I haven't noticed Bella barking at shadows but she did bark at my husband's headlights the other night! We have a back door out of the garage and when he pulled into the garage about a week ago his headlights shined through a tiny slit under the door into the backyard and onto the back fence. She was outside at the time and just stood and barked at the light on the fence, backing up the whole time. Another scaredy dog!