The (Carbondale) Southern Illinoisan reports that typically the 2.5-mile-long (4-kilometer-long) stretch of road in Southern Illinois is closed to automobiles for the annual migration of the animals between Sept. 1 and Oct. 31.

But this year because the late-season warm weather delayed the migration, the decision was made to keep the road closed until Tuesday to make sure stragglers don’t get run over. Some of them are considered threatened and endangered in Illinois and the United States.

Though vehicles won’t be allowed onto the road, it will remain open to people traveling on foot.