There is very little known about the post-release survival of hand-reared pipistrelle bats Pipistrellus spp). We radio-tracked 12 pipistrelle bats, hand-reared and released under three different protocols: i) limited pre-release flight training and overwintering (n = 5); ii) prolonged pre-release flight training, but with limited space (n = 2) and iii) prolonged pre-release flight training in large flight cage (n = 5). Of the five bats reared under the first protocol, four were recovered, grounded, within 48 h and the signal from the fifth bat lost on day two, due either to tag failure or from the bat flying out of the study area. Both bats in the second group flew strongly on the night of release but on the second and third nights only one emerged and flew briefly. The signals from both bats remained stationary on subsequent nights. In contrast, bats from the third group were tracked for between five and ten nights, indicating that they were able to survive independently following release. These preliminary results suggest that post-release survival depends on extensive pre-release conditioning in a large flight cage, rather than the limited flight opportunities traditionally provided within domestic houses by bat carers. Other factors that may affect post-release survival are discussed and further work is encouraged to determine whether rehabilitated bats integrate with the local population.

We recently used radio-tracking to demonstrate short-term, post-release survival of five orphaned, hand-reared pipistrelle bats. Here, we present further evidence of short-term, post-release survival and also demonstrate longer term survival using re-sighting data of ringed common (Pipistrellus pipistrellus) and soprano (Pipistrellus pygmaeus) pipistrelle bats. Ten bats (five common and five soprano pipistrelles) were radio-tracked for between one and ten days. Three of these were retrieved after one, two and four days, respectively. In addition, five of the 39 (13%) ringed bats returned to their release boxes between 38 and 1,389 days after release, at least two of which survived over the winter in the wild. A sixth ringed bat was retrieved 27 days after release after becoming trapped in a house. We also identified potential barriers to successful rehabilitation. Two of the ten bats radio-tracked in the current project became trapped within buildings and another bat had to be retrieved following entanglement with debris. We therefore recommend that attention be paid to giving bats the opportunity, prior to release, in identifying and using small exit holes similar to those found in buildings and loft spaces. We also recommend allowing bats to self-release following prolonged pre-release flight training in a large flight cage situated in suitable bat habitat.