Survival of Bristle-thighed Curlews equipped with externally mounted transmitters

Telemetry devices are widely used in avian research, but the degree to which the deployment of such devices affects the survival of study subjects is often not addressed. It is generally assumed that such effects are less pronounced in large-bodied species that conduct relatively short migrations and carry relatively light telemetry devices. We studied Bristle-thighed Curlews Numenius tahitiensis over the period 2012–2017 at a nonbreeding site on the island of Oahu, Hawaii. We used leg-loop harnesses to equip 11 curlews with externally mounted, solar-powered satellite transmitters that constituted ca. 3% of their body mass, and compared the annual survival of these birds to 37 curlews marked only with uniquely engraved leg flags. Despite the species’ large size and the small mass of the transmitters, we documented potential negative effects of externally mounted transmitters on the survival of Bristle-thighed Curlews. We also documented apparent effects of age and sex on the survival of curlews, underscoring the difficulty of disentangling the effects of research techniques on study subjects. Understanding and publicizing the potential effects of research itself on wildlife are crucial steps in the process of refining technical applications and improving the welfare of study animals. We urge researchers to critically assess and report the effects of similar research techniques to minimize deleterious effects in future studies.