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Age-specific survival of Florida's Crested Caracaras

Morrison, Joan L.
Journal of field ornithology 2003 v.74 no.4 pp. 321-330
adults, breeding, breeding sites, females, fledglings, habitats, juveniles, life history, males, models, nesting, population dynamics, probability, radio telemetry, survival rate, Florida
To evaluate the status of Florida's threatened Crested Caracara (Caracara cheriway) population, knowledge of life history parameters and population dynamics is required. Using the program MARK, I estimated survival rates for adult and juvenile Crested Caracaras from breeding areas in southcentral Florida during the period February 1994 through March 2000. Annual adult survival probabilities estimated from resightings of banded individuals and derived using model averaging were 0.876 for males and 0.906 for females. Results of modeling monthly juvenile caracara survival from radiotelemetry data identified differences in survival for two age groups: juveniles (up to age 3 years) and adults (age >3 years). Using this age-effects model, monthly survival for juvenile caracaras was estimated to be 0.970, indicating an annual survival rate of 0.694 and an overall probability of 0.334 of an individual surviving to age 3, when it could potentially become a breeder. Juvenile caracaras experienced periods of decreased survivorship beginning at two months after fledging, which coincides with the fledglings' independence, and about one year after fledging, when juveniles typically leave their natal breeding area. Along with protecting suitable nesting habitat to enhance survival and breeding of adults, conservation and management strategies for Florida's caracaras should focus on identifying and protecting areas where groups of individuals in the juvenile age class congregate. Such protection would enhance survival of these individuals, thus ensuring their continued recruitment into the breeding population.