Dens are often found to contain two litters, one consisting of young with eyes not yet open and the other of pups about a month old. One litter may be large and the other small, the latter probably belonging to a young female that, apparently at a loss for a place to den, had taken up quarters with her mother. Young females usually whelp about 10 days to 2 weeks later than the older ones. An occasional den may harbor three litters. At a den where two litters are found there is usually only one male, which would suggest polygamy. Under normal conditions a pair of coyotes is found with every den unless one parent has been killed. If this happens to be the female and the pups are young, they die. If they are old enough to eat meat, the male parent cares for them, as he does his part in providing food. Denning Sites and Habits Coyotes do not select denning sites according to any recognizable rule, but many of them return to the same general locality year after year, even though dens are regularly dug out and the pups killed by den hunters. If the female is killed, the male may bring his new mate to the same den the next season. A dug out den that has not been badly damaged in removing coyotes may remain unoccupied for two or three seasons and then be used again, as was the case with the den in Conejos County, Colo., shown on the title page. [Illustration: B27874; B4847A Figure 1.--A, Coyote and a litter of 10 taken from a den in San Luis Valley, Colo., in cooperative predator-control operations; B, coyote den (directly beneath hunter) in a hillside thicket in rugged country, Lance Creek, Wyo.] Dens may be found in a canyon, wash-out, or coulee, on a bank or hillside (fig. 1, B), in a rock bluff, or even in level ground, as in a wheatfield, stubblefield, or plowed field. They have been discovered under deserted homestead shacks in the desert, under grain bins, in a drainage pipe, under a railroad, in a hollow log, in a thicket, and under a clump of thistles that had blown into a canyon. As a rule, instead of digging all new dens, coyotes will enlarge abandoned badger or rabbit holes or use deserted porcupine dens in rocky promontories or canyon walls. Usually they start cleaning out the holes several weeks prior to whelping. They generally claw out the dirt in one direction from the mouth of the den, where it piles up into a mound, although some dens have no such mound (fig. 2, A).