EFFECTS OF BAT-BANDS AND BANDING ON A POPULATION OF PIPISTRELLUS-NANUS (CHIROPTERA, VESPERTILIONIDAE) IN MALAWI

This study provides information about the effects of flanged metal bat -bands, and the procedures associated with banding and frequent census ing, on a population of Pipistrellus nanus, a particularly small vespe rtilionid bat. The bats were censused at their roosts in a banana plan tation, at intervals of approximately two weeks, for 10 months; 120 ba ts were banded and 75 were recaptured (447 recaptures). The best data came from a cohort of 64 adults (banded during the first six censuses) , 25 of which were recaptured 9-15 times. Band-status (the effect of t he band on the bat) was recorded each time a bat was captured. We reco gnised four classes of band-status ranging from class 1 (band-free wit h no injuries, observed on 66% of occasions) to class 4 (band-immobile with an unhealed wound, observed on 11% of occasions). Analyses of th e results showed that (a) the majority of bats were in class 1 on most occasions, but some had injuries (classes 2-4) which often improved o r deteriorated unpredictably; (b) the band-status changed in relation to time after banding, following an unexplained pattern; (c) band-stat us was not affected by seasonal changes in climate, or by the sex of t he bat; (d) banding did not affect flight and foraging, or mass, or '' survival'' in the population; and (e) roosting behaviour was not adver sely affected. Bats banded when we were inexperienced (census 1) were more prone to injuries than bats banded when we had improved our bandi ng technique. Banding enabled us to study the social behaviour and rep roduction of this species and we believe that the results justified ba nding one small population of this common, widespread species. We pred ict that other species of small vespertilionids may respond similarly to banding, but extrapolation to species in other families is probably not justified. We recommend that flanged bat-bands should be fitted a s loosely as possible, that new bat-banders should be trained by exper ienced banders, and that banding of bats is permitted only when there are very good scientific reasons for the banding and when harm to indi vidual bats and populations is likely to be minimal.