Documentation of breeding and winter habitat use by Northern long-eared bats on Nantucket Island, MA
Nantucket Conservation Foundation
Prior to 2015, the federally threatened Northern long-eared bat was not known to be present on the tiny coastal island of Nantucket. The presence of this species was confirmed when a dead specimen of a lactating female was handed in to the Nantucket Conservation Foundation. Given that this species is doing so poorly due to white nose syndrome elsewhere in the northeast, and due to the fact that so little was known about the habitat requirements of northern long-eareds on Nantucket, it became a high priority for us to find out more about what areas of the island these bats were occupying and how populations were faring here. Since receiving a SM4Bat FS recorder from the Wildlife Acoustics Scientific Product Grant earlier this year, we have been able to survey much of the island in order to document areas of activity of Northern long-eareds. Additionally, the data recorded from our SM4Bat has helped us pin point potential areas to mist net so that we can efficiently capture bats, place transmitters on them and locate maternity colonies. We have detected Northern long-eared bats in nearly every location that we've put out our detector!
Our summer field season is winding down, but we still have bats on the brain. Now that we know that Nantucket is home to many Northern long-eared bats, we must find out if they are hibernating here. We will continue to deploy our detector throughout the winter in order to document any winter time activity for these bats and to help us pin down potential locations of hibernacula.
Over the summer field season, we used our SM4Bat FS recorder to survey much of Nantucket in order to document areas of activity of Northern long-eared bats as very little is known about habitat use by this species on the island. We documented acoustic evidence of Northerns in nearly every location that we put out our detector, however the highest number of calls were recorded in the vicinity of pitch pine stands and fewer in hardwood forests. Beginning in mid-September, we began placing our detector in areas where we had found particularly high levels of acoustic activity in order to identify potential locations to place mist nets for late fall capture. As we experienced an unusually warm fall, we continued to collect calls on most nights of in to late November. Based on our acoustic data, we set mist nets near a pitch pine stand close to a water source, and captured 10 Northern long-eared bats in late October. We placed radio transmitters on them and tracked them to what we assume to be potential hibernation sites that we will be monitoring over the winter. Nantucket lacks mines and caves – traditional hibernacula for Northern long-eared bats – so we have placed a high priority on finding and characterizing alternative hibernacula here. We will keep our detector deployed throughout much of the winter in order to document any activity and to help us locate potential locations of other hibernacula.
All has been fairly quiet on the acoustic front this winter. After a successful late fall 2017 mist-netting and radio-telemetry session, we were able to identify some areas that may contain hibernacula for Northern long-eared bats on Nantucket Island. We detected NLEB on our SM4Bat FS through mid-December and believe they are hibernating here in crawl spaces of houses. We deployed our detector throughout the winter in the vicinity of where we think they are hibernating. We did not record any calls in January or February, and the back to back to back March Nor'easters are not helping either. As soon as we start seeing calls of NLEBs on our detector again, we will begin mist-netting with hopes of catching bats as soon as they come out of hibernation. Another aspect of our project that we know little about is the exposure of Island bats to Pd, the fungus that causes White-nose Syndrome. To date, only one island bat has tested positive for Pd at very low levels. Otherwise, our bats appear healthy and suffering the effects of WNS to a lesser degree than bats elsewhere in the Northeast. Capture rates remain high and several maternity colonies have been identified. Swabbing bats as soon as they emerge from hibernation will give us a better idea of the prevalence of exposure to Pd on Nantucket. Our detector will help us to know as soon as bats start flying this spring!
For a tiny island with more than 45% protected open space and a long history of visiting and resident scientists, natural historians and conservationists, the recent addition of a new mammal species to the list for Nantucket Island was quite a surprise. In the summer of 2015, a dead specimen of the federally threatened Northern long-eared bat was found on a trail in a pitch pine forest on the Island. This discovery kicked off a flurry of activity for us at the Nantucket Conservation Foundation. Populations of this species have declined across the northeast by >90% due to White-nose Syndrome, so it immediately it became a high priority for us to learn about habitat use on island and how populations are faring here. The SM4Bat FS detector and Kaleidoscope Pro software we received from the Wildlife Acoustics Scientific Product Grant has allowed us to begin to survey much of the island in order to document areas of activity of Northern long-eared bats.
In the summer of 2017, we moved our detector weekly to various locations across the island to get a handle on the types of vegetation communities with high activity of Northern long-eared bats. We documented acoustic evidence of Northerns in nearly every location that we put out our detector, however the highest number of calls were recorded in the vicinity of pitch pine stands and fewer in hardwood forests and scrub oak shrublands. Our detector also helped us pin point potential locations to place mist-nets in order to capture bats and affix them with radio transmitters to document locations of maternity colonies.
As a bonus, our detector and the software helped us learn what other bat species were present on the island in the summer. It was always assumed that Nantucket had no resident bat species outside of the spring and fall migration season. We were able to determine that we likely have breeding red bats on Nantucket as well.
In mid-September, in anticipation off fall swarming activity, we began placing our detector in areas where we had found particularly high levels of acoustic activity throughout the summer. We experienced an unusually warm fall and continued to collect calls on most nights through mid- December. Nantucket lacks mines and caves – traditional hibernacula for Northern long-eared bats – so we have placed a high priority on finding and characterizing alternative hibernacula here. We kept our detector deployed throughout much of the winter in order to document any activity lending further evidence that northerns are present throughout the winter and likely hibernating locally.
A further piece of the puzzle that we wished to explore was whether Nantucket bats were exposed to Pd, the fungus that causes White-nose Syndrome. We did not record any calls in January or February, but began to pick up a bit of activity towards the end of March and early April. We began mist-netting soon after they emerged from hibernation and with the help of Sam Hoff, a PhD student from University of Albany, we were able to collect swabs to sample for Pd presence. To date, only one apparently healthy island bat tested positive for Pd at very low levels. Otherwise, our bats appear healthy and we are optimistic about the status of the Northern long-eared bat on Nantucket. We will continue to deploy our bat detector across the island in to the future to keep tabs on their populations here.