Other Environmental Themes

Of Cactus, Bats, & Men

Rising 60 feet above the Sonoran desert of northern Mexico, cardon is the world's largest cactus. These plants, which may live 100 or more years, offer food and shelter to many animals, including owls, hawks, ospreys, swallows, and woodpeckers. When cardon's white flowers bloom each spring, a host of birds, bats, and moths feast on its abundant nectar and pollen. But the identity of its main pollinator, the lesser longnosed bat, has only been known for about a decade.

With a 13-inch wingspan, the bat routinely flies 50 miles from its roost to forage each night. It is a culinary specialist, feeding primarily on flowering agave plants and tall "columnar" cacti such as cardon, saguaro, and organ pipe. The lesser longnosed bat has a long, narrow tongue with a brushy tip that enables it to quickly sop up lots of nectar. That's important, since most visits to a flower last about a second. As the bat sips nectar, pollen clings to its head and chest. The bats carry more pollen to other plants than insects and birds, picking up thousands of grains with each drink.

Lesser longnosed bats follow the blooming of cardon and other cacti on their several thousandmile long journey from southern Mexico to Arizona, New Mexico, and back. Like the monarch butterfly and other migratory species, the bats are endangered, facing a battery of threats. As more desert land is converted to farms and pastures, the distance between feeding spots widens. The bats also compete directly with the liquor industry, because their main food source, agave plants, is a key ingredient of tequila—a beverage that's growing in popularity. Mine closings have decreased the number of available roosting sites, while the animals are also at risk from people who mistake them for vampire bats—a cattle pest—and try to kill them with poison and dynamite their caves. If lesser longnosed bats are to have a chance of flourishing, we will need to address the full array of hazards they face along their entire migration route—a tall order for a small animal with no constituency to speak of.