Investigating the Nightlife at Moses Coulee

Story Highlights
  • At Moses Coulee, our scientists and volunteers are making great strides in studying bats. Specialized audio equipment helps us study their unique calls.

    You can help! Each summer we invite volunteers to help us listen for bats at the coulee. Our next bat surveys are scheduled for July 29-30, 2011. Contact liz_jonhson@tnc.org for details

Located in Douglas County, Moses Coulee Preserve covers over 4,000 acres of shrub steppe.

Bats, especially evening (or vesper) bats, are mysterious in many ways. Bats are excellent at hiding away during daylight hours, they fly quickly, and some species are difficult to distinguish from one another. Their breeding habits, social habits, migratory habits and habitat needs can be difficult to track.

At Moses Coulee, our scientists and volunteers are making great strides in studying this elusive species.

Sonobat: A High-Tech Hearing Aid

Moses Coulee is the hot spot for bats in Washington state, home to 14 of the 15 native species of bats. Most bats produce echolocation calls unique to their individual species. Though usually far beyond the range of human hearing, specialized audio equipment has made it possible to record the high frequency calls and determine the presence of individual bat species.

To do this we use a sonogram analysis program called Sonobat to import and interpret our recorded bat calls. Sonobat works by creating a full-spectrum and time-expanded visual image of each recorded call. Simply put, Sonobat displays each call’s full audio frequency in slow-motion time and the resulting image can then be analyzed to determine which species of bat was recorded.

Citizen Scientists

Of the 14 bat species making use of the coulee, the spotted bat, Euderma maculatum, is the only species which produces an echolocation call audible to the unaided human ear. The call can best be described as a series of soft metallic clicks heard as the bats fly overhead searching for insect prey. As the bats zero in on prey, the clicks speed up to a rapid buzz, referred to as a feeding call.

The Conservancy found an opportunity in this simple detection method and created a citizen science project where volunteers of all ages are invited out on selected nights to help conduct acoustic surveys of the bats as they fly up and down the coulee. By taking a short time to train and educate volunteers on the species and its dependence upon the surrounding intact and undisturbed landscape, we share our message of habitat protection and conservation in a meaningful way.

Simultaneously, we are able to gather useful data on spotted bat presence and behavior as they emerge from their night roosts to forage along the coulee walls and grab drinks of water from the nearby falls and lake.

You Can Help!

The Conservancy has conducted spotted bat surveys every year in late summer since 2003. Each year brings veteran participants, who love the opportunity to spend a night sitting quietly out in the coulee under a star filled sky, and new volunteers eager to learn and listen for the distinct call of the spotted bat.

This year will mark the Conservancy’s ninth year completing the bat surveys. The surveys are scheduled for July 20-21, 2012. Contact Julie Edwards for details

Go Deeper: The Bat Grid

The Conservancy is an active participant in the Bat Grid Inventory and Monitoring Group, a partnership of 20 agencies and organizations designed to collect as much baseline data about the presence of bats in Washington and Oregon as possible.

By training people to collect data in the same way, the Bat Grid enables all the organizations and agencies interested in bats to collaboratively build a huge archive of data and allow researchers to investigate questions across longer periods of time and greater geographic areas than ever before.


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