Bat Population Monitoring at Acadia National Park

An eastern small-footed bat emerging from a rock crevice.
An eastern small-footed bat emerging from a rock crevice. The small wing band on the bat allows biologists to identify this individual bat, should they catch it again in the future.

NPS/Jonathan Fiely

Bats are an important part of ecosystems and food webs. Though some species of bats feed on fruit, seeds, or pollen, all of the species that live in Acadia are insectivores. They consume huge numbers of insects every night, filling a unique ecosystem role as nocturnal insect predators. Unfortunately, a new disease called white-nose syndrome is affecting bats across the United States. To better protect bats, park biologists are studying how local bat populations are changing.

Research Highlights

  • Most bats in the park are hibernating bats that are sensitive to white-nose syndrome.
  • The disease has dramatically reduced bat populations and continues to infect bats.
  • Little brown bats and northern long-eared bats, once very common, are now rare.
  • Much remains to be learned about white-nose syndrome, bat biology, and bat habitat use in Acadia.

How are park biologists studying bats? What have they learned?

Biologists use a variety of techniques to study bats. Since 2008, special “mist nets” have been used to catch bats at specific sites in the park. By recording the number of bats caught each year, biologists can calculate an index of bat abundance. This index shows an 86% decline in bat populations since the arrival of white-nose syndrome in the park.
Line graph showing the sharp decline of the bat index of abundance in the park following the arrival of white-nose syndrome.
Graph showing index of bat abundance in Acadia National Park from 2008-2017. The index is derived from bat captures per unit effort.
Captured bats can reveal important information about local populations. Park biologists can learn when females give birth to their pups (bat babies), the locations of roost sites and movements of mothers and pups, and when and where these mother bats and pups are most vulnerable to disturbance. Biologists also can assess bat health and learn if bats are infected with the fungus.

After capturing a bat, a tiny radio-tracking device can be temporarily attached to the animal. Biologists can then follow bats to important habitats. Once identified, these areas can be protected from park or visitor activities. For example, park biologists have documented different female bats using the same rock features and spots on buildings as maternity roosts over several years. Limiting disturbance to these areas can help protect bat populations.

Biologists have other creative ways of studying these unique animals. Bats use echolocation to navigate and catch insect prey during the dark of night. People can’t hear these bat calls, so scientists developed acoustic call detectors to record the sounds. Special software is then used to analyze the recorded calls, which allow biologists to identify the bat species that made each call, the time of the call, and interpret the bat’s activity (i.e., feeding or navigating) when the call was made.

In all, eight species of bats have been documented in Acadia. These include the federally threatened northern long-eared bat (Myotis septentrionalis), the state endangered little brown bat (Myotis lucifugus), and the state threatened eastern small-footed bat (Myotis leibii). Since 2012, little brown bats and northern long-eared bats are rarely observed.
A close-up of a northern long-eared bat being held by a biologist.
A northern long-eared bat being examined by a biologist.

NPS/Morgan Ingalls

What is the park doing to protect bats?

The data from these efforts provides information to park managers on how to conserve bats and their habitats. Protecting important habitats where bats raise their young or where they hibernate for the winter will help bats while scientists study how to manage the disease. Nevertheless, much remains to be learned about bats, especially as habitats and environmental conditions continue to change.

White-nose syndrome is an extraordinarily dangerous threat to bat populations—sadly, some species may disappear from the park and perhaps across New England.

For more information:

Contact Acadia National Park Biologist Bruce Connery.

Last updated: September 21, 2018