern California. The objectives of this study were 1) to estimate summer calf survival, annual calf survival, and determine recruitment rates for Roosevelt elk (Cervus canadensis rooseveltii) in the area, 2) to evaluate the effects of sex, study area, estimated birth weight, and birthdate on summer calf survival, and 3) to identify factors influencing elk survival by investigating mortalities across all age classes. During 2017 and 2018, our study captured and marked 58 calves and 29 cow elk in Del Norte and Humboldt counties. Preliminary analysis suggested that summer survival was high, with survival rate varying during the first 14 weeks of life. Annual calf survival also appears to have been high, but the analysis is ongoing. A total of 42 mortalities (tagged and opportunistic) was investigated from December 2016 through October 2018, but this work will continue through May 2019. This work is an ongoing collaboration and this information will be used by the California Department of Fish and Wildlife in the management of this game species.
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