Drought and development are taking an increasing toll on natural water sources in North America’s arid western regions. Bats, birds and many other wildlife species are being forced to turn for survival to an assortment of livestock watering troughs, tanks and ponds.
Unfortunately, many of these vital artificial water supplies are installed, located or maintained in ways that deny access to bats and other wildlife – and often put drinking bats at severe risk of drowning.
The Water for Wildlife program led by Bat Conservation International, with support from the Offield Family Foundation, the USDA Natural Resources Conservation Service and others, is working to solve these problems through research and education.
Bats probably rely more than any other wildlife on livestock water supplies. Studies of bat physiology have documented water loss of up to 50 percent of body weight in a single day, and even the most desert-adapted bat species periodically need water to survive.
Bats drink on the wing. To get water, they must fly down to the surface, scoop up a drink and keep flying up and away from the pool – a process that requires an unobstructed “swoop zone.” Obstacles in the approaches can prove deadly. Like many other animals, bats are very susceptible to drowning if trapped in a water tank without a structure that allows them to escape.
Yet a survey of 367 livestock troughs on private and public lands in 11 western states found that fewer than 10 percent had adequate escape structures. And more than half had potentially hazardous obstructions over the water, most often braces or fencing.
The minimum size of the water features that bats can use varies according to each species’ flight characteristics. A few of the most maneuverable bats can drink from open water with dimensions as small as three by four feet, although they prefer larger open areas.
An analysis of data on bats captured by biologists near western water sources indicates that most bat species need open water surfaces at least 10 feet long by no less than 2.5 feet wide. Some species apparently require tanks or rivers with stretches of open water at least 50 feet long, and several need 100 feet.
The Water for Wildlife program is publishing, early in 2007, a handbook for ranchers and range managers that explains the value of considering bats and other wildlife in the design and maintenance of livestock water supplies. It offers advice on ensuring bats and birds can use the water and provides plans for building and installing escape structures.
Your can help ensure that water remains safely available to wildlife, including bats, by supporting Water for Wildlife. Contact firstname.lastname@example.org.