flying bat
Hooray for Halloween!
Bats 'n bugs
Befriending bats
Best brain bank
Grave robbers
Gorgeous graves
Eptesicus fuscus, big brown bats (above right).
© Merlin Tuttle, reprinted courtesy of Bat Conservation International.


Lasiurus borealis, Red Bat
Image courtesy of Bat Conservation International, Inc..
Bats, brains, and burying grounds

Guano happens
We hope by now you're convinced that bats are plucky, not yucky. Now we've run into a bat fan who organizes workshops showing how bats can play a role in the classroom.

Bat cluster

In annual workshops for 35 teachers, Patricia Morton of Texas Parks and Wildlife joins several colleagues to spend a day demonstrating how to incorporate bats into the classroom.

Bats battle bugs
Answering the question of which insects bats are eating, and how many they are devouring, is the goal of a project run by Gary McCracken, a professor of ecology and evolutionary biology at the University of Tennessee in Knoxville. McCracken studies the 100 million Mexican free-tail bats in central Texas. Mexican free-tails are gregarious critters that migrate north from Mexico in the spring and occupy caves to breed. One cave near San Antonio houses 20 million to 40 million bats, mainly mothers and their kids. Mother bats are choosy, Morton observes. "Bats use caves with certain characteristics, with an internal dome that traps heat, and lots of surface area where the pups can roost."

Talk about a mob scene: She says one square meter of cave surface can house more than 500 baby bats.

The free-tails can fly up to 3 kilometers above the ground, and hunt up to 50 kilometers away from the cave. Most hunting takes place at between 200 and 1,000 meters. red bat

Bats have a rapid metabolism: A mother bat, weighing half an ounce, eats 70 percent of her body weight each day, and since most of the adult cave-dwelling bats are female, that accounts for a lot of insects.

McCracken has found that the free-tails gobble huge amounts of the worst agricultural pests in the United States. The research used a variety of techniques:

  • Doppler radar tracks bats and clouds of their prey, moths migrating north from Mexico

  • Microphones on balloons or kites detect bats' feeding and echolocation sounds.

  • DNA and isotopic analysis pin down exactly which insects are being eaten.

McCracken's team has found that the 100 million Mexican free-tails in South-central Texas eat 1,000 tons (!) of insects each night. Many of their prey are corn earworms and tobacco budworm. To get some idea of how damaging these insects are, U.S. farmers spend $1 billion for insecticides to control them in corn, cotton and other crops.

While McCracken tries to dial in on the exact economic impact of this gobbling, he observes that the bats "are eating unbelievable amounts of these insects, and the implication is that they are having major effects" in cutting insect populations and crop losses.

Interested in diseases that cause brain losses?

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