The poem starts with a puzzle: dead bats lie around wind turbines, yet many have no broken bones. The answer, as the title says, is a hidden danger. The spinning blades create zones of low pressure, and the sudden change bursts the delicate vessels in the bats' lungs. They "drown in the air," a phrase that captures how strange and cruel the death is.
The speaker doesn't shout or lecture. The tone is quiet and observant, almost like a scientist's report, but small details give away real sorrow. The bats' "stiff calipers" of ears and silent sonar make them seem finely made creatures undone by something they could never have anticipated. The line about 50 million years of evolution stresses how new and unfair the threat is.
The ending shifts to myth. The turbines turn like an "uncaptained ship," a new Flying Dutchman under a "glue-eyed moon." The mood is eerie and mournful, as if the machines carry on blindly, with no one in charge of the harm they cause.