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.
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