Walking along one of Peru’s rainforest foot path’s is an adventure you’ll never forget. No matter where you look, there’s something new and exciting to see. Up in the tree canopy, red howler monkeys leap from branch to branch and yell what sounds like hideous insults down at you. You round a corner, spooking a tayra, a large weasel. Nearby, a Bolivian squirrel darts up a tree, it’s bushy tail twitching with irritation.
Smiling, you pause long enough to watch the squirrel disappear into the canopy which is when you see a tree with tightly rolled leaves. One of the leaf rolls seems to be trembling. You gently start to unravel it. It quivers against your fingers as you work. Your heart pounds. Hoping you’re about to reveal a brightly colored, benign insect rather than a poisonous spider, you continue to work at the leaf, both eager and a little scared to reveal its hidden secret.
Instead of a large bug, huddled up inside the leaf is one of the smallest bats you’ve ever seen. It’s so tiny, it hardly seems real. Sunlight glints off the bat’s longish, reddish brown fur as it fastens the disc-like suckers attached to its thumbs more firmly to the newly unraveled leaf and glares up at you with intense, intelligent eyes. Behind the bat, a tail membrane that’s several shades darker than the animal’s hair and seems nearly as big as the bat’s body fan’s out on the leaf.
Congratulations, you’ve just become one of the very few people to have stumbled upon the hiding spot of a LaVal’s disk-winged bat, an extremely rare species of bats that’s named after Richard K. LaVal, an American zoologist.
The best place to stumble upon members of this species is near streams. They seem to prefer finding roosting leaves in areas that don’t attract a great deal of traffic (human or animal) and that are close to flowing water sources, which presumably attracts the types of insects this particular bat species prefers eating. Most sightings of this bat have taken place in parts of the rainforest where there are quite a few evergreen trees. LaVal’s disk-winged bats have been found in both Peru, Brazil and Ecuador. It’s possible that their habitat extends even further, a hypothesis that’s based on the 2004 discovery of a LaVal’s disk-winged bat fossil in Columbia.
Sadly, very few resources have been devoted to the study of the LaVal’s disk-winged bat. The little bit of information that does exist is primarily presumed. What we do know is that this tiny, adorable bat is a member of the thyropteridae and that it’s insectivorous.
One of the reasons that so little is known about LaVal’s disk-winged bats is because very few end up in the mist nets researchers set up. This could be because the bats are wiley and able to avoid capture, but the more likely reason is that the nets simply haven’t been set up across the specie’s flight paths.
The few times researchers have found LaVal’s disk-winged bats revealed mixed information about the species. For example, researchers in Ecuador found some in a low-level mist net that had been erected in a terra firm forest that was near a palm swamp, while another instance of the species making its way into mist nets took place in Southern Peru were mist nets had been set up in an upland forest setting that featured shrubs, rolling hills, and minimal understory. When I was researching the species, ICUN (the page was published in 2016) indicated that less than 10 specimens had ever been collected
The second reason researchers haven’t dedicated much time to the species is because it’s preferred range isn’t easy to get to. This species prefers to live in parts of the rainforest that remain intact and which are difficult to access. While the location makes research challenging, it’s good for the bats. It means that they’re natural roosts and feeding areas likely haven’t been disturbed and that their population remains strong.
The ICUN currently has the LaVal’s disk-winged bat listed as DD, which means data deficient.
“Thyroptera Lavali: LaVal’s Disk-Winged Bat.” Encyclopedia of Life. Web. Accessed 4
“Thyroptera Lavali” ICUN Red List of Threatened Species. Web. Accessed 4 November 2017.