Spotted Bat and Big Free-Tailed Bat in Northern New Mexico

Abstract

Mortality in big free-tailed bats, Tadarida molossa, led to investigations which resulted in collecting 61 of these bats, 2 spotted bats, Euderma maculatum, and other species. Bats were captured in mist nets over water. T. molossa flew at air temperatures as low as 550 F; young were generally captured earlier in the evening than adults. Individuals of this species flew at an elevation of 25 feet, singly or in groups of two or three. They flew in light rain and in less inclement weather and appeared to be attracted by captives of the same species. Euderma maculatum were captured when air temperatures were 580 and 64'. The rectal temperature of a resting spotted bat approximated its environmental temperatures, and the bat became torpid at lower temperatures. Captive bats of both species died after they developed lung lesions and other pathological conditions not seen in the field. Although rabies is known in T. molossa and may have been present, the infection was not confirmed in these specimens. The spotted bat, Euderma maculatum (J. A. Allen), was formerly known from New Mexico by a single adult male found dead during September, 1903, in the Biological Laboratory of the New Mexico College of Agriculture and Mechanic Arts (Miller, 1903), now known as New Mexico State University, University Park, Dona Ana Co., New Mexico. An immature female big free-tailed bat, Tadarida moossa (Pallas), captured October 10, 1956, at Carlsbad Cavern, New Mexico, was reported earlier (Constantine, 1958). The present report concerns collections of two Euderma and sixty-one T. molossa at a locality in northern New Mexico. In August, 1958, the writer received a report from the New Mexico Department of Public Health indicating that rabies had been diagnosed in bats found moribund at Ghost Ranch, 12 miles NW Abiquiu, Rio Arriba Co., New Mexico. In that month and the next the problem was investigated as time permitted. Field studies and collections were followed by laboratory observations and attempts to adapt bats to captivity for experiments and other purposes. Experiences are as follows. Field Studies. The Ghost Ranch is in the pifion pine-juniper belt, on the boundary between watered canyons and dry open range. The main buildings of the ranch are situated at the entrance of Arroyo del Yeso, the walls of which in this area are composed of one hundred foot cliffs of Entrada sandstone. The elevation at the canyon entrance is