Remotely releasable collar mechanism for medium-sized mammals: an affordable technology to avoid multiple captures

Collar-mounted monitoring devices for collecting behavioural or positional data (e.g. sound recorders, accelerometers, GPS, VHF) are increasingly used in wildlife research. Although these tools represent an improvement in terms of data quality, they require capturing animals. Using remotely releasable collars allows for reducing the number of captures by half; however, currently this technology is primarily available for large mammals. Here, we present a locking mechanism design that is remotely releasable and light enough (22 g) for medium-sized mammals (>1 kg), can run in low-power mode for years, is reusable directly after recharge, and has a material cost of less than €50. An Android application operates this mechanism over a Bluetooth connection. We developed custom-purpose software for both the locking mechanism and the Android application. We tested two collars equipped with this locking mechanism in field-like conditions on two ring-tailed lemurs Lemur catta. The release mechanism has an operational range of 10–50 m and can run in active mode (allowing remote release) for several hours. Implementation of the presented release mechanism for collars on medium-sized mammals provides a low-cost solution to reduce the number of captures. We demonstrate that some low-cost technical improvements of tools used for studying wildlife can have significant effects on reducing the stress experienced by animals during capture. Detailed description of this new mechanism design provides a starting-block for potential adaptations for a broader range of species.