Impact of PIT tagging on recapture rates, body condition and reproductive success of wild Daubenton's bats (Myotis daubentonii).

A successful and safe methodology for the subcutaneous insertion of passive integrated transponder (PIT) tags in a small- to medium-sized bat (average mass 9 g) under isoflurane-induced anaesthesia is described. Passive integrated transponder (PIT) tagging had no significant impact on the rate of recapture, body condition index (BCI) (bodyweight/forearm length) and reproductive success of tagged individuals, and no visible injuries or health problems were observed in any of the recaptured bats. Tagging success, in terms of retention and function, was 92 per cent (n=61) by the third year of using the method. Sixteen per cent (n=39) of bats tagged during the three-year study period were not producing positive scans with the microchip reader when recaptured after previously successful tag insertion, indicating that the tags were either working their way out of the bats or ceasing to function.