By Sophia Yin, DVM, MS
With over 52 million pet dogs in the U.S.alone and a multi-billion dollar pet food and supply industry, it’s clear dogs are part of family life in America. To those who actually own and live near dogs, another fact is also clear—some dogs just talk too much. It’s “Bark! Bark! Let me in” or “Bark! Bark! Feed me” or “Bark, Bark! A leaf just fell.” Dogs can be such champions of conversation that many communities have passed ordinances forcing them to shut their yaps.
Anyone who’s experienced these annoying oratories in the dead of night is probably wondering, “What’s the deal?” Do some dogs just like to hear the sound of their voices, or are they actually communicating specific messages? In fact, many researchers have concluded in passing that barking isn’t a specific form of communication; rather, it’s just a loud, obnoxious way for dogs to say, “Hey. Look at me!” The more specific information comes from reading body expression and olfactory messages (which is why dogs spend so much time sniffing each other—they’re gathering the latest gossip).
Well, a groundbreaking study presented at the Animal Behaviour Society’s annual conference in Bloomington, Indiana says that this earlier view was off-base—probably. (Note that I’m calling the study ground-breaking because, one, I did it—as part of my Master’s degree; and two, I actually published a portion of it in a real-life scientific journal that deals with animal behavior—the Journal of Comparative Psychology—rather than in some obscure place such as “The Journal of Toe Fungus in Cats, Pigs, and Horses.”)
In this study, the researcher (me), found ten barking dogs and recorded them, with help from the owners, in three different situations. In situation 1, the disturbance situation, the dog was recorded while barking at the sound of the doorbell. In situation 2, the isolation situation, I recorded the dog when it was locked outside, isolated from its owner. And in situation 3, the play situation, I recorded barks as the dog was playing with its owner or another dog.
In this devious plot to collect barks, the owners and I set up each situation many different times on many different days over a three-month period. This allowed me to collect over 4600 barks. Once I’d collected enough barks, I collaborated with my co-conspirator, Dr. Brenda McCowan, research professor at UC Davis who specializes in acoustic communication in animals ranging from dolphins to chickens and cattle. She’s the one with the computer program that carefully and objectively takes 120 measurements of pitch and loudness along the duration of each bark.
In short, we found that the “Hey!- Someone’s-at-the-door” barks (a.k.a. disturbance barks) were relatively low-pitched, harsh barks with little variation in pitch or loudness. Dogs blurted these barks at full volume and sometimes so fast that the barks were fused into what I coined “superbarks.” (What the heck, might as well have some fun.)
The “Hey!-I’m-locked-out-here-by-myself” barks (a.k.a. isolation barks) were higher pitched, more tonal and more frequency-modulated than the disturbance barks. They often occurred as single barks rather than in clusters. Although, some dogs definitely developed a more insistent, repetitive quality like “Someone forgot me out here. Hey. Hey. HEY!”
The play barks were similar to the isolation barks except that they usually occurred in clusters rather than singly.
So what can we conclude from this exemplary work of science? Well, unfortunately, we can’t tell whether dogs intentionally alter their barks to deliver a message to other dogs or people. Basically the only way to do this is to teach the dog English so that he can tell us, “I am now intentionally changing my bark to deliver this message.” In any case the variation in the barks most likely reflects an internal emotional state associated with the situation.
What we can tell is that because there are specific bark subtypes, barks have the potential to communicate specific information to both dogs and people. Not specific information like, “Timmy’s stuck in the well! The one to the left of the big oak tree. You gotta get him loose!” More like, “I’m locked out and I want in,” or “Intruder alert! Intruder alert!”
To determine the function of the barks, we’d have to perform yet a second devious experiment whereby we trick dogs by playing recorded barks from known contexts and see how they respond. Their responses would tell us the function of the barks. We haven’t started this yet, but in the meantime as dog owners, you can listen to your own dogs and note the types of barks that occur in specific situations. If you can distinguish the “woof” that means the toy’s stuck under the bed versus the “ruff” when a cat’s trespassing versus the “arf” which means a friend is approaching, you’re on your way to understanding what your dog’s trying to say.
To learn more about my research on barking, visit my research page here.
You can also test your bark interpretation skills with this interactive quiz.
Epilogue: Recently Adam Miklosi’s lab has tested the ability of humans to recognize barking in dogs. Click on the links to see what they found:
Pongrácz, P., Miklósi, Á., Molnár, Cs., Csányi, V. 2005. Human listeners are able to classify dog barks recorded in different situations. Journal of Comparative Psychology, 119: 136-144.
Pongrácz, P., Molnár, Cs., Miklósi, Á. 2006. Acoustic parameters of dog barks carry emotional information for humans. Applied Animal Behaviour Science, 100: 228-240.
Molnár, Cs., Pongrácz, P., Dóka, A., Miklósi, Á. 2006. Can humans discriminate between dogs on the base of the acoustic parameters of barks? Behavioural Processes, 73: 76-83.