Lily, our new rescue doodle of 1 month is a barker. She barks mostly inside while sitting in front of the glass front door. Anything moving get a response - leaves blowing, vehicles, especially cats, walkers and the oh so interesting school bus. She is on guard duty non-stop! Zeke, on the other hand has never been much of a barker, only when the door bell rings. Now he thinks he needs to guard us too. I'm hoping this is a developmental stage so I'm holding off a while before taking drastic measures to curtail this activity. Lily is making some progress in coming away from the door when called, making little puffing noises when she's been called down. What's so funny is that they are both pretty quiet when outside, big chickens I guess.(lol)
We had something similar happen when we adopted Kirby. Dex was never a big barker, but Kirby seems to think he needs to protect us. We've had Kirby for over a year and refrained from anything more than verbal corrections. Well I finally had it with all the barking and brought home an air can from work (one of those cans you spray into your keyboard to clean it). When the doodles barked I sprayed it (in the room they were in, but not very close to them) and said "hush" - they stopped barking immediately. Next time I just showed them the can and said "hush" and they stopped. I haven't had to spray the can again for this training...I just say "hush" and they stop. I have had to threaten Kirby 2x ("Do you want me to get the can?")...hehe...he must understand because this causes him to stop barking.
I'm also using the can for "drop it"/"leave it" training with Dexter. He's a little thief. We are having positive results here too.
This is working well for us, but if you just rescued a dog I wouldn't do anything more than verbal corrections for now (to not scare her). Kirby totally trusts us now so I am less hesitant to use a little negative correction.