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Most bats echolocate at a frequency unheard by the human ear, however, some desert species emit echolocation calls within the range of human hearing.
Spotted bats (Euderma maculatum) are an elusive and widely-distributed species throughout the semi-arid deserts of North America. Sometimes called the “Oreo cookie bat,” they sport large, pink ears and spotted fur. Spotted bats roost high among sheer cliffs, but their clicking calls can be heard while they hunt for owlet moths in the canyons of Central Oregon.
The first spotted bat was “officially” documented in Oregon in 1979 when researchers in the Alvord Desert accidentally captured one in a mist net left open overnight. Only four more spotted bat records were reported in the state over the next 24 years, and the idea that spotted bats were extremely rare, or possibly even extirpated, took hold. In 2005, however, listening surveys combined with mist-netting surveys of Central Oregon revealed that spotted bats may be more abundant in the region than previously recognized.
Biologists still have limited understanding of spotted bat distribution and seasonal patterns in Oregon. What we do know is that their calls are most commonly heard near the canyons and cliffs of eastern Oregon’s High Desert.
Pallid bats (Antrozous pallidus) are another of Oregon's high desert bat species. They have a wide range, spanning from Canada to Mexico. While pallid bats typically produce inaudible, high-frequency echolocation calls, this behavior changes while rearing pups. When in the vicinity of summertime maternity roosts, pallid bats will lower the frequencies of their calls to within the range of human hearing.
Serendipitously, both the spotted bat and pallid bat are found in similar arid cliffs and canyons habitats such that both species can be effectively surveyed simultaneously.
We are sending volunteers out to search for both the spotted and pallid bat. Surveys take place just after dark in a variety of locations, from city parks to the remote desert. This is a family-friendly research project and an excellent opportunity to get to know Oregon's night sky!
To sign up for group or individual surveys, please click here.
We will be hosting group outings this year in and near central Oregon. These will be overnight trips where we travel to a campground, train volunteers, and head out for group surveys just before sunset. After the surveys, we will return to camp and sleep under the stars. The Bat Hub is happy to provide transportation, but volunteers are welcome to drive themselves if they prefer. Group surveys will take place:
As in previous years, we encourage folks to go out and listen for bats on their own, after they have completed the necessary training. This will involve driving to a pre-determined survey site and listening for bats for one hour after sunset.
This year, we are adding more formalized surveys for our field crews and partner organizations. Aural surveys will be conducted across Oregon, Washington, and Idaho. Help us to gain a better understanding of spotted bat occupancy and pallid bat maternity roost site selection by spending a few evenings listening for the subtle clicks of the most interesting chiropterans in the Pacific Northwest.
These surveys will follow the NABat survey design and so may be convenient for anyone already conducting passive acoustic monitoring. A virtual training for our partner protocol can be found here (skip to 1:30:00).
We have compiled a playlist of audible spotted and pallid bat calls for surveyors to familiarize themselves with the echolocation and social calls. That playlist can be found on our YouTube channel.
To sign up to participate or just explore where audible bat surveys are being conducted, check out our web map.
If you have any questions or would like to receive project updates, please contact Sara Rose to be added to our list of project partners.
Please note that there is no previous biology or backcountry knowledge required to become a community scientist. There are options for all physical abilities and outdoor experience. Find us on Facebook and Instagram.
For any questions, please contact Sara Rose, volunteer coordinator. We appreciate your interest in the Audible Bats Project.