Bottleneck
Habitat fragmentation
Animals move daily and seasonally to survive. Humans do, too, but we have different modes of transportation to get from here to there. When obstacles are in our way, we usually can get around them somehow, someway.
Animals are smart, but their migration to different habitats have been engrained through generations to get to areas they know will provide the nourishment they need to survive. When those locations are blocked or have obstacles, they don’t process that information like a human and simply go another way – at least not right away.