I have a 3.5 year old neutered male rottweiler who has started exhibiting some new behavior that troubles me.

My wife and I work with a couple local rescue groups and are currently fostering a year old female am staff. The dogs get along great but I have noticed a shift in the pack dynamic.

My rott has never been much of a barker in general but would always let out a woof or 2 if he saw someone outside and then he would usually run to me where ever I was in the house to make sure I heard him.

Now with the am staff in the house she has grown very vocal when seeing people outside and my dog has taken a back seat. He has never been one to be overly dominant when we bring in new foster dogs and this time was no exception. He seems much more concerned with what we humans think than the other dogs.

He has always been great with people, loving affection and eager to greet people. However the other day we were at one of the large pet food chains getting some food and a few people asked if they could take a closer look at him. The 1st two people to come and pet him where men and my rottie started barking at them as they got close and reached to pat his head. No growl at all, he just dropped his ears and started barking with a warning tone. After that I figured it best to have people keep their distance but before I could say anything a woman came up on my left where my rotty was in heel and started petting him and he showed no signs of aggression.

Earlier my wife had taken him to the rest room for a drink where he barked at a female store employee but then 20 minutes later when my wife was handling the female am staff and I had the rott we joined up after looking in different sections of the store and the same female store employee was happily greeted when we came upon her petting or foster dog.

We passed dozens of people and dozens of dogs in the store and he only showed a mild interest in anyone and was even introduced to an 11 week rott pup to which he gave a bunch of sloppy wet kisses.

Anyways, he wasnt snarling or baring his teeth but his barking was a clear warning for people to "back off" and while I dont think he would follow through with a bite I certainly dont want to test the theory.

Its almost as if the female am staff has displaced him on the hierarchy ladder. He seemed content prior to another dog coming onto the scene but now seems as if he just doesnt want to go any lower so tries to exert dominance over strangers.

Does anyone have some solid advice as to how curb his bad habit.

Some additional information if it helps. I work with him almost daily during the warm months but now that its so cold out its down to a few times a week. Sit, come, down, heel (even off leash) he does rather well. He is an indoor family pet, is not allowed on the furniture or bed.