How would you design ownership in a game? Humans respect ownership, but animals do not. Yet, an animal may have a den that it considers its own and returns to every night. This ownership is not respected by neither humans nor other animals.
Should these concepts be separate or can the same design be used for both, with the difference being that ownership can either be respected by some, all, or none.

I don't agree. If birds come across a nice place to build a nest, only to see half a nest already there, they assume some other bird is building a nest there, and they move on. They don't respect ownership when they don't recognize ownership, but neither do people. We understand that everything man-made has an owner, but with unused patches of land, most people wouldn't know what to assume. That's how I think about it anyway.

It all depends on the type of game. In what context are you thinking? What's the concept of the game?

It's a simulation game. I have coded a human AI and am trying to figure out if it can be generalized for the animals also.

A very easy answer to this question (which is not necessarily easy to _implement_) is to rely on a fuzzy logic system.

e.g., both humans and animals have various _indicators_ of ownership of varying degrees. We tend to assume a house is owned. We tend to assume a tilled field is owned. We don't associated much ownership with deep forest, unless it's marked on a map as being "XYZ National Park" or the like. Animals rely a lot on smell and such for similar purposes.

There's also the question of how much we care about ownership. And how much we want the thing in question. And how risky we think it is to retrieve it. And so on. All of these can be measure on a fuzzy scale, then combined using various functions to come to a final fuzzy number: should we try to obtain the thing. As a fuzzy number, that can be further combined with other decision points (should we run away from the thing? should we build a kazoo? etc.) and used in a decision system to select the final course of action.

I don't agree. If birds come across a nice place to build a nest, only to see half a nest already there, they assume some other bird is building a nest there, and they move on.

This is threat/conflict avoidance behaviour. Might is right in nature, and a larger bird would not care.

Perhaps human ownership is the same, where we respect it out of fear. If I can join the two concepts I will have a foundation to build on.

well you have objects, and owners, and entities.

objects have owners.

but not all entity types respect ownership of all object types.

so you're going to need a matrix of which entity types respect the ownership of which object types. some sort of lookup table or 2d matrix is typical for this.

when it time to do the ownership thing, consult the table to see if you even have to worry about the "violates ownership" check, or whether you can simply proceed as though the object had no owner (IE the ownership is not recognized / honored / respected).

How deep do you want your game to be?

Personally if I was simulating animals, I'd have them be more aggressive and less submissive depending on what they are doing. A carnivorous animal with a recent kill would be more aggressive as would an animal with cubs/offspring etc.

A nesting animal might also be dangerous.

As for humans a human makes an obvious claim to land or items by marking it their own, where an animal might pee on land a human will put up signs, e.g. "no trespassing" or "joes farmstead". Part of taking ownership of land could be to name it, or risk renaming it.

That's my own idea on the matter :)

To answer your question directly, the same system should be used for ALL entities, humans included. Using a separate system for humans and animals is rather obtuse. We are animals, and use the same system of ownership that other animals use, only more complex. By designing the animal system as a base ownership mechanic, you can just add more complex ownership behaviors for the humans. An animal will usually recognize the habitation of another animal and avoid it. The only exceptions are that predators do not respect the habitats of prey (but do respect the habitats of other predators and dangerous non-prey) and no animal will respect a boundary of ownership which it does not recognize. The elephant does not notice the anthill and therefore does not respect the queen's ownership of said hill. A squirrel does not respect the ownership of human roads. By the time it's brains are splattered across the dividing line, the issue of whether that stretch of road is owned by the state or by the county is moot. You are addressing a very complex psychology. Expect to fail. Test, test, and retest the system until it is somehow functional.

Humans respect ownership

The majority of human history disagrees with that. ^_^

Humans "respect" ownership when the risks and punishment of getting caught exceeds the necessity and the rewards of getting away with it.

If: A) the necessity is huge enough (e.g. you are literally starving, and you see a loaf of bread)
B) the reward is great enough (e.g. a bunch of diamonds or bars of gold or very large numbers in a digital bank account at your fingertips)
or C) the risk of getting caught is virtually non-existent...

...then human "respect" goes flying out the window, along with the thief and the loaf of bread or sack of diamonds.

Ancient Greek philosophers theorized about this, conceptualizing the One Ring of Power. Their conclusion is essentially, the primary reason to be moral is to not be enslaved by immorality.

Basically, humans don't respect property, unless by "respect" you mean the kind that comes at the end of a big stick, and then it's the stick (and the wielder) they 'respect', not the idea of ownership itself. That stick can be government-ran police, court systems, etc... or getting one's butt kicked by a homeowner who finds you in his garage.

That same 'respect' can just as easily exist in the animal realm - All rabbits acknowledge and respect the fox's claim to the den. Animals, and humans, ""respect"" the property of the biggest animal. In the forest, the wolf, in Russia, the Putin, in Syria, the Assad, in the USA, the criminals, police, and government officials (who sometimes overlap).

I don't agree. If birds come across a nice place to build a nest, only to see half a nest already there, they assume some other bird is building a nest there, and they move on.

Or they lay their own eggs in the nest, to trick the original nest-builders to raise their young for them.
Or they eat the eggs already in the nest. Or they steal the materials used in the nest to build their own nest.

This firm once existed, I'd have you to know,
Messrs Lion, Wolf, Tiger, Fox, Leopard & Co
These in business were join'd, and of course 'twas implied,
They their stocks should unite, and the profits divide.