Mediterranean geckos (Hemidactylus turcicus) in two temperate zone urban habitats

Background/Question/Methods

Hemidactylus turcicus, the Mediterranean Gecko, is a potentially invasive species that has successfully colonized many urban and suburban areas outside its natural range. In the United States, H. turcicus is reported to have invasive potential in warm, southern states from Florida to southern California.  The literature suggests that introduced populations of Mediterranean Geckos do not occur outside the immediate vicinity of humans and they are most often found on anthropogenic structures such as the exterior surfaces of buildings. We evaluated two populations of H. turcicus in a temperate region of the central United States, one at the University of Central Oklahoma (UCO) and another at the Oklahoma City Zoo (ZOO).  Mark and recapture sampling was conducted at UCO from 2006-2007 and during 2008 at ZOO.  The sizes of the populations at the two sites were estimated using the Schnabel method and population densities were calculated using those estimates. Demographic data, including age class of captured animals, sex of adults, and gravid status of adult females were collected at both sites.  

Results/Conclusions

Population densities in animals per ha of land and per ha of building footprint area were similar at the two sites, but considerably lower than population densities reported in warmer regions of the country.  Low population densities at our temperate zone sites might be a function of the limited time available for foraging and reproduction in colder climates which likely reduces the invasive potential of this thermoconforming species in temperate zones.  Population density per ha of building exterior wall area was higher at ZOO than at UCO, while the spatial extent of the population at UCO was higher than that at ZOO.  These differences in the Oklahoma populations might be related to the higher building density and land cover by anthropogenic surfaces at UCO between buildings, which might facilitate diffusion dispersal there relative to ZOO.   We are currently evaluating characteristics of individual buildings at the UCO campus to determine what microhabitat characteristics facilitate successful colonization of some buildings there and inhibit it on others.