How cold does it need to be to kill Florida's iguanas and Burmese pythons?
Temperatures in Palm Beach County are expected to plunge into the chilly 50s and upper 40s Tuesday morning with daytime highs lingering in the low 70s through the week's end.
But the dip in mercury readings driven by a biting northerly wind are unlikely to cull South Florida's invasive green iguana or Burmese python populations.
While the pernicious reptiles may be cold-stunned temporarily — a paralysis that can cause iguanas to fall from their perches in trees — the sunny days forecast at least through Friday gives them time to warm up and regain their mobility.
What temperature do iguanas 'freeze' and potentially fall out of trees in Florida?
Florida Fish and Wildlife Conservation Commission officials said iguanas can become immobilized or sluggish when temperatures hit between 40 and 50 degrees. Longer cold snaps with overcast skies that prevent basking for warmth can be deadly as the paralyzed iguanas become easy prey to vultures, bobcats and coyotes.
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Also, when the lizards are immobilized by the cold, their digestive systems sour and they die from bacterial infections. Iguanas that fall from trees onto streets are also in danger of becoming road kill.
Pythons have an advantage that iguanas don't — they can generate heat by shivering.
The last significant die-off of iguanas and pythons caused by cold weather occurred during the winter of 2010 when between Jan. 2 and Jan. 13, West Palm Beach's overnight lows dipped into the 30s nine times.
For Palm Beach, Broward and Miami-Dade counties, it was the coldest 12-day period since at least 1940, according to the National Weather Service. By the end of February, the NWS declared 2010 the coldest winter for South Florida in three decades.
A study published later that year by University of Florida wildlife ecology professor Frank Mazzotti and colleagues found that some pythons who died during the cold spell didn't seek shelter from the cold. Others, however, did find burrows to hide in during the cold and survived. It was unclear whether the survival behavior was learned, genetic, or happenstance.
"While it is indisputable that large numbers of pythons died, attempts to interpret these deaths with respect to python ecology are complicated by a number of factors, including behavior, availability of refuges, and unknown variation in detection probabilities," the study said.
By Wednesday, overnight temperatures will creep back into the low 60s in coastal Palm Beach County. Daytime highs will gradually warm through the week with Saturday and Sunday lingering near 75 degrees.
The normal daytime high for this time of year in West Palm Beach is 75 degrees. The normal overnight low is 59 degrees.
Kimberly Miller is a veteran journalist for The Palm Beach Post, part of the USA Today Network of Florida. She covers real estate and how growth affects South Florida's environment. Subscribe to The Dirt for a weekly real estate roundup. If you have news tips, please send them to kmiller@pbpost.com. Help support our local journalism, subscribe today.
This article originally appeared on Palm Beach Post: Iguana, pythons in Florida can 'freeze' die from cold weather
