Myotis bats

Whiskered Bat

Myotis mystacinus

Description and identification

The whiskered bat is one of three small Myotis species in the UK. It is very similar to the two other small Myotis, the Alcathoe bat and the Brandt’s bat; the latter of which is found in Nottinghamshire, whilst to date the former has only been found in North Yorkshire, Sussex, Surrey and Kent. It is only really possible to tell apart these three bats (the ‘WAB’ bats) when holding them in the hand, and it comes down to differences in their coat, teeth and male genitalia. Often a DNA sample needs to be taken to confirm their identity. Whiskered bats have a dark face and ears, with a long tragus. They look shaggy and have dark brown back hair with variably grey sides and a paler tummy.

The echolocation calls of the whiskered bat are short (3-6ms) typically ranging from around 85 kHz down to 32 kHz. A lot of experience is required to separate the whiskered from other Myotis species based on sonograms alone and even then, identification is unlikely to be certain.

Status and distribution

The whiskered bat is found across England, Wales and southern Scotland, where it is widespread but rare. It is widespread in Ireland but is even rarer there.

There are several known whiskered bat roosts in Nottinghamshire including several maternity roosts in buildings. A small number of tree roosts have also been found in the county.

Conservation

Protected in the UK under the Wildlife and Countryside Act, 1981. European Protected Species under Annex IV of the European Habitats Directive.

Roosts

Whiskered bat forms maternity colonies of 20-60 females, where they raise their young in cavities in buildings, such as behind timber cladding. They will roost in trees, favouring crevices behind flaking bark29, although until very recently, they had not been recorded roosting in bat boxes in Nottinghamshire. Owing to the difficulty in distinguishing whiskered bat from Brandt’s bat, we still do not know for certain which of these two species has been found roosting in an NBG bat box scheme, set up in Colwick Country Park.

Solitary roosts of male and non-breeding female bats use a wide range of roosting locations both in trees and on buildings. They have been found beneath ridge tiles and behind bargeboards and in a wide range of tree crevices.

In winter whiskered bats are generally recorded hibernating in humid caves, disused railway tunnels and churches but in Nottinghamshire their winter refuges remain largely undiscovered.

Food and foraging

Whiskered bats show a preference for hunting along woodland edges, orchards and in parkland where they exploit mainly flying insects such as mosquitoes, midges, craneflies, small moths and lacewings. Analysis of their diet shows that whiskered bats also feed on day-flying insects, indicating that they are able to ‘glean’ or pick insects from vegetation.

Brandt’s Bat

Myotis brandtii

Description and identification

Brandt’s bat is very similar in appearance to the whiskered bat (and to Alcathoe bat); in fact the former two species were only separated in 1970. Genetic testing of the two species showed that although of similar appearance they are not closely related to each other but share a closer relationship with other Myotis species30. Records from before 1970 could therefore relate to either species and even today records are often referred to as whiskered/Brandt’s in the Nottinghamshire bat database; unless the bat was closely examined in the hand or has been identified by DNA analysis of droppings. Like the whiskered bat they have dark brown fur on the upperparts but this can become golden-tipped in older animals. Their ears and tragus are slightly lighter in colour than those of the whiskered bat.

As with all Myotis bats the echolocation call of Brandt’s bat is broadband and of short duration and in most cases it is indistinguishable from other similar species.

Status and distribution

Due to the difficulties of distinguishing the WAB bats from each other, there is a high probability of error in identification, which may be masking differences in range between whiskered and Brandt’s bats. At present the safest option is to say that the distribution range is likely to be similar to the whiskered bat. In Nottinghamshire, Brandt’s bat was formerly considered to be much rarer than the whiskered bat but since the advent of more detailed surveys i.e. trapping and DNA analysis of droppings, this may not be the case at all.

Conservation

Protected in the UK under the Wildlife and Countryside Act, 1981. European Protected Species under Annex IV of the European Habitats Directive.

Roosts

Brandt’s bat forms maternity colonies of 20-60 females in holes in trees or behind loose bark. They will also use several features within buildings including roof voids, ridges, crevices in timber beams and behind cladding. Males, as with the majority of UK species, generally roost alone. Both sexes hibernate in cool humid sites such as tunnels, bridges, stone buildings and caves.

Roosts have been found in Nottinghamshire in buildings (including a purpose made bat loft above a bird hide) and in old trees.

Food and foraging

Brandt’s bat typically prefers woodlands which are linked to wetland habitats. It hunts for small flying insects such as moths, midges, crane-flies and other Diptera (fly) species. They will hunt over water in a similar manner to Daubenton’s bat but will usually be higher above the surface. They will also glean non-flying invertebrate species from foliage.

Daubenton's Bat

Myotis daubentonii

Description and identification

A smallish bat with quite short ears, the Daubenton’s bat is also known as the ‘water bat’ as it feeds almost exclusively over water. Often seen just inches above the surface of calm ponds, lakes and rivers, it has a distinctive pale belly. Its fur appears reddish brown, but its face is pink and bare around the eyes. They have very large feet which they use to scoop up their insect prey.

Daubenton’s bat produces the characteristically short echolocation calls produced by all the Myotis bats. On a heterodyne detector they sound like a rapid series of dry clicks, almost the sound of burning stubble. Recordings of calls made by time expansion detectors often show the calls to be more S-shaped rather than the straighter calls produced by other Myotis bats. The frequency range typically goes from 85-35 kHz and calls are loudest between 40 and 50 kHz.

Status and distribution

Present across all of Great Britain and Ireland, the Daubenton’s bat is expanding its range across the UK, possibly due to the creation of artificial waterways and lakes. In Nottinghamshire one has been recorded hunting over a roadside run-off pond!

The Daubenton’s bat is monitored across the UK as part of the National Bat Monitoring Programme’s ‘Waterway Survey’ and ‘Hibernation Survey’. The Hibernation Survey has shown a marked increase in the national population between 2013 and 2016; however this was not reflected in the Waterway Survey over the same time period. The Bat Conservation Trust considers the population to be stable since 1999, the baseline year for monitoring.

In Nottinghamshire it has a widespread yet scattered distribution. The majority of records are of bats in their foraging areas and only a few roosts are known.

Conservation

Protected in the UK under the Wildlife and Countryside Act, 1981. European Protected Species under Annex IV of the European Habitats Directive.

Roosts

In summer Daubenton’s bats use a variety of places for their maternity roosts including holes in trees, buildings and bridges. In Nottinghamshire only five roosts have been discovered; one in a tree, two in buildings, one in a bridge and one in a rock crevice, although the species has been recorded throughout the county.

Winter, or hibernation roosts of Daubenton’s bat are generally in underground sites, old mines, tunnels, ice houses or caves. Due to the lack of suitable underground caves and mines in Nottinghamshire, it is likely that many Daubenton’s that remain in the county hibernate in manmade structures and trees and remain undetected.

Food and foraging

Daubenton’s bats catch insects which are close to, or on the water’s surface with their large feet, or by scooping up prey with their tail membrane. Daubenton’s bats primarily feed on aquatic midges, mayflies and caddis flies. Whilst they usually rely on waterways to feed, they are also associated with woodland, and sometimes solitary bats can be found foraging in this habitat.

The Daubenton’s bat is not as fast as some of the other UK bats, flying at approximately 25km/h and most bats will hunt within 6-10km from their roost.

Echolocation Calls

Daubenton's bats produce the characteristically short calls produced by all the Myotis bats. On a heterodyne detector they sound like a rapid series of dry clicks. They produce a fast series of calls which speeds up when the bat turns. Recordings of calls made by time expansion often shows the calls to have a 'knee' at around 45kHz rather than the straight calls produced by other Myotis bats.

Click below to play a video with time exspanded and heterodyne bat echo location calls.

The video below taken during a bat walk shows Daubenton's bats flying low and sinuously over the water catching flies. Occationally they dip and catch a fly from the water surface with their large hairy feet and tail membrane. Note, you can often see their heat reflection in the water.

Higher up in the shot are Soprano pipistrelles darting back and forth, up and down catching midges. They can eat upward of 2000 a night when they are producing milk to feed that years pup.

Natterer’s Bat

Myotis nattereri

Description and identification

The Natterer's bat is the largest Myotis bat currently present in Nottinghamshire. It has relatively long light brown fur to its topside and buff white fur underneath. It has a relatively long pink muzzle and pointed ears with a flick at the tip - a bit like the end of a skii.

Status and distribution

Natterer's bat is widespread in the UK with the exception of northern Scotland. The British population of Natterer’s bat is recognised as being internationally important in a European and worldwide context.

Natterer’s bat saw a period of significant population decline from the 1950’s, most likely due to the toxicity of timber treatment chemicals used in the attic spaces of dwellings and churches. The population is now classified as stable with some signs of a slow increase since 1993/4.

The first record of a Natterer's bat in Nottinghamshire is from 1984, soon after the advent of the North Nottinghamshire Bat Group, when it was recorded from the caves of Creswell Crags. As both the North and South Nottinghamshire Bat Groups began their work to document the distribution of bats in their local areas, it was discovered occasionally all over Nottinghamshire. Today it has been recorded from almost all parts of the county, but it is still a scarce animal.

Conservation

Protected in the UK under the Wildlife and Countryside Act, 1981. European Protected Species under Annex IV of the European Habitats Directive.

Roosts

The Natterer's bat is a species which favours historic buildings, often built of stone under a slate roof. They are also strongly associated with churches, where summer maternity roosts of up to 200 have been recorded in other counties. As a result, rural village churches represent a critical resource for the conservation of the species in the UK.

In the churches where Natterer’s bats have been recorded in Nottinghamshire, colonies are smaller, consisting of around 20 to 60 individuals.

Unlike many other bat species in the county, the maternity roosts are not exclusively made up of nursing females and up to a quarter of the colony can be both adult and immature males.

Natterer’s bat will make use of a wide range of roosting sites, with a third of roosts found in buildings and two thirds in tree cavities, sometimes very low to the ground.

Over the winter months these bats are generally recorded hibernating in caves, disused railway tunnels and churches but in Nottinghamshire their winter refuges remain largely undiscovered.

Food and foraging

Natterer’s bat shows a preference for wetland and woodland habitats, which include villages and town suburbs supporting mature gardens, river valleys, treelines and copses or wooded churchyards. Recent research into the feeding behaviour of colonies living in churches found that their least favourite hunting habitats were arable fields and built-up areas.

The Natterer's bat exploits its aerial prowess by hunting in and around tree branches and flying within tight cluttered areas to catch a wide range of invertebrates. It has the ability to fly and hover so that it is almost stationary and can pluck (or glean) a spider from the middle of its web without damaging a single strand, leaving the web fully intact minus its resident.

Other invertebrates that make up the diet of Natterer’s bats include flies, moths, beetles and bugs and whilst moths make up the largest proportion of prey species eaten, remarkably the second largest amount of prey species is spiders.

Click below to play a video with time exspanded and heterodyne bat echo location calls.

Below is a thermal video of bats flying around inside a church to warm up their muscles before going out to hunt insects. White is hot. Some bats appear to be flying as a pair. They are most likely monther and her pup from that year.