Ammonia Tolerance of the California Leaf-Nosed Bat

Abstract

A series of 59 California leaf-nosed bats, Macrotus californicus, was exposed to varying concentrations of anhydrous ammonia. Physiologic responses noted in the bat were compared to the same responses as recorded in the literature for man and other experimental animals. Recordings were made for the following: cardiac and respiratory rates, blood non-protein nitrogen, urine urea and ammonia and animal and gassing chamber temperatures. An elevation of non-protein nitrogen over the mean normal was evident but no significant elevation of urine urea and ammonia was noted. Resistance to the gas was demonstrated by decreases in respiratory and cardiac rates. Toxic manifesta- tions attributable to ammonia were noted in distinct visceral damage, corrosion of the skin and mucous membranes and pulmonary edema. Maximum sublethal con- centration tolerated for an exposure time of 9 hours was 3,000 ppm. Investigators have often mentioned the extremely unpleasant working condi- tions in the ammoniated atmosphere of caves and mines frequented by large numbers of bats (Krutzch and Sulkin, 1958; Eads et al., 1955; many others). During certain times of the year concentrations of ammonia in Cueva del Tigre, 14.9 miles SSE, Carbo, Sonora, Mexico, are elevated to a level such that reflex res- piratory arrest was experienced by E. L. Cockrum (personal communication). The cave at this time was in use as a maternity colony for an estimated 2 to 3 million bats. Since this condition occurs in the normal habitat of these animals, interest was aroused regarding their unusual tolerance to ammonia. No in- formation has been presented on the physiologic response of a bat to ammonia concentrations. This study was made, therefore, to determine the physiologic effects of ammonia inhalation on the California leaf-nosed bat, Macrotus cali- fornicus Baird.