The digging necessary to capture pups depends largely on the nature of the soil and the location of the den (fig. 2, B). Some dens are so shallow that little digging is required; others cannot be dug out; and some burrows lead straight into a bank or under a hardpan ledge. Much work can be avoided by running a shovel handle or long stick as far as possible into the hole to ascertain its direction and then digging a pit down to the den instead of following the burrow. Where digging is extremely difficult, the animals may be disturbed and induced to move, frequently to a den from which they can be more readily taken. Usually they move from a quarter of a mile to a mile away and can easily be tracked. If pups can be seen back in a den but cannot be reached in digging, a forked stick or a wire so twisted as to catch in their fur has been employed to save labor; but if the den or burrow branches and turns, such an instrument is never wholly satisfactory, as some of the whelps are likely to be missed. Before digging is begun, the den entrance should be blocked to prevent the escape of the mother coyote, should she be inside the den. When the pups are of suckling age she is often in the den with them, but when they are old enough to play and be fed outside she seldom goes into it. It is difficult to tell her whereabouts by her tracks, as she backs out of the den unless disturbed and the tracks all appear as if made in entering. Pups are wobbly on their legs when only 2 or 3 weeks old, so that if a pit 18 inches deep is dug just outside the mouth of the den they fall into it when they attempt to crawl out and are easily captured. Smoking the young out of the den is not satisfactory as a rule but is sometimes successful. A good smoker can be made by soldering a half-inch hose coupling to the spout of a bellows-operated bee smoker and using sulphur and pieces of burlap as fuel. A piece of garden hose about 10 feet long can be attached and worked down into the den close to the pups, preferably behind them. The operator should stand back from the mouth of the den, armed with a good club to dispatch the pups as they come out. Throwing a handful of calcium cyanide into a den and stopping the hole with dirt is an effective method of fumigation, but this chemical must be handled with extreme care--as a rule by experienced workers only--as it is also dangerous to man.