The whiskered bat is classified as at a low risk of extinction worldwide but classified as vulnerable in the UK. Whiskered bats are subject to the extensive legal protection provided to all bat species. The total UK population is estimated at 30 to 40,000 individuals.
Tracks and Trails:
Droppings of whiskered bats often accumulate beneath the ridge line but less at chimneys or gable ends.
Whiskered bats are widespread in Cornwall, and locally common, but they have been relatively poorly recorded. Earlier records could refer to either whiskered or Brandt’s bats. They are found throughout England and Wales and into southern Scotland and Northern Ireland and across Europe into Asia as far as southern Japan
Monitoring of summer maternity and hibernation roosts by licensed bat workers. Mist net trapping by licensed bat workers. Emergence surveys. Bat detector monitoring. Cat kills and incidental reports.
A small bat (up to 8 g in weight) with rather shaggy fur. Despite its name the whiskered bat does not have especially prominent
whiskers, although it does have more fur around the eyes and muzzle than most other bats. The fur is dark brown on the back whilst the underside is greyish-white. The upright ears are black and pointed and the tragus (the central ear lobe) is narrow and pointed. The face is dark. However, none of these characteristics help to distinguish the whiskered bat from the virtually identical Brandt’s bat, indeed the two species were only recognised as separate in the UK in the early 1970s. Even experienced bat workers have trouble determining which species they are holding - subtle differences including the relative size of the teeth and the shape of the penis are all that split the species’ appearance, although the face of the whiskered bat tends to be darker and less reddish than that of the Brandt’s bat and the individuals tend to be smaller.
Both bats echolocate between 32 and 89kHz, strongest at 45 kHz, and the dry click of the call is generally slower and less regular than that of Daubenton’s bats. Whiskered bats roost in old buildings under tiles, or behind roof timbers (especially along the ridge), or in wall cavities. They will also use modern buildings and bat boxes. They are sometimes found in mixed roosts with pipistrelles, brown long-eared bats, and even Brandt’s bats. In the winter they hibernate in caves, mines, or partially underground sites such as old limekilns, generally close to the entrance
where it is coolest.
Whiskered bats roost in crevices: they land and then crawl to their roost sites, so they
can use much smaller access points than horseshoe bats. They emerge soon after
sunset and are active throughout the night.
Whiskered bats tend to hunt in the tree canopy and fly regular patterns along hedge lines and woodland edges. They seem to favour riversides and wet areas. Moths and flies, such as dungflies and bluebottles, make up most of their diet but they also glean some prey such as spiders from leaf surfaces.
Whiskered bats usually mate in autumn before entering hibernation and the single
pup is born in late June or early July. The pup can fly at 3 weeks, and 3 weeks later
can hunt and feed itself. Most individuals breed in their second year and these tiny
bats have been recorded living for 19 years. In late autumn the normally solitary
males are sometimes recorded in large swarms, an activity that is not fully understood
but which may be related to mating or communication.
As with most bat species, the most important threats are man made: loss of roosting
sites, impacts on feeding sites, insecticides and wood treatments, domestic pets, road
traffic, and wind turbines. Alongside these the bats have to survive natural hazards
including the occasional hawk or owl, terrestrial carnivores and even rodents when
the bats are roosting or hibernating.
Relatively little is known about the impact of infectious disease as a cause of bat mortality in the UK although there is concern about white nose syndrome, a fungal disease identified in America where it has caused mass fatalities in hibernating bats. This disease has been identified in Europe and UK bat workers constantly monitor roosts for signs.
In 2000 Rowena Varley from the Cornwall Wildlife Trust Bat Group was called to a house in Wadebridge to deal with a sticky situation. A fly paper, hung to deal with annoying insects, had also captured 16 whiskered bats. The 5 mothers and 11 juveniles were carefully unstuck using a combination of margarine and baby shampoo before being returned to their roost.
Did you know?:
Although these tiny bats normally stay close to their roosting sites in the UK, in Europe one tagged individual was recorded as travelling over 2000 km.
© David Chapman