I'd wondered about this for a long time myself. Dogs will even go
through the motions of "digging" when they soil the carpet indoors, or
when they make a deposit on the sidewalk. Obviously, pawing around on
a rug or on concrete doesn't cover anything.
I've found some interesting information on this subject. For reasons
of copyright, I am posting just an excerpt. For more info, I encourage
you to read the entire article:
"WHY DOES A DOG SCRATCH THE GROUND AFTER DEFECATING?
...The original explanation of this action was that it is a remnant of
the time when the wild ancestors of dogs used to cover their faeces
like cats. It was thought that domestication had eroded the efficiency
of the action, leaving it now no more than a useless vestige of a once
There is no truth in this, however, because recent observation of
wolves in their natural state has revealed that they, too, perform the
same kind of scraping actions. There has been no 'decay' due to
domestication. Another suggestion was that the dogs were attempting to
scatter their faeces, widening the area over which they were leaving
their personal scent... However, although dogs always scrape their
feet very close to their faeces, they always seem to avoid touching
them. This leaves two possible explanations.
First, it has been noticed that in the wild state, when wolves scratch
the earth, they disturb the soil and the ground litter over an area of
several feet. This leaves a conspicuous visual marker alongside the
odour signal of the faeces...
Second, it has been pointed out that the only efficient sweat glands
on a dog's body are those between its toes, and the animal may merely
be adding yet another personal odour to the one already present in the
faeces. We may not find this idea convincing, because although our
human noses can detect canine faeces all too easily, our response to
the smell of canine foot-sweat is non-existent. In the odour-rich
world of dogs, however, it is possible that this additional form of
scent-marking has its own particular messages to impart, which provide
further fascination to the canine obsession for taking a walk. In all
probability, both the scent factor and the visual factor play a role,
when the dog makes its scraping action in a natural environment."
Surat City Online
Here's an excerpt from another good article:
"Dogs have an obsession about marking their territory because of the
dog's heritage as a member of a pack, living within a specific and
well-delineated territory. This territory contains all of the
commodities needed to sustain the pack, including various valuable
resources, their mates and their progeny. Making it clear to other
dogs that they have now crossed a line with respect to territory tells
outside dogs they have crossed into 'claimed' territory, which can
avoid unnecessary fighting.
Dogs use more than just the smell of urine to define their territory.
Feces is also used to define territory, and there are visible clues as
well, including pawing and scratching the ground. The territorial
message, like handwriting, remains after the sender has gone,
providing a long-lasting reminder to infiltrators that they are
entering a forbidden zone."
So it appears that when he makes digging gestures around his
excrement, a dog, far from trying to cover it up, is actually trying
to call attention to it by disturbing the surrounding ground and
depositing extra scent which marks it as his own distinct production.
Presumably this will cause the next dog who comes along to sniff at it
and be impressed. Having walked my own three pooches past many such
dogpiles, I can testify that they are indeed fascinated to encounter
the calling-card of a stranger.
Search terms used:
"why does a dog" + "defecating"
"why does a dog" + "feces"
"why does a dog dig"
"why does a dog scratch"
"why do dogs" + "defecating"
"why do dogs" + "feces"
"why do dogs dig"
"why do dogs scratch"
Thanks for the interesting question! If anything is unclear, or if a
link does not function, please request clarification; I'll be glad to
offer further assistance before you rate my answer.