Bat Populations – Stewards of Texas

Impacts to Texas Bat Populations

Texas has the largest bat colony in the world in San Antonio’s Bracken Cave Preserve with nearly 20 million bats. Other famous sites such as Austin’s Congress Avenue Bridge and Fredericksburg Old Tunnel State Park draw tourists from across the world. 32 of the 47 bat species found in the United States call Texas home as well.

Bats are an important part of our ecosystem, pollinating our plants and controlling mosquito populations. A study by leading bat researchers showed that bats save farmers $12 to $172 per acre in pest control costs nationally each year. In Texas alone, they estimate that bats saved $1.4 billion by eating crop pests.

Wind turbines are negatively impacting Texas’ native bat populations, but data is limited and mostly exists only in national studies or other areas around the world. Although Texas Christian University (TCU) is working on a bat monitoring program with the help of NextEra Energy (a wind company), forgive us for being skeptical of what information they put out.

Collision Fatalities

Numerous studies have documented high numbers of bat fatalities at wind farms. In one year alone, it was estimated 600,000-900,000 bat fatalities occurred from wind turbines in the United States.

Barotrauma

Bats are killed by barotrauma (rapid air-pressure reduction near moving turbine blades), meaning the pressure change causes tissue damage to their lungs.

Habitat Displacement

The construction and operation of wind farms result in habitat loss and changes in bat activity. Research found that when wind turbines were placed close to existing roosts, bats hunted around the turbines and suffered casualties. When wind turbines were placed further from roosts, the bats avoided the area, leading to a loss of habitat.

Limited Populations

Most species of bats only have one pup per year, and not all survive their first year. This slow reproduction rate emphasizes why bat populations are so vulnerable to population declines. The cumulative effects of increased mortality from wind farms could lead to significant declines in bat populations over time.