Mexican Long-Nosed Bat: Leptonycteris Nivalis

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Photo of Mexican long nosed bats flying

The Leptonycteris nivalis (Mexican long-nosed bat) is a migratory species that occurs in pine-oak deciduous forests and desert scrub from central Mexico to the southwestern United States.

Currently, this bat is listed as endangered by the International Union for the Conservation of Nature in the United States and Mexico. Over the last 10 years, this bat’s population has declined 50 percent. ¹

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Mexican Long-Nosed Bat Description

Leptonycteris nivalis, the Mexican long-nosed bat, is 7-9 cm long and weighs 18-30 g. The bat has a long tongue, reaching up to 7.6 cm, and an elongated muzzle.

Typically, the fur is yellowish-brown or grayish above and cinnamon-colored below. The Mexican bat has finer hair, extending above and beyond the tail membrane, as well as distinct cranial and dental characteristics, although similar in appearance to the endangered lesser long-nosed bat (L. curasoae yerbabuenae).

Habitat Of The Mexican Long-Nosed Bat

Mexican long-nosed bats are found in desert scrub vegetation covered by agaves (century plants), mesquite, creosote bush, and a variety of cacti that serve as their primary source of food.

Although the Mexican long-nosed bat’s population status is uncertain, there are strong indications that they are declining. The largest recorded population of this species in North America is around Big Bend National Park in Texas. ²

Mexican Long-Nosed Bat Range

This bat has only been recorded in southwestern New Mexico and Trans-Pecos Texas in the United States and is considered a highly colonial, cave-dwelling, migratory species. Researchers have caught this species in Big Bend National Park, Brewster County, and Presidio County’s Chinati Mountains.

From June to August, Mexican long-nosed bats occupy areas in Texas and New Mexico, after which time they move to winter in Mexico from the United States. ³

Behavior Of Mexican Long-Nosed Bats

While patterns of movement are not well known, it is believed that Mexican long-nosed bats move each year from central Mexico to northern Mexico, with part of the population crossing the border into Texas and New Mexico. From June through August, the colony of bats at Big Bend (TX) occupies their northern roots, and afterward they move south to Mexico for the winter.

In understanding its history of life and recent decline, the Mexican long-nosed bat’s feeding ecology is of great importance. These bats are nectar feeders that emerge at night to feed on the showy plant flowers such as agave or plants of the century (Agave). They are very powerful, highly maneuverable fliers, and they can hover in flight while they feed, like hummingbirds.

The bats will ingest pollen and consume the nectar, picked up inadvertently on their fur as they feed and later ingested during grooming. The pollen provides vitamins and minerals, and it is rich in protein. ⁴

Mexican Long-Nosed Bat Reproduction Cycle

From April to early June, young people are born in Mexico, then move northwards with their mothers. It is believed that females give birth to one or perhaps two young each year. By a combination of odor and distress cries made by their offspring, mothers of this bat species may recognize their own young.

Young bats are nursed for about one month and can generally fly by 5 weeks of age. In Texas and northern Mexico, only a few males have been observed, indicating that males and females geographically segregate, with males rarely appearing in the most northerly part of the species’ range.

Diet Of Mexican Long-Nosed Bats

Mexican long-nosed bats are nectarivores. They feed primarily on Agave plants. Researchers have suggested that short ears’ physical adaptations and the presence of a triangular noseleaf are proof that they use their sense of smell to locate Agave rather than echolocating plants.

These bats also feed on pollen from cactus flowers and certain berries or fruits. Leptonycteris nivalis feeds in flocks overnight when Agave plants are flowering. The migratory patterns also correspond to some Agave plants’ flowering patterns, such as mezcal, pulque, and tequila plants.

By hovering over the blooming Agave and by clinging to herbaceous vegetation, Mexican long-nosed bats forage. Since L. Nivalis eat a lot of nectar, there is very little need for water. ⁵

Threats To The Mexican Long-Nosed Bat Species

The causes of the decline have not been identified with full certainty, but they are likely to be related to human activities. The major threats are probably the modification or destruction of roost sites and foraging habitats. Pesticides, competition for roosts and nectar, natural catastrophes, disease, and predation may be other threats.

Mexican long-nosed bats are likely limited, as with other colonial roosting bats, by the number of sites that provide the proper roosting environment, especially for parturition. A significant limiting factor for nivalis may be the availability of roost sites free from disturbance. Although no known long-nosed Mexican bats’ roosts have been rendered unusable, roosting caves are increasingly subject to human destruction and disruption in general.

Both the bats present at the time of the destruction and the roost’s physical conditions may be affected by vandalism and deliberate destruction of roosts. A significant issue for bats all over Mexico is that all bats in a roost are often destroyed by uninformed citizens, believing them to be vampire bats. ⁶

Sources:

“Mexican Long-Nosed Bat Conservation Case Study | The Mohamed Bin Zayed Species Conservation Fund.” Mohamed Bin Zayed Species Conservation Fund, www.speciesconservation.org/case-studies-projects/mexican-long-nosed-bat/3080. Accessed 15 Jan. 2021.
U.S. Fish and Wildlife Service. “Pollinators | Fish and Wildlife Service.” U.S. Fish And Wildlife Service, 17 June 2019, www.fws.gov/pollinators/features/Mexican_long-nosed_bat.htm#:~:text=The%20Mexican%20long%2Dnosed%20bat,comparison%20to%20other%20bat%20species.
“Mexican Long-Nosed Bat (Leptonycteris Nivalis).” Texas Parks & Wildlife, Texas Parks and Wildlife Department, tpwd.texas.gov/huntwild/wild/species/mexlongnose. Accessed 15 Jan. 2021.
Clarke, R. 2002. “Leptonycteris nivalis” (On-line), Animal Diversity Web. Accessed January 14, 2021 at https://animaldiversity.org/accounts/Leptonycteris_nivalis/
Medellin, Rodrigo. “MEXICAN LONG-NOSED BAT (Leptonycteris Nivalis) RECOVERY PLAN.” Esadocs Defenders, U.S. Fish And Wildlife Service, 8 Sept. 1994, esadocs.defenders-cci.org/ESAdocs/recovery_plan/940908.pdf.