Late autumn to late spring is hibernation, but they will come out to look for a drink or food if necessary.
Maternity roosts begin forming in May. A single pup is born in early July (rarely twins) and by three weeks, the pups are begining to fly. They will start to leave the roost to forage at 5 weeks (mid-August).
The males live on their own or in small roosts and seek out the females in spring and autumn.
There are 17 breeding species of bats in the UK - one of which was only confirmed at the start of 2010 with records for a further 13 non-breeding species which include 5 American species.
Bats will fly through out the year, but February is the month you are least likely to see a bat.
Bat watchers also get to see owls, badgers, foxes and otters . Horseshoe bats are more closely related to fruit bats than vesper bats.
ALL bats and their roosts are protected by UK and European law.
The largest known "roost" is of straw coloured fruit bats, that assemble in numbers of 5 to 10 million in Kasanka National Park, Central Zambia from October to January - during which time it is estimated that they eat 262,000 tonnes of fruit and distribute a lot of seeds!
The largest known roost in the UK contains 1800 to 2000 greater horseshoe bats.
If you have any concerns about a planning proposal contact the relevant Council and ask to speak to their ecologist. If you are in our area ( Bristol, Bath, South Gloucestershire and North Somerset) then you can also contact the Avon Wildlife Trust- they have a planning team and have produced some useful guidance