Little Brown Bats Surviving and Reproducing at Deer Creek Impoundment

The Forest Service’s on-going efforts to help bats are paying off thanks to research and management working together on the Lakewood-Laona Ranger District of the Chequamegon-Nicolet National Forest in northeastern Wisconsin.

At least 51 Little Brown Bats (Myotis lucifugus) lived in the bat houses at Deer Creek Impoundment this summer. July 26 and 27, 2017, staff from the Northern Research Station’s Institute of Applied Ecosystem Studies and the Lakewood-Laona Ranger District of the Chequamegon-Nicolet banded bats at the impoundment, as part of a genetic study to determine where and why bat populations that are resistant to White Nose Syndrome (WNS) occur. The expansion and dispersal of resistant WNS populations is of critical importance to future bat management.

The first night, three 18-foot tall nets were set up near the bat houses. There was a lot of silent excitement as 51 bats emerged from the houses and swooped around the area, but only two bats were captured during the emergence; a juvenile male and a juvenile female. A third and fourth little brown bat were captured between midnight and 2AM.

All bats were weighed and measured, received a band on a wing, and provided a tissue sample for genetic analysis before being released on-site.

The next day, two banded bats were observed roosting amongst the other bats in the bat houses.

Before sunset, an additional two nets were added across likely flyways near the bat houses to increase capture success.  The bats emerged later than the previous night, and in a few minutes, ten bats were tangled in the nets. As the delicate process of removing bats began, the nets were closed, and everyone focused on processing the catch. Before the night was over an additional three bats were captured in subsequent checks of the nets.

The adult bats showed slight signs of wing damage, indicating they spent the winter fighting WNS infections and had survived. Pseudogymnoascus destructans, the fungus that causes WNS, was first detected in Wisconsin and Michigan in 2014.  Several juvenile bats were also caught, proof that at least some of these Little Brown Bats were able to reproduce despite being exposed to the disease that has killed millions of bats in North America since it was discovered in a New York cave in 2006.

The hope is that these 17 banded bats will be re-sighted this winter during hibernacula surveys, and some of them will survive to return to Deer Creek Impoundment and reproduce next summer. Bats are an important part of the northwoods landscape, eating mosquitos and insect pests that plague our farms and forests. The Lakewood-Laona Ranger District currently has bat houses installed at five of its impoundments and at the Oconto River Seed Orchard, with more bat house installations being planned.