N27 2015 Northeastern Naturalist Notes Vol. 22, No. 4 R.H. Thompson, A.R. Thompson, and R.M. Brigham A Flock of Myotis Bats at Sea Richard H. Thompson1, Aaron R. Thompson1, and R. Mark Brigham2,* Abstract - We report an instance of a large number of Myotis bats, probably Myotis lucifugus (Little Brown Bat), landing on a fishing vessel and roosting overnight on it and on some of its gear ~110 km from the nearest land in the Gulf of Maine. This sighting was considerably beyond what would be considered a normal distance from land (~10 km) for these bats to fly. Records of temperate insectivorous bats finding their way onto ships at sea in the Atlantic off northeastern North America are not uncommon (Brown 1953, Carter 1950, Mackiewicz and Backus 1956, Norton 1930, Peterson 1970). Most instances involve migratory species that commonly fly long distances (Bonaccorso and McGuire 2012). These migratory species have been previously reported from this area in the fall, suggesting the possibility of a migratory movement across the Gulf of Maine from Nova Scotia, although Broders et al. (2003) concluded that these species are extralimital to Nova Scotia. Petersen et al. (2014) summarized the records of North American and European bats on northeastern Atlantic islands. Of the North American species, Eptesicus fuscus (Beavois) (Big Brown Bat; 1 record on a ship in Iceland), Lasiurus cinereus (Palisot de Beauvois) (Hoary Bat; 3 individuals on Iceland and 1 on the Orkney Islands), Myotis lucifugus (Le Conte) (Little Brown Bat; 2 on a ship in Iceland), and M. septentrionalis (Trouessart) (Northern Longeared Bat; 1 on a ship in Iceland) have been recorded. Here, we report an instance of a large number of Myotis, probably Little Brown Bats, flying onto a fishing vessel and roosting on some of its gear in the Gulf of Maine, beyond what might be considered a maximum distance (~10 km) for them to commute to foraging areas or to fly from land (Peterson et al. 2014, Sjollema et al. 2014). R.H. Thompson and A.R. Thompson (the 2 senior authors) were the fishermen on the boat and made the observation. They conveyed the account to R.M. Brigham, who, herein, provides a description of the event. Although the event occurred more than a decade ago, we are confident of the facts and have sought independent verification where possible to minimize the possibility of obscu ring the facts. R.H. Thompson and A.R. Thompson did not record the precise date, but they know that the event occurred over 2 days in late July or early August 2003. The location was in the Gulf of Maine, about 1–10 km southwest of a feature known as Southwest Bank, which is within several kilometers of the international boundary between Canada and the US and ~110 km from the nearest land (Nova Scotia). The crew of the vessel (Ocean Pride II; 13.7 m long x 6.4 m wide) had set 5 strings of fishing gear for Gadus morhua L. (Atlantic Cod), Pollachius pollachius L. (Pollock), Urophycis spp. (hake), and Melanogrammus aeglefinus L. (Haddock) on day 1 of the event. The weather was clear with warm temperatures and no wind, and the sea was termed a “slicker” because it was so calm. Based on data from the National Ocean and Atmospheric Administration’s National Data Buoy Center for the Gulf of Maine, there was nothing resembling a storm in the area that might have blown bats offshore between 25 July and 7 August. The maximum wind speed over that period was 12.2 km/hr with only 4 hourly records of >10 km/hr winds. During the 2-week span, maximum wave height was 2.9 m, with the vast majority of records below 1.0 m, and temperatures 1PO Box 201 Lepreau, Dipper Harbour, NB E5J 2T1 Canada. 2Department of Biology, University of Regina, Regina, SK S4S 0A2 Canada. *Corresponding author - mark.brigham@uregina.ca. Manuscript Editor: Jacques Veilleux Notes of the Northeastern Naturalist, Issue 22/4, 2015 2015 Northeastern Naturalist Notes Vol. 22, No. 4 N28 R.H. Thompson, A.R. Thompson, and R.M. Brigham ranged from 14.0–23.7 °C (http://www.ndbc.noaa.gov/). The sun was low in the western horizon and the boat was anchored for the day when the senior authors first noticed a few bats flying around the vessel at least an hour before bats would be expected to be flying. Assuming the bats were Little Brown Bats (see below) and a flight speed of 20 km/hr (Fenton and Barclay 1980), the bats were ~5.5 h flying-time away from the closest land (they could have come from even farther). The sighting in itself is exceptional, made even more so because the bats were first observed at the beginning of dusk, suggesting the bats may have already day-roosted in the area—an observation that ties in with the observation of bats roosting in “high fliers” (see below). As dusk fell, dozens of bats circled the boat. When it was almost dark, A.R. Thompson was standing on the stern of the vessel, with his arms straight out. Bats landed on him, crawled up his sleeves and down his collar. By the time it was dark, dozens of bats were hanging in the rigging, a few had made their way into the wheel house, and 1 or 2 made it into the boat’s living quarters. A.R. Thompson relocated the latter group to the deck unharmed. All of the bats were similar in appearance, flew in a slow maneuverable fashion, and had a wingspan estimated at 20–25 cm. These observations, along with their coloration when viewed in the hand, strongly suggest that they were Little Brown Bats. Northern Long-eared Bat is the only other species that fits the description, but this species is very sedentary and almost strictly a forest-dwelling species (Broders et al. 2003) and so highly unlikely to have flown so far out to sea. Near daylight on day 2 when it was time to prepare to retrieve the fishing gear, bats by the dozens were everywhere on the vessel, not flying but roosting. The day was spent retrieving the sets, each end of which was marked by a “high flier” (Fig. 1). These devices are large buoys with a weight on the bottom and a 1.2–2.5-m-high pole to which is affixed a metal radar reflector (~25 cm x 25 cm) on top so that the gear can be found in bad weather. As the 10 high fliers were retrieved during the day at distances of 2–8 km from the previous night’s anchor site, bats flew out of the radar reflectors where they had been roosting. Presumably the bats had used them as roosts the night before. This observation suggests that there were more bats in the area than just those seen on the boat. By nightfall on day 2, while the boat was still approximately the same distance from l and, all bats had dispersed. There were no other fishing boats in the near vicinity, and none of the senior author’s colleagues fishing in the area reported seeing any bats. R.H. Thompson has fished with groups of boats that anchor for the night at dusk and recalls instances where there has been an occasional single bat flying around. In these instances it is common for boat captains to talk on the radio about such sightings. There was no such conversation in regard to the instance we report. Given the weather conditions, it is hard to surmise that the bats were lost and somehow at sea by mistake. However, at some point almost every summer, fishermen report that large numbers of biting flies (Dipterans) descend on vessels. Many flies had been in the vicinity of Ocean Pride II ~1 week before the bats were seen. The flies, slightly smaller than houseflies, bit the crew the instant they landed and were most probably Stomoxys calcitrans L. (Common Stable Flies). It is likely, but impossible to confirm, that the bats were flying offshore in pursuit of these insects. Consistent with the NOAA data, neither R.H. Thompson nor A.R. Thompson recall any strong offshore winds during the time before the bat record, suggesting that neither the flies nor the bats were likely to ha ve been blown offshore. In times of thick fog and poor visibility, R.H. Thompson has commonly encountered groups of songbirds that presumably have sought refuge and rest on the boat. Typically the birds die within hours, suggesting they were exhausted; the incident we report seems of N29 2015 Northeastern Naturalist Notes Vol. 22, No. 4 R.H. Thompson, A.R. Thompson, and R.M. Brigham a very different sort. Given that high fliers are likely relatively common across the ocean during the summer fishing season, it is possible that their use as roosts by bats is more common than has been documented and it is possible that the event we describe has happened on other occasions but has simply not been reported. If this behavior is more than just a one-time occurrence, there may be bat-conservation implications if offshore wind turbines are installed in this area. Bats have been documented trying to land on offshore turbines (Ahlén et al. 2009). We hope that the publication of our observation stimulates others to report similar instances. Whether or not our observation represents a unique event, the lack of any weather condition which might explain it, makes the rationale for the bat’s behavior highly perplexing. Acknowledgments. We are grateful to Don McAlpine, Steve Marshall, Hugh Broders, Jacques Veilleux, and 2 anonymous reviewers for their thoughtful comment s. Figure 1. A “high-flier” device that marks the end of a long string of fishing gear, with the 25 x 25-cm radar reflector on top. 2015 Northeastern Naturalist Notes Vol. 22, No. 4 N30 R.H. Thompson, A.R. Thompson, and R.M. Brigham Literature Cited Ahlén, I., H.J. Baagøe, and L. Bach. 2009. Behavior of Scandinavian bats during migration and foraging at sea. Journal of Mammalogy 90:1318–1323. Bonaccorso, F.J., and L.P. McGuire. 2013. Modeling the Colonization of Hawaii by Hoary Bats (Lasiurus cinereus). Pp. 187–205, In R.A. Adams and S.C. Pedersen (Eds.). Bat Evolution, Ecology, and Conservation. Springer Science + Business Media, New York, NY. 640 pp. Broders, H.G., G.M. Quinn, and G.J. Forbes. 2003. Species status, and the spatial and temporal patterns of activity of bats in Southwest Nova Scotia, Canada. Nor theastern Naturalist 10:383–398. Brown, N.R. 1953. An addition to the list of mammals of Nova Scotia: The Eastern Red Bat. Canadian Field Naturalist 67:139. Carter, T.D. 1950. 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