John R. Wheeler

Abundance of Cottontails and Their Fleas at Red Bluff Ranch, New Mexico

Estimates of cottontail (Sylvilagus auduboni) abundance were positively correlated with overall flea indices (r = 0.857) and with the predominant flea species index (Hoplopsyllus glacialis affinis) (r = 0.743). Some flea species found on these cottontails are known transmitters of plague in New Mexico. The life history of Spilopsyllus cuniculi is closely linked with that of the wild rabbit Oryctolagus cuniculus with significantly higher populations of fleas in March and April (Allan 1956). Populations of wild fleas on cottontails (Sylvilagus sp.) may also be linked with the populations of the host. Cottontail abundance and their flea parasite abundance are recorded in this paper. The cottontail is Americas most hunted game species. According to Allen (1954) between 30 and 50 million are taken in an ordinary year. As man hunts this abundant game species, he may come in contact with diseases which cottontails or their fleas may transmit. One of these is plague caused by the bacterium Pastuerella pestis. Plague was first isolated from the tissues of a wild rabbit Sylvilagus nuttalli in Lincoln County, Washington, in 1939 (Eskey 1939). In New Mexico, from 1949-1960, five cases of human plague have resulted from association with desert cottontail S. auduboni (Kartman 1960). Two human infections in California were acquired after cleaning brush rabbits (S. bachmani) in 1921 and 1936 (Kartman 1960). 1 This research was supported by the U. S. Army Medical Research and Development Command, Office of the Surgeon General, Washington, D. C. (Contract No. DADA17-67-C-7016). 422 The data presented in this paper are part of a current study evaluating use of insecticides to control ectoparasites of wild mammal populations. We are indebted to D. Walker, Manager of Red Bluff Ranch, for allowing us to study cottontails on the ranch. MATERIAL AND METHODS The study area, the 56,000-acre Red Bluff Ranch is located 30 miles north of Roswell, Chaves County, New Mexico. Red Bluff has floral associations typical of the Lower Sonoran life zone: mesquite (Prosopis juliflora), creosote-bush (Larrea tridentata), and gramma grasses (Bouteloua sp.). More complete descriptions of the flora and fauna can be found in Rael et al. 1968. Cottontails were collected in Sherman and National live traps baited with unhulled oatmeal, milo, and corn. One hundred traps were set at 20-ft intervals (stations) along a line 1,000ft long, a Sherman and National live trap at each station. Usually seven trapping periods (100 trap nights per period) were conducted each month in one area. One trap night was considered as one trap (Sherman or National) set over night. When trapping was started late in the month and continued into the following month, the trapping period became bi-monthly. The rabbit index is for This content downloaded from 207.46.13.124 on Wed, 22 Jun 2016 05:44:26 UTC All use subject to http://about.jstor.org/terms ABUNDANCE OF COTTONTAILS AND THEIR FLEAS Forcum et al. 423 Table 1. Overall flea indices and cottontail estimates at