NABat: How the USGS Tracks North America's Bats

U.S. Geological Survey Fact Sheet 2020–3008, February 2020. By Brian E. Reichert and Suzanna C. Soileau.

Bats under pressure

North American bats face growing threats. The fungal disease white-nose syndrome (WNS) has killed more than 6 million bats of many species since it appeared in 2007, and it now spans the continent. Wind turbines, which physically endanger bats, and habitat loss and fragmentation threaten some species too. And because bats are secretive and fly only at night, where they live and how many there are is still poorly known.

Why they matter. Bats make up a fifth of all mammal species and live on every continent but Antarctica. They keep ecosystems healthy by eating insect pests, pollinating plants and spreading seeds. As the main predators of many night-flying pests, they likely save farmers billions of dollars a year in the United States and elsewhere.

At risk. Eight North American bats are federally endangered or threatened, and more than half are of conservation concern in the United States, Canada or Mexico:

• Florida bonneted bat (Eumops floridanus)
• gray bat (Myotis grisescens)
• Hawaiian hoary bat (Lasiurus cinereus semotus)
• Indiana bat (Myotis sodalis)
• Mexican long-nosed bat (Leptonycteris nivalis)
• northern long-eared bat (Myotis septentrionalis)
• Ozark big-eared bat (Corynorhinus townsendii ingens)
• Virginia big-eared bat (Corynorhinus townsendii virginianus)

The program

The North American Bat Monitoring Program (NABat) began in 2015 to gather what is needed to conserve and manage bats across the continent. It uses standardised surveys to track the 47 bat species of the United States, Canada and Mexico, at local, state and range-wide scales — helping managers spot early signs of decline, estimate extinction risk, set priorities and judge whether management works.

The USGS leads, manages and coordinates NABat and does its own bat research. It:

• builds platforms for common standards and protocols — collecting, managing, validating, curating and delivering data;
• develops statistical models and management tools for acoustic and colony count data;
• links NABat with the WNS surveillance and diagnostic database, for earlier detection, risk assessment and control;
• acts as the hub for communication and coordination across countries.

The results inform decisions on WNS surveillance and bat vulnerability, on reducing the effects of energy development, on conservation before species are listed, and on land management.

Tools and projects

Acoustic surveys. Bats find their way and catch insects in the dark by calling almost continuously, above the pitch humans can hear, and listening to the echoes. Recording and analysing those calls lets scientists survey bats, map where species live, document range expansions and new occurrences, and set baselines as WNS spreads.

The probability of finding little brown bats across Colorado, modelled by the USGS from recorded bat calls — blue higher, red lower. Maps like this track where species live and their status before white-nose syndrome or other threats arrive.

Colony counts. Where bats gather in large numbers in caves, winter and summer colonies are surveyed for distribution and local abundance. The counts show the patterns and causes behind colony size, hibernation behaviour and habitat use, and feed models that predict which regions and species are most at risk from WNS — so management and surveillance can be targeted.

A bat ecologist from the Kentucky Department of Fish and Wildlife Resources counts bats. Photo: Ann Froschauer, U.S. Fish and Wildlife Service.

The Partner Portal is a one-stop shop for guidance and resources, with an interactive map and database of NABat projects. Anyone can share bat monitoring data there: https://sciencebase.usgs.gov/nabat/#/home/ (choose "Request an Account").

Built on partners

Partners' data are NABat's foundation: they give the baseline on where bats are and how many, measure the effect of threats, and underpin conservation priorities and checks on management. Partners are encouraged to send not only new data but also legacy data (from before NABat) and found data (collected outside the formal design), which NABat folds into status and trend assessments.

Partners who contributed data in 2019 included:

Sources

• Reichert, B.E., and Soileau, S.C., 2020, U.S. Geological Survey science in support of the North American Bat Monitoring Program (NABat): U.S. Geological Survey Fact Sheet 2020–3008. https://doi.org/10.3133/fs20203008 · https://pubs.usgs.gov/publication/fs20203008
• Boyles, J.G., and others, 2011, Economic importance of bats in agriculture: Science, v. 332. · Irvine, K.M., and others, 2020, bat occupancy model predictions for Colorado: USGS data release, https://doi.org/10.5066/P9LXCTC4
• The introduction, the partner counts and the figures come from the fact sheet's PDF. Its bat photographs sit inside the text layout, and its banner photo is credited to a state agency, so neither is reproduced here.
• NABat: https://www.nabatmonitoring.org/
• Rewritten in hubnx's own words.