Friday, 1 June 2007

Norfolk's special bat

Built sometime around 1581, Paston Great Barn is an incredibly important building. Not only is it a scheduled ancient monument but it also supports a breeding colony of one of our rarest bats. This is the barbastelle, a species about which are only now beginning to gain a better understanding of its ecology and social behaviour. The breeding colony at Paston was first discovered in August 1996 and at the time it was the only known such colony in Britain. Since then, other breeding colonies have been found in West Sussex, Hampshire, Wales and Somerset, although all of these are in trees, rather than a building. It is worth noting, however, that the use of buildings is more typical on the Continent. It is likely that more colonies will be discovered over the coming years but, even so, there is no doubt that this remains a precariously rare and thinly distributed species.

The barbastelle is, by British standards, a medium sized bat, with dark brown, oily, fur. Short in the face and with large, almost square, ears, the barbastelle has evolved to feed on small prey items located and captured through a slow and manoeuvrable flight. Although the preferred habitat appears to be mature natural or semi-natural woodland, it is clear from studies of the Paston bats that the species is actually rather flexible in its requirements. Radio-tracking studies of the bats, both here and in Sussex, show that barbastelles will feed beneath the canopy during twilight, moving out into more open areas once it becomes properly dark. The bats at Paston make use of the coastal strip between Mundesley and the gas terminal at Bacton, foraging along the shoreline or over the grassy cliffs. Here they take mainly small moths, though other insects also feature, especially when they become abundant.

Paston Great Barn supports a nursery roost, with females and youngsters present during the summer months. Mature males normally roost separately but they have been caught visiting the barn, suggesting that they seek out receptive females with which to mate. This behaviour is only known because of the efforts of Norfolk Bat Group who have devoted time to studying and protecting the bats at Paston. Juggling the conservation requirements of the bats and the barn is not necessarily straightforward.

Because of the difficulties of working with these small, delicate and nocturnal creatures there is still much to learn. Records of barbastelles from elsewhere in Norfolk (from the North Norfolk coast and Breckland) suggest that there are other breeding colonies to be found within the county. Most likely, these will be in trees, located within areas of unmanaged mature woodland, making it all the more difficult to pin them down.

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