Aim: 

To study the thermoregulatory behavior of the green iguana (Iguana iguana) maintained in captivity within an enclosure during summer (mean temperatures: June max 27°C, min 20 °C; July max: 30 °C, min 21 °C, August max: 31 °C, min 22 °C) in the central part of Mallorca, Balearic Islands (Spain) with ad libitum water, food and free access to different thermal niches.

Methods: 

Three green iguanas were implanted with I-Button data holders recording the abdominal temperature (0.1°C) every hour during three summer months. Six additional temperature data holders were located in different places of the maintenance enclosure to record the environmental temperature. The difference between abdominal and environmental temperature served to plot the thermoregulatory responses of the animals.

Results: 

Four main thermoregulatory modes were recorded. Type I: dawn temperature rise (mean duration: 3.4 h, temperature increase 4.07°C/h), followed by a descent (duration: 5.0 h, -2.1°C/h) and thermoconformity during the remaining time until dusk. Type II: rapid temperature rise, similar to Type 1 followed by steady, near-maximal temperature maintained until dusk. Type III: thermoconformity, with <2°C difference with environmental temperature. Type IV: undefined, with a variable profile of body temperature.

Conclusion: 

The green iguana has been shown to behave as a facultative behavioural thermoregulator in the defined geographical location and season, with capacity to maintain a controlled body temperature independent from the environment