Despite their long, bulky shape, crocodiles can climb trees, according to a new study by the University of Tennessee. Though scientists have already observed such behavior, lead researcher Vladimir Dinets of Tennessee's psychology department was the first to study it in depth.
Dinets and colleagues Adam Britton and Mathew Shirley observed crocodiles in Australia, North America, and Africa and charted four different species (of the 23 total species present on earth, according to crocodilian.com) that could climb. They reasoned that the reptiles used trees to scan the area and regulate their body temperatures when there wasn't ample or safe enough basking ("laying out") space on dry ground. As proof for trees as a surveillance post, many of the crocodiles dove into the water when a researcher came too close.
"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," the authors wrote. "Likewise, their wary nature suggests that climbing leads to improved site surveillance of potential threats and prey."
Crocodiles don't venture extraordinarily high because (a) they aren't extremely gifted climbers (and become less so as they increase in size) and (b) it isn't necessary. Some species observed, like the Central African slender-snouted crocodile (a slightly below average sized croc and the most frequently documented "climbers"), only go as far as a tree trunk fallen horizontally across a river bed. Others, like the American crocodiles (as well as American alligators) perch themselves slightly higher, on the branches of Mangrove trees grown outward on river banks (see picture below).
Though newborn Australian crocodiles are equipped to "climb vertical brickwork" (but lose that ability as they grow), crocodiles as a whole are not physically suited for climbing. Even as the authors note the similarities between climbing a "steep hill" and a "steep (tree) branch," they attribute a fair amount of crocodiles' aboreality to their "amazing agility on land."
Because crocodiles show no physical signs of tree climbing ability, the authors note that scientists, specifically paleontologists, should be open to the possibility that the ability exists in other extinct crocodile species, despite what the fossil evidence says.
"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."
