here's a great link on judging the sex of blackies also.....I agree on the 2 things pointed out above and also have heard of folks using objects, be it a hung stick at a certain height or the barrel of a drum as measurements as to just how big a bear is. Also you can get them to stand by hanging bait or dripping molasses or honey on a tree....works in Mn wouldnt see why it wouldnt work elsewhere! You would have to figure out how big they would be nose to tail but I am sure after looking and measureing a few rugs at the local taxidermists you can hang your baits or mark a tree at a certain heigth to give you an estimate!

Also how a bear comes into a bait. If they come in shy and slow there is usually a bigger bear around. Its pretty obvious they are not king of the forest! If that sucker comes in and has no worries, sits down and owns the place..that is more likely then not the biggest bear in your neck of the woods! Hope that helps some..here is the link.

http://fwp.state.mt.us/bearid/