When Arizona Game and Fish Department biologists went to survey a Mexican free
-tailed bat (Tadarida brasiliensis) nursery colony this past June, what they found was alarming. Bats lay dead and dying under the bridge, the ground littered with spent .22-caliber rifle cartridge cases.
The colony of approximately 5,000 made its summer home under a highway bridge 60 miles northeast of Phoenix. Biologists eventually counted 575 dead bats, but many more likely crawled away to die undetected. At the time of the killing, female bats would be suckling newborn young or about to give birth.
The Game Department called BCI to request assistance in posting a reward to apprehend the perpetrators. Following BCI's initial $200 contribution and a great deal of local publicity, the reward quickly grew to over $1,000. The incident provoked a tremendous public outcry, and outraged citizens volunteered tips on the anonymous Operation Game Thief hotline.
Bats are protected under Arizona game laws, and it is a Class II misdemeanor to kill them without a permit. Maximum penalties are four months in jail plus fines. Soon after the reward was posted, Game Department officials and police arrested two men for the crime. The case has not yet come to trial.
Mexican free-tailed bats are still among the United States' most abundant bats, but even their numbers are declining rapidly. Incidents like this one, as well as vandalism at their overwintering roosts in Mexico, have contributed substantially to the growing problem. Free-tails, like many other bat species, are especially vulnerable to human attack. Because free-tailed bats form dense aggregations, sometimes numbering in the millions, a single act of vandalism can have tremendous impact on even the largest colonies.