Also relevant to this lecture is ch. 22 in Smuts et al. which this lecture is partially based on.
You might wander nomadically, like the cedar waxwing. They don't often come back to same place twice. This type of spatial use is rare; most animals don't do that. Why? Because it's safer when you know territory, otherwise you'll waste energy looking for food, water, and safe spots. Most animals who wander nomadically do so 'cause they have to 'cause there's limited resources.
You might wander seasonally. This is seen in African ungulates like the zebra, for example, and also birds of course. You may ask, "Why bother? Migration is dangerous, difficult, and expensive in terms of energy." (Or you might not ask but I'll tell you anyway.) They do it because of seasonal changes; habitats become too cold or too dry, and food availability varies. Primates don't do this too much 'cause they're in the tropics so they're not too affected by seasonality.
Most animals stick in one place. The advantage to this is local knowledge. You know where the dangers are, where the food and water are, when and where not to go, and you also know other individuals or groups of the same species in the area. (Don't confuse staying in one place with the issue of dispersal; to avoid inbreeding, at least one sex must move once in its life, but just because a species disperses doesn't mean that they're nomadic. But dispersal comes later.)
What do primates need to have in their home range to be able to stick around? Food is always good. Water is, for some species. Some who live in the tropical rainforest can lick the dew off leaves, but in arid areas it's really important to have a water source. Shelter is not an issue for some species like ones who live in rainforest canopy, but for baboons who sleep on sleeping cliffs to escape from predators, their possible ranges are affected by the availability of cliffs. Also, the last thing you need are mates! You've got to be around the other sex or your territory will be uninhabited within one generation.
This brings us to the question, How long is long enough to watch a group? How do you make your recommendation measurable? You could watch them until they don't go anywhere new anymore, but that's a little imprecise. A more consistent way is to call it at a year. This is good 'cause sometimes there's seasonal variation.
Gibbons: Monogamous groups with small territories. They have aggressive defense involving displays, chases, and fights. They sing to defend their territory. When two couples meet up, they'll display, sing, and chase. Between-group aggression is sex-specific; males fight males, and the females fight females.
Mangabey: (cercocebus) Large home ranges with almost complete overlap but exclusively-used core areas. Males utter a distinct call upon contact and groups mutually avoid each other. They use a call called a whoop gobble to let others know they're there. If someone hears it, they move away and they all avoid each other. This is unless there is a specific resource that they might all want to feed at like a good fruit tree.
Gorillas: Large home ranges with almost complete
Adult males are the primary participants in aggression. Males initiate aggressive displays including chest-beating, branch-breaking, and charges. The females and young are rarely involved in conflicts. Our professor says that while he has never seen an adult male charging and displaying, everyone else who has agrees that it's quite intimidating!
Why don't all primates defend territory? It seems pretty nice since you get exclusive use and all, right? As long as there is competition for resources, there is the potential for territory defense but the problem is, it has to be economically defendable; the benefits of defense must outweigh the costs.
Check out the diagram from Krebs and Davies on home range size plotted against the costs and benefits. Costs increase linearly as the home range size increases, but benefits are a curve which will level off eventually. This is because you only need so much; getting more access to food won't mean anything if that's all you can eat. So, eventually the two lines cross. In the region where the benefits are greater than costs, that's where you'd expect defense of territory to happen. However, if benefits are always lower than costs then you don't expect territory defense to happen. People in primatology don't really use this type of approach quantitatively since in primates it's all too complex and too hard to measure well, but it is useful conceptually to help you think about relative costs and benefits.
One obvious cost for primate territoriality is related to the necessary size of home range for your food type. If it needs to be huge then it's too hard to defend it, but if you only need a smaller one then its easier to defend. Another factor is how hard it is to get around in your habitat. If you're a quick animal then maybe it's practical for you to defend your territory, but if you are really slow then don't even bother.
Some guy said, if d=diameter of home range and drl=day range length, you'll see territoriality when drl > d. In other words, if you can cross your whole territory in a day, then you'll defend it 'cause it won't cost you too much energy and time, but if it takes a long time to get through your territory then you won't.
Intergroup behavior also varies between the sexes. We will do more on this later, but males and females have different agendas; A female's output is limited by access to food/resources, while males are limited only by access to mates. This means that females only fight when resources are limited and defendable. Depending on the situation, sometimes they'll fight and sometimes they won't fight. Female participation depends also on the composition of group. In some species, the females stay where they're born, but in others they disperse and live with strangers. So the females who stay make a sharp distinction between members of their groups and nonmembers so they fight more. In dispersing species, the females could care less if someone is attacking the group. Thus, both ecology and population structure both predict whether females will join in the fight.
For males, however, it always pays off to get more female access, so they always have conflict. This is very consistent. You can make a reliable prediction that males will fight other males.