The Mexican long-tongued bat (Choeronycteris mexicana) is 1 of 3 migratory, nectarivorous bats that seasonally occur in the extreme southwestern United States (US); the other 2 species are Leptonycteris curasoae and L. nivalis. Unlike the species of Leptonycteris, C. mexicana is not known to form large maternity colonies and is rarely encountered in groups of more than 12 individuals (Hoffmeister 1986). Possibly because of a propensity to form small roosting groups, the number of C. mexicana historically encountered is relatively low compared to other bat species. Although the range of C. mexicana extends from the southwestern United States into Honduras, less than 1500 individuals have been documented since its discovery in 1844 (Petryszyn and Cockrum In Press). Roosting and habitat needs of C. mexicana are poorly understood and it is unclear how such requirements might influence the apparent scarcity of these bats.
Choeronycteris mexicana is known to roost in a variety of situations, typically in shallow caves or near the entrances of more extensive structures (Arroyo-Cabrales et al. 1987). Roost sites have been reported from various vegetation zones, including tropical deciduous forests at southern latitudes (Davis and Russell 1954), but roosts are frequently found in oak-conifer woodlands in the northern part of its range (Hoffmeister 1986). Mexican long-tongued bats are known to feed on nectar, pollen, or fruit of various flowering plants throughout their range (Gardner 1977). Although mutualistic relationships likely exist between C. mexicana and its food plants, very little is known about the role that this species plays as a pollinator or seed disperser of such plants. The identification and elucidation of mutualistic relationships are necessary steps toward effectively conserving ecosystems in the southwestern US (Allen-Wardell et al. 1998). Given the potential importance of C. mexicana as a pollinator and its apparent scarcity in the southwest US, current status and habitat requirements of the species need to be determined. Furthermore, the majority of C. mexicana historically encountered north of the Mexican border were adult females and young (Petryszyn and Cockrum In Press), indicating that the southwestern US is an important breeding area. The objective of this study was to assess recurrence of C. mexicana at historical roost sites in Arizona and New Mexico, count numbers of bats present, and gather data on roost and habitat characteristics.
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Recurrence of Mexican long-tongued bats (Choeronycteris mexicana) at historical sites in Arizona and New Mexico