SPRINGFIELD, Mich. (AP) — A wildlife official says hundreds of birds found dead along railroad tracks in southern Michigan died because they didn’t get out of the way of an oncoming train.

Thomas M. Cooley, a wildlife biologist/pathologist with the Michigan Department of Natural Resources in Lansing, told the Kalamazoo Gazette that the official cause of death is trauma due to being struck by a train.

Cooley says tests were negative for toxins that might have rendered the birds too ill or disoriented to fly.

He says 400 to 500 crows died. An investigation began after the birds were found dead earlier this month in Springfield, southeast of Grand Rapids.

Springfield City Manager Nathan Henne says Amtrak passenger trains that use that stretch of track “are really cooking when they go through there.”