Our environment changes rapidly with loss of animal habitat increasing daily. Why might an animal's insticts cost it it's life in this situation?
So far all I can think of is the deer that sense a sourse of food on the oppiste side of a road. Which causes them to cross and get hit by cars...
Animals with smaller habitats compete with other animals for available food and shelter. Therefore, they're more in danger of being killed by other animals and of lacking sufficient food.
By the way -- deer and some other animals are adept at adjusting to smaller environments. I know of some residential neighborhoods with deer populations that eat the home owners' plants -- and drive them nuts!