Super Sniffers

Retrievers rely heavily on their acute sense of smell to find birds in dense cover

© Chris Jennings

By Gary Koehler


Nick was a good upland dog, but he also hunted ducks, at least until ice-up, when the weather turned brutally cold. Although always ready to go in spirit, he just wasn't built for the extreme conditions of the late season.

One of my most memorable duck hunting experiences with Nick occurred during the Illinois early teal season. I scored a double on greenwing drakes that glorious morning. One bird was dead on the water. The second was crippled and made its way into a dense stand of bulrush. Nick retrieved the first downed teal, and then turned his attention to the cripple. I had no clue where the bird was hiding. The rushes appeared to be impenetrable, but the dog entered the tangled morass and emerged 10 minutes later with the fugitive greenwing in his mouth.

That was an amazing retrieve, made possible by the remarkable bird-finding ability of a gun dog's nose. Indeed, all dogs are blessed with a sense of smell that is thousands of times more acute than our own. Just how powerful are our dogs' sniffers? Well, that's a bone of contention among scientists, who have been studying the matter for decades. Some researchers argue that dogs' olfactory senses are 10,000 times superior to those of humans. Others say 100,000 times.

And some insist that the number is 1 million. Translating even the minimal estimate into a simple sight analogy yields mind-boggling results: what we would be able to see at a third of a mile, a dog would be able to see from more than 3,000 miles away.

The biology behind a dog's scenting ability is even more extraordinary. Unlike humans, dogs have airways that separate the breathing and smelling functions, allowing them to sniff more or less continuously. One study revealed that a hunting dog holding its head into the wind sniffed a continuous stream of air for up to 40 seconds, or through at least 30 respiratory cycles.

While humans have only about 65 square inches of olfactory membranes, dogs may have as many as 900. And although we boast about 5 million scent receptors in our noses, dogs far surpass that with as many as 200 million, depending on the breed. These extraordinary differences are magnified even further when we consider that a dog dedicates about 40 times more of its brain to the process of smelling than we do.

We can't imagine what it would be like to detect odors in parts per trillion. But retrievers rely on such capabilities when they use their noses to find wayward ducks and geese. Fewer downed birds are lost when you hunt with a dog, and much of that success owes to a canine's keen sense of smell.