Conservation and management of the American crocodile

Abstract

The American crocodile is a rare and endangered species, the range of which has contracted to disjunct locations such as Hispaniola, Jamaica, Cuba, Panama, and southern Florida. In an attempt to determine what factors might be limiting population growth, an extensive collaborative research program was conducted in 1978-82 in southern Florida. Limiting factors explicitly studied included climate, hurricanes, population dispersion, nesting habitat, fertility, predation, nest chamber environment, juvenile survivorship, artificial mortality, disturbance, and environmental contamination. No single natural factor limits the population, although in concert various factors result in low adult recruitment rates. Such natural limitations explain the natural rarity of this tropical species at the temperate limits of its range. Two artificial sources of mortality are death of adults on roads and the flooding of nests by high groundwater tables. These sources of mortality are potentially controllable by the appropriate management agencies. Active management, by such means as protection of individuals, habitat preservation and enhancement, nest site protection, and captive breeding, is also appropriate for assuring the survival of a rare species. The American crocodile has survived in southern Florida in face of extensive human occupancy of parts of its former nesting habitat, demonstrating the resilience of a threatened species. This case history illustrates the efficacy of conducting research aimed at testing specific management hypotheses, the importance of considering biographical constraints limiting population status in peripheral populations, the need for active management of rare species, and the role of multiple reserves in a conservation and management strategy.

Roadkills of vertebrates in Venezuela

“…I). According to KUSHLAN (1988), among the causes of unnatural mortality for American crocodiles, Crocodylus acutus Cuvier, 1807 (Crocodylidae), the most common cause of death was being struck by automobiles. Opossums occur in very different habitats, both natural and anthropogenic, and even in the centres of big cities (CORDE- RO 2000).…”

Road-killed bats, highway design, and the commuting ecology of bats

“…Collision with vehicles is the primary cause of death of moose Alces alces in the Kenai National Wildlife Refuge in Alaska (Bangs et al 1989) and of barn owls Tyto alba in the UK (Newton et al 1991). Road kill also takes a significant toll on Iberian lynx Felis pardina populations in southwestern Spain (Ferreras et al 1992), white-tailed deer Odocoileus virginianus in New York (Sarbello & Jackson 1985), wolves Canis lupus in Minnesota (Fuller 1989), and American crocodiles Crocodylus acutus in southern Florida (Kushlan 1988). While much documentation of road-kill mortality has focused on terrestrial mammals, birds, reptiles and amphibians, the impact of highways on bat populations has only recently been identified (Kiefer et al 1995, Wray et al 2006, Lesinski 2007, López et al 2007).…”

Climate Change Impacts on Florida’s Biodiversity and Ecology

“…The framework included: increased mortality during road construction, increased mortality from collision with vehicles, modification of animal behavior, alteration of the physical environment, alteration of the chemical environment, spread of exotic species, and increased alteration and use of habitats by humans (increased accessibility). Collision with vehicles has been documented to be a significant cause of mortality for several Florida species, including the Florida black bear (Neal et al 2003) and the Florida panther (Kautz et al 2006, Coffin 2007, and as a limiting factor in the recovery of the endangered American crocodile in Florida (Kushlan 1988). In the case of the Florida panther, the incidence of roadkill mortality has been reduced with the installation of underpasses along Interstate 75 and State Road 29 (Kautz et al 2006).…”