Marking ability is considered a hereditary trait, but training is required to bring it out in the dog.

Transforming a raw‐recruit puppy into a first-class working retriever takes a lot of training, which in turn requires a generous supply of time. Success also depends on the pup having certain hereditary traits, namely retrieving instinct, birdiness, marking ability, memory and trainability. Fortunately, the people who developed various retriever breeds were dedicated hunters, so they bred in the right characteristics from the earliest days.

And in ensuing years, serious breeders have maintained, and sometimes intensified, those characteristics.

Of these, marking is the most mysterious, therefore the most widely misunderstood. A beginner tends to expect too much. If the retriever doesn't race out and immediately pounce on the downed bird, an uninformed neophyte often starts tooting a whistle and waving arms to help the dog. Nothing could do more harm to a young retriever's marking ability. Assuming the bird has fallen in cover, whether on land or in water, when the dog reaches the general location of the fall, nothing looks the same as it did from his owner's side. Therefore, even with the help of his nose, the pooch usually has to hunt the area around the fall to find the bird. No retriever can "pin" or "button" every mark.

Area of the Fall
Clearly, a working retriever should be allowed a reasonable area around a fall to hunt without being accused of disturbing cover unnecessarily. As long as a retriever hunts therein, the dog is doing a proper job. However, if the retriever strays outside of the area for a bit, the boss should step in and handle the dog to the bird as in a blind retrieve.

How large an area should you allow your retriever on any given mark? It depends on several factors, for which I can give you only general guidelines. However, these guidelines, plus your own experience with your dog, will help you develop a sense of a reasonable area of the fall.

A basic rule of thumb says that on a windless day, the area of a fall should be a circle around the bird with a radius of about 10 percent of the distance from the handler to the bird. Thus, for a 30-yard retrieve, the area of the fall would be a circle around the bird with a radius of about three yards, or a diameter of about six yards. For a 50-yard retrieve, the circle would have a radius of about five yards. For a 75-yard retrieve, it would have a radius of about 7.5 yards. And so forth.

However, any significant wind would change both the shape and location of the area of the fall. Once in the area, the retriever hunts mostly with its nose, not its eyes. Therefore, the dog needs more room on the downwind side of the bird and less on the upwind side.

Because scent spreads as it is blown, the area of the fall would become cone-shaped, with the bird nearer the narrow end of the cone.

Modifying Factors
Hazards, such as cover and terrain variations, and land-water-land marks between the handler and the bird affect the difficulty of a retrieve, and therefore, increase the size of the area of the fall. If the dog is able to maintain constant line-of-sight visual contact with the spot where the bird fell, the job is fairly simple. However, if hazards along the way force the retriever to lose visual contact, the job becomes much more complex. Thus, the area of the fall is necessarily larger for a mark with such hazards.