Mexican long-nosed bat (Leptonycteris nivalis)

Aptly named for its elongated muzzle ^{(2) (4) (5)}, the Mexican long-nosed bat is also recognised by its prominent noseleaf, short ears, long, relatively narrow wings, and lack of a visible tail ^{(2) (4) (5) (6)}. A medium-sized bat species ⁽³⁾, it has quite long, soft fur, which is sooty or drab brown in colour, with the individual hairs having white bases and silvery tips. The underparts and shoulders are paler ^{(4) (7)}. The tail membrane, which stretches between the hind legs, is narrow and moderately hairy, with a conspicuous fringe of short hairs ^{(2) (4) (7)}, while the base of the forearms is haired, and the legs and feet are also moderately hairy ⁽⁷⁾. Individuals in the north of the range may be slightly larger than in the south ⁽⁴⁾.

This species can be distinguished from the closely related lesser long-nosed bat, Leptonycteris yerbabuenae, by its larger size and longer, fluffier and less reddish fur, and from the southern long-nosed bat, Leptonycteris curasoae, by its larger size, lighter fur and wider, more hairy tail membrane ^{(4) (7)}.

Also known as

big long-nosed bat, greater long-nosed bat.

Size

Head-body length: 7 - 9.5 cm ⁽²⁾

Forearm length: 4.6 - 5.9 cm ^{(2) (3)}

Weight

18 - 30 g ^{(2) (3)}

The Mexican long-nosed bat is a colonial species, typically roosting in large groups that may number as many as 10,000 or more, and which may occupy the same roosts from year to year ^{(1) (2) (6) (7)}. The bats emerge well after sunset, and feed on the nectar and pollen of night-opening flowers of agaves, cacti and other plants. Fruit and insects are also occasionally taken, although the insects may be eaten accidentally while feeding on the flowers ^{(1) (2) (4) (6) (8)}. This species is a vital pollinator of several agave and cactus species ^{(3) (4) (6) (9)}, and shows a number of adaptations for its specialised diet. The long muzzle houses an impressively long tongue, which can be extended more than seven centimetres to reach deep into flowers, and which has hair-like ‘papillae’ on its tip, ideal for lapping up nectar ^{(2) (4) (6)}. This species is also a strong, agile flier, able to hover while feeding and to fly long distances quickly and efficiently ^{(4) (5) (6)}.

Mexican long-nosed bats mate between October and December, the female giving birth to a single young, or rarely two, the following May or June ^{(1) (3) (4) (6) (7)}. The young are weaned by about four to eight weeks, and can fly by five weeks old ^{(2) (6)}. The females and young then migrate north, as far as the southern United States, following the flowering patterns of the food plants. The bats remain in the north of the range until August, before moving south again to spend the winter in Mexico ^{(1) (2) (3) (6)}. Interestingly, only part of the population migrates, with adult males rarely being found in the northern parts of the range ^{(2) (3) (4) (6)}. The numbers arriving in the United States may also fluctuate greatly from year to year ^{(1) (7)}, possibly related to the food supply in Mexico ⁽³⁾.

The Mexican long-nosed bat is reported to occur from southeast Arizona, southern New Mexico and western Texas in the USA, south to southern Mexico and Guatemala ^{(1) (2) (4) (6) (7)}. However, its presence in Guatemala may need confirmation ⁽³⁾.

This species inhabits desert scrub with Agave, mesquite, creosote bush and cacti, as well as pine-oak and deciduous forest ^{(1) (2) (3) (4) (6) (7)}, generally at elevations up to around 3,500 metres, although it has also been recorded at over 5,000 metres ^{(1) (3)}. Roosts are located in caves, mines and tunnels, or sometimes in hollow trees or abandoned buildings ^{(1) (2) (3) (4) (6)}.

Classified as Endangered (EN) on the IUCN Red List ⁽¹⁾.

The Mexican long-nosed bat has undergone a major population decline in recent years ^{(1) (3) (6)}, and several caves in Mexico that once contained large numbers of bats now contain only small numbers or none at all ^{(1) (6) (9)}. The main threat to the species is believed to come from a decrease in its food supply, due to habitat clearance and the exploitation of agaves for the production of alcoholic drinks such as tequila ^{(1) (3) (6) (9) (10)}. This harvest poses a particular threat as the agaves are harvested just before blooming, preventing the plant from flowering, and, since agaves grow for 10 to 20 years, flower only once and then die, it can also prevent the agaves from reproducing ^{(1) (6)}. The Mexican long-nosed bat’s dependence on a continuous supply of food plants along its migratory routes also means that loss of the plants in any single area could have negative consequences for this species ⁽⁹⁾.

Other threats to the Mexican long-nosed bat include disturbance and destruction of roost sites, wild fires, the ingestion of pesticides used on plants, and predation, for example by domestic and feral cats ^{(1) (3) (6) (10)}. In addition, bat colonies in Mexico are often destroyed in an attempt to control vampire bats ^{(1) (2) (3) (6) (9)}.

The only known colonial roosting site of the Mexican long-nosed bat in the United States is protected within the Big Bend National Park, Texas ^{(1) (3) (6)}, and the species is listed as Endangered on the US Endangered Species List ⁽¹¹⁾. A Recovery Plan is in place for the species ⁽¹⁰⁾, and recommendations for its conservation include the protection of roost sites and foraging habitat, public education, ecological studies, maintaining and restoring habitat and food plants along its migratory routes, and population monitoring ^{(1) (3) (6) (10)}. Efforts are also underway to locate further roosting sites ⁽⁶⁾. In Mexico, two caves are proposed for protection in Tamaulipas, and the species is also included in a collaborative Program for the Conservation of Migratory Bats of Mexico and the USA, which is undertaking a range of conservation activities ⁽³⁾.

Perhaps most vital to the conservation of this species will be the maintenance of large areas of wild agaves ^{(1) (12)}. A breakdown in the bat’s relationship with these plants would have significant effects not only on the Mexican long-nosed bat, but also, through its vital role in pollination, on its food plants, and therefore on the many other species, including humans, which rely on them ^{(3) (9)}.

To find out more about the Mexican long-nosed bat and other Mexican bat species, see:

• Texas Parks and Wildlife: Mexican Long-nosed Bat (Leptonycteris nivalis):
  http://www.tpwd.state.tx.us/huntwild/wild/species/mexlongnose/
• Program for the Conservation of Mexican Bats (Programa para la Conservación de los Murciélogos de Mexico, PCMM):
  http://pcmm.bioconciencia.org.mx/eng/eng_index.html

For more information on bat conservation see:

• Bat Conservation International:
  http://www.batcon.org/
• Hutson, A.M., Mickleburgh, S.P. and Racey, P.A. (2001) Microchiropteran Bats: Global Status Survey and Conservation Action Plan. IUCN/SSC Chiroptera Specialist Group, IUCN, Gland, Switzerland and Cambridge, UK. Available at:
  http://data.iucn.org/dbtw-wpd/edocs/2001-008.pdf

This information is awaiting authentication by a species expert, and will be updated as soon as possible. If you are able to help please contact:
arkive@wildscreen.org.uk

Colonial

Relating to or belonging to a colony (a group of organisms living together in a group).

Deciduous forest

Forest consisting mainly of deciduous trees, which shed their leaves at the end of the growing season.

Feral

Previously domesticated animals that have returned to a wild state.

Noseleaf

A fleshy structure surrounding the nose, common to many bats. It is believed to function in focusing echolocation calls (high-pitched calls used in orientation and to locate prey) emitted from the nose.

Pollination

The transfer of pollen grains from the stamen (male part of a flower) to the stigma (female part of a flower) of a flowering plant. This usually leads to fertilisation, the development of seeds and, eventually, a new plant.

Pollinator

An animal that in the act of visiting a plant’s flowers transfers pollen grains from the stamen (male part of a flower) to the stigma (female part of a flower) of a flowering plant. This usually leads to fertilisation, the development of seeds and, eventually, a new plant.

1. IUCN (June, 2010)
   http://www.iucnredlist.org/
2. Nowak, R.M. (1991) Walker’s Mammals of the World. The Johns Hopkins University Press, Baltimore and London.
3. Hutson, A.M., Mickleburgh, S.P. and Racey, P.A. (2001) Microchiropteran Bats: Global Status Survey and Conservation Action Plan. IUCN/SSC Chiroptera Specialist Group, IUCN, Gland, Switzerland and Cambridge, UK. Available at:
   http://data.iucn.org/dbtw-wpd/edocs/2001-008.pdf
4. Hensley, A.P. and Wilkins, K.T. (1988) Leptonycteris nivalis. Mammalian Species, 307: 1-4. Available at:
   http://www.science.smith.edu/departments/Biology/VHAYSSEN/msi/pdf/i0076-3519-307-01-0001.pdf
5. Macdonald, D.W. (2006) The Encyclopedia of Mammals. Oxford University Press, Oxford.
6. Texas Parks and Wildlife: Mexican Long-nosed Bat (Leptonycteris nivalis) (June, 2010)
   http://www.tpwd.state.tx.us/huntwild/wild/species/mexlongnose/
7. Reid, F.A. (2009) A Field Guide to the Mammals of Central America and Southeast Mexico. Second Edition. Oxford University Press, New York.
8. Sánchez, R. and Medellín, R.A. (2007) Food habits of the threatened bat Leptonycteris nivalis (Chiroptera: Phyllostomidae) in a mating roost in Mexico. Journal of Natural History, 41: 1753-1764.
9. Arita, H.T. and Wilson, D.E. (1987) Long-nosed bats and agaves: the tequila connection. Bats, 5(4): 3-5.
10. U.S. Fish and Wildlife Service (1994) Mexican Long-Nosed Bat (Leptonycteris nivalis) Recovery Plan. U.S. Fish and Wildlife Service, Albuquerque, New Mexico. Available at:
    http://ecos.fws.gov/docs/recovery_plan/940908.pdf
11. U.S. Fish and Wildlife Service: Species Profile - Mexican Long-Nosed Bat (Leptonycteris nivalis) (June, 2010)
    http://ecos.fws.gov/speciesProfile/profile/speciesProfile.action?spcode=A0AE
12. Moreno-Valdez, A., Honeycutt, R.L. and Grant, W.E. (2004) Colony dynamics of Leptonycteris nivalis (Mexican long-nosed bat) related to flowering Agave in northern Mexico. Journal of Mammalogy, 85(3): 453-459.