What Do Those Barks Mean? To Dogs, It's All Just Talk     The popular understanding of dog barking is almost like a silly riddle: Why do dogs bark?    Because they can! But a small band of researchers around the world, trying to separate fact from speculation, are finding that dogs almost always bark for a reason, even if that reason isn't apparent to humans. The bark has evolved into a complicated means of communication between dogs and, potentially, between dogs and people, say a group of animal behaviorists, or ethologists, working from a University in Germany. Most wild canids, including wolves, dogs' nearest relatives, bark as a form of close-range communication, researchers say. The wolf's bark - one of a number of basic vocal sounds, including hauntingly harmonic howls - is short, low-pitched and gruff, often described as ''noisy'' because it lacks harmonic or tonal qualities identified with more musical vocalizations. The bark is usually associated with defense of den or pups, a warning to back off, a protest, threat or an actual attack. By comparison, dogs are virtuoso barkers, capable of flights of sonic fancy. Dog barks can be noisy, harmonic or a combination of the two, depending on their context and purpose.  Last year in The Archives of Animal Breeding, an international journal, the results of a study comparing vocalizations in 11 European wolves and 84 dogs from nine breeds, including poodles, Weimaraners, American Staffordshire terriers, German shepherds, Alaskan malamutes, bull terriers and Kleiner Munsterlanders were published. The results graphically portray how different barks express different emotions, including loneliness, fear, distress, stress and pleasure, as well as a need for care among puppies -- and serve to alert other dogs, people or animals to changing external circumstances. This work on barking calls attention to the complex social life of dogs that we have barely begun to comprehend. Noisy barks can relate to defensive and offensive threats, social insecurity, physical distress. Harmonic barks, however, are used as a signal for social play, in active and passive submission to another dog or person and when making social contact. Recordings of dogs engaged in normal behavior helped to demonstrate how dogs were barking in specific situations. After a while scientists were able to tell what a dog was doing by its bark.  Recorded mixed play barking among German shepherds, poodles and Weimaraners that had noisy and harmonic components, and a ''noisy play bark'' among American Staffordshire terriers and bull terriers that indicated a turn on the part of the dogs from play to more aggressive behavior was also helpful. Like many canid vocalizations, these barks are often associated with physical cues, like a wrinkling of the brow, staring, raised hackles, pinned back ears, an upright or lowered tail and other submissive or threatening postures. But in a wide range of breeds physical expression is limited because of the lack of a tail, floppy ears and other physical characteristics.  A few breeds, like the poodle and the American Staffordshire terrier, appear limited in their vocal repertory, although none as severely as the barkless basenji. As many as a dozen variations of some types of barking were among several of the breeds tested, including the German shepherd and Alaskan malamute. Often subtle variations corresponded to ''dialects'' and were used by dogs in identical situations at different times, for reasons not yet clear. Evolutionary biologists and behaviour scientists examined the barks of 30 dogs to determine whether there were identifiable sonic differences between the bark of a distressed or stressed dog, as seen when one is left at home all day and suffering separation anxiety, and an unstressed dog wanting, for example, to go out. Researchers have found distinctive differences. The bark of a distressed or stressed dog is high-pitched, atonal and repetitive, while those of unstressed dogs are more harmonic. The findings have obvious value to animal behaviorists trying to determine whether a tireless barker is responding to some external event or expressing its feelings on being left at home alone. The single biggest underappreciated part of dog behavior is that much of what dogs do is about soliciting information. They want confirmation of what is happening or want to test a hypothesis. Barking is a means of doing that. It is thought that during domestication dogs evolved new sound units, their vocal communication got much more important for conflict solving, establishing a social state and other demands of social life. Discovering why and how that happened and examining the differences in barking between breeds and between individual dogs are among the issues researchers must still address. This also involves studying the degree to which dogs and people understand those barks. Dr. Overall said researchers also needed to study the apparent capacity of dogs to apply barks to different contexts and objects. For example, one dog, shepherd named Flash, was found to have a separate bark for each species that visited his backyard, this included fox, deer, woodchuck and the neighbor's cat. A discerning owner who pays attention will be able to read these barks sucessfully.  In southern India, scientists found that the free-ranging dogs they studied, had separate barks for elephants, humans, monkeys, other dogs and strange cats. It seems that dogs are able to call individual dogs with individual barks.  There are many interesting facts 'sleeping' in our dogs' vocalizations.'