A pain in the neck: weak links are not a reliable release mechanism for radio-collars

Abstract

Collars are an attachment method commonly used to mount data collection devices on wildlife. Removal of collars at the completion of a data collection period is a high priority for the purpose of animal welfare, but retrieval of collars can often be difficult. Weak links or other drop-off devices are used by researchers with the intention of improving collar retrieval rates, and for mitigation of animal welfare risks associated with collar entanglement. However, the design and effectiveness of such devices is not regularly reported in detail in the literature. We surveyed wildlife researchers to collate and communicate their experiences with weak links, and assess their attitudes towards collaring Australian mammals in the 35–5500 g weight range. Forty-five researchers responded to the survey, of whom 25 had used weak links in at least one study. There was very little consistency between the performances of weak links, with researchers finding them effective in less than half of the scenarios reported upon. Outcomes varied depending on the type of material used for the link, the species being collared, and the environmental conditions under which the collars were being deployed. We recommend (1) researchers test weak links prior to deployment; (2) users to not rely upon weak links as the primary method of collar retrieval; and (3) continued communication of design and outcomes of all radio-collars deployed including those with weak links.