Population ecology of Florida Key deer

Increases in urban development, habitat fragmentation, and human-deer interactions threaten the recovery and management of Key deer. Urban development is of particular concern because previous studies have documented that highway mortality accounts for the majority of the total deer mortality, and is related to urban growth. The study objective was to evaluate the impacts of urban development on the demographics of the deer population. Key deer were radio-collared (n = 314) as part of 2 separate field studies (1968–72, 1998–00), in addition to the collection of mortality data and survey estimates (1966–00). Collectively, these data were used to estimate survival, mortality, habitat use, density, ranges, and dispersal. Furthermore, a Population Viability Analysis (PVA) also was conducted for the Key deer using these estimates. Highway mortality accounted for the majority (50%) of the total deer mortality. Other human-related mortality factors, such as fence entanglement and dog-kills, have increased in recent years. Efforts to reduce deer mortality were encouraged, however, the resulting increase in deer numbers might lead to high deer densities. Current density estimates (450–515) suggest that population increases over the last 30 years on Big Pine and No Name keys have placed the deer population at or near carrying capacity. Further increases in deer numbers might result in damage to vegetation and an increased likelihood of disease. A need to stabilize deer numbers via other alternatives (e.g., contraception) might be necessary. Upland vegetation types such a pinelands and hammocks are important to Key deer, and the acquisition and management of these vegetation types is recommended in the future. Deer dispersal between islands is low, and that might require biologists to manage other island populations using translocations. Prior to conducting deer translocations, however, factors that limit the self-increase of deer numbers should be identified. Severe hurricanes continue to threaten the Key deer population. The only Insurance against the risk of population extinction is to increase the number of deer on other islands and to initiate a captive propagation program. PVA results suggest some additional development can occur on Big Pine and No Name keys without jeopardizing the overall viability of the Key deer. Future development should be directed in areas where the least impact to the deer population would be expected. The implementation of a Habitat Conservation Plan for Key deer on Big Pine and No Name keys is recommended to solve the current environmental conflict between efforts to protect the Key deer, and economic and social pressures for development.