Great Basin National Park's 2015 Bat Surveys

By Bryan Hamilton, Wildlife Biologist, and Margaret Horner, Biological Science Technician, Great Basin National Park. First published in The Midden*, Vol. 15, No. 1, Summer 2015.*

A Townsend's big-eared bat (Corynorhinus townsendii) and its call pattern. NPS.

White-nose syndrome

White-nose syndrome (WNS), caused by the fungus Pseudogymnoascus destructans, has killed millions of bats in the U.S. and Canada, and it keeps spreading. Bats matter: they're crucial to ecosystems, and their insect control alone is worth billions of dollars a year to agriculture. The Park Service has funded a proactive effort to limit WNS's impact.

The park's response

• Education and screening: Lehman Caves visitors are asked whether their clothes, shoes or gear have been in other caves or mines; if so, they must change or disinfect them first.
• Inventory and monitoring: with the Nevada Department of Wildlife, park biologists are gathering baseline data on bat communities by mist netting, acoustic surveys, radio telemetry and PIT tagging — to learn about species, habitat use, survival, numbers and home ranges.

A hoary bat (Lasiurus cinereus) and its call pattern. NPS.

Listening for bats

Acoustic monitoring identifies species by their echolocation calls, which differ in timing, frequency, amplitude and slope. It has limits, but it's very promising.

A colony in Lehman Caves

The previous year's surveys caught 34 bats leaving Lehman Caves. Townsend's big-eared bats live only in caves and mines, relying on particular microclimates to hibernate, give birth and raise young. The many females and juveniles caught suggest the cave holds a maternity colony — and with over 30,000 visitors passing through, the park needs to know more to manage visits and protect the bats.

Next steps

• PIT tags: park biologists were to learn tagging from Colorado Parks and Wildlife. Readers at cave entrances would log each tagged bat's ID, date and time as it comes and goes — revealing survival, home range and seasonal activity to guide cave management.
• Radio telemetry: Nevada Department of Wildlife biologists would help track bats to their foraging areas, home ranges and roosts.
• Public surveys: two bat surveys open to the public were planned for summer 2015, at Lehman Cave (July 21) and Upper Pictograph Cave (August 1), with mist netting and acoustic work.

Sources

Based on "Park Prepares for 2015 Bat Surveys," by Bryan Hamilton and Margaret Horner, The Midden — Great Basin National Park, Vol. 15, No. 1, Summer 2015, National Park Service; a work of the United States government in the public domain.