GeneRector: Now you have asked a hard question! I am not sure I can answer it. Trying to tell the differance between a 150lb bear and a 200lb bear is difficult to do. But trying to decide between a 150 and 300 lbs is a bit easier. You will be able to tell that there is a differance!
Every body seems to have a different theory on how to rate a black bear's size, in the wild.
The only for sure thing I know is It takes looking at a few bears over time and It's easier on the ground then in a tree.
I have had guys tell me I shot a huge bear and when you got up to it, it was 125lbs. Also just as many miss judge the other way.
Here is what I have told folks over the years that may help you. Keep in mind it's not 100%.
If your up in a tree stand:
The head should look smaller in relationship to the body. Big body small head = (read a lot of times) decent black bear. (again I stress this is not exact but will help you, I think.) If the bear is walking directly away from you, and you can see is bear butt and nothing else (read big hind quarters) it's a decent bear. If they are broad side and they look like the head is really small and the front shoulders are small compared to the belly and hind quarters, its a good bear. Just think of a steer with a big belly and bloated he weighs a lot. Now think of a young steer with a sleek look and no bloat. He's usually lighter than the big belly one. Also old black bears may have battle marks and worn ears from fighting
Lastly: Foot prints. I have found foot prints to be a poor judge of black bear size. I have seen some big foot prints over the years that came from some small young bears. Ever seen a young male dog with big feet? He is going to be big some day but he isn't yet, just his feet are. His body has not caught up to his foot size. I have found the same thing with black bears. Now if the ground is harder and his track is deep, might be a brusier.
Sorry for the long post but I truely wanted to give you the best help I know.
