In the journal Herpetology News, Vladimir Dinets of the University of Tennessee at Knoxville and his colleagues have reported the results of their study of the reptiles' tree-climbing and tree-basking behavior.
Observation of crocodile species on three continents -- Australia, Africa and North America -- revealed four species climbed trees, usually above water, but how far they ventured upward and outward varied by their sizes, the researchers said.
Smaller crocodiles were able to climb higher and further out than the larger ones, they said; some species were observed climbing as far as 13 feet high in a tree and 16 feet out on a branch.
"Climbing a steep hill or steep branch is mechanically similar, assuming the branch is wide enough to walk on," the researchers reported. "Still, the ability to climb vertically is a measure of crocodiles' spectacular agility on land."
Tree climbing and basking are believed to be driven by two conditions, they said: thermoregulation and surveillance of habitat.
"The most frequent observations of tree-basking were in areas where there were few places to bask on the ground, implying that the individuals needed alternatives for regulating their body temperature," they said. "Likewise, their wary nature suggests that climbing leads to improved site surveillance of potential threats and prey."