Technical Issue With the Logger or is the Bird Dead – What Information About Mortality Rate Can GPS/GSM Dataloggers Deliver?

Abstract

Delivering information on bird movement is the main reason for utilization of dataloggers in research. It was, however, very soon discovered, that information regarding mortality factors can sometimes be of higher conservation value. Since 2011, the “Aquila” company is offering GPS/GSM dataloggers. Today an attempt is made to measure the efficiency of Aquila dataloggers in delivering solid data regarding bird mortality rate. Analysed were 111 devices used in Eastern Europe and Asia within 7 scientific projects from 2017 to 2021. The results show that over 67% of the devices are either still operational or were collected providing evidence of the bird mortality problems. Of the remaining 33%, further probable mortality issues could be withdrawn from the delivered data, despite lacking clear evidence, for half of the cases. In total, fate of 18% of the tagged birds remains unknown.