Leptonycteris nivalis
Mexican long-nosed bat

Leptonycteris nivalis is a migratory species, with a range that includes W Texas, New Mexico, and SE Arizona (U.S. Fish and Wildlife Service, 2000), and extends south spanning Mexico, Honduras, and Guatemala (BCI, 2001).

The Mexican long-nosed bat primarily lives at elevations ranging from 1,550 - 9,330 feet in habitats described as “desert scrub, open conifer-oak woodlands, and pine forest habitats in the Upper Sonoran and Transitional Life Zones” (U.S. Fish and Wildlife Service 2001). During the day, L. nivalis roosts in sheltered places like caves, hollow trees, and mines. However, information on roosting habitats is limited (U.S. Fish and Wildlife Service, 2000).

Leptonycteris nivalis is 70-90 mm long, weighing 18-30 g. Their hair coat on their back is pale brown to gray. They have three vertebrae in their tail; however, it is not visible externally. L. nivalis has a third finger that measures 105mm. Long hairs protrude from and extend past a narrow piece of skin along the inside edge of each leg called the interfemoral membrane or uropatagium. They have an elongated snout with a triangular nose leaf on the end. In order to feed on nectar, Mexican long-nosed bat have a long tongue with inward-pointing, elongated papillae at its tip (U.S. Fish and Wildlife Service, 2000). The dental formula is 2/2, 1/1, 2/3, 2/2x2 = 30 (Davis & Schmidly, 1997).

The average life span of the Mexican long-nosed bat is approximatly 10 years (Texas Parks and Wildlife, 2001).

The migratory behavior exhibited by L. nivalis may be derived from the symbiotic relationship it has with Agave sp., its primary food source. Agave sp. flower once at night and then perish. The Mexican long-nosed bat's night activity and its migratory pattern matches the northward, seasonal flowering pattern of Agave. L. nivalis is a colonial species that forages for food in large flocks (U.S. Fish and Wildlife Service, 2000). The most extensively studied colony is at Emory Peak Cave, in Texas. It is a colony of juveniles with both female and male adults interdispersed (Davis & Schmidly, 1997).

In general Mexican long-nosed bats are nectarivores. They feed primarily on the nectar of Agave spp. Researchers have suggested that Mexican long-nosed bats physical adaptations of short ears and the presence of a triangular noseleaf are evidence that they use their sense of smell to locate Agave sp. plants rather than echolocation (Arita and Wilson, 1987). Mexican long-nosed bats feed secondarily on pollen from cactus flowers, and some berries and fruits. Leptonycteris nivalis feeds at night in flocks when Agave sp. are blooming. Its migratory patterns also match the blooming patterns of certain plants of Agave such as A. angustifolia (mezcal plant), A. salmiana (pulque plant), and A. tequilana (tequila plant) (Arita, 1991). Mexican long-nosed bats forage by hovering over the blooming Agave and by clinging to herbacious vegetation. Since L. nivalis eat a lot of nectar, their demand for water is very low to absent (New Mexico Game & Fish, 2000).

L. nivalis has a very important role in the ecosystem; its presence directly and indirectly affects many biological interactions within its community. Many plants, like Agave, depend on the bat for the cross-pollination that maintains crucial genetic diversity within each plant species. Other species are dependent on plants pollinated by L. nivalis for their food and shelter. These include bees, moths, lizards, hummingbirds, woodpeckers, orioles, finches, sparrows, and field mice (Arita & Wilson, 1987). A decline in L. nivalis population could mean a reduction in the Agave population and many other species that rely on these plants, thereby changing the dynamics and interactions within the community. Leptonycteris nivalis has a mutualistic or symbiotic relationship with Agave, its primary food source (U.S. Fish and Wildlife Service, 2000).

Leptonycteris nivalis has been known to roost on attic and parking garage ceilings. Beyond the inconvenience of having a bat living in your home, long-nosed bats produce large amounts of bat excrement or guano that can sustain bacteria and insects. The breakdown process of guano also releases large amounts of ammonia, which if humans are exposed to for periods of time can cause lung deterioration (Garza, 2001).

Agave sp. are of great economic importance in Mexico. Fibers called henequin are produced from the leaves of certain species of Agave. These fibers are exported, and they generate a substantial amount of revenue for some regional and local economies in Mexico. Tequila, another highly exported good produced in Mexico is primarily produced from Agave tequilana. The sale of tequila in international markets also produces a large amount of revenue for the country. The reproductive success of Agave spp. relies on the Mexican long-nosed bat to pollinate and cross pollinate plants. Without the bats, Agave seed count would drop to 1/3000th of normal (Arita & Wilson, 1987). L.nivalis also produce mass quantities of guano, which can be collected and used as fertilizer (Garza, 2001).

Leptonycteris nivalis was listed in 1988 as an endangered species by the US Fish and Wildlife service and by the state of Texas. In 1990, New Mexico listed L. nivalis as endangered, and in 1991 L. nivalis was listed as endangered under the Mexican Endangered Species Act. The Mexican long-nosed bat population has been steadily declining over the years due to declining number of roost sites and the increased harvesting of Agave sp. to make liquor; these harvests decreased the primary food source of the bats (U.S. Fish and Wildlife Service, 2000). In southern Mexico many L. nivalis have been mistaken for Vampire bats and killed in attempts to reduce the number of that species (Texas Parks and Wildlife, 2001). Efforts of conservation focus on increasing the abundance of roost sites, protecting existing roost sites, protecting critical Agave sp., and expanding biological information including the obtainment of an accurate population estimate (U.S. Fish and Wildlife Service, 2000).

To some extent, lack of information regarding basic life history for this species may be attributed to the combination of Leptonycteris nivalis with Leptonycteris curasoae in classification of these species from 1940-1962 (U.S. Fish and Wildlife Service, 2000).