Migrant Lizard, Having Made It in New York, Heads Elsewhere – via Herp Digest

by Jim Dwyer, 8/25/16 New York Times 

For centuries, New York City has been the gateway to a new land, and now residents believed to have originated around warm, sunny Tuscany are moving on after a few years of city life. How they managed to get by in this colder, more crowded climate is being studied by Colin Donihue, a biologist doing postdoctoral studies at Harvard University.

“It looks like they’ve moved up the Metro-North line into Connecticut,” Dr. Donihue said. “There’s also a population in Hastings-on-Hudson.”

His subjects are Italian wall lizards, escapees from pet stores in the Bronx and on Long Island during the past 40 to 50 years. They are less than four inches long. On the ground, they move at Usain Bolt speeds. They are also sprinters in evolutionary change.

“It’s a body plan that has been around for hundreds of millions of years,” Dr. Donihue said. “That’s the cool part of this story. We have this historical perspective that evolution is one of these processes that takes a really, really long time. But we’re also finding that evolutionary changes can take place over a few generations.”

The same lizard family proved its rapid adaptability when it was introduced to an island off Croatia. Instead of their usual fare of all insects, all the time, the lizards began eating flowers, berries and leaf bits. A researcher found that after being on the island for 36 years, they had developed a new pocket in their gut to help them process the plant material. What the New York branch did to survive city life and migration north is being studied by Dr. Donihue and Max Lambert and Greg Watkins-Colwell, colleagues at Yale University.

The adaptability of species to urban life is an area of blooming interest; cities are the dominant human ecosystem. Their intense environments make them ideal laboratories for watching the pace and character of change, as Menno Schilthuizen wrote in The New York Times’s Sunday Review last month. In Vienna, spiders learned to build webs near streetlights, letting them catch a bounty of moths. In Amsterdam, Madrid, Berlin and Prague, among other places, European blackbirds that left the forests for cities now sing at a higher pitch so they can be heard over traffic, and have developed calmer temperaments.

The boundaries of ecosystems, never really fixed, have been broken by long-distance air and ship travel. Bird-eating snakes got to Hawaii in the landing gear of airliners, and feral camels wound up roaming Australia, as Alan Burdick chronicled in his acclaimed 2005 book, “Out of Eden: An Odyssey of Ecological Invasion.”

How did the Italian lizards get to New York? A Bronx commercial pet dealer sold about 120 of them in the late 1960s as natural pest control to the township of Mount Laurel, N.J. Legend has it that a pet truck got in a crash in the Bronx. “That’s the origin myth,” Dr. Donihue said. More reliably documented are the lizards that made a break for it about 15 miles from the Bronx, getting out of a damaged carton at a pet store in West Hempstead, N.Y. Still others were released in Ohio, Kansas and British Columbia.

Around New York City, the lizards have been found in at least four of the five boroughs: at Queens College in Queens; the New York Botanical Garden and Pelham Bay Park in the Bronx; Washington Cemetery in Midwood, Brooklyn; and Baker Field in Upper Manhattan.

The Italian lizards are not pushing out native New York lizards; there were none. “Across the board, this is just an interesting ecological oddity,” Dr. Donihue said.

His study of their movement into Greenwich, Conn., was reported last month by Peregrine Frissell in The Hour, a local newspaper. Dr. Donihue hopes to track the lizards, though he has yet to find any tags that fit. He wants to find out how far north they can move, and what they do to survive winters much colder than in their native range. As hiding spots from predators like cats, snakes and birds, the rocky beds of the train tracks could be lizard nirvana, Dr. Donihue noted.

If these lizards are leaving the city for Connecticut, it is the reverse of the journey of Chester Cricket, the star of the 1961 book “The Cricket in Times Square.” Smelling liverwurst, Chester hops into a picnic basket in Connecticut and ends up being cared for by a boy whose family runs a newsstand in the Times Square subway station.

Do the lizards have a lovable classic in them?

“I think it’s possible they are jumping on a train,” Dr. Donihue said. “But it’s more likely that they are just running up the train tracks. They’re really fast, and it’s a straight runway.”

Italian lizards invade Greenwich, CT – via Herp Digest

Greenwich Time, By Peregrine Frissell, Sunday, July 24, 2016

GREENWICH — Non-native Italian wall lizards have begun to appear in town, according to a Harvard researcher who says they may be riding the Metro-North train into Fairfield County.

Harvard post-doctoral fellow Colin Donihue has been studying their migration and plans to return to Greenwich next month as he tries to solve the mystery of how they got here and how they are surviving in a much cooler climate than they are used to.

There has been a population living in Bronx, N.Y., since a pet truck crashed and led to their escape to the urban wild in the 1960s, Donihue said. He it’s possible this population has spread north using the Metro-North train lines.

“It’s a really nice expressway for them to travel distances,” Donihue said. “Those little guys move pretty fast.”

He said the loosely packed stone beneath the tracks provides good shelter from predators and easy access to backyards full of insects and warm laundry ducts.

“It seems these little Italian wall lizards are really making use of human heat sources in order to make it through the winter,” Donihue said. “It’s also great habitat to hide from predators.”

Another explanation could be that an area resident went on vacation to Italy, where they are very common, and brought some back to live in their garden, Donihue said. He said there are populations in Kansas and Los Angeles that are known to have started that way.

He has sent tissue samples to geneticists at the University of California-Merced to see if the lizards, which are harmless to humans and pets, found in Greenwich are related to those from the Bronx.

Donihue is trying to find more specific information about the migration patterns of these lizards. He has considered trying to put GPS chips on them like people do with their pets or larger wild animals, but all the current models are too large for the small, 4-inch body of the lizard to handle.

He has seen some backyards with as many as 15 to 20 lizards, which leads him to suspect the entire Greenwich population is in the hundreds, but somewhere shy of 1,000. Donihue said he first needs to figure out how far from the tracks they have strayed to determine a more accurate population estimate.

He is also trying to determine if they have reached beyond Greenwich’s border into Stamford.

Donihue’s research is focused on how animals adapt to live in human landscapes. He has been studying a sister species of the lizard in Greece for the past five years, and is interested in discerning how the Connecticut lizards are changing to thrive in such a different environment.

“It would feed into this bigger question of what makes an invasive species successful, and how can we understand how those species are evolving to live side-by-side with humans,” Donihue said

He believes their metabolisms are slowing down and becoming better regulated than their relatives in Greece and Italy to adjust to the cold, but he doesn’t think that’s the only thing allowing them to expand this way.

“We’re starting to talk about animal personalities, so maybe these lizards right at the invasion front are more risk-taking or interested in trying out new types of food or exploring different areas,” Donihue said.

The only lizard native to Connecticut is a skink, which has a blue tail that is much longer than the Italian invaders, which tend to be greener in color.

Greg Watkins-Colwell, collection manager at the Peabody Natural History Museum at Yale University, has worked in the field locating lizards with Donihue.

He said Donihue first learned about the lizards when someone posted a picture of one on Facebook.

“It’s one of those odd things where social media actually made a difference,” Watkins-Colwell said.

Watkins-Colwell isn’t sure how far north the species will reach, but the rest of the communities along Metro-North could be fair game.

“It kind of makes sense for a lizard that is adapted to live on stone walls and archeologic ruins to use what is effectively a pile of rock as its habitat,” he said. “It’s interesting from a conservation perspective, because you can predict where they will be. You can start watching for them up the line.”

If you have seen a wall lizard, contact Donihue at colin_donihue@fas.harvard.edu.