Italian wall lizards, brought into California from Sicily in 1994, have carved out their own niche in the suburbs of Los Angeles. Some homeowners enjoy the occasional reptile sighting, but environmental organizations, including the Museum of Natural History of Los Angeles, have deemed the small, long tailed lizards an invasive species, The Los Angeles Times reported.

Except scientists don't exactly know how invasive the wall lizard has become, which is why Greg Pauly, curator of herpetology at the Natural History Museum of Los Angeles, tracks the hardy reptiles.

"The question is, what becomes established, and then what impacts are they having on our native species?" Pauly said. "We can't do any studies on how invasive lizards are impacting native lizards if we don't know that they are here. It's pretty scary that we still don't have a good idea of the biodiversity of L.A."

Pauly's team, consisting of high school sophomore Hayden Kirschbaum, her dad, Kenneth, and naturalist Jim Hall, search neighborhoods known for high wall lizard populations and typically catch around 10-12 per outing. The captured reptiles are euthanized and studied in the lab, according to the Times.

"It's super fast and it's super painless," Pauly said of the euthenization process. "You don't get into this line of work because you want to kill animals. Every time I think, 'Does this animal need to be sacrificed?'"

The outings also  help map the spread of wall lizards.

"Since I started studying this population, I've seen literally a thousand wall lizards in this area and just two native lizards," said Pauly. "The takeover feels pretty complete."

Wall lizards aren't the only species to arrive as pets from overseas and establish themselves in southern California. Pauly's traveled to other neighborhoods with gecko and anole populations, according to the Times.

"What we've shown this past summer is there are a ton of these introduced species in Southern California," Pauly says. "Now we want to know what kind of impact they are having."