MIAMI – In South Florida, a peculiar occurrence captures the attention of onlookers nationwide as cold-stunned iguanas descend from trees when temperatures dip below a certain threshold. While it may appear strange, there is a scientific explanation behind this phenomenon.
Among the various iguana species inhabiting Florida, the green iguana stands out as the most prevalent, tracing its origins back to Central and South America. As per the Florida Fish and Wildlife Conservation Commission, green iguanas are classified as invasive within the state.
Iguanas, like all reptiles, struggle to cope with cold climates due to their cold-blooded nature, necessitating external heat sources for temperature regulation. Ron Magill, the Communications Director at Zoo Miami, notes that once temperatures fall below 50 degrees Fahrenheit, iguanas become sluggish. When the mercury drops below the mid-40s, they enter a dormant or cold-stunned state, sometimes toppling from their arboreal perches. Despite appearing lifeless, they maintain vital bodily functions while in this state, a self-protective measure until temperatures rise above 50 degrees.
Magill emphasizes that the impact of cold weather on iguanas varies based on individual size, with larger specimens enduring lower temperatures for extended periods. Adult male iguanas can grow up to 5 feet in length, weighing as much as 20 pounds.
Many iguanas in South Florida have adapted by burrowing deep underground for insulation against the cold. They also gravitate towards large bodies of water, typically retaining higher temperatures than the ambient air, aiding their survival during brief cold spells.
The influx of green iguanas, Mexican iguanas, and spinytail iguanas from Central and South America into South Florida has transformed them into an invasive species, transcending mere nuisance value. These giant reptiles have caused substantial structural harm and even power disruptions. Reports abound of iguanas ravaging gardens, invading pools, and even infiltrating toilets. Additionally, they pose a risk of transmitting salmonella to pets.
Experts warn that the unchecked proliferation of iguanas threatens Florida’s native fauna, including gopher tortoises, sea turtles, and burrowing owls. In response, Florida prohibited the ownership of iguanas as pets in 2021. The absence of natural predators in the state has enabled one female iguana to lay up to approximately 70 eggs annually.
Non-native invasive species such as iguanas do not enjoy protection in Florida except under anti-cruelty statutes, permitting landowners to humanely eliminate them with consent.
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