As ski resorts put in quad chairs, they have to widen runs.
People think that the displaced bird can just move next door.
That's not true. The nesting area next door is already taken by a bird that's defending its territory. The displaced bird must move to a less secure nesting site that's more apt to be exposed to weather or predators. And it's unlikely that the bird will successfully reproduce. As humans reduce wildlife habitat, animals are squeezed into smaller areas only for a short period, say wildlife experts.