WDFW -- Crossing Paths Newsletter

Bat behavior monitored

The rare Townsend’s big-eared bat colony north of Spokane that is featured on WDFW’s “BatCam” on the website (http://wdfw.wa.gov/wildwatch/) is being monitored by Eastern Washington University graduate student Theresa Mathis under the direction of Dr. Peggy O’Connell. Theresa’s latest report provides some interesting insight into bat behavior and seasonal activity that BWS managers with other more common bats might find interesting:

“This has been a very exciting year for observing Washington’s easternmost colony of Townsend’s big-eared bats. With the first appearance of bats to the maternity colony on April 4th , I thought we were off and running. However, the bats had very different ideas. Throughout April, May, and June the bats came and went. The most bats present were 52 on June 26th. Many days there were no bats present at all.

Then the “season” began with a bang on July 5th with the arrival of 85 bats. By July 7th their numbers had increased to 103. The first birth observed occurred midmorning on July 9th. The entire process, from the onset of labor until the young was cleaned up and nursing, took approximately 1 1/2 hours, at which point, the mother flew off with her young.

Just eleven days later, on July 16th, the first juvenile was seen roosting alone.

By July 20th juvenile bats were roosting in clusters together and the first juvenile flights were observed July 24th.

By August 1st some of the juveniles were emerging with the adults. It appears they are staying near the cabin and just trying out their wings.

Some possible things to see via the bat cameras on the website is “allogrooming” or bats grooming each other. This doesn’t happen often but is quite interesting to watch when it does. They bite around the ears and the neck, sometimes they bite along the back and then the belly, but most of the attention is paid around the neck and base of the ears.

Most of the crawling that is seen is probably being done by a juvenile bat. They will land and crawl from one cluster to another. Or, if the mother has left it roosting alone, it may crawl to another nearby bat.

As of August 3rd many of the mothers were still carrying their young and nursing continues. Many of the young are getting quite large and they seem to lag behind during flight and landings. You may also catch a glimpse of a juvenile roosting on the back of an adult female with a young under her wing.

Emergence, or when the bats leave the roost at night to forage, is generally occurring between 8:45pm and 9:30pm. Once the adults have left the cabin the young bats can be seen flying around inside the cabin. Several can be caught in one image at a time on the camera. On nights when emergence is not being taped we will try to focus the camera on a group of roosting juveniles. However, as they are very active (think toddler) they may move out of camera range.”