Territorially

[Zinjanthropos]

What are the advantages of being a territorial species? Territory implies a range with borders or limits and above all.....prime real estate. Defend or attack it? 

A pride of lions for example. The most powerful or dominant lions own the ideal area. Others are dispatched to the outer limits of lion country. Does it stand to reason that the perimeter is a much less friendlier to survival area than the idyllic central zone? Yet those who survive the hostile outposts eventually earn the good ground through aggressive behavior, displacing  former owners.

Can we equate this to humans?

[C C]

In regard to those who actually defend a selected habitat, it may be to ensure that the area's resources aren't diminished / obstructed by competitive intruders. As well as preventing nesting from being disrupted and keeping rival males away from a mate or harem. Bluebirds, for instance, usually avoid nesting any closer than circa 100 meters from each other. However, if there are little or no interspecific issues with other bird species (just the conspecific kind relating to members of one's own kind), then the resource reason may seem to make little sense. More detailed inspection might reveal that the bluebird's choices of food, nesting materials, and roosting sites differ from those of other avian types. However, there's surely some overlap in needs and their consumption. For instance, a wren also competitively seeks interior nesting cavities and may eat a worm as much as a thrush. But the latter former prefers brushy cover whereas the the bluebird prefers open grassy areas to forage.

In the case of migrating animals with a hierarchal social structure, a claim to "my territorial space which you don't enter without permission" is of course constantly changing and mobile. Subject to the ranking status of the individuals involved, and may embrace a distinct "sub-family" of members within the larger troop (not just jealously guarded females but also their young; as well as dominant females who defend boundaries).

[Zinjanthropos]

Casually speaking.....When you watch documentaries it's usually the strongest lion that gets the good turf. However their successors will come from the fringes of that territory. Evolution appears to favor the the conquering animal to be the one who can survive outside the prime area boundaries thus possibly guaranteeing a more powerful successor(s), plus the fact that the dominant breed. IOW it's good for the overall health of the central pride and future stock to have the breeders run the gauntlet. I find it odd strategy to have to relinquish less powerful animals to the sidelines, have them struggle and die, just to preserve the species. But I guess it works for lions.