Bats: an important resource

This post contributed by Terence Houston, ESA Science Policy Analyst
This week, the Ecological Society of America is holding its 96th Annual Meeting in Austin, Texas.  As over 3,000 ecologists participate in the meeting’s numerous scientific sessions, a highlight in Austin that most meeting attendees will make every effort to see are the city’s famous bats.

As seen in the video below, between March and November, every evening around dusk, onlookers near the Ann W. Richards Congress Ave. bridge in Austin are treated to the mass emergence of the Mexican free-tailed bat. According to Bat Conservation International, “it is estimated that more than 100,000 people visit the bridge to witness the bat flight, generating ten million dollars in tourism revenue annually.”  People gather on the bridge and on boats to witness the emergence of the bats each evening.

Austin’s Congress Ave. bridge contains the largest urban population of bats in the world, around 1.5 million bats. However, in the wild, there are even larger ‘bat communities.’ The densest populations of the Mexican free-tailed bats are found in the Braken Cave of San Antonio, Texas where the bat population can number upwards of 20 million. It’s estimated that colonies that contain multiple millions of bats can consume 250 tons of insects per day.

The Mexican free-tailed bat (as known as the Brazilian free-tailed bat) has a wide range from the western United States, through Mexico, Central America and extending through the northern part of South America. They prefer warm climates and migrate to Central America in the winter. The bats have an average lifespan of approximately 18 years. The bats feed primarily on insects, including those which can become crop pests for farmers.

The ability of insect-eating bats to consume such mass quantities of pests has made them an invaluable component for both ecosystem and economic health in the areas they inhabit.  For example, researchers in an Ecological Society of America journal article estimated that Brazilian free-tailed bats saved roughly $740,000 in pesticide costs. During a June congressional hearing of the House Natural Resources Subcommittee on Fisheries, Subcommittee Chairman John Fleming (R-LA) quoted a Science magazine article placing the value of insect-eating bats to U.S. agriculture being between “$3.7 to 53 billion each year.” Chairman Fleming also noted that “as a doctor, I was interested in learning that some 80 different medicines come from plants that need bats to survive.”

The focus of the Congressional hearing was on the impact white-nose syndrome on bat populations as well as the pivotal role insect-eating bats play for the agricultural industry through pollination and pest control. The fungus that causes the disease, Geomyces destructans, is capable of killing 80 to 100 percent of bats in a given cave. The Obama Administration is already considering two of the nine bat species impacted by White-Nose Syndrome for protection under the Endangered Species Act. The U.S. Fish & Wildlife Service (USFWS) said in a Federal Review notice that protections may be warranted for the Eastern small-footed and Northern long-eared bats.

Thankfully, the Mexican free-tailed bat has thus far, been among those bat species that have not yet been impacted by White-Nose Syndrome. At the same time, the massive loss of bat populations across well over a dozen states and other parts of North America are already incurring adverse ecological and economic impacts and more research is necessary to understand and ascertain the cause and hopefully find a cure for the disease.

For Fiscal Year (FY) 2010, Congress appropriated $2.4 million to the USFWS for study into White-Nose Syndrome. Unfortunately, the funding that was supposed to be allocated for FY 2011 for further research was stripped as part the April compromise to fund the government for the remainder of FY 2011.  Looking toward the future, the subsequent Congressional hearings do give hope that a bipartisan consensus will emerge among lawmakers that appropriating some funds to bat research is a worthy investment.