A snake historically found in most Arizona watersheds but not seen along the Colorado River for more than 100 years has turned up again.
The Arizona Republic reports biologist Michael Lester discovered a northern Mexican garter snake, which was designated as a threatened species in 2014, along the river in 2015.
Jeff Servoss, a herpetologist lead for the U.S. Fish and Wildlife Service's northern Mexican garter snake recovery program, says he doesn't believe the program is directly responsible for the snake's apparent re-appearance.
Servoss says he thinks the snake has always been in the area but just "in exceptionally low density."
Servoss attributes the snake's frequent re-appearance near Bill Williams River, at least in part, to populations of lowland leopard frogs, a critical prey for the snakes.