OpenDropOff: An open‐source, low‐cost drop‐off unit for animal‐borne devices

Abstract

The use of animal‐borne devices in wildlife studies is increasing due to the miniaturization of sensors and reductions in component costs. Retrieval of animal‐borne devices is often advantageous for several reasons, including data retrieval and animal welfare considerations; however, commercially available drop‐off units are often prohibitively expensive and/or unreliable. Here, we present ‘OpenDropOff’, an open‐source, low‐cost electronic drop‐off unit for remotely detaching animal‐borne sensors from individuals. OpenDropOff devices function by using heat, produced by running an electrical current through resistance wire (nichrome), to melt nylon (e.g. fishing) line, detaching sensors from animals at or after a pre‐determined time. OpenDropOff can be constructed using commercially available components (costing < USD $15 in total; approximately 10% or less of many commercially available drop‐off units) and can be customized to fit project‐ and species‐specific needs. Fourteen OpenDropOff devices have been field deployed on koalas (Phascolarctos cinereus) (n = 11), swamp wallaby (Wallabia bicolor) (n = 1), Australian brush turkey (Alectura lathami) (n = 1) and Australian white ibis (Threskiornis molucca) (n = 1), with the only detachment failure occurring after a device was damaged during the koala’s unrelated death. OpenDropOff devices provide a wider range of researchers with a reliable, cost‐effective tool for detaching animal‐borne sensors. Their use could allow researchers to more efficiently allocate project resources, and their flexibility provides an opportunity to mitigate animal welfare concerns surrounding the use of animal‐borne devices.

WildWID: An open‐source active RFID system for wildlife research

“…Open‐source technologies are increasingly being used by wildlife biologists, and our active RFID system adds to the growing body of devices freely available (e.g. OpenDrop; Rafiq et al., 2019). WildWID provides a low‐cost, adaptable alternative to commercially available RFID systems, and their successful deployment across a range of species highlights their applicability to a range of systems and questions.…”

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

“…This time window may be problematic for species and situations for which it is hard to predict when a particular animal can be found at a specific time and location. However, many currently available devices do not provide this flexibility but are rather programmed to be released at a given time (Matthews et al 2013, Rafiq et al 2019). In its current form, the locking mechanism can run in Active mode for almost four hours (i.e.…”

“…Moreover, equipping smaller animals requires the consideration of additional constraints, such as size and weight restrictions, while current devices designed for larger animals often rely on bulky, heavy and non‐reusable squib (explosive) release mechanisms (Chapman and Hamerly 1988, Marshall et al 2005). There is therefore a clear need for a cheap and open‐access solution (Rafiq et al 2019).…”

Telemetry tails: a practical method for attaching animal-borne devices to small vertebrates in the field

“…There are two options for dropoff type attachments: (a) attachments that are programmed to detach at a specific time and date (e.g. Cypher et al 2014;Rafiq et al 2019;Klauder et al 2021), and (b) attachments that passively detach due to natural degradation of materials (e.g. Opiang 2009;O'Mara et al 2014;Evens et al 2018;Rayner et al 2021;Ross et al 2022).…”