Effects of Intraperitoneal Transmitter Implants on Yellow - Bellied

I implanted radio transmitters in 183 yellow-bellied marmots (Marmota flaviventris); transmitters were replaced <6 times in 73 animals, for 300 surgeries. Surgical procedures were simple, effective, and largely trouble-free. Survival 30 days later was >98%, and growth rates (21 g/day) were the same for animals with or without implants. Pregnancy rate (0.52 litters/yr) and mean litter size (4.3) of implanted females were similar to pregnancy rate (0.48) and litter size (4.2) of females without implants. Intraperitoneal implants offer an alternative to radio collars for yellow-bellied marmots. J. WILDL. MANAGE. 53(2).320-323 Radio telemetry is an important tool in studies of free-roaming mammals. Transmitters typically are attached to animals by external collars; radio collars, however, are impractical for some species because of life-style or body shape (Smith and Whitney 1977). Hence, surgical implantation of sealed, physiologically inert transmitters into the peritoneal cavity has been explored as an alternative. Early attempts in the 1960's produced equivocal results (Shirer and Downhower 1968), but with improved procedures and equipment, the approach has been applied successfully to several species of mammals (Smith and Whitney 1977, Melquist and Hornocker 1979, Garshelis and Siniff 1983, Davis et al. 1984, Eagle et al. 1984, Green et al. 1985, Madison et al. 1985, Koehler et al. 1987). Intraperitoneal surgery, however, involves a number of risks, including the stress of anesthesia and surgery (Smith and Whitney 1977, Smith 1980), postoperative infection (Eagle et al. 1984, Green et al. 1985), incision dehiscence (Melquist and Hornocker 1979, Smith 1980, Eagle et al. 1984, Koehler et al. 1987), and physical blockage of internal organs by the transmitter (Guynn et al. 1987, Koehler et al. 1987). Moreover, effects of implanted transmitters on survival, growth, and reproduction have been suspected, although these suspicions appear unfounded for some species (Smith and Whitney 1977, Smith 1980, Eagle et al. 1984, Madison et al. 1985, Reid et al. 1986, Guynn et al. 1987, Koehler et al. 1987). Since 1983 I have used intraperitoneally implanted radio transmitters to study dispersal in the yellow-bellied marmot. Previous attempts to attach transmitters to marmots, by collars, harnesses, or subcutaneous implants, were problematic (Downhower 1968, Thompson 1979). I describe a successful surgical procedure and assess the effects of implants on survival, growth, and reproduction of marmots. G. L. Florant showed me the surgical technique, and K. B. Armitage generously provided unpublished data and helped in many ways. M. P. Bray trapped animals and assisted with surgery. K. B. Armitage, G. L. Florant, R. S. Hoffmann, and N. A. Slade kindly reviewed the manuscript. Financial support was provided by grants from Sigma Xi, the Theodore Roosevelt Memorial Fund of the American Museum of Natural History, the American Society of Mammalogists, the Rocky Mountain Biological Laboratory, the Lee R. G. Snyder Memorial Fund, and the University of Kansas; by a Graduate Honors Fellowship and a Graduate Summer Fellowship from the University of Kansas; and by a University of Kansas General Research Grant and National Science Foundation grants DEB8121231 and BSR86-14690 to K. B. Armitage.