Record Details

Bock, Brian C;Paez, Vivian P;Rand, A Stanley;Burghardt, Gordon M
Life table and stochastic matrix projection analysis for a population of Green Iguanas (Iguana iguana): implications for conservation and control
Iguanas: Biology, Systematics, and Conservation
Book Section
John B Iverson, Tandora D Grant, Charles R Knapp and Stesha A Pasachnik
Monograph 6
Herpetological Conservation and Biology
Iguana iguana
The Green Iguana (Iguana iguana) may be the most studied of all Neotropical squamate species. Given that many populations are over-exploited, and other introduced populations represent problems for native species, it is surprising that so few of the publications on the species have had a demographic focus. Here we resurrect data that formed the basis of previous publications on a population of Green Iguanas in Panamá that included female growth rates, nest site fidelity, and nesting migrations and hatchling growth rates and dispersal. We reanalyze these data from a demographic perspective, using a maximum likelihood modeling approach, to obtain estimates of survival for nesting females and hatchlings. These results, combined with available information on age at first reproduction, fecundities, and hatching success rates, permit us to construct a life table for this population that is concordant with information on its demographic tendencies (a 13.6% annual decline in number of nesting females). We then produce a stochastic projection matrix and conduct sensitivity and elasticity analyses to identify those vital rates that most influence the population growth rate. Both analyses suggest that survival rates during the first two to three years of life most strongly influence demographic tendencies. These results are interpreted both from the perspective of proposing management measures to help over-exploited iguana populations recover, and also to help control or eliminate introduced populations. We suggest that modifying hatchling and juvenile survival and growth rates would be a viable strategy for either augmenting or reducing Green Iguana population sizes