bullmastiff behaviour

Question
There is a bullmastiff in our neighborhood and it cornered a walker the other day and now it "stalks" our house.  Every time it is loose it stands across the road and barks at our house.  It just stands there and barks and this evening when my children and I were outside, it started barking and began to paw the ground so hard it made grass fly behind it.  Is this a sign of an attack waiting to happen?

Answer
The pawing you speak of is usually a marking behavior (normally male, hind legs push dirt backward) and often accompanies urinating and even defecation.  It can also be a display of dominance (normally directed at another dog.)  This dog is behaving in a very proprietary manner; does he live across the street from you (is he somehow "guarding" his territory or nearby it?)  The dog may simply be demonstrating over excitement and even fear, although this does sound alarming as you describe it and you are obviously quite concerned.  When you say he "cornered" a walker, I presume you mean he did not bite but attempted to control in some manner (and no doubt scared the person to death.)  I haven't got sufficient information to determine the dog's motivation.  Don't you have leash laws in your area? Do you have an animal control officer? If not, call the police.  This is a very large dog behaving in a very odd manner and its owner doesn't seem to be anywhere in sight.  Someone should bring this behavior to the owner's attention and I suggest the police (or state police, if your town police aren't serious enough) are the ones to do it.  Meanwhile, don't confront this animal.  It's not likely he will pursue you for no reason.  Keep an eye on the children, don't allow them outdoors by themselves.  The dog may be perfectly harmless but you don't want to find out the hard way.