Long-legged Myotis (Myotis volans)
Myotis or "mouse-eared" bats can get confusing! We have seven different kinds here in Washington and there are many more throughout the United States and the world. Many look very much alike, even to the point that scientists have had to lump them together in a "Myotis spp." category in their research. All are small to medium sized and "mouse" colors of gray or brown. Many even have similar echolocation calls.
The Long-legged Myotis is actually one of the easier ones to identify in the field. It is also called the "hairy-winged" bat and if you look under the wings you will see that its fur extends from its body onto its wings as far as its elbows and knees. M. volans is strictly a western bat found from southeastern Alaska to Mexico. It seems to prefer mountain forests, but is also found in moist coastal forests and along waterways in rangeland throughout the west. It uses rock crevices, tree hollows and loose bark, manmade structures, and even fissures in the ground for day roosts.
The Long-legged Myotis is an aerial hunter taking its prey on the wing. Emerging early, it hunts in open areas over water, above treetops or in clearings and it can detect its prey 15 to 30 feet away. Its preferred food is moths, which make up 75-95% of its diet. But it will also take other prey including termites, spiders, small beetles, flies, etc. It is considered an asset to our forests because of its consumption of the spruce budworm moth.
We actually know very little about the biology of the Long-legged Myotis. What little we do know is similar to other myotis. They form maternity colonies that may number in the hundreds. One baby is born in late June or July.
At the end of summer they go to caves or mines to hibernate, but first they "swarm", flying in and out of the cave but rarely roosting. This behavior may serve as courtship and/or to acquaint young bats with the hibernation sites. One thing that is unusual is that the young males appear to be sexually active at this time, although the age when females become sexually mature is not known. After mating, they hibernate in small groups.
In the past, the Long-legged Myotis was considered common. But very little research has been done on it and we do not know a great deal about its population dynamics. Therefore, we cannot determine what impact humans are having on it. As a result, Washington lists it as a Species of Concern.