In Florida, why are iguanas falling from trees?

Florida, renowned for its sunny and warm climate, occasionally faces cold snaps that create a bizarre and concerning phenomenon: iguanas falling from trees. This unique occurrence is primarily observed in the green iguana population, an invasive species in Florida. The reason behind this strange event is deeply rooted in the biology of these reptiles and the climatic conditions of Florida.

Understanding the Biology of Iguanas

Green iguanas are ectothermic, or cold-blooded, creatures. This means they rely on external sources of heat to regulate their body temperature. In their native habitats, which are typically warm, this is not an issue. However, Florida’s occasionally fluctuating temperatures present a challenge.

When temperatures in Florida drop into the 40s and 30s Fahrenheit, as observed during certain winter cold fronts, these iguanas experience a dramatic change in their physiological state.

As the temperature falls, the iguanas enter a hibernation-like state, known as torpor. In this state, their metabolic processes slow down significantly, and they become less responsive. This sluggishness is a protective mechanism, allowing them to conserve energy until warmer conditions return. However, it also comes with a notable downside: loss of muscle control.

The Fall of the Iguana

This loss of muscle control is the key to why iguanas fall from trees during cold weather. Many green iguanas in Florida reside in trees, a behavior that ordinarily offers safety from ground-based predators. However, as their bodies cool and enter torpor, they lose their grip and, consequently, fall to the ground. These fallen iguanas can appear to be dead, but they are often still alive, albeit in a state of shock or dormancy.

The Impact on Florida’s Ecosystem

The green iguana is an invasive species in Florida, first sighted in the 1960s, and has since proliferated across several counties. While primarily herbivores, they have been known to pose a threat to native fauna, including endangered tree snails.

Their presence also affects the infrastructure by digging burrows that can damage sidewalks, foundations, and seawalls. The Florida Fish and Wildlife Conservation Commission (FWC) has provided several recommendations for deterring iguanas, including removing plants that attract them and using physical barriers.

Human Interaction and Safety

When encountering a ‘frozen’ iguana, the FWC advises caution. These animals can transmit salmonella, posing a health risk to humans. While green iguanas are not protected in Florida, except by anti-cruelty laws, the FWC recommends humane methods for handling them. In cases where iguanas freeze, they may suffer brain damage, leading to the recommendation of humanely euthanizing the animal.


The phenomenon of iguanas falling from trees in Florida is a stark reminder of how wildlife can be affected by changing environmental conditions. It underscores the challenges faced by non-native species in adapting to environments that are significantly different from their original habitats.

For Florida residents, it’s a phenomenon that requires understanding, caution, and responsible action, balancing the well-being of these reptiles with the health and safety of the community and the preservation of local ecosystems.