Info on Bats | Can Bats Lead Us to Clean Water in the Desert?

Info on Bats | Can Bats Lead Us to Clean Water in the Desert?

By Theresa Laverty, Ph.D. Candidate in the Department of Fish, Wildlife, and Conservation Biology, Colorado State University

Conservation Biology, Colorado State UniversityDesert life depends on reliable access to water. In Namibia’s stark Namib Desert, where I spent 18 months doing research for my Ph.D., wildlife concentrates around natural springs. Increasingly, animals there also rely on man-made ponds intended for livestock.

But water can vary both in quantity and quality, and animals have different needs. Some species, like the kangaroo rat, can survive without drinking water for years by obtaining it instead from its food. More often, the movements of desert animals are restricted by reliable access to water.

Part of my research examines relationships between bat species and water quality in an African desert. Based on my observations, I believe that in arid places, people may be able to locate usable water sources and detect changes in the quality of sources they are already using by observing bats.

FOLLOW THE BATS

In the Namib Desert, pools of freshwater are rare and isolated. The ephemeral rivers of Namibia flow only a handful of days each year, so it is very hard for aquatic insects and fish to travel between bodies of water. But since bats can fly, they can find freshwater sources over large areas, and may visit multiple ponds in a single night. One question I am studying is whether bats are more likely to travel to seek out high-quality water than to find food.

There are more than 1,300 bat species worldwide, living in diverse environments on every continent except Antarctica. They pollinate plants, disperse seeds and consume insects – including disease-spreading vectors like mosquitoes.

Because their wings are large and uninsulated, bats are vulnerable to dehydration. Even the most desert-adapted species need water. Water quality affects them directly when they drink and indirectly when they consume insect prey, many of which spend part of their lives growing in water. This makes bats excellent indicators of water quality. In extreme cases, they have died after drinking water contaminated with insecticides or heavy metals.

To find high-quality surface waters, people could observe bat activity levels using acoustic detectors to record bats’ echolocation calls. Although mostly inaudible to humans, people can typically identify bats to the species level by their calls. Monitoring species that are associated with high-quality water over time would help municipalities detect changes in water quality. During my time in Namibia, I observed that activity by all local bat species dwindled at springs with high salt concentrations.

Water chemistry affects different bat species in different ways. For instance, one study found that certain species in Israel’s Negev Desert, such as the lesser horseshoe bat (Rhinolophus hipposideros), avoided drinking water of lower quality, while other species appeared to be more pollution-tolerant.

Scientists are still trying to discern whether and how well bats tolerate salty drinking water. A study from western Australia suggests that elevated salt levels in surface waters due to gold mining may decrease bat activity, foraging and drinking. If this is true, people living in those areas could detect changes in water quality, such as increased salinity, by gauging activities and drinking patterns of sensitive bat species. With new tools such as bat detectors for smartphones, this is becoming easier and cheaper than testing water samples in labs.

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