No need to apologize, your questions were legitimate. I think your posting on an older thread instead of starting your own kind of threw me off. I did not notice the dates and was responding to some other comments. I don’t see that we totally answered your question.
What is ethical depends on you. We all have our own morality. As you can see from some of the responses we have different opinions.
What’s legal depends on where you live and what the local laws are. It varies from state to state (if you are in the US, I don’t assume that much). Different cities, counties, HMO’s, everybody that can have rule might have their own. You cannot assume the law here is the same as the law wherever you are or even in the next county. You have to do local research. Local animal control can be a good place to start.
In many (probably most) places it is illegal to trap an animal and release it anywhere other than on your own property without the landowners permission. Some places will allow you to release an animal in a park or certain areas, but you need to check with the rangers or whoever is in charge before you do that. Some places legislate how you are or are not allowed to kill a trapped animal, if you can even legally kill one. Occasionally animal control will take an animal off your hands, but that’s not normal. I’ve had local law enforcement officials say just take care of it and don’t tell anybody. Some people advocate the SSS method: shoot, shovel, and shut up, but if someone else sees or hears you shooting they may not shut up. Many areas with trash pick-up specifically ban dead animals form that trash. How you dispose of an animal can be a real problem legally.
Most predators are not legally protected but some may be. Or there may be certain seasons you are allowed to trap them. In most states you are allowed to protect your animals from predators, though there may be some laws against discharging guns, especially in suburbia.
Dogs are often specifically covered in state legislation. In Arkansas and Oklahoma you can legally protect yourself, family, and animals from a threatening dog. But you are not allowed to just shoot any dog that enters your property. It has to be threatening or sometimes actually attacking your animals. Dogs cannot read “no trespassing” signs. If a hunting dog trees a raccoon on your property and is raising a ruckus barking at the coon, you cannot shoot him. He is not threatening you. But if he attacks your chickens you can. Some people have spent time in jail and paid pretty hefty fines for shooting dogs that enter their property. I have had dogs attacking my chickens before. The first thing I grabbed was my shotgun. The second was my camera to document why I grabbed the gun.
When I notice a dog has been abandoned out here and it has not yet learned to kill, I’ve been known to drop it off at the local pound.
I have killed snakes that are in my coop eating eggs or baby chicks. But if I can, I take them to a friend’s place (non-poisonous of course). I have her permission to turn them loose there. I keep a pillow case near the coop but I can’t always catch them. In Arkansas it is illegal to kill a snake.
Legally it can be a real mess. A lot of that depends on where you live.