Do Bats Drink Blood?: Fascinating Answers to Questions about Bats

Three: Bat Life

THREE Bat Life Question 1: What do bats eat? Answer: Bats eat a surprising variety of foods. About 70 percent of bats are insectivorous, meaning they eat insects such as moths, caterpillars, beetles, flies, grasshoppers, planthoppers, leafhoppers, crickets, termites, mosquitoes, and flying ants. A single bat can eat more than one thousand small swarming insects, such as midges (Chironomidae), in an hour. Some insect-eating bats, such as the pallid bat (Antrozous pallidus) and species of slit-faced bats in the genus Nycteris, also include scorpions in their diet. In Bracken Cave in central Texas, a colony of as many as twenty million Brazilian free-tailed bats (Tadarida brasiliensis) emerges in a huge cloud at dusk. Michael Novacek described them as “flying vacuum cleaners . . . with their large, flabby mouths opened wide . . . sweeping through clouds of insects ,” consuming up to their own body weight in insects during the course of a night. This bat species is a valuable ally to agricultural interests vital to human health. They consume vast quantities of moths that lay eggs that develop into caterpillars, including serious agricultural pests. Researchers have used DNA analysis to identify some species of moths that are eaten by Brazilian free-tailed bats, including the corn earnworm or tomato fruit worm (Helicoverpa zea), the tobacco budworm, (Heliothis virescens), the fall armyworm (Spodoptera Frugiperda), and the beet armyworm (Spodoptera Exigua). The larvae of these pests feed on an amazing variety BAT LIFE 35 Figure 12. Myotis yumanensis, a Yuma myotis, chases a moth. (Photograph courtesy of Michael Durham, www.DurmPhoto.com.) of crops and ornamentals, including alfalfa, apple, artichoke, asparagus, avocado, barley, beet, Bermuda grass, broccoli, cabbage , cantaloupe, cauliflower, celery, collard, cotton, corn, cowpea , cucumber, eggplant, flax, grape, lettuce, lima bean, melon, millet, oat, okra, onion, orange, papaya, pea, peach, pear, peanut , pepper, plum, potato, pumpkin, radish, raspberry, rice, ryegrass , safflower, snap bean, sorghum, soybean, spinach, squash, strawberry, sugarbeet, sugarcane, sunflower, sweet potato, timothy , tobacco, tomato, turnip, watermelon, and wheat. About 80 percent of the diet of the big brown bat (Eptesicus fuscus) is often agricultural pest insects. Both the big brown bat and the evening bat (Nycticeius humeralis) have heavy jaws and include beetles in their diet. Many big-eared bats feed on moths. Species of Myotis bats eat mainly dipterans (flies and midges), 36 DO BATS DRINK BLOOD? small beetles, and small moths. Other bat species are generalists in their feeding behavior, feeding on a variety of insects. Some insects that bats like to eat, such as termites, ants, and caddis flies, are sporadic in occurrence, although numerous when available. Since many insects are agricultural pests, bats provide an enormously beneficial service at no cost to people or the environment. Figure 13. Micronycteris nicefori, Niceforo’s big-eared bat, captures a roach. (Photograph courtesy of M. D. Tuttle, Bat Conservation International, www .batcon.org.) BAT LIFE 37 Most of the remaining species are nectivorous (nectardrinkers ), or they are frugivorous, meaning they are fruit-eaters, sometimes also eating leaves or flowers. Bats pluck fruit from a tree with their mouth, sometimes with the aid of their wings and even their feet. If they carry the fruit away from the tree to eat it, they drop large seeds away from the parent plant, and if they eat fruit with small seeds, the seeds pass through their digestive system , where enzymes help the seeds to germinate when they fall to the ground in the bats’ droppings. In these ways, bats help spread the seeds from mangos, peaches, figs, dates, and many other kinds of plants. By distributing seeds over large areas, bats help renew vegetation and aid in the regrowth of rain forests. Nectar-drinking bats feed on cactus flowers and other plants that bloom at night. Nectar bats have long snouts that fit neatly inside the flowers they prefer, and many have tiny hairs on their tongues that help them lap up the nectar from inside the flowers . While they are drinking, the bats’ faces become covered with pollen that they carry to the next flower, helping to fertilize the plant and enabling it to bear fruit. Bats pollinate agave, saguaro and organ pipe cactus, banana, eucalyptus, and many other plants in this way (see color plate D). Less than 1 percent of all bats feed on small vertebrates in addition to insects. There are about eight species of fish-eating (piscivorous) bats found in the genera Nycteris, Myotis, and Noctilio...