About the maps

About the maps
What do the maps show?
Are the records accurate?
Are you sure the records are accurate?

In common with just about every other wildlife group, the Bat Conservation Trust produced a millennium atlas showing bat distribution across the country. The maps below are Durham Bat Group’s contribution to this and show the distribution of bat records throughout Durham with the occasional intrusion into Cleveland.

The outline of County Durham divided into 10km squares. Each species has its own map. Some of the records don’t differentiate between very similar species. For example, most of our records are from the period before it was realised that the pipistrelle was actually two separate species. Hence there is a map for all pipistrelles as well as maps for the two individual species (similarly with Whiskered/Brandt’s). 'R' indicates roosting in that particular 10km square. 'O' indicates observation of a species in a square where no roosts have so far been recorded.  There is no significance to the position of the character within the square. 

One criticism that is often levelled at wildlife records of any kind is that they really only represent the distribution and activity of wildlife recorders. For many species there may be a cluster of records supplied by a keen naturalist, but the species may go unrecorded in other parts of its range just because no-one has looked for it there. Our bat records go some way to escaping this criticism as most of them result from members of the public contacting the Bat Group. This may be because they have found an injured bat or because of their concern, or interest, regarding a colony of bats that happens to be using their building as a roost. Durham Bat Group has been answering these bat calls on behalf of the Statutory Nature Conservation Organisation since the early 1980s and now has almost four hundred separate roosts on its database. Unless you consider that people in certain parts of the county are more likely to express their concern or interest in bats, it is probably a fair assumption that, by now, our records are a reflection of where the bats are in the county (at least the ones that are associated with buildings).

One truism about wildlife records that certainly does apply to our records, however, is that they are out of date as soon as they are published. Just after the maps were compiled, a Bat Group field outing to a lake near Spennymoor turned up Nathusius’ Pipistrelle. This was the first record for the county other than a post-breeding dispersal record in Teesdale. Also, bats that don’t tend to roost in buildings, such as Noctules and Daubenton’s, may well be more widely distributed than our records show. This is where you come in.  If you identify a bat that isn't shown on the map, don't criticise the map - REPORT THE OBSERVATION!