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).