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1 November 2005 Survival, cause-specific mortality, sex, and ages of American black bears in Washington state, USA
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Wildlife managers often rely on data from hunter-harvested animals for monitoring structural and numerical changes of hunted animal populations, including American black bears (Ursus americanus). Some analyses of hunter-harvested animals assume that sex and age data from harvested animals accurately reflect the demographic structure of the population. We compared sex and age structure from black bears harvested by hunters to estimates of survival rates and causes of mortality for 136 radiomarked male and female black bears at 3 locations in Washington state. These areas reflect the vegetative and geographic variation within Washington and differ in amount of precipitation, vegetation conditions, behavioral ecology of bears, and hunter harvest. We estimated survival rates from marked bears for hunting and non-hunting seasons to determine whether these data may be represented in the hunter-harvest sample, and compared median age and survival rates for marked bears with life-table survival estimates for bears killed by hunters in each of the 3 regions during 1994–99. We compared survival rates from marked bears and from hunter-harvest data before and after a 1996 voter initiative that banned hunting bears with hounds and bait to determine whether changes in harvest regulations influenced survival of bears and was detectable in hunter-harvest data. Humans accounted for 98% of mortalities for study-marked bears, and legal hunter harvest and hunter-wounding loss accounted for 64% of documented mortalities. Survival rates calculated from marked males (0.73) and females (0.93) were similar to those from hunter-harvested males (0.76) and females (0.83). Median ages for bears from hunter-harvest data were greater than for study-marked bears. We lacked power to detect possible differences in survival rates between pre- and post-initiative periods among marked bears or hunter-harvest samples. We conclude that data from hunter-harvest reports may be adequate for management objectives; however, they do not represent all mortalities, with non-reported hunter harvest, wounding loss, and depredation control hunts likely accounting for additional mortalities.

Gary M. Koehler and D. John Pierce "Survival, cause-specific mortality, sex, and ages of American black bears in Washington state, USA," Ursus 16(2), 157-166, (1 November 2005).[0157:SCMSAA]2.0.CO;2
Received: 6 August 2003; Accepted: 1 June 2004; Published: 1 November 2005

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