Ospreys nest at a range of densities, from very solitary (many kilometers from the nearest neighboring nest) to loose colonies, with nests less than 100 m apart. Colonies may form because the presence of established nests is a signal of suitable habitat to arriving individuals, or because good nest sites are often clustered together, such as on an island or along a power line. Grouping of nests is uncommon in raptor species because most raptors defend a feeding territory around their nest. Ospreys defend their nest or nest site, but do not defend a territory around the nest. It is not profitable for an osprey pair to defend a territory around the nest because their prey are patchily distributed, mobile, and often located several kilometers away from the nest.