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Fig. 1 | Animal Biotelemetry

Fig. 1

From: Best practice recommendations for the use of external telemetry devices on pinnipeds

Fig. 1

Examples of improvements in ETD attachment methods over time. The attachment methods allow different placements and attachment durations, and may have different impacts on study animals (Recommendations # 9 and 10). a Adult female Antarctic fur seal on Bird Island, South Georgia. The female is carrying an opto-mechanical depth recorder (Meer Instruments, Palomar Mountain, CA, USA; red cylinder, 210 × 50 mm, 700 g) and a VHF beacon (Telonics Inc., Mesa, AZ, USA, clear epoxy cylinder, approx. 100 × 30 mm, 100 g) that are attached using a harness of nylon webbing worn by the animal, illustrating older tag technology and attachment methods. This was one of the early investigations into pinniped diving behavior and its relationship to prey distribution from the late 1970s through the mid 1980s [23]. Photo © DP Costa, 1983. b Juvenile California sea lion at Año Nuevo Island in 2016, instrumented with a SPOT6 Argos transmitter (72 × 54 × 24 mm, 119 g, Wildlife Computers) attached with Loctite Quickset™ 10-min, 2-component Epoxy (Product # IDH1289278, Henkel Corp., Düsseldorf, Germany). This epoxy cures within about 8–12 min at ambient temperatures between 10 and 18 °C, while generating comparably little reaction heat if sufficiently thin layers are used. Care needs to be taken with larger devices that may trap reaction heat between fur and tag. In warmer temperatures, frozen gel-packs can be used to slow reaction and cool epoxy and tags (Recommendation # 10). The back-mounted attachment shown here typically results in fewer Argos uplinks at sea, and lower quality location estimates, than head-mounted transmitters shown in Figs. 3b and 5b. This animal was part of a study examining the movement and diving behavior of juvenile California sea lions, an age class about which very little is known due to their transient state and the resulting difficulty in recapturing them [77]. These animals were instrumented opportunistically during handling for a project studying the occurrence Leptospirosis in the Año Nuevo population (Recommendations # 5 and 6). The wet pelage across the shoulders and fore-flippers is from water and ice used to keep the animal cool (Recommendation # 7) and slow exothermic epoxy curing. Photo © PW Robinson, 2015, NMFS Permit #17952. c Dorsal and plantar (inset) views of a SPOT Argos transmitter (Wildlife Computers) attached to the interdigital webbing on the hind-flipper of a spotted seal. Photos © PL Boveng, 2016, NMFS Permit #19309. d Nylon mesh is superficially glued to the fur of an adult Weddell seal using Devcon type 14265 5-minute two-component epoxy (ITW Performance Polymers, Chicago, IL, USA), study details are given in [49]. In the study area in McMurdo Sound, no natural predators are present to possibly cue in on increased visibility that could result from the white patch. In areas with predators, dark mesh should be used. The Devcon epoxy is quicker setting than the Loctite Quickset epoxy referenced in Panel B, making it more suitable in colder climates. At lower temperatures, providing additional heat via hot-packs (e.g., snap to heat gel packs) may be required to enable curing. Otherwise epoxy may simply freeze, giving the appearance of curing, but without adhering power. Channels formed from heat shrink tubing allow the subsequent attachment of ETDs via plastic or metal zip ties. This method allows for easy device removal by cutting ties, and the mesh base remains on the animal and is shed during the annual molt. Plastic ties work well in temperate climates, but become brittle in cold climates where metal ties provide more secure tag retention. For stainless steel ties, using retained-tension ties prevents loosening that occurs in standard ball-lock metal ties on rigid backing. Some researchers wrap tags in self-fusing rubber splicing tape (e.g., 3-M Temflex™ type 2155) that can then be glued to a mesh base, sometimes in combination with zip ties, for quick removal by cutting ties and tape. Photo © J Skinner, 2012, NMFS Permit #15748

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