Bat Population Monitoring at Sagamore Hill National Historic Site

For some surveys, biologist use special nets, called "mist nets," to catch bats. Here, a biologist carefully removes a bat that's been captured in a mist net.

Why is the park interested in bats?

Bats are an important part of ecosystems and food webs. Though some species of bats feed on fruit, seeds, or pollen, the species that live in New York 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, biologists are studying how local bat populations are changing.

Research Highlights

• Seven species of bats have been documented in the park, including a federally and state threatened species—the northern-long eared bat.
• Northern long-eared bats may be the most common bat in the park. It’s possible that Long Island provides a refuge for this federally threatened species.
• White-nose syndrome has dramatically reduced the abundance of some bat species.

How do biologists study bats? What have they learned about bats in the park?

Biologists use a variety of techniques to study bats. Bats use echolocation to navigate and catch insect prey during the night. People can’t hear these bat calls, but biologists can use special microphones, called acoustic detectors, to record the sounds. By analyzing the bat calls, biologists can identify which bat species are present in an area.

Scientists have other creative ways of studying these amazing animals. Special nets (i.e. mist nets) are used to catch bats at sites in the park. After capturing a bat, biologists can identify the species, determine the sex of the animal, evaluate its age, and examine the wings for damage from the white-nose fungus.

To date, seven species of bats have been documented at Sagamore Hill. During acoustic surveys in 2017, the most frequently detected bat was the federally threatened and state endangered northern long-eared bat (Myotis septentrionalis; see figure below). Across much of the Northeast, northern long-eared bat populations have been decimated by white-nose syndrome. That said, recent data indicates that northern long-eared bats remain relatively common on Long Island—it’s possible that Long Island is serving as a refuge for these rare bats.

Figure 1. Activity levels of bat species recorded by an acoustic detector over 172 nights at Sagamore Hill National Historic Site, April – October, 2017.

Three species of tree bats have been documented at Sagamore Hill—the silver-haired bat (Lasionycteris noctivagans), the eastern red bat (Lasiurus borealis), and the hoary bat (Lasiurus cinereus). Tree bats migrate south for the winter and are not susceptible to the disease—no tree bats have been observed with symptoms of white-nose syndrome.

In contrast, little brown bat (Myotis lucifugus) populations have been dramatically reduced by the disease. Once the most common bat in New York, little brown bats are now rare across the Northeast. In the park, very few little brown bat calls have been recorded in recent surveys.

Despite their listing as a federally threatened species, northern long-eared bats appear to be relatively common at Sagamore Hill. Why is this the case? Biologists aren't sure, but ongoing research will hopefully help answer this important question.

NPS photo / Morgan Ingalls

What is the park doing to protect bats?

The data being collected on bats is helping park managers conserve bats and their habitat. Protecting trees and snags where bats raise their young and minimizing the loss of mature forests will help reduce the impacts of the disease. There is still much to learn and research efforts are ongoing. White-nose syndrome is an extraordinarily dangerous threat to bats—sadly, some species may ultimately disappear from the region.

Want to learn more?

• Bats in national parks
• White-nose syndrome response team
• Bust some bat myths!

For more information:

Contact National Park Service Biologist Lindsay Ries.

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