Gecko Collection: A Vital Resource

Geckos are amazing. Depending on the species — there are 1,500 species — they can defy gravity, glide through the air and even run on water (sort of). Geckos live in warm climates on all the continents except Antarctica. In the U.S., their native range is from southern California to South Texas.

So what are they doing in Stacey Wright’s Northeast Philadelphia living room?

“I think it came in when I moved a plant inside from the porch. The cat saw it before I did,” said Wright, who happens to be an Academy Visitor Services coordinator. “I had to fight the cat to get it. I didn’t want the cat to eat it in case it’s poisonous.”

Being a typical Academy employee who cares deeply about nature and the environment, Wright wrestled the few-inches-long gecko from her cat, secured it in a plastic cup for her SEPTA commute to work, and handed it over to Herpetology Collection Manager Ned Gilmore to be identified, catalogued and subsumed into the collection.

Turns out the critter is an insect-eating Mediterranean house gecko, Hemidactylus turcicus, an invasive species spotted with increasing frequency hanging out on the exterior of houses in Philadelphia’s Fox Chase, Northern Liberties and South Philly neighborhoods. Several have made their way into Wright’s living room.

All this has made the Academy’s gecko specimens and research data a hot commodity these days, as researchers from the community science project GeckoWatch are using the information to track the distribution of geckos where they don’t usually occur in nature. We asked for an explanation from Gilmore and gecko expert Aaron Bauer, PhD, professor of biology at Villanova University.

Holy Gecko! Are we being invaded by Mediterranean house geckos?

Gilmore: I wouldn’t say invaded, but they seem to be all over the place. There was a population in Baltimore for a while, and now they are spreading in the Philadelphia area.

Should we be worried?

Gilmore: They eat roaches, spiders and other insects, which is not necessarily a good thing but maybe it is if they are in your house.

Why did you choose to study the Academy’s collection of geckos?

Bauer: Pennsylvania and New Jersey are a “new frontier” in the expansion of geckos, and the Academy is the one collection that has voucher specimens that confirm their occurrence in the region.

How is the Academy’s collection helpful to your research?

Bauer: The Academy’s collection allows us to confirm the specific identity of the geckos, and it helps us date the arrival and spread of the geckos in the region. In addition to Hemidactylus turcicus several other gecko species have introduced populations in the U.S.

How did the Mediterranean house gecko come to the Philly area in the first place?

Bauer: Geckos (or perhaps their eggs) were likely accidentally transported with goods being shipped from some place where the geckos were already established.

Does climate change have anything to do with the spread of this gecko species to Philly?

Bauer: Philly’s winters are too cold to allow the geckos to live outside year-round.  So, although climate change may have allowed the gecko to expand northward in the southern U.S., its arrival in Philadelphia is more a matter of chance. Nonetheless, warming temperatures may mean that their chances of becoming established are better and that the chance of more introductions may increase.

What are you finding so far in your Philly gecko project?

Bauer: Our data from Philly complement work all over the country that shows us that this gecko is amazingly adaptable. In their natural habitat in the Mediterranean, they occur in very restricted habitats. Once they got to America, however, they found a way to survive in the deserts of the southwest, in subtropical Florida, in continental climates in the southern Midwest, and now in the urban Northeast. Philly is especially interesting because the geckos must overwinter in protected habitats inside houses or other buildings. Thus, we would predict that their ability to spread would be limited in comparison to areas where they can move freely throughout the year.

Anything else you’d like to add?

Bauer: Modern transportation systems for goods, both nationally and globally, coupled in some places, with climate change, make the spread of introduced species ever more common. Although we now know that geckos are here, it will be important to keep tracking them to understand how and why they move through the area or remain localized. People can help by taking cell phone photos of geckos with date and geographic coordinates and providing this to GeckoWatch.

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By Carolyn Belardo, Aaron Bauer and Ned Gilmore

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In the Academy’s “Spotlight on the Collections” series, we tell stories about specimens chosen by our scientists and also how researchers and others around the world depend on our collections for issues involving climate change, water quality, evolution, and biodiversity and extinction.

To read the first installment in the Spotlight on the Collections series, visit “Protecting America’s Food Supply.”