Improving radio transmitter attachment methods for small mammals through captive trials and field studies

Radio tracking can be used to collect information about animal movement, home range, behaviour and habitat use. Many field studies have fitted radio transmitters to small rodents using permanent nylon cable tie collars and successfully collected movement and fate data. The approach to animal welfare within the context of scientific research prioritises minimising adverse effects on the research animals. While a range of electronically activated release mechanisms exist in radio tracking collars for larger mammals, weight and size restrictions make these unsuitable for smaller animals (< 30 g). Our aim was to identify a radio transmitter model and attachment method of an appropriate size and weight, which would remain attached to a house mouse ( Mus musculus ) for >20 days to collect movement data and then detach or show signs of detaching after 30 days. Laboratory and field trials established that cable ties with a cotton thread weak-link, using heat shrink to attach a customised radio transmitter worked for wild house mice in agricultural fields. Glue-on methods did not stay attached for long enough to obtain more than a few days tracking data. Short summary Collecting meaningful radio tracking data for small mammals weighing <30 grams relies on selecting radio transmitter attachment methods suitable for the target species while prioritising animal welfare. Developing a non-permanent radio transmitter attachment for house mice is challenging due to size and weight constraints however, by trialling methods in the laboratory and field we developed a suitable radio collar with an in-built weak-link. Our non-permanent weak-link radio collar is an important improvement on existing permanent radio collars for small mammals. ### Competing Interest Statement The authors have declared no competing interest.