Bats do it. So do dolphins, whales, and even some rats and shrews. Echolocation is the amazing ability to navigate and possibly even "see" using sound waves; it's a sixth sense that's rare in nature. But now another obscure mammal may have joined the ranks of creatures with this extraordinary ability: the Vietnamese pygmy dormouse.
If confirmed, it would make this rodent the first arboreal — or tree-climbing — mammal known to use echolocation, reports New Scientist.
Perhaps it shouldn't come as too much of a surprise. Pygmy dormice are competent acrobats in the trees, and yet they're nearly blind. Life in the trees should be perilous without some way of navigating around the high-up weaves of branches. So exactly how these rodents manage an arboreal lifestyle has been something of a mystery.
To test them for their ability to echolocate, Aleksandra Panyutina at the Russian Academy of Sciences in Moscow and her team took advantage of having access to the small population of these seldom-studied endangered critters that reside at the Moscow Zoo. They filmed the dormice climbing amongst branches in their cages while recording the sounds they produced.
By syncing the video with the audio, it became obvious that the rodents made more chirps while they were moving. These chirps were also similar to the rapid, ultrasonic pulses that bats use when they echolocate, strongly suggesting that the animals were using the sounds to navigate.
Researchers have not yet tested whether the dormice can actually hear echoes from the calls — which is essential to the function of an echolocation sense — but all the evidence so far suggests that they must. The animals even have large, bat-like ears ideally designed for such an ability.
The research is not just exciting for what it reveals about dormice; it could also help to answer an age-old question about whether flight or echolocation was the first thing to evolve in bats. If a tree-climbing, nocturnal rodent has evolved the ability to leap among branches with ease in the dark, then it strengthens the idea that bats could have acquired echolocation before they fully took to the air too.
“It is conceivable that the terrestrial ancestors of echolocating bats used echolocation in a similar way,” said Gareth Jones, a bat researcher at the University of Bristol in the United Kingdom.
The research has been published in the journal Integrative Zoology.