||The Mammals of Texas -
Mexican Long-nosed Bat
Chiroptera : Family
Phyllostomidae : Leptonycteris nivalis (Saussure)
Description. A medium-sized bat with
short ears, no tail, and a distinct nasal leaf; forearm
furred above at elbow; upperparts drab brown, the hairs
white basally; underparts pale drab, tips of hairs
silvery. Dental formula: I 2/2, C 1/1, Pm 2/3, M 2/2 X 2
= 30. External measurements average: total length, 83 mm;
foot, 17 mm; ear, 15 mm; forearm, 58 mm. Weight, 24 g.
Distribution in Texas. A Mexican species
that enters Texas in the Big Bend region. Known in Texas
from southern Brewster and Presidio Counties.
Habits. This is a colonial, cave
dwelling bat that usually inhabits deep caverns. The only
known colony of these bats in the United States is found
in a large cave on Mt. Emory in Big Bend National Park.
The number of bats using the cave fluctuates widely from
year to year with yearly estimates of population numbers
ranging from zero to 13,650. Reasons for this instability
are unknown, but it may be that this colony forms only in
years when over-population or low food supply in Mexico
force the bats to move northward. This bat has recently
been classified as endangered by the U.S. Fish and
At the Emory Peak cave, L. nivalis
forms a large cluster with half-grown young and adults
intermingled. Adult males and females may be present.
They share the cave with a large colony of big-eared bats
(Plecotus); each colony roosts in a different part
of the cave, but not more than 6 m apart. The air in this
cave in considerably cooler in summer than that outside,
and a distinct breeze blows through it at all times. The
cave is not used in winter; the inhabitants migrate to
Mexico. This bat has a strong, musky odor similar to that
of the Brazilian free-tailed bat.
L. nivalis feeds on the nectar
and pollen of flowers, especially those of the century
plant (Agave sp.). The seasonal occurrence of L.
nivalis in Texas is probably related to food
availability as their presence seems to coincide with the
blooming of century plants in June. These plants open
their flowers at night and attract bats with copious
amounts of nectar. As the bats feed, their fur gets
coated with pollen grains. When they fly to another plant
in search of more food, they transfer the pollen to a new
flower, assisting in cross-fertilization of the plants.
This mutual relationship is so strong that both the bats
and the century plants cannot survive without the other.
As the flower stalks of the agaves die by late summer,
the bats disappear as there is nothing left for them to
The breeding season is restricted to
April, May, and June. Females give birth to one young
annually. The young are born in Mexico, prior to the
bats arrival in Texas, and are weaned in July to
August, which is the peak of the rainy season and the
peak of flower abundance.
Photo credit: Merlin D. Tuttle, Bat Conservation