Demographics and population persistence of Gehyra variegata (Gekkonidae) following habitat fragmentation

Predicting the effects of habitat fragmentation on the demographic characteristics and habitat use of a species is critical for managing that species in fragmented habitat. In contrast to other geckos, Gehyra variegata exhibits a high level of occupancy in remnant habitat in the Western Australian wheatbelt. In this study, I compare the population characteristics of G. variegata in 12 smooth-barked Eucalyptus woodland remnants with those in similar woodland communities in three nature reserves. Population sizes in the remnants ranged from 11 to 545 and were highly correlated with remnant size while sex ratios and age structure were reasonably consistent among remnant and nature reserve populations. These data suggest that populations are most affected by habitat or characteristics associated with habitat such as food and shelter availability and are inconsistent with stochastic effects associated with small population size. Habitat use varied markedly between remnant and nature reserve populations, with the lizards largely confined to logs or eucalypts in habitat remnants but using shrubs in the nature reserves with high frequency. This indicates that habitat change has caused G. variegata to alter its habitat usage and emphasizes the value of being able to occupy a wide variety of habitats. Comparison of the demographic characteristics of G. variegata populations with those of other species of geckos suggest that the generalist habitat requirements, stable population structure, and long life expectancy in adulthood (all typical of G. variegata) are important contributors to its ability to persist in remnant habitat.