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Individual Highlight

Long-term Attachment of Miniature Data-loggers Reveal Novel Aspects of Bat Ecology

Photo of A bat with an attached GPS tag. Ted Weller, USDA Forest ServiceA bat with an attached GPS tag. Ted Weller, USDA Forest ServiceSnapshot : Migratory routes used by bats and their behavior during migration have long been difficult to ascertain. Data logging tags were attached to hoary bats using dissolvable sutures. Long distance, but non-directional, movements during the migratory period were recorded as were long bouts of torpor during winter. Both of these observations greatly expand knowledge of ecology of this species.

Principal Investigators(s) :
Weller, Ted 
Research Location : Humboldt Redwoods State Park, Humboldt County, California
Research Station : Pacific Southwest Research Station (PSW)
Year : 2015
Highlight ID : 815


Most temperate bat species engage in annual movements between their summer and winter habitat. Migratory movements have been inferred from patterns in distributional records, stable isotope ratios, and, in certain circumstances, recoveries of marked individuals. But the actual migration routes used by bats and their behavior during migration are difficult to ascertain. Forest Service scientists teamed with the U.S. Geological Survey, Bat Conservation International, and a veterinarian to pioneer the use of dissolvable sutures to attach two types of tags to migratory hoary bats: GPS tags and newly developed tags which log, temperature, activity, and light levels. During autumn 2014, Forest Service scientists attached eight GPS tags and six multi-data-loggers to male hoary bats. They obtained 10 GPS locations from three bats and retrieved data from two loggers. GPS tags revealed that some hoary bats regularly travel more than50 kilometers (about 31 miles) per night, but flight directions were not predictable. One hoary bat traversed 1,000 kilometers (about 621 miles) during October 2014 with the last fixed location 130 kilometers (about 81 miles) from its starting point. Multi-data-loggers accurately logged light levels and ambient temperatures and allowed the scientists to construct nightly activity budgets for individual bats, in one case over an 8-month period. By linking activity and temperature data from the data logger with local weather data, the scientists were able to determine that one bat engaged in multi-week bouts of torpor during the winter. The distance and direction of migratory movements as well as use of long-term torpor during winter are new aspects of this species’ ecology.?

Forest Service Partners

External Partners

  • Bat Conservation International
  • USGS
  • Wildlife Veterinary Consulting LLC

Program Areas