When most people envision crocodiles and alligators¹, they think of them waddling²（摇摆蹒跚） on the ground or wading³ in water -- not climbing trees. However, a University of Tennessee, Knoxville, study has found that the reptiles⁴ can climb trees as far as the crowns. Vladimir Dinets, a research assistant professor in the Department of Psychology⁵, is the first to thoroughly⁶ study the tree-climbing and -basking⁸ behavior. The research is published in the journal Herpetology.

 

Dinets and his colleagues observed crocodilian species on three continents -- Australia, Africa and North America -- and examined previous studies and anecdotal observations. They found that four species climbed trees -- usually above water -- but how far they ventured upward and outward varied⁹ by their sizes. The smaller crocodilians were able to climb higher and further than the larger ones. Some species were observed climbing as far as four meters high in a tree and five meters down a branch.

 

"Climbing a steep hill or steep branch is mechanically similar, assuming the branch is wide enough to walk on," the authors wrote. "Still, the ability to climb vertically¹⁰ is a measure of crocodiles' spectacular agility¹¹（敏捷，灵活） on land."

 

The crocodilians seen climbing trees, whether at night or during the day, were skittish¹²（活泼的） of being approached, jumping or falling into the water when an approaching observer was as far as 10 meters away. This response led the researchers to believe that the tree climbing and basking are driven by two conditions: thermoregulation and surveillance of habitat.

 

"The most frequent observations of tree-basking were in areas where there were few places to bask⁷ on the ground, implying that the individuals needed alternatives for regulating their body temperature," the authors wrote. "Likewise, their wary¹³ nature suggests that climbing leads to improved site surveillance of potential threats and prey¹⁴."

 

The data suggests that at least some crocodilian species are able to climb trees despite lacking any obvious morphological adaptations to do so.

 

"These results should be taken into account by paleontologists who look at changes in fossils to shed light on behavior," said Dinets. "This is especially true for those studying extinct crocodiles or other Archosaurian taxa."

 

Dinets collaborated¹⁵ with Adam Britton from Charles Darwin University in Australia and Matthew Shirley from the University of Florida.

 

Research by Dinets published in 2013 found another surprising crocodilian characteristic -- the use of lures¹⁶ such as sticks to hunt prey. More of his research can be found in his book "Dragon Songs."

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