Migration bottlenecks are areas where the animals' movement is constricted by topographic feature(s) or human development. Maintaining safe movement through the bottleneck is critical to the corridor remaining intact. Within the Sublette herd corridor, bottlenecks were identified along the outlets of several finger lakes along the Wind River Front, as well as at certain points along State Highway 189/191 where WYDOT has constructed over- or underpasses to facilitate safe crossing. Bottlenecks were identified as being 'vital habitats' for big game.