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B.B. Ackerman

Publications and source records attributed to B.B. Ackerman.

7 recordsLinked to original sources

Evaluating cost-efficiency and accuracy of hunter harvest survey designs

Effective management of harvested wildlife often requires accurate estimates of the number of animals harvested annually by hunters. A variety of techniques exist to obtain harvest data, such as hunter surveys, check stations, mandatory reporting requirements, and voluntary reporting of harvest. Agencies responsible for managing harvested wildlife such as deer (Odocoileus spp.), elk (Cervus elaphus), and pronghorn (Antilocapra americana) are challenged with balancing the cost of data collection versus the value of the information obtained. We compared precision, bias, and relative cost of several common strategies, including hunter self-reporting and random sampling, for estimating hunter harvest using a realistic set of simulations. Self-reporting with a follow-up survey of hunters who did not report produces the best estimate of harvest in terms of precision and bias, but it is also, by far, the most expensive technique. Self-reporting with no followup survey risks very large bias in harvest estimates, and the cost increases with increased response rate. Probability-based sampling provides a substantial cost savings, though accuracy can be affected by nonresponse bias. We recommend stratified random sampling with a calibration estimator used to reweight the sample based on the proportions of hunters responding in each covariate category as the best option for balancing cost and accuracy. ?? 2011 The Wildlife Society.

Wildlife Society Bulletin↗

Survival estimates for Florida manatees from the photo-identification of individuals

We estimated adult survival probabilities for the endangered Florida manatee (Trichechus manatus latirostris) in four regional populations using photo-identification data and open-population capture-recapture statistical models. The mean annual adult survival probability over the most recent 10-yr period of available estimates was as follows: Northwest - 0.956 (SE 0.007), Upper St. Johns River - 0.960 (0.011), Atlantic Coast - 0.937 (0.008), and Southwest - 0.908 (0.019). Estimates of temporal variance independent of sampling error, calculated from the survival estimates, indicated constant survival in the Upper St. Johns River, true temporal variability in the Northwest and Atlantic Coast, and large sampling variability obscuring estimates for the Southwest. Calf and subadult survival probabilities were estimated for the Upper St. Johns River from the only available data for known-aged individuals: 0.810 (95% CI 0.727-0.873) for 1st year calves, 0.915 (0.827-0.960) for 2nd year calves, and 0.969 (0.946-0.982) for manatee 3 yr or older. These estimates of survival probabilities and temporal variance, in conjunction with estimates of reproduction probabilities from photoidentification data can be used to model manatee population dynamics, estimate population growth rates, and provide an integrated measure of regional status.

Marine Mammal Science↗

Population biology of the Florida manatee: An overview

In the following overview we discuss progress toward meeting the three objectives of the 1992 workshop: to provide a synthesis of existing information about manatee population biology; to evaluate the strengths and weaknesses of current data sets and approaches to research on manatee population biology; and to provide recommendations for research. We discuss progress in six topics that were assigned to working groups at the workshop: aerial survey and estimation of population size, reproduction, age structure, mortality, photoidentification and estimation of survival, and integration and modeling of population data. The overview includes recommendations by working group participants (*2 0'Shea et al. 1992). This workshop on manatee population biology was the most recent conference on the topic since 1978 (*BrowneIl and Rails 1981). Partly as a result of recommendations made at the 1978 workshop, several long-term population-related research projects were established. Therefore, we also measure progress in relation to knowledge available at the time of the earlier workshop. Finally, we provide a brief synopsis of pertinent new information on manatee population biology that became available between the 1992 workshop and publication of the proceedings and our conclusions about the status of the Florida manatee.

Information and Technology Report↗