A summary of bat records for 2021
While some records are still awaited for the year there are 2664 records in the database. 22 of these are negative records, usually generated when a known or potential bat roost such as a bat box has been inspected without any occupants being noted. 82 records are referred to Vespertillionidae, the family, in taxonomic terms, to which all bats found in the Isle of Man belong. Individual records are referred to this group where they have been submitted by a member of the public unable to identify the sighting to a species or genus or, more usually, where an acoustic recording is of poor quality and cannot be assigned to a species.
As previously reported acoustic recording of bats has expanded markedly in recent years and now provides the bulk of the records. Indeed, for two of our species, Nathusius’ pipistrelle (Pipistrellus nathusii) and lesser horseshoe bat (Rhinolophus hipposideros) acoustic recordings are the only evidence of their presence on the island.
The records will be discussed in order of their increasing frequency:
Nathusius pipistrelle (Pipistrellus nathusii)
Only three records during the year, all in June. One at Silverdale as an incidental record during a roost count for common pipistrelle and two at Miss Guyler’s Meadow, a Manx Wildlife Trust reserve north of Sulby.
Lesser horseshoe bat (Rhinolophus hipposideros)
A concerted effort was made to record this species following confirmation of its presence the previous year. A spring survey of the Chasms, lowering detectors down on string, was rewarded with 8 separate records between April 12th and 17th with a further two in September and November. An evening visit to the Chasms on May 2nd gave Bat Group members a view of one flying down in one of the crevices while a few recordings were obtained at a sea cave south of Pt St Mary on May 19th.
Daubenton’s bat (Myotis daubentoni)
Usually considered a species associated with still waters where it trawls for emerging insects with its large hind feet, Daubenton’s bat can be recorded in other habitats. Of the 72 records this year 14 might be said to be of more open countryside, including two of the Wildlife Trust’s northern meadow reserves, 3 Andreas gardens with overgrown hedges and 5 along a lane in Santon. Four records were from a pond adjacent to the Ayres. Most summer records, perhaps unsurprisingly, were from the lake at Ballachrink Bird Sanctuary but the Spring survey of the Chasms produced 23 separate records showing that they probably hibernate there underground. The most surprising record was of a male rescued from the door frame of the public toilets on Victoria Road in Peel. No maternity roosts are known for Daubenton’s bats
Brown long-eared bat (Plecotus auritus)
The brown long-eared bat is regarded as a quiet bat, hovering close to foliage to pick off its prey. Consequently many records are obtained at the roost, either direct visual observation or when the bat passes close to the acoustic detector. 43 of the 153 records are associated with roosts in this way. Other survey encounters included scrub habitat in Ramsey, farmland with hedges in Lezayre, Santon and Malew, 8 records around Cringle reservoir and 5 in Glen Shoggle, Ballaugh. They will hunt in conifers as evidenced by the Glen Shoggle records but also Claughbane plantation (now Ramsey Woods) where 3 records were obtained at the maze above the quarry and one at the western edge of the plantation. During the Chasms surveys two records were obtained in April and two in September. One record was obtained on the beach at Blue Point while a male was collected for rehabilitation and release from the school gate at Jurby. Two maternity roosts of this species were counted with 10 individuals in each.
Natterer’s bat (Myotis nattereri)
This is another quiet bat which owes is position in this sequence, with 156 records, principally to the spring and autumn surveys of the Chasms giving 34 records for April and 41 for the period September to December. As with Daubenton’s bat the Chasms would seem to be a major hibernation site. A hay meadow reserve, Miss Guyler’s Meadow, albeit with well grown hedges, produced the most summer records, 18, while another Wildlife Trust reserve, Ballachrink Bird Sanctuary had 10. Ballalough Nature Reserve in Castletown produced 5 records, Glen Shoggle 4 and Cringle reservoir 3. No maternity roosts of Natterer’s bats were counted during the year.
Myotis species
Recordings of bat calls are assigned to Myotis sp. when the specific characteristics of a recording required for identification to species level are absent. Most records are thus generated by some of the longer surveys, eg the Chasms and Ballachrink Bird Sanctuary but there also a number around Fistard, 7, and at Bradda Glen and a further four in Archallagan Planatation. There were 177 records of Myotis species.
Pipistrellus species
Recordings of bat calls are assigned to Pipistrellus sp. when social calls are recorded and there are 221 such records this year. Social calls might be inter- or intra-specific antagonistic behaviour or associated with mating behaviour or mother-young interactions depending on the time of year. As such they are always produced when there are more than one bat flying and so nearly always complement records of the two commonest species of pipistrelle. There were 221 records of Pipistrellus sp.
Soprano pipistrelle (Pipistrellus pygmaeus)
Early records did not distinguish between the two pipistrelle species but it is now possible to do so with modern detectors. Soprano pipistrelles emit calls at a higher frequency than common pipistrelles although very occasionally they might overlap. There are 248 records of soprano pipistrelles and, as discussed elsewhere, there are more in the north (214) of the Island than the south (34). Northern records were obtained in all the surveys discussed above, plus my garden in Jurby East (8), while in the south the Chasms produced 4 records, Pt St Mary 3 and Archallagan plantation 2. The remainder were on private land or obtained during surveys for planning purposes. Only one soprano pipistrelle maternity roost was counted during the year with 98 bats seen to emerge.
Whiskered bat (Myotis mystacinus)
Whiskered bat records are now coming in from all over the Island, including my garden with 4 records in March. Sites with more records include some of the year’s longer term surveys such as Ballachrink Bird Sanctuary where they were recorded at four different sites during each of the months May to October, with peak activity in August, after the young have started flying. Miss Guyler’s Meadow was another site with monthly recording surveys but with lower numbers while a site in Ramsey had intermediate numbers of recordings through the summer. Shorter term surveys with Whiskered activity included four sites in Andreas parish with 14 records in total, Glen Shoggle in Ballaugh (12 records), a private site in Lezayre (5), Cringle and Archallagan plantations (8 and 7 respectively), Ramsey Woods (7), an estate in Santon (15), Ballalough reedbeds in Castletown (4) and Maughold Head broughs (2). Surveys for planning produced 99 records from eight surveys, three of which were long-term. Long-term surveys at the Chasms in April and again from September through to December produced 63 records. Only one whiskered bat roost was counted during the year with 6 bats seen emerging. There were 350 records of Whiskered bat in total.
Leisler’s bat (Nyctalus leisleri)
Leisler’s bats are strong, high fliers with a loud call which can be recorded at 100m distance. Records are therefore less tied to habitat than is perhaps the case for other bats and most forays with a bat detector will pick up at least one call of this species. There were 426 records of Leisler’s bats in 2021, with the majority associated with the longer term surveys described above. Those at Ballachrink Bird Sanctuary are particularly notable for the high activity levels in May and June which probably reflect feeding activity by pregnant females from known maternity roosts on the outskirts of Douglas. There were 27 records from this site, 32 from Miss Guyler’s Meadow in Lezayre, 13 from Ramsey Woods, 10 from Glen Shoggle, 11 from Cringle plantation and 6 from Archallagan. All the sites mentioned above had numerous records but notable sites not previously mentioned include a private garden in Regaby with 10 records but involving several hundred recordings including vey many social calls and 8 records from the end of the Chasms Road in Pt St Mary in June, while the Chasms only produced 7 records in the autumn. Three maternity roosts were counted but only one had emerging bats and 97 bats were counted.
Common pipistrelle (Pipistrellus pipistrellus)
With 742 records during 2021 this species lives up to its name. Of 169 separate surveys conducted this year only 10 failed to record common pipistrelle. Numerous records are therefore associated with all the sites so far discussed while there are also 16 individual records of bats taken into care, usually cat casualties, from all corners of the Island. This species was also recorded during several vehicle transects some of which included travelling over high ground such as Lamb Fell and Eairy. 17 maternity roosts were counted with the largest count being 219 while 4 had no bats.