Ball Chain Transmitter Attachment for Ranid Frogs and Kangaroo Rats
Galen B. Rathbun, U.S. Geological Survey, Biological Resources Division, Piedras Blancas Research Station, San Simeon, CA 93452-0070 USA
Often, one of the greatest challenges facing field biologists that use radio-tags is developing effective attachment methods. We have successfully used ball or bead chain as a quick, safe, and precise method of radio-collaring giant kangaroo rats (Dipodomys ingens) and radio-belting California red-legged frogs (Rana aurora draytonii). We needed to develop particularly safe radio-tags because both species are on the federal Endangered Species List. Our radio-tags were attached or replaced on either species within 1-2 min of capture with little discomfort or stress to the animals. Rapid deployment was possible because of the precision of the chain, and the ease of snapping it onto different transmitters fitted with chain connectors. The connectors were attached to the radios with epoxy prior to deployment. We radio-tagged 48 kangaroo rats and tracked them for up to 18 days each, and we radio-belted 47 frogs, some multiple times, for an average of 88.4 days each. As with any collar or belt, fit is critical to reduce loss, skin abrasion, and entanglement. We found that the chain belts were sometimes eventually lost when they slipped over the extended legs of the frogs (24 cases). Only one collar was lost on a kangaroo rat, when the chain failed due to corrosion associated with a skin abrasion. Skin abrasions from the radio-tags were minimal in both species because of the smooth and flexible nature of the chain. Entanglement of the frog belts with objects generally was not a problem, except in habitats where submerged shoots of bulrushes (Scirpus sp.) were common (3 cases). Front foot entanglement in the kangaroo rat collars was minimal (1 case). We believe ball or bead chain has great potential for attaching radio-tags in other species.
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