Effects of Backpack Transmitters on Captive Lesser Adjutant Storks (Leptoptilos javanicus)

Abstract

Satellite and GPS transmitters provide valuable information for bird conservation, though their attachment may have behavioral and/or physical effects. Captive Lesser Adjutant Storks (Leptoptilos javanicus) in Cambodia were divided into a control group (n = 7) and an experimental group (n = 7), and their behavior was monitored during three periods of 22 days each. The experimental group was fitted with dummy backpack transmitters in the second period. Each group included one individual capable of flight (n = 2); all other individuals had the feather vanes of one wing clipped. Both groups interacted by pulling, nibbling or pecking on their own or another bird's transmitter (6.8% of the total interaction time in the experimental group, < 1% in the control group). One individual capable of flight had a skin abrasion when removing the tag, which was likely caused by a tight fit of the backpack rather than its flying ability. The experimental group showed significantly more reflex movements (e.g., sneezing, yawning) in the third period (P = 0.017), but outside factors were assumed to have caused this difference. Despite measurable transmitter effects, no evidence was found that the birds' wellbeing was affected. This study provides a safe transmitter attachment method for Lesser Adjutants that aids future conservation.