I have recently had some close encounters with coyotes which provided some really good video clips of a young mother and two cubs. Coyote mothers are single moms. So when they are out hunting, their cubs are left unattended. Later they will go with her and learn to hunt for themselves. In the final scenes the cubs escape into a hole in the ground. That hole is actually a small culvert that has a small amount of water running through it. So it was not their den, but a very effective escape route.