That's thinking pretty highly of yourself, saying you can A: make an animal happy based on human ideas B: thinking you can determine an animals happiness based on some "sense". Animals have different personalities just like humans. The fact that properties are usually fenced completely shoots a hole in the "happy animal" theory.
They don't want to be contained any more than people want to be in prisons...........
First, you are very much anthropomorphizing to assume that animals have some objective sense of "captive" versus "free" and would always choose the latter. You state that you can't subscribe human emotions to animals, yet here you are doing exactly that. But I'll cater to you for a moment: Many people do, in fact, prefer being in prisons to being in general society. There are many cases of this, but the example that sticks in my mind is the guy who intentionally went out and shot a postal worker, just because he knew that shooting/killing a federal employee is automatic life in prison. Seems his life was falling apart around him, his finances were in shambles, and he knew that in prison at least he would be protected and he could count on daily meals....
Animals, obviously, can't reason it out to this extent, but the end result is the same. Guaranteed food, protection, and safety or the very real possibilities of being eaten by a predator or starving to death. If they could rationalize the options, which do you think they would choose?
Fences are as much for protection as they are to keep them in. How many people do you know who let their dogs run free, but they never wander far? I know my dogs much prefer being "locked up" in the house than outside, even in good weather. They'll scratch at the door and whine to be let in. Most people call that "spoiled." :roll: And there have certainly been occasions when my horses have gotten loose on the neighbors' unfenced property, only to meader (or sometimes gallop) right back home and wait at the fence. Hell, when the weather's bad or night starts to fall, they're always lined up at the gate waiting to come in the barn, be "confined" to their jail cell stalls, eat their meals and sleep on their comfy deep bedding. No stall vices, no stereotypies, no signs that this lifestyle is remotely stressful for them.
As for animals being "happy," well, I just plain don't like that word. They do, of course, have emotions, but happy isn't one I think they experience too commonly, whether domestic or wild. I don't think most people spend a large portion of their lives being "happy," either. Let's try "content," instead. And yes, a student of the animal can absolutely determine an animal's quality of life and contentment based on health and behavior. It's not rocket science. And if there is any doubt, researchers can confirm the signs of emotional well-being by looking at physiological processes, brain chemicals, etc. And that's all emotions are, anyway--human or animal.
If an animal's basic needs are being met and their instincts are being catered to, yes, they will have a good quality of life.