Browsing by Author "Schwarz, Lisa Kimberley"

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Survival rate estimates of Florida manatees (Trichechus manatus latirostris) using carcass recovery data
(Montana State University - Bozeman, College of Letters & Science, 2007) Schwarz, Lisa Kimberley; Chairperson, Graduate Committee: Daniel Goodman; Scott Creel (co-chair)
The Florida manatee (Trichechus manatus latirostris) is classified as an endangered species and is also protected under the Marine Mammal Protection Act. The manatees' coastal distribution coincides with areas of high human density, making manatees particularly vulnerable to human impacts. Important management decisions on both the state and federal level rely heavily on extinction models that require estimates of survival and reproductive rates. Current mark-recapture methods are unable to estimate survival rates for younger age classes because many young manatees lack the unique scarring used to identify individuals. Using an age-ratio technique, this research utilizes carcass recovery data to provide estimates of survival rates of Florida manatees < 4.5 years old while quantifying and incorporating all sources of uncertainty. The age-ratio technique requires counts of carcasses in each age class, carcass detection probabilities, and the proportion of animals alive in each age class. In order to determine the count of carcasses in each age class, several models were designed to estimate carcass age at death.