There are two types of feeding burrows. The first and more common consists of a cut made just above water level in the side of a vertical bank. If possible, it is behind a portiere of hanging grass or weeds, so as to be completely screened from view. This is merely a safe place to which the muskrat can take its food and eat without being bothered by enemies. The second type of feeding burrow is more elaborate, consisting of several such chambers along the bank connected by short tunnels. These seem to be community shelters since they are used by several individuals at the same time. The added safety provided by the connecting tunnels seems to be the advantage in this type of dining room. The shelter burrow not only affords escape from enemies, but may be a sleeping burrow as well. It consists of two tunnels which start at different levels under water and join just before they reach the main chamber, which of course, is above water level. The two tunnels assure an escape route if one or the other is invaded by an enemy. Each muskrat may have several of these shelter burrows. The one used as a sleeping burrow will be furnished with a soft nest of shredded leaves. Cattail leaves are a favorite material for this purpose. Wet, green cattail leaves in a damp underground cavern make a poor bed by most standards, but no doubt, it seems a dry, cozy retreat to the muskrat as it emerges dripping from its underwater tunnel. The breeding burrows are large and elaborate in design. There is reason to believe they are not always the work of one individual. They may even represent combined efforts of several generations of muskrats. Often they are a labyrinth of tunnels connecting many nesting chambers, each with a nest of different age. This can be determined by the yellowing of the shredded leaves. As might be expected, there are usually a number of tunnels leading from this maze into the water. A half dozen of these underwater entrance tunnels is not unusual. All this room gives the young a place to exercise before they are able to take to the water. Young muskrats are surprisingly precocious. They are able to leave the nest when very small, and at 4 weeks of age are weaned and capable of taking care of themselves, although only about one-fourth grown. At this stage, they are peculiar looking little individuals. The fur is still in the woolly stage, dark and bluish in color. The guard hairs have not yet appeared, and altogether they have an unkempt appearance. This rapidly disappears, however, when they leave the burrow. Their progress is so rapid that young born early in the spring are believed to breed during the following fall.