Attracting and capturing coal tits parus ater: Biases associated with the use of tape lures

Abstract

Possible biases related to the use of recordings were assessed by comparing captures ofCoal Tits Parus ater with mist nets in presence and absence of tape lures. Samples netted with and without tape lures differed in age composition but not in body size. Moreover, tape lured nets caught resident birds less frequently than expected. Group size of flocks captured with the use of recordings was larger than those captured without. Tape lured juveniles had higher levels of subcutaneous fat reserves than Coal Tits captured at random, whereas this difference was not detected in adults. Attraction of dispersing juveniles and habituation to the tape lure by more resident individuals seemed to explain the patterns observed. Caution and knowledge of the biasescaused by decoys is recommended before designingbird population studies which rely on the capture of birds by this method. © 2000 Taylor and Francis Group, LLC.