20 
PROCEEDINGS OF THE CALIFORNIA ACADEMY OF SCIENCES 
Series 4, Volume 65, Supplement I 
and in the Huachuca Mountains in southern Arizona, Mexican long-tongued bats ranked eleventh 
in relative abundance among 13 species documented (two captures out of 145 individuals; Sidner 
and Davis, 1994). 
Foraging and Dietary Analysis. — Mexican long-tongued bats are nectar and pollen feed¬ 
ers and are well-known pollinators of several species of columnar cacti, agaves, and other plants in 
the United States, Mexico, and Central America (for example, Hevly, 1979; Valiente-Banuet et al., 
1996; Arizaga et al., 2000; Arias-Coyotl et al., 2006; Trejo-Salazar et al., 2015). In the deserts of 
southern Arizona and northern Mexico, stomach contents of this species consisted mainly of pollen 
grains from agave flowers but also included pollen from ceroid cacti (such as giant saguaro, 
Carnegiea gigantea) and a range of other plants (Hevly, 1979). The giant saguaro cactus has open 
flowers at night when bats are active and requires cross-pollination for fertility (McGregor et al., 
1962). Mexican long-tongued bats have been shown experimentally to be effective pollinators of 
this iconic plant (Alcorn et al., 1961). 
In some areas, some species of columnar cacti and agaves are dependent on nocturnal polli¬ 
nation for successful reproduction, and nectar-feeding bats may be their chief pollinators (Valiente- 
Banuet et al., 1996; Arizaga et al., 2000). However, in the southwestern U.S. these bats are not their 
exclusive pollinators. Although the absence of lower incisors indicates specialization for nectar 
feeding (Howell, 1974), Mexican long-tongued bats also eat cactus fruits and may act as seed dis¬ 
persers (Godinez-Alvarez and Valiente-Banuet, 2000). When feeding on nectar, these bats have 
been timed to visit individual flowers an average of less than one second per flower (Arizaga et al., 
2000), but can hover in flight for up to 17 seconds (Voigt and Winter, 1999). 
Roosting Habits. — Roosts of Mexican long-tongued bats can be in shallow caves, rock 
shelters and wide rock crevices, abandoned mines, tunnels, and buildings (Campbell, 1934; Olson, 
1947; Huey, 1954a; Baker, 1956a, Mumford et al., 1964; Cryan and Bogan, 2003). Roosting places 
are often in light shade rather than dark recesses (Findley et al., 1975). Hoffmeister and Goodpaster 
(1954) reported these bats to be present in nearly every mine tunnel or cave they visited in the 
Huachuca Mountains of southeastern Arizona in 1949-1951, often roosting at the same sites as 
Townsend’s big-eared bats. This observation of co-occurrence of the two species was also made in 
the Huachuca Mountains in 1933 (Campbell, 1934). 
Mexican long-tongued bats seldom roost in tight clusters but can form colonies in the U.S. that 
are small (less than 50 and usually fewer than 17; Hoffmeister and Goodpaster, 1954; Huey, 1954a; 
Cockrum and Ordway, 1959; Cryan and Bogan, 2003; Fleming et al., 2003). Average group size 
was 4.5 bats at 18 roost sites visited in Arizona and New Mexico in 1999, where bats roosted in 
well-lit areas near entrances (Cryan and Bogan, 2003). Roosting bats are usually alert and quick to 
exit roosts upon even minor disturbance (Cockrum and Ordway, 1959; Mumford and Zimmerman, 
1962; Mumford et al., 1964). Year-to-year fidelity to the same roosting sites or sites within the 
immediate proximity has been documented (Mumford et al., 1964; Cryan and Bogan, 2003). 
The first record of Mexican long-tongued bats in southern California was of a group of five 
individuals roosting on rafters in a dark comer of a garage in San Diego in 1946; later that year a 
few others were noted roosting in basements and garages in the same region (Olson, 1947). Sub¬ 
sequent investigations found these bats roosting at 11 other locations (where 39 bats were collect¬ 
ed) in the San Diego area, all in or around buildings and in light shade (Huey, 1954a). They also 
are known to roost during the day in buildings in Arizona and New Mexico (Hoffmeister and Good¬ 
paster, 1954; Cryan and Bogan, 2003). This species also will night-roost in abandoned buildings 
(Findley, 1957; Watkins et al., 1972). 
Population Ecology.— Litter Size, Natality, and Female Reproduction: Females give 
birth and raise young while in the southwestern United States during summer. Four of five bats 
