Post-hibernation Emergence of the Northern Long-eared Bat (Myotis septentrionalis) in Virginia: Movements and Day-roost Use
Dates
Start Date
2014-10-01
End Date
2016-12-31
Summary
With the onset and spread of White-nose Syndrome (WNS) in the eastern United States, several formerly common bat species are now threatened with widespread regional extirpation. For example, the northern long-eared bat has shown precipitous declines and reproduction in surviving bats appears curtailed suggesting functional extirpation in some areas (Francl et al. 2012). This species has been proposed for Federal listing as endangered with the final determination scheduled for April 2015 (Federal Register § 78:61045-61080). Primarily, the species is associated with deciduous forests from New England through the mid-South and Midwest. In addition, to species facing recent declines, WNS has reduced populations of species already state- [...]
Summary
With the onset and spread of White-nose Syndrome (WNS) in the eastern United States, several formerly common bat species are now threatened with widespread regional extirpation. For example, the northern long-eared bat has shown precipitous declines and reproduction in surviving bats appears curtailed suggesting functional extirpation in some areas (Francl et al. 2012). This species has been proposed for Federal listing as endangered with the final determination scheduled for April 2015 (Federal Register ยง 78:61045-61080). Primarily, the species is associated with deciduous forests from New England through the mid-South and Midwest. In addition, to species facing recent declines, WNS has reduced populations of species already state- or federally-protected, i.e., the endangered Indiana bat (Myotis sodalis).
With roosting and foraging habits for both species in upland and riparian forest systems along with multi-tree/snag non-random associative maternity roost social networks of > 50 ha for the northern long-eared bat (Silvis et al 2014a) and networks > 150 hectares for the Indiana bat (Silvis et al. 2014b), protection and management of these species intersects most forest stewardship activities that could remove day-roosts, (e.g., harvesting and prescribed fire). For Indiana bats, summer maternity (female) and male day-roost selection (typically medium to large boles with exfoliating bark, e.g., shagbark hickory Carya ovata or sugar maple Acer sacharrum medium- to full-sunlight), are known for the Northeast and elsewhere (Kurta et al. 1993, Menzel et al. 2001, Britzke et al. 2003, Carter and Feldhammer 2005, Watrous et al. 2006, Johnson et al. 2010, Timpone et al. 2010). However, day-roost use by northern longeared bats is less well-documented, especially in the Northeast (Sasse and Pekins 1996, Broders et al. 2006, Johnson et al. 2009). There appear to be considerable differences in roost site selection between the two species. Unlike Indiana bats during the maternity season, northern long-eared bat maternity colonies often select multiple, small understory boles such as black locust (Robinia pseudoacacia) and sassafras (Sassfras albidum) snags that originated 50-90 years previous following oldfield succession or a stand replacement forest disturbance events (Menzel et al. 2002b, Silvis et al. 2012). Further, outside of the summer maternity season, data on the types and conditions of day-roosts used by northern long-eared bats is limited to the fall swarm in the central Appalachians of West Virginia for males (Ford et al. 2006b). With the overall reduction in overwintering physiological status of WNS-impacted bats, understanding post-emergence and summer habitat selection has become an important component of maximizing northern long-eared bat and Indiana bat survival and recovery.
Prior to WNS, acquisition of data on summer habitat selection and maternity colony dynamics, focused on local mist-netting. However, given the recent declines in northern long-eared bats and Indiana bats, capture bats at hibernation site during spring emergence and subsequent tracking probably is the more efficacious technique for establishing where summer maternity colonies will occur on the landscape. To date, we are unaware of any spring emergence studies of the northern long-eared bat in the Northeast or elsewhere. For Indiana bats, several pre-WNS attempts have been made following individuals post-emergence along migration routes to eventual summering areas in the Northeast with high success in New York and Pennsylvania but unfortunately low success in Virginia (Hobson and Holland 1995, A. Hicks, unpubl. data, J. Chenger, unpubl. data).
In addition to the paucity of post-emergence and maternity colony locations for northern longeared bats in much of the Northeast, we also lack an understanding of the connections between their maternity colonies and winter hibernacula, pre- or post-WNS. Unlike the Indiana bat, the northern long-eared bat's cryptic hibernation behavior (utilizing difficult to survey cracks/crevices in caves, mines and emergent rock structure) has resulted in few winter observations of bats banded in the previous summer(s). Although typically considered a short distant migrant, northern long-eared bats can migrate > 250 kilometers (km) from their hibernacula (Griffith 1945). In contrast, Indiana bats make both short-medium and long-range (> 500 km) migrations from winter hibernacula (Menzel et al. 2001, Kurta and Murray 2003, Britzke et al. 2013). Summer observations of both species in regions considerable distances from known cave or mine features do occur. Prior to the onset of WNS, northern long-eared bats have been documented in eastern Virginia within the lower Piedmont/ upper Coastal Plain, (i.e., Washington D.C. Metro area, Fort A.P. Hill, and Fort Pickett) (Johnson et al. 2008, M. St. Germain, unpubl. data) and throughout all of New York (primarily through acoustics and NYS Department of Health records). Evidence exist suggesting year-round occupancy of northern long-eared bats in the Coastal Plain of North Carolina, south of the Great Dismal Swamp (Morris et al. 2009, K. Matthews, unpubl. data, and J. Grider, M.C. Kalcounis-Rueppell, unpubl. data). Similarly, Indiana bat maternity activity away from cave or mine features has been documented in the lower Piedmont/Upper Coastal Plain of Carroll County, Maryland (Johnson and Gates 2007) and in multiple counties in New York (R. Niver, unpubl. data).
These distances have been documented primarily from pre-WNS spring emergence studies with repetition of these studies since the dramatic declines in regional Indiana bat populations have been documented. Data post-WNS are generally lacking. Northern long-eared bat populations in eastern Virginia presumably are linked to winter hibernacula west of the crest of Blue Ridge and northern long-eared bat and Indiana bat populations in southeastern andnortheastern New York are linked to winter hibernacula in the Hudson River Valley west of Taconic Mountains or to the north near the Champlain Valley where karst formations and mines occur. Accordingly, if the northern long-eared bat is listed as endangered, posthibernation migration pathways solidly linking hibernacula with summering areas also will be critical data for maximizing northern long-eared bat survival and recovery. For Indiana bats, this remains a priority data-gap as well.
Objectives:
Based on fall 2014 hibernacula swarm data to be collected by Virginia Department of Game and Inland Fisheries and winter data from the New York State Department of Environmental Conservation, select 2-3 caves with the highest remaining number of extant northern longeared bats for nightly spring emergence harp-trapping or spring entry/collection, and acoustic monitoring deployment during the March 21-April 15 periods in 2015 and 2016 to determine timing and distribution of northern long-eared bat emergence. In Virginia, additional criteria will be proximity to public lands,( e.g., George Washington-Jefferson National Forest, Shenandoah National Park, Cumberland Gap National Historical Park, state forests or state wildlife management areas). In New York, sites have already been selected based on multiple years of post-WNS winter surveys. Barton Hill Cave has been selected for northern long-eared bats (largest population in New York). If for some reason, northern long-eared bats cannot be captured, Williams Lake Cave complex has been selected for the Indiana bat based on extensive pre-WNS data.
Radio-tag and track 10-15+ northern long-eared bats at each surveyed 10-15+ northern long-eared (primary target in Virginia, secondary in New York) or Indiana bats (primary target in New York, secondary in Virginia) in New York from each cave to determine if postemergence migration is short- or long-distance to both female maternity areas and male summering areas.
Identify post-emergence day-roost trees/snags and surrounding forest stand conditions for both species to determine if roost preferences are specific or random and if roost resources are abundant or limited in the local landscape; where possible determine early spring colony size.
