Aiding the northern long-eared bat
Service and partners team up in battle against deadly white-nose syndrome
Bats provide valuable ecosystem services that impact the world’s economy and our lives. They pollinate cash crops and forests, disperse seeds, produce fertilizer and control pests by devouring insects. Many bat species are in decline, however, due to habitat loss and disease, especially white-nose syndrome (WNS).
The Service has been working with partners promoting conservation, research and innovation to fight back at the national level. In the eastern half of the U.S., the northern long-eared bat (NLEB) has seen severe population declines due to white-nose syndrome (WNS), a disease.that kills bats by increasing the amount of energy they use during winter hibernation and by creating physiological imbalances that can inhibit normal body functions.
Moved by population declines caused by WNS, the U.S Fish and Wildlife Service (Service) listed the NLEB as threatened under the Endangered Species Act on April 2, 2015. At the time, its distribution and behavior in eastern North Carolina was poorly understood. The NLEB was only recently discovered in eastern North Carolina, in 2007.
The North Carolina Department of Transportation (NCDOT) provided funding for five years of NLEB surveys and studies to better understand the species’ distribution and behavior in eastern North Carolina. NCDOT took on this conservation measure to generate the data needed to streamline ESA Section 7 consultations for a large number of transportation projects in eastern North Carolina. NCDOT, the Federal Highway Administration, and the U.S. Army Corps of Engineers entered into a formal five-year agreement (2015-2020).
Four environmental consulting firms were contracted to assist in surveys and studies. Biologists from the Service and the North Carolina Wildlife Resources Commission also conducted bat surveys in eastern North Carolina. Spring/summer mist-netting surveys were conducted to map out the distribution of the species in eastern North Carolina. The researchers also netted and tracked bats during fall/winter to determine where and how NLEBs spend the winter. Additionally, a special maternity study was conducted during spring/summer 2019 to acquire information on reproduction. Since the studies began in 2015, the number of counties in eastern North Carolina with NLEB capture records has increased from four to 18. These captures occurred during all four seasons of the year within the Coastal Plain. Nearly all the captures occurred less than 30 miles from the ocean or sounds and generally occurred either in or adjacent to swamps. Despite significant survey efforts, no NLEBs have ever been captured in the Piedmont Region of North Carolina. The lack of captures within the Piedmont suggests geographically separate populations of these bats in North Carolina, with the centrally-located Piedmont separating the population in the Mountain Region from the population in the Coastal Plain. This hypothesis is supported by North American Bat Monitoring Program acoustic data which suggest little to no presence of NLEB in most of the Piedmont of North Carolina.
Perhaps the greatest discovery was the documentation that NLEBs are present and active during the winter in the outer portions of the Coastal Plain. Prior to these studies, it was generally understood that all NLEBs hibernate in caves or mines during the winter. However, small transmitters were attached to 44 bats over three seasons, and the bats were then tracked through all months of winter and were observed utilizing multiple tree cavities. These winter roost trees varied in species and size and mostly occurred in or adjacent to swamps.
This portion of the state is nearly devoid of caves or mines suitable for hibernacula, but also experiences milder winters in comparison to most of the species’ range. Although insect activity is reduced during winter, it appears that there is sufficient prey available for the bats to forage during most of the winter. However, during record low temperatures in January 2018, some bats did go into torpor (a state of decreased physiological activity, usually by a reduced body temperature and metabolic rate) for a few days until temperatures returned to normal.
Because federal protections focus mostly on the locations where NLEBs roost during the pup season (a sensitive life stage), researchers conducted maternity studies in spring/summer 2019. In the northeast corner of the Coastal Plain, 20 reproductive females were tracked to 64 roost trees. Although tree species and sizes varied, most were swamp species and tended to be smaller in size than expected.. Reproduction in the Coastal Plain occurs somewhat earlier than in more interior populations of the species. In the Coastal Plain of North Carolina, non-volant (non-flying) pups are likely present in maternity roosts during the months of May-June as opposed to the June-July dates from previous studies in other regions.
So far, there is no evidence in the Coastal Plain of WNS or the fungus that causes the disease. Since it is a cold-loving fungus that is generally found in caves and certain types of mines, the lack of caves or suitable mines in the area and the warmer winter temperatures may preclude it from persisting in the Coastal Plain of North Carolina. Even if the fungus was detected in the Coastal Plain, without dependence upon caves or mines for hibernation, this population of bats is less likely to experience mortality from WNS. Since the NLEB populations in the mountains of North Carolina and in most other portions of its range have plummeted, there is hope that the Coastal Plain NLEB population in North Carolina may serve as a refugium for the future survival of the species. Additionally, recently discovered NLEBs in coastal South Carolina may further contribute to this hope.
The studies have provided us valuable information about the bat. Knowing that most winter and maternity roosting sites are in or adjacent to swamps will help us target our conservation efforts more effectively. The Service is now better equipped to provide science based recommendations that will influence not just transportation projects, but any project involving tree removal or forest management.
Gary Jordan, Fish and Wildlife Biologist
email@example.com, (919) 856-4520