change roost sites. The female bats usually give birth to a single pup in early July, though births have been recorded as late as mid-August. The female bats normally give birth to a single young in late summer, and the baby is occasionally carried by its mother for the first few days. The young bats usually make their first flights at around three weeks old, and at six weeks they can forage for themselves. Breeding colonies usually disperse by early September, although a few bats may use the colony site as a roost until early October. The male bats probably remain solitary or in small groups but are occasionally found with females in spring or autumn. Mating seems to take place in the autumn, but very little is known about the mating behaviour. Both sexes reach sexual maturity at one year old. Serotine bats mainly use buildings for summer roosts, especially those older buildings with high gables and cavity walls, and often occur in churches; modern buildings are used infrequently. The roost is normally accessed at or near the gable apex or the lower eaves. The serotine bat is hardly ever found in trees, which were the most likely pre-human roost sites, and the species seems to be very oriented towards using buildings. The roost is sometimes shared with pipistrelles or brown long-eared bats, and this species has also been recorded associating with Natterer's bats, whiskered bats and noctule bats. Only a few serotine bats have been found in winter, but it seems likely that most hibernate in buildings in cavity walls and disused chimneys. There are a few records of them being found in the coldest parts of caves, either in roof crevices or in accumulations of boulders. The foraging activity of serotine bats peaks at dusk, and there is a second period of activity around dawn. They commute on average to and from feeding areas per night, and forage in up to five distinct areas per night. This species uses three main feeding strategies: short flights, ground feeding and aerial hawking. It normally forages quite low, above the ground. Diet Similarly to the Nyctalus or Plecotus species, the serotine is mainly an aerial hawker focusing on hunting flying insects. Echolocation The frequencies used by this bat species for echolocation lie between 25–55 kHz, have most energy at 31 kHz and have an average duration of 8.8 ms. Conservation