Biology:Twilight bark

Twilight Bark (sometimes, Twilight Barking and Barking Chain) refers to the often-noted behavior in domestic dogs (Canis lupus familiaris) of exchanging barks or howls across long distances, typically in the quiet hours of early evening. The term 'Twilight Bark' was coined by author Dodie Smith for her 1956 children's book, The Hundred and One Dalmatians, and the phenomenon figures prominently as a plot device in the book and in the 1961 animated Disney movie. Her 1967 sequel novel is The Starlight Barking.

The original usage is:

Many people must have noticed how dogs like to bark in the early evening. Indeed, twilight has sometimes been called "Dogs' Barking Time." Busy town dogs bark less than country dogs, but all dogs know all about the Twilight Barking. It is their way of keeping in touch with distant friends, passing on important news, enjoying a good gossip.

—Dodie Smith, The Hundred and One Dalmatians