I need a dog for a specific job, but I don't know what it's called

And this is making finding information a challenge.

Let me explain. I want a dog that I could train to guard an orchard and garden from maurading wildlife. I have no livestock. About a 3 acre area. Every night. I don't want a dog that will bark endlessly, I don't want a dog that feels the need to kill it or chase it for 10 miles. Just make it go away. I want the dog to know the mailman is cool, the kids and cats must be tolerated.

So is this a guard dog? A watch dog? A dog that herds animals away? A LGD? (Probably won't bond with Apple trees, lol. What instincts would the dog be working from?

And breed suggestions? Training suggestions?

I don't know what it is called either, but it comes from a natural territorial instinct and is basically "property protection". Some dogs are better at it than others. A laid back but watchful, cautious breed is the best choice as wound-up or overly protective dogs tend to not do well when strangers approach. They should be well socialized to people and to any other pets you have, but most dogs naturally will not want wildlife on their property. Some are better than others at keeping them at bay.
Hounds tend to be chasers, many famous guarding breeds tend to be over protective, but LGD type breeds could do well. Even if they don't bond to the trees : ) they still have a territorial instinct. They like to be outdoors, are watchful but aren't quick to chase or attack, and some of them are very good with strangers (some are very cautious and wouldn't do well around strangers, but it depends also on the individual dog and how they are raised).
While dogs tend to be happiest in pairs, I will warn that two dogs together tend to rile one another up and be more likely to run off or attack, especially if they were raised together and bonded.

So in the end I would suggest finding a Shepherd dog or Shepherd dog mix. An older puppy is best as a young one will just want to be with you and an adult may not be trained for what you want.

I hope this helps. Best of luck!

Thanks! But do you mean A shephrd like a German shepherd, or a header like an autralian sheperd?

The terminology does get confusing. : )

I usually call dogs like Australian Shepherds "herding dogs" and shepherds are the livestock guardians. So German Shepherds included, but also Great Pyrenees, Maremma Sheepdog, and the like. Shepherd dog mixes (you can find some adorable shepherd mixes at shelters, litters of puppies are common there) of smaller sizes (more like 70-80 lbs instead of 100 lbs) could work nicely if you are on a fairly small piece of land and the wildlife you want to keep away is fairly small too.