Noteworthy Records of Bats from Islands in the Gulf of California

Abstract

Information on bats inhabiting the islands in the Gulf of California is scanty and includes reports by Reeder and Norris (1954), Banks (1964a, 1964b, 1964c), and Orr and Banks (1964). Distributional records for Baja California were given by Orr (1960), Jones et al. (1965), and Woloszyn and Woloszyn (1982). The present paper reports noteworthy distributional records and observations concerning habits and reproduction for five species of bats collected from five islands in the Gulf of California. These results were made possible by the efforts of biologists who participated in two trips to the islands. The first trip was in May 1975 and the second was part of the Expedition Anepantla in June and July of 1979. Bats were collected with mist nets in brushy areas, glens, and over dry stream beds. Additionally, skulls and postcranial skeletal material were obtained from caves. Specimens reported in this paper are deposited in the Instituto de Biologia, Universidad Nacional Aut6noma. Leptonyeteris sanborni Hoffmeister.-Isla San Jose: two adult females were captured on 28 June 1979. Skulls of this species were collected along with those of Macrotus and Plecotus (see accounts below) from a cave on the island. Isla del Carmen: 27 individuals were netted during the first days of July 1979. Fifteen were females without embryos and 12 were males with abdominal testes. Mean (range) body weight of the 27 specimens was 19.8 (18.4-28.4 g). Many of the bats had cactus pollen on their faces. These localities represent the first records of Leptonycteris for islands in the Gulf of California. The records are not unexpected, however, because L. sanborni has been reported from peninsular Baja California (Baker and Cockrum, 1966; Woloszyn and Woloszyn, 1982) and is common on the west coast of Mexico (Sonora-Baker and Cockrum, 1966; Sinaloa-Jones et al., 1972). I follow Davis and Carter (1962) in using the name L. sanborni. The specific name verbabuenae was proposed by Martinez and Villa-R. (1940) and its taxonomic status has been discussed at length by Ramirez-P. and Alvarez (1972) and Watkins et al. (1972). Macrotus waterhousii californicus Baird.-Isla San Jose: one skeleton was obtained from a cave along with remains of Leptonycteris and Plecotus on 1 July 1979. Isla del Carmen: one male was captured on 4 July 1979. Isla San Esteban: one male was caught on 9 July 1979. Specimens collected from San Jose and San Esteban were adults with scrotal testes measuring (in mm) 1 by 1 and 3 by 2, respectively. During the evenings of capture, these bats were observed flying over beaches, eating pill bugs (Isopoda). Villa-R. (1967) reported Macrotus from Isla San Jose; the specimens reported herein for Isla del Carmen and Isla San Esteban are new records. Jones et al. (1965) reported this species as being one of the most common bats in southern Baja California. I follow Anderson and Nelson (1965) in arranging californicus as a subspecies of M. waterhousii; however, Davis and Baker (1974) and Greenbaum and Baker (1976) have presented evidence that M. californicus should be recognized as a distinct species. Pipistrellus hesperus australis Miller.-Isla Montserrate: one nonpregnant adult female was captured on 20 May 1975. Isla Santa Catalina: one adult male was netted 3 July 1979 with scrotal testes measuring (in mm) 3 by 1. Two specimens of this species were reported by Banks (1964a) for Isla Montserrate; Orr and Banks (1964) first recorded specimens from Isla Santa Catalina. Pipistrellus hesperus australis occurs in southern Baja California (Jones et al., 1965; Woloszyn and Woloszyn, 1982). Plecotus townsendii pallescens Miller.-Isla San Jose: ten skulls of juveniles were collected on 1 July 1979 from a cave along with remains of Leptonycteris and Macrotus. This material represents the first record of this species from the island. Orr and Banks (1964) reported a single specimen of Plecotus from Isla Santa Catalina. Antrozous pallidus minor Miller.-Isla Santa Catalina: two adult males and one nonpregnant adult female were captured 3 July 1979. The males had descended testes measuring (in mm) 4 by 2 and 5 by 3. These specimens represent the first records of Antrozous for an island in the Gulf of California. Martin Vol. 67, No. 1 212