The wetlands at the University of Washington, Bothell and Cascadia Community College campuses serve as a serene place for the public to admire, for ducks, bald eagles and goldfinches to call home, for crows to roost and for salmon and trout to swim. There’s also an unseen bat population that Bothell’s wildlife biologist, Greg Green, is keeping an eye on … or an ear to!
Greg monitors bats year-round through an ultrasonic, acoustical detector that extends 10 feet off the ground in the wetland.
He says, “All calling bats that pass within 30 meters of the detector are recorded.”
In summer, Greg gets 50 to 75 recorded bat passes each night.
His goal is to determine when bats become most active or return from migration in the spring, when they hibernate and when they move south in the fall. For hibernating bats, Greg records whether they are waking during the winter months and looking for food and water.
Greg identifies the bats according to species using a software program called SonoBat. The program records and identifies each bat’s unique call.
“The bats most common at the wetland are the Big Brown Bat and Silver-Haired Bat, followed by the Little Brown Bat,” he says.
So why do we care about these little guys?
As bats eat insects, pollinate plants and scatter seeds from fruit trees, they are viable to a healthy ecosystem. What an advantage for us to have these bats eating mosquitoes, termites and other pests! It’s their protein and our gain. And, the Silver-Haired Bat even feeds on moths.
“We have a few species of local moths that breed in the winter, which the Silver-Hairs may be waking up to exploit,” says Greg.
There’s a condition, however, that worries Greg. The disease, called white-nose syndrome, hit Little Brown Bats on the East Coast. This fungus destroys hibernating bat colonies, which Greg says, “May rival the passenger pigeon with respect to individual loss.”
As of now, the disease appears to not have affected the more than 15 species of bats in the Pacific Northwest.
As for their roosts, Big Brown Bats seek out buildings where they hibernate and form maternal colonies. Silver-Haired Bats like trees and roost under bark or in woodpecker cavities. The Silver-Haired Bat generally migrates south for winter.
Greg’s detector also found California Myotis and Yuma Myotis, which are tiny “mouse-eared” bats. They, too, roost and hibernate in buildings.
Greg discovered, other than the Silver-Hairs and California Myotis, none of the other bat species became active last year until mid May. Bat activity peaks in July when the pups emerge, with most activity stopping in September.
“All hibernating bats wake up every few weeks to replenish water, which they get by licking the dew off their fur or from the walls of caves,” says Greg.
But, a building or tree-hibernating bat may have to venture out in winter to find water.
If you’re tempted to go looking for bats, please don’t disturb them. In winter hibernation, if they have to suddenly awaken, they’ll use a month’s supply of fat trying to escape and may starve before spring. We need these gentle little creatures to stick around and stay healthy. They need a safe habitat, as they play a vital role in creating a flourishing environment.
Suzanne G. Beyer is a Bothell resident.
