Animals in North America have a problem — they’re having a hard time moving around.

Migration is key for the survival of a lot of species. But in many places, developments like roads, highways, towns, industrial plants, or even entire cities form roadblocks that limit how far animals can move before they encounter humans in a potentially dangerous way. That's bad news on any day, but especially now that temperatures are on the rise. According to a study from the Proceedings of the National Academy of Science, only 41% of natural lands in the United States are connected enough to allow animals to trek safely toward cold enough habitats.

Keep Reading Show less
Most Shared
True
Rocky Mountain Wolf Project

It's been four days since a group of armed men took over the headquarters of the Malheur National Wildlife Refuge in Oregon on Jan. 2, 2016.

Ammon Bundy, leader of the armed occupiers at Oregon's Malheur National Wildlife Refuge. Photo by George Frey/Getty Images News.

Keep Reading Show less
Heroes