The Dippers comprise a small group of birds which have undergone special adaptation to suit them to a more or less aquatic life. They appear to be closely allied to the Troglodytidae* or Wrens, on the one hand, and to the Turdidae, or Thrushes, on the other.
The nidification of these birds is very peculiar—the nests are very large and domed, and the eggs are pure white—and is certainly more like that of the former than that of the latter family.
In the Dippers the bill is very like that of the Wrens, it is almost as long as the head, narrow and straight, the tip slightly bent down and notched; the nostrils are covered by a large mem¬brane and there are no rictal bristles; the wing is short and rounded; the tail exceedingly short and the tarsus long, smooth and very strong, with short, powerful claws.
The sexes are alike and the plumage of the young is barred. A semi-adult plumage is acquired in the first autumn moult but the feathers of parts of the breast and throat are fringed with white, these fringes being lost by abrasion in the succeeding season. The head is narrow in front and the feathers of the fore¬head very short, lying close to the head. The plumage generally is very firm and dense.