Recruitment and Loss in an Unhunted Subtropical White-Tailed Deer Population

Abstract

Reproduction and mortality of white-tailed deer (Odocoileus virginianus seminolus) in eastern Everglades National Park, Florida, have been studied by live-capture and radiotelemetry since March 1987. As of 1 September 1989, 106 captures of 68 individuals have been made, and 58 deer have been radio-monitored for 81 deer-years. Estimated minimum pregnancy rates of adults and yearlings have averaged 82 and 33%, respectively. There is no evidence of breeding among female fawns. Only singleton fawns have been observed. Most (57%, n = 49) experienced 3-year-old mothers have recruited young (raised fawns to yearlings) compared with 1 of 9 (11%) inexperienced 2-year-old mothers. Estimates of annual fawn mortality have varied from 18% to 58% (x = 34%). Estimated annual mortality of yearlings (37%) approximates that of fawns. Radio-tagged deer 2 years old have been lost at an annual rate of 17%; there is some indication that the mortality rate of 2-year-olds is higher than that of older adults. Predation by Florida panthers (Felis concolor coryi) has accounted for most (67%, n = 15) deaths of deer 1 year old. Assuming a field-observed sex ratio of 1:2 for yearlings and adults and given preliminary estimates of age-specific rates of natality and mortality, annual net recruitment to the population is estimated at 7%. This may be offset by the loss of dispersing young males. The Everglades deer population appears to be highly k-selected and relatively stable, indicative of a system with consistently low primary productivity.