Nature of the Dog
For dog training, knowledge is golden. The more you know about the nature and attributes of dogs, the better you will do as a trainer. When you have a better grasp of the world in which a dog lives, you will be a better trainer.
First and foremost is communication. To train a dog you need to be able to communicate what you want. The dog's primary communication channel is his eyes. Dogs bascally don't communicate with sound. The communicates with body language, posture, attitude and motion. If you take a pack of dogs for a 2 hour hike, you will see a whole lot of communication occurring, but you will hear little to no sounds from the dog. You will notice that most good dog trainers are fairly quiet of voice and calm of mannerisms. These two traits make it easier for the dog to learn.
The dog's audible communications are basically confined to signaling territory and aggressive displays. Wolves howl and dogs bark to signal their territory. Dogs growl to signal a threat to attack. Beyond those two functions, most dogs do not use noise to communicate. Nearly all the dog's communication is received through his eyes in terms of body language, posture, attitude, etc.
A Dog's Eyes
A dog's eyes are constructed a bit differently from a person's eyes. In the eye, the retina is lined with two types of light receptors, rods and cones. Rods are for low light and motion detection, cones are involved with color vision. Dogs have more rods and less cones than people, thus dogs have much better motion detection and night vision than people do. Dog's also have poor color vision. Some studies suggest that dogs see similarly to a person who is red-green colorblind. Thus to a dog a bright orange training dummy lying on green grass is difficult to see. It appears as a grey object lying on a grey background.
A dog's superior motion detection allows him to differentiate in the first few feet of fall, a crippled bird vs a dead bird. This handy fact allows the hunter to easily train the dog to prefer and focus on cripples.
If you wait for 3 to 5 minutes before sending the dog for dead birds, and send him quickly on cripples, then dead birds will have a lower value to him. Conversely cripples will have a higher value and he will, over time, preferentially look for them and preferentially go for retrieving cripples over dead birds. You will have fewer cripples escape.
A Dog's Ears
A dog can hears sounds up to four times the distances that humans are able to. He identifies a sounds location much faster than a human can. A dog does a lot of hunting with his ears. A great example was shown on National Geographic TV recently:
In Yellowstone Park in winter, a fox is ambling along on the light crust of a deep snow cover. He pauses every 15 or 20 feet and stands motionless with head cocked. Then continues on his way. Suddenly he stops and freezes. His head cocks left. He cranes his neck and cocks his head right. Seconds pass as he resets his ears several times. His muscles tense into a tight crouch. He suddenly leaps straight up several feet and dives headfirst down into the snow. His body goes out of sight leaving only the very tip of his tail wiggling in the sun. A few seconds later he surfaces, chomping voraciously on a plump field rat that he has snatched out of its burrow, three feet below the surface of the snow.
This fox has echo-located a rat three feet deep in the snow. He has pinpointed his location within a fraction of a centimeter and snatched him for supper. The fox's cousin, the dog has similar talents.
A dog can identify a sound's location much faster than a human can, as well as hear sounds up to four times the distance that humans are able to. A dog does a lot of hunting with his ears. Humans hear 20 Hz (cycles per second) to 20 kHz (20,000 Hz). The dog's hearing range is approximately 40 Hz to 60,000 Hz. Dog can hear a much higher range of frequencies than people can.
The important training points on ears are several. The dog does a lot of his marking of falls with his ears, especially on water. The dog can hear four times better than humans. Therefore when his whistle stopping degrades, it usually signifies a need for more training rather than a need for a louder whistle.
Higher pitches stimulate a dog's prey drive and drive up activity levels. Thus when training the dog you might keep your voice in the lower frequency ranges to get better responses from the dog.
An important point on safety is to keep the dog behind you, well away from the shotgun blast cone when shooting. When shooting from a pit blind the noise down in the bottom of the blind can be deafening. When shooting from a pit blind, place the dog outside the blind and in a position to be away from the blast cone.
An important point in training is to blow the stop whistle quite softly when the dog is close to you. That will condition him to respond to a low volume sound. What is loud to you who are blowing the whistle is soft to the dog 200 yards away.
The Dog's Nose
The question is not "Does Pup have a good nose?" He has a nose better than you or I can conceive of. The question is, " does he want to seek with that nose the odor that you want him to seek?" The quality of a dog's nose is not a matter of genetics, rather it is a matter of behavior. To be a useful and effective searcher for a target odor a dog must be trained to seek that odor to the exclusion of other odors. He must be trained to love that odor. For gundogs Mother Nature has supplied that propensity to seek the odor of birds. Natural selection has programmed dogs to seek prey to survive. The dog's love of bird scent is inherited from his ancestors. A good trainer simply reinforces that propensity by allowing the dog to succeed frequently during his training days. The good trainer engineers the training so that the young dog generally finds the bird or dummy. Simply allowing the dog to succeed preserves that genetic behavior of seeking bird scent. For the gundog a good nose is a product of inheritance.
On the other hand, for explosive detection, Search and Rescue, and other secondary target odors the dog must be trained to love the target odor and to seek it to the exclusion of other more naturally attractive odors. For dogs in the job of detecting secondary target odors a "good nose" is a product of good training, not a product of inheritance.
How good is a dog's nose? Better than human's can measure. Sandia Laboratory performed a study in 2002 on the sensitivity of the nose of trained explosive detection dogs. They determined by dilution and extrapolation that the trained dogs could detect a concentration of target odor down in the range of 100 parts per trillion. That in Sandia's words is "the equivalent of one molecule per sniff"
With a good working knowledge of the dog's communication preferences and an appreciation of his sensory capabilities, you will succeed at being a better trainer to your dog.