Effects of Ear-Tagging with Radiotransmitters on Survival of Moose Calves

Abstract

A critical assumption of radiotelemetry studies is that the radiotransmitters themselves do not influence mortality, Here we report the effects of marking techniques on survival of moose (A/ces alces) calves from birth to the beginning of the autumn hunting season. We marked and followed 181 moose calves with ear tags and 71 with ear trausmitiers, and we also followed 175 unmarked control calves, all with marked mothers, in 5 study areas in Sweden; 2 areas had resident brown bears (Ursus arctos), and 3 did not. Survival was lower for calves with ear transmitters than for those with ear tags (P < 0.001 ) and for control calves (P < 0.001). There was no difference in survival between control calves and calves with ear tags (P = 0.09). Survival was lower in areas with hears, but bears apparently did not prey differentially on calves marked with ear transmitters. Marking newborn moose calve ith plastic ear tags did not have measurable effects, but we do not recommend marking calves with ear transmitters, because of the high mortality rates calves experienced.