Conservation and Biodiversity

Why American bats are declining

American bats are disappearing. Bat populations have sharply declined in the last decade, losing a third to a half of the total population. But what caused this change that lead many bats to be classified as endangered? The answer is simple: a fungus.

The fungus Pseudogymnoascus destructans, a cold-loving organism that infects the bat’s skin, spreads through bat-to-bat and human-to-bat interaction, the latter being extremely common when bats hibernate.

The fungus was first observed in 2006 in Howes Cave near Albany, New York, and has since spread as far west as Texas. The fungus has already killed an estimated 5.7 million to 6.7 million American bats.

Bats are valuable parts of both ecosystems and economies, contributing more than 3 billion dollars to the U.S. economy alone. Bats are also central to American agriculture, eating insects and pests and pollinating flowering plants, trees and cash crops like mangoes and bananas.

The Forest Service estimates that since the introduction of the fungus in 2006, more than 2.4 million pounds of insects have gone uneaten, insects that are now harming American crops. With less bats, farmers resort to less natural solutions like pesticides, which come with their own set of problems.

Is there hope for American bats?

To stop the decline and extinction of American bats, we must act now. But it’s going to be an uphill battle.

Bats have high offspring mortality rates, and only give birth to one bat per year, so though we can slow their decline, we may never fully revive bat populations. States and counties in the U.S. have restricted visits to caves and closed some caves entirely. This, however, is only a short-term solution.

Researchers are exploring long-term solutions that benefit American bat populations. In one study, researchers isolated bacteria naturally found in the bats. The researchers determined that the bacteria hinder the fungus. The scientists developed a treatment to improve the bacteria in the bats. They achieved a 50% bat survival rate with their treatment compared to an 8% bat survival rate without.

Furthermore, U.S. Geological Survey disease specialists and bat ecologists are collaborating to improve our understanding of the fungus and our response to the disease. Long-term solutions are scarce, but you can make an impact by avoiding caves, spreading White Nose Syndrome awareness, or donating to organizations such as Bat Conservation International.

April 22, 2020 is the 50th anniversary of Earth Day. Now is the time to act to save American bats and other vulnerable species. Donate to Earth Day Network’s Protect Our Species Campaign.