|
|
| Home Page | What is Batscapes? | People & Bats |
| Bat Species | Junior Page | Advice and FAQ's |
| Bats & Landscape | News and Events | Links & Contacts |
Over the last century British bats have suffered huge population declines. Even our most common species, the pipistrelle, is estimated to have suffered a 70% decline since the 1970s. Greater horseshoe bat populations decreased by an estimated 99% over the last century talking it to the brink of extinction in Britain, though it managed to hang on in our region. The greater mouse-eared bat was less fortunate and was declared extinct in Britain in 1991, the first mammal to have been declared extinct in this country since the wolf. Causes of these declines are considered to be related to disturbance of roosts, use of chemicals and changes in farming and forestry.
Bats are more closely tied to humans than probably any other wild British mammal. They live in our houses and buildings and hunt for food around our farms and gardens. As such we are able to influence the success or demise of bats, and their fate is largely in our hands.
Top
Bats have quite an unusual lifecycle, which for many bat species brings them into close contact with people. Unlike most of our other small mammals bats are long lived creatures with a slow reproduction rate. This means they can be very vulnerable to plummeting populations, with many years needed for their numbers to recover. Whereas mice will typically live for up to 2 years and can produce 50 young per year, by comparison a horseshoe bat can potentially live over 30 years, but can only give birth to a single baby each year or second year.
One of the reasons that bats can live so long is that they spend much of their lives in a deep sleep, known as torpor. This is particularly marked in the winter when the torpor extends into hibernation, though even then they can occasionally rouse at intervals. In the spring they come out of hibernation and need to eat large numbers of insects to regain their normal body weight. A particularly cold or wet spell at this time can prove disastrous as in such weather few insects will fly and the bats risk starvation.
In early summer female bats congregate together and with most of them already pregnant (having mated the previous autumn) they seek out favoured roost sites that provide the warm sheltered conditions in which to bear and raise their single young. Such roosts are called maternity roosts and are of particular importance, with bats loyally returning year after year. Around half our bat species now typically use houses for maternity roost sites, however the number of suitable and accessible maternity roost sites in houses is limited, and so they are highly prized. During the day the bats will sleep deeply in torpor then in the evenings the mothers fly out to hunt, leaving their babies often in the care of non-breeding female bat ‘babysitters’. Through the night they will return to suckle their babies and on this rich diet the young grow quickly and are able to fly out and hunt with their mothers in a matter of a few weeks.
With the young thus gaining their independence the maternity colonies start to disperse, typically towards the end of summer. At this time the males (who have had no role in raising the young) set up mating roosts to which they try to attract passing females. Successful males can build up a harem of females through the autumn, however as the weather cools with the approach of winter both males and females seek out sites such as large trees or caves in which to hibernate. At this time although the females have mated they are not in fact pregnant. Instead they store the sperm in their body until the spring when they will ovulate and become pregnant so timing their births for the early summer when food is more plentiful.
TopHouses and other buildings can often attract bats searching for a suitable roosting site, and as the number of undisturbed caves and standing hollow trees has diminished many species are now greatly dependent on the availability of building roosts. The bats do not make access holes themselves, nor do they build nests or chew wood or wires inside the roost, they are simply making use of the warm enclosed positions that many buildings provide, particularly around their roofspaces.
The time of year when most bats are likely to be in our roofspaces is in the summer, when female bats gather together in what are termed maternity roosts, to give birth to and raise their single baby. At this time there may be dozens of bats resident, though within a few weeks the young are weaned and the maternity roost starts to disperse. For these few weeks however the bats are extremely vulnerable and disturbance at this time can account for many bat deaths. In the past the treatment of roof timbers with lindane based sprays led to many bats being poisoned as the spray gave off toxic chemicals which remained active for years. Similarly work on roofs at this time can expose the vulnerable youngsters leading to their death while the blocking of exit holes can lead to the bats inside starving to death. Many of these actions were carried out accidentally in the past, however bats and their roosts are now legally protected and any work which may affect them requires that the roost owner takes free advice from English Nature before proceeding in order to prevent such deaths.
Bats are typically found roosting in the summer in south-facing aspects of roofs, though wall cavities and behind board cladding are also favoured sites. Many people are unaware when they have bats using their houses, however standing outside at dusk on a warm summers evening is the best opportunity to see any emerging bats. By using a bat detector an identification of the bat species can often be made from their echolocation calls. In winter individual bats can sometimes be found in deeper cracks and crevices, or collectively in cellars or ice houses. If you have bats in your house and would like to learn more about them then contact the Batscapes Project Officer.
Top
Horseshoe bats can be easily distinguished from other British bats by their distinctive horseshoe-shaped nose leaf and habit of hanging freely from ceilings with their wings wrapped partially around their body. When hanging, greater horseshoes are around the size of a small pear and lesser horseshoes the size of a plum. If you see or have seen bats fitting this description then please do let the Batscapes Project Officer know.
The project area is one of the few remaining hotspots for the two species of horseshoe bats in Britain. A century ago greater horseshoes were found across southern England from Cornwall to Kent while their cousin the lesser horseshoe was found across much of Britain as far north as Yorkshire. Today both species are largely restricted to pockets of southwest England and Wales. It is estimated that greater horseshoes have suffered up to a 99% population crash in Britain over this time and lesser horseshoes have fared little better. There are now only thought to be 20 or so remaining greater horseshoe maternity roosts. Thankfully at many of these sites their numbers now seem to be slowly rising, however a prolonged cold or wet spring could easily see numbers plummet. Lesser horseshoes are showing a more marked increase in numbers over the past 5 years in Britain however across much of Europe their numbers are continuing to fall, making British populations all the more important.
Key to the continued recovery of our Horseshoe bats is the continuation and extension of farmland and woodland managed in a wildlife friendly manner. This together with the protection of roost sites from loss or disturbance should see colony numbers rise leading hopefully to the creation of new colonies elsewhere within the project area and beyond.
TopPeople can make a huge difference to the conservation of local bats, and by doing so will be helping to secure a safe future for endangered species directly on their doorstep.
Do you know of a bat roost in your property or area?
Because bats are very secretive it is very difficult to know where they are roosting. Even householders with roosts in their own houses are often unaware of the bats being there, but for projects like Batscapes we rely on the public to tell us where local roosts are. Bats are most commonly found roosting in houses in the summer and can be spotted by watching for the bats emerging at dusk. If you see bats emerging from a building or tree then please tell the Batscapes Project Officer so we can add it to our database to help us build up a picture of where our local bats are. If you wish then either the Batscapes Project Officer or an Avon Bat Group member should be able to visit with a bat detector to identify which species of bat is present and give you information on roosting bats.
Put up a Bat Box
Bat boxes are used by several species of bats for roosting in and can be placed either in trees or on walls. For details on where to buy them, how to make them and where to place them check out the Bat Conservation Trust website.
Attract bats to your garden
If you live close to a bat roost then you may well have bats flying over your garden. Certain plants are particularly attractive to night flying insects like moths and by having a few of these in your garden you can increase the likelihood of passing bats stopping by to feed. Night scented stocks, evening primrose, dame’s violet, tobacco plant, soapwort, honeysuckle and ivy are amongst the insect attracting plants recommended for a bat friendly garden. Garden ponds are also major attractions for flying insects and hence bats, and with a recent decrease in ponds in our countryside, garden ponds play an increasingly important role. For more information on bat-friendly gardening it’s worth checking out the Warwickshire Bat Group website and look under “gardening for bats”.
Become a Trainee Bat Warden
The Batscapes project in conjunction with Avon Bat Group is looking to provide free training on bats to interested members of the public to help them become more active in bat conservation as local ‘bat wardens’. A series of training sessions are planned to provide people with the skills necessary to monitor their local bats, search out new roosts in their area or care for injured bats. The time commitment necessary for trainee wardens is not great as every additional effort is welcomed, while with a network of trainees our knowledge of local bats as well as our ability to help them would be hugely increased. See News and Events for forthcoming training days or contact the Project Officer to find out more.
Join us on a practical habitat management work day
There will be a number of events where we will be doing practical habitat management tasks that will benefit our local bats. Check out the News and Events page for further details, and come along and join us.
If you are a Farmer or own land
Because of the way bats use our countryside, sympathetic management of farmland, grassland and woodland can be hugely beneficial to their successful survival. For land within range of known horseshoe bat roosts the project field officers can offer free visits to farms and large landholdings to share their expertise on making such sites bat friendly and the grants available to achieve this. For more information see Bats & Landscape.
Join the Avon Bat Group and the Bat Conservation Trust
For £5 a year you could join Avon Bat Group or for £21 you could join the Bat Conservation Trust and get Avon Bat Group membership for free. Both organisations do an immense amount of work for bats as well as producing newsletters, running events, training etc.
Help monitor bat numbers
If you have a bat roost in your property then you could add to our national understanding of how bat populations are faring by taking part in a colony count for the National Bat Monitoring Program organised by the Bat Conservation Trust. If you don’t know of any roosts then why not try the Sunrise Survey element of the same program. Either way by simply counting out emerging bats for a couple of evenings, or taking a sunrise walk on a set summer morning you can be part of the biggest bat monitoring program in Britain.
