Science

Protecting Wild Animals Has Never Been More Urgent. But There’s a Reason It Can Be Harder Than It Seems.

Ineffective “bat bridges” in the U.K. have something to teach us.

Photo illustration by Slate. Photo by webclipmaker/iStock/Getty Images Plus and CreativeNature_nl/Getty Images Plus.

This essay is adapted from Beyond Belief: How Evidence Shows What Really Works , by Helen Pearson . Copyright © 2026 by the author and reprinted with permission of Princeton University Press.

Near the border of Norfolk in England, some weird-looking wire bridges span a busy road. They consist of pairs of poles on each side of the road, with a strip of wire mesh strung between and running down to the ground on either side. These are bat bridges, and they are a good example of a well-meaning conservation idea gone wrong.

The bridges appeared in 2014, when an extension of the A11 road was being built.…