A banding study of Plecotus auritus was carried out in northeast Scotland between 1978 and 1991. A total of 526 bats were caught, and of these 211 had the procedures involved in the doubly labelled water technique performed on them (injection with isotopes, and in most cases removal of a small blood sample from the interfemoral vein). Recaptures of these bats in subsequent years allowed a direct comparison to be made between the proportions of recaptured bats which had been injected, those which had been both injected and bled, and those which had had neither procedure performed on them. The proportion of bats recaptured did not differ between the test and control groups, which suggests that these procedures had little or no effect on the long-term survival of this species, over and above any effect of the initial capture and handling.
Entwistle, A. C., Speakman, J. R., & Racey, P. A. (1994). Effect of using the doubly labelled water technique on long-term recapture in the brown long-eared bat (Plecotus auritus). Canadian Journal of Zoology, 72(4), 783-785. https://doi.org/10.1139/z94-105