The ones I see are out in the mountains and are generally around the size of a cocker spaniel, I'd say. They're very nervous, though, and we've never had any problems with them. They have sentinels that sit out and watch for trouble, and give an alert signal when there is any sign of danger. It's a piercing scream that sounds very much like a bird of prey and travels for miles. I think they're cute things and they always make me smile. They always provide an opportunity to work on my stop whistle, too
Groundhogs and Wood Chucks are the same, Marmots are related, but a little different. Based on our experience there is also a larger version known as a Lab Chuck. Much more destructive than a Wood Chuck. Chews up logs, kindling and tchotchkes . Fortunately ours don't seem to favor furniture.
I believe I may have spotted one it was running round a field with and umbrella wrapped round its head earlier today
From National Geographic: The groundhog, or woodchuck, is one of 14 species of marmots. http://animals.nationalgeographic.com/animals/mammals/groundhog/ So, all groundhogs are marmots, but not all marmots are groundhogs!
Looks like our Marmots that we see in the Cascades Mountains are either Yellow Bellied or Hoary, both are high altitude animals and larger than Wood Chucks. I knew they were related but did not realize that they were classified as Marmots also. Our native Lab Chuck is much larger weighing up to 85#