02 February 2012

Bat

Bram Stoker has a lot to answer for! Bats have suffered a lot of bad press thanks to their fictitious association with vampires and witchcraft. In fact, British bats are entirely harmless and their insect diet makes them more friend than foe of human creepy-crawly haters.

If bats flew during the day everyone would know how abundant they are along our canals. These night time visitors to the waterways are major consumers of flying insects – a fact that should be music to the ears of boaters!

Bats make up a quarter of all mammal species, with nearly 1,000 different bat species existing across the globe. 18 of these can be found in Britain, the most common being the tiny pipistrelle, which weighs less than a 2 pence coin. In the days when Britain was covered in trees, bats often roosted in hollowed-out tree trunks or caves. However, now that so much deforestation has taken place, bats have been forced to seek alternative roosts.

Many of the Canal & River Trust's 200-year-old tunnels, bridges, buildings and aqueducts are home to bats. This means we have to take care when working with any of our heritage structures or trees, as bats, which are protected by law, may be present.

The best example of this is perhaps the Pontcysyllte Aqueduct World Heritage Site, which is a pipistrelle bat roost. Renovation work on the aqueduct was carried out without disturbing the bats, and their roosts all remained in place.

Protecting heritage and nature

During the renovation of the aqueduct, work was undertaken without delays or detriment to the bats, and their existing roosts were maintained.

Roger Thomas, Chief Executive of the Countryside Council for Wales, said: "The recent works at Pontcysyllte show the value of cooperative working to conserve both the structure and the species. Pontcysyllte brilliantly demonstrates that the presence of protected species doesn't have to be a barrier to restoration and other works."

The waterways provide an incredibly important natural passage for the movement of wildlife, such as bats, bringing the countryside into the heart of our towns and cities, as well as some of our intensively farmed landscapes. These corridors bypass the perils of our roads, providing vital links in an increasingly fragmented countryside.

Daubenton’s bats, also known as the 'water bat', are common to the waterways. They use the canal and river network extensively for foraging and getting around safely – for bats the canals are a cross between Tesco and the M1.

Bats can be spotted around dusk as they venture out to hunt their insect prey. They use a highly sophisticated form of radar (or high-frequency squeak) which bounces off objects back to the bat. This tells it the size, location, velocity and even texture of whatever is in its path.

Bats are less likely to be seen during the winter months, when they hibernate in cool and humid shelters. During this time the bat's body system slows down and its heart rate drops. It is important not to disturb any bats during hibernation - the act of waking will use up vital fat reserves, which are needed to sustain the bat until spring.

Bat facts

Appearance: Bats often display characteristics peculiar to their species, for example the long-eared bat has unusually lengthy ears. In Britain, the most common bats have a small body, short legs, fairly narrow wings and a short tail. Colours vary from colony to colony, but ears and muzzle are dark and body hair a shade between orange-brown and grey-brown

Size: Again, this is dependent on species. Pipistrelle bats measure 3-5cm with a wingspan between 19-25cm. The greater horseshoe bat and the noctule bat have a wingspan up to 38cm

Weight: 3-9g (Pipistrelle)

Lifespan: Average 4-5 years

Diet: Small flying insects

Family: Chiropetra - meaning hand-wing in Greek. This is an apt description, as the bone structure of a bat's wing resembles extended human fingers with the skin stretched tight between them up to the fingertips