Large reptiles and cold temperatures: Do extreme cold spells set distributional limits for tropical reptiles in Florida?

Abstract

Abstract. Distributional limits of many tropical species in Florida are ultimately determined by tolerance to low temperature. An unprecedented cold spell during 2-11 January 2010, in South Florida provided an opportunity to compare the responses of tropical American crocodiles with warm-temperate American alligators and to compare the responses of nonnative Burmese pythons with native warm-temperate snakes exposed to prolonged cold temperatures. After the January 2010 cold spell, a record number of American crocodiles (n = 151) and Burmese pythons (n = 36) were found dead. In contrast, no American alligators and no native snakes were found dead. American alligators and American crocodiles behaved differently during the cold spell. American alligators stopped basking and retreated to warmer water. American crocodiles apparently continued to bask during extreme cold temperatures resulting in lethal body temperatures. The mortality of Burmese pythons compared to the absence of mortality for native snakes suggests that the current population of Burmese pythons in the Everglades is less tolerant of cold temperatures than native snakes. Burmese pythons introduced from other parts of their native range may be more tolerant of cold temperatures. We documented the direct effects of cold temperatures on crocodiles and pythons; however, evidence of long-term effects of cold temperature on their populations within their established ranges remains lacking. Mortality of crocodiles and pythons outside of their current established range may be more important in setting distributional limits.

Can animal habitat use patterns influence their vulnerability to extreme climate events? An estuarine sportfish case study

“…Tropical species in Everglades National Park and in the subtropics, both are unable to physiologically tolerate extreme cold temperatures (thermal specialists Tewksbury, Huey, & Deutsch, ), and can display behaviors that hinder their survival during extreme cold spells (Boucek, Gaiser, et al., ). For instance, tropical American Crocodiles show maladaptive behaviors during extreme cold spells compared with more temperate American Alligators (Mazzotti et al., ). During these events, American Crocodiles bask out of the water to warm themselves even though basking during cold windy days has a deleterious cooling effect.…”

Investigating Sub-tropical Community Resistance and Resilience to Climate Disturbance

“…This added protection may be particularly important for highly managed tropical fisheries that due to harvest are increasingly responsive to climate stressors (Britten et al 2014;Santos et al 2016;Stevens et al 2016). On the other hand, habitats that have landscape features that offer high resistance to these disturbances, could be identified and set aside as refuges for endangered and or imperiled tropical species occurring in the sub-tropics such as American Crocodiles (Mazzotti et al 2016). Similarly, these cold spell refuge habitats could serve as key introduction sites of the species being considered for assisted migration programs and translocation conservation strategies.…”

“…Decreases in the frequency of these events may also increase the population stability of threatened tropical species occurring within the sub-tropics (i.e., American crocodile; Mazzotti et al 2016), as well as increase habitat suitability in the sub-tropics for tropical species threatened by climate warming (Liu et al 2012;Kemp et al 2016). Regardless of the fate of extreme cold spells in the future, our special issue highlights key responses that we can expect subtropical systems to exhibit in light of these extreme events.…”

“…Tropical species in Everglades National Park and in the sub-tropics, both are unable to physiologically tolerate extreme cold temperatures (thermal specialists Tweksbery 2010), and utilize behaviors that hinder their survival during extreme cold spells (Boucek et al 2016a). For instance, tropical American Crocodiles show maladaptive behaviors during extreme cold spells compared to more temperate American Alligators (Mazzotti et al 2016). During these events, American Crocodiles will attempt to bask out of the water to warm themselves, despite that basking in the cold windy days during events have deleterious cooling effects.…”

“…During these events, American Crocodiles will attempt to bask out of the water to warm themselves, despite that basking in the cold windy days during events have deleterious cooling effects. In contrast, American Alligators, adapted to coping with cold, will actively seek warm water refugia during these events (Mazzotti et al 2016). Like American Crocodiles, snook exhibit somewhat mal-adaptive movement behaviors with respect to risk from cold disturbances.…”