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The Center for Native Grasslands Management

Title: Survival and cause-specific mortality of northern bobwhites in western Oklahoma
Year: 2004
Author(s): Cox, S. A., Peoples, A. D., DeMaso, S. J., Lusk, J. J., Guthery, F. S.
Source Title: Journal of Wildlife Management
Source Type: Journal
pages: 663-671
Original Publication: http://  
Abstract: We present descriptive data on survival and cause-specific mortality of northern bobwhites (Colinus virginianus) in western Oklahoma, USA, during 1991–2002. We captured and radiomarked 2,647 bobwhites (286 adult [ad] M, 1,064 juvenile [juv] M, 185 ad F, and 1,049 juv F) to obtain estimates. We estimated that annual survival (Nov–Oct) averaged 0.068 ± 0.018 (SE) and ranged between 0.018 ± 0.048 and 0.211 ± 0.038. We pooled data over the study period and found that sex–age classes survived at similar rates. We estimated average annual isolated rates of bobwhite mortality (rates in the absence of other causes) to be 0.63 ± 0.027 from raptor predation, 0.45 ± 0.021 from mammal predation, and 0.45 ± 0.043 from harvest. Under the additive theorem of probability, the isolated rates translated to an average annual mortality rate of 0.88 ± 0.017. The bobwhite population had variable and sometimes low survival in November–February inclusive. Low monthly survival (<0.5, n = 7) during winter was due primarily to harvest (0.57 ± 0.099 losses/known-fate individual) and raptor predation (0.25 ± 0.051 losses/known-fate individual). We discuss evidence indicating that radiotransmitters handicapped bobwhites and resulted in survival estimates biased low and to uncertainty in interpretation of cause-specific mortality.