AS TEMPERATURES DROP, EXPECT TO SEE DAZED IGUANAS

By the Lake & Wetland Management Biology Team

Ah, December!  ’Tis the season for decking halls, singing carols, drinking gallons of eggnog and wassail, and in south Florida, frozen iguanas, lots and lots of frozen iguanas.  Adore or despise them, Green Iguanas (Iguana iguana) introduced as releases from the pet trade have become a permanent addition to south Florida’s wildlife.  And during the winter months when many are trimming trees, cold-dazed iguanas in south Florida are falling out of them whenever the mercury dips.

Despite its name, the Green Iguana is usually only vibrant green when young, assuming an array of other hues as it ages.  Adult males can be especially colorful, splashed in a rainbow of jade, black, white, gray, yellow, copper and orange.  A native of tropical Central and South America, the Green Iguana has adapted well to life in south Florida.  Mature males can attain lengths of 6.5-feet and as adults, Green Iguanas have few predators.  Being herbivorous, Green Iguanas treat south Florida as a big salad bar and thrive on a steady diet of both native and exotic vegetation.  They have an especial penchant for red flowers and can often been seen grazing, cropping grass along canal banks.  This vegetarian diet often puts iguanas at odds with gardeners and landscapers and the big lizards’ resulting copious droppings foul walkways, pool decks and lawns.  Further, iguanas’ muscular forelimbs make them accomplished diggers and their nesting and burrowing activities cause a great deal of erosion and expense along our lakeshores and canal berms.

South Florida would seem a paradise for these adaptable lizards, that is until we experience a winter cold spell.  The winter of 2010 was especially cold and put a significant dent in Florida’s iguana numbers.  Under 50°F iguanas become sluggish.  Under 40°F iguanas become catatonic and go into a torpor.  Larger adults are more likely to weather temperature drops in deep burrows.  Smaller and mid-sized individuals tend to roost in trees and shrubs and are far more susceptible to exposure, causing iguanas to literally tumble from the trees and resulting in widespread mortality.  Cleanup of iguanas that succumb to the chill following extreme cold snaps can be gruesome and costly, but such events are heartily appreciated by our native Black & Turkey Vultures, aquatic turtles, alligators and other wildlife able to enjoy such a grisly banquet.  Winter freezes are also one of the few factors that keep south Florida’s burgeoning iguana population in check.  Happy holidays, Everyone!