Manager, Community Science
Natural History Museum of Los Angeles County
Natural History Museum of Los Angeles County
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GeckoWatch is a community science project to map the fine-scale distribution of nonnative geckos in the continental United States. The project is an outgrowth of a collaborative effort by Robert Espinoza and Jeanne Robertson (California State University, Northridge), Aaron Bauer (Villanova University), Heather Liwanag (Adelphi University), and Greg Pauly (Natural History Museum of Los Angeles County) to examine what factors are allowing the Mediterranean House Gecko to be such a successful and rapidly-expanding colonizer. Although the initial focus was on Mediterranean House Geckos, we realized that similar questions could be asked about any of the nonnative geckos in the United States. The first step to asking these questions is to understand the rapidly changing distributions of these species. And the only way to rapidly collect these distributional data all across the continental US is to enlist the help of numerous community scientists.
Below is a list of nonnative gecko species in the continental United States and the states in which established populations have been documented.
Mediterranean House Geckos (hereafter, MHGs), Hemidactylus turcicus, have been widely introduced throughout the New World from their native range in the eastern Mediterranean. They were first reported in Florida in 1910 and have since spread as far north as Baltimore, MD and as far south as southern South America. By the 1950s, coincident with the development of the interstate highway system, this species began to spread rapidly westward throughout the humid Gulf States and, most recently, into the desert Southwest and Mediterranean habitats of California. They are currently established in 22 states (21 states in the continental US plus Hawaii) and the primary route of dispersal is apparently as cargo stowaways. As human commensals, these geckos inhabit a niche (often called the “porch light niche”) in the US that is not occupied by any native vertebrate (although some treefrogs do forage at porch lights, this is not a primary foraging strategy for these species); thus, they likely have an insignificant impact on native vertebrates. They may, however, negatively impact populations of their invertebrate prey. Future studies of impacts of MHGs on native species would greatly benefit from increased knowledge of the distribution of this species.
In their introduced range, MHGs occur in extremely diverse climates: from the high humidity environments of the southeastern US to the hot, dry deserts of the southwestern US. Research by GeckoWatch scientists will determine whether introduced MHG populations have evolved physiologically and/or morphologically to adapt to their new local climates. Alternatively, MHGs might be an extremely plastic species with broad tolerances to diverse climatic conditions. To place this work in the appropriate environmental context, however, we must first determine the fine-scale distribution of MHGs and characterize the specific climates they experience. This is where GeckoWatch plays a critical role in our investigation.
Lastly, as we determine the current fine-scale distribution of MHGs in North America through community science, we can then compare the current distribution to historical records to test models of range expansion and understand the time course of expansion for this introduced species.
We have every expectation that GeckoWatch will produce new distributional records including new records for states and counties. A similar community science project led by several of the GeckoWatch scientists already resulted in documenting the first established populations of Mediterranean House Geckos in Los Angeles County and the first Indo-Pacific Geckos in Los Angeles and Orange Counties. These latter two records also are the first records of this species in the state.
If community scientists contribute observations to GeckoWatch that document an established population of a species in a county or state where it has not previously been documented, the GeckoWatch scientists will work with the original observer to help them publish their record in the peer-reviewed scientific literature.