Why Willow Barks...

Willow is a barker. Jewel Barks when her ball is stuck, but Willow barks. She barks when she is being demanding, if we have ignored her chicken clucks. She barks when she see's other dogs. At night, out of the blue she goes to the patio and barks. Sometimes, she works her self into a state where she can't stop barking. Most distressingly is in the middle of the night, when she hears someone enter the building (we are talking after midnight when we are sound asleep), she starts barking loudly and runs out of the bedroom to the front door.

Turns out they were bred this way. From Wikipedia....
"The Shih Tzu was bred to sit around the palace of the Emperor of China and bark when people or animals approached. It is believed that this ornamental breed was created by breeding the Bei-jing gou (Pekingese) with a Tibetan dog breed, the Lhasa Apso. Recent DNA analysis confirms that this is one of the oldest breeds of dog. The Shih Tzu is also known as the Chinese Lion Dog or the Chrysanthemum Dog"