It would be valuable to know more concerning the life histories of the other birds considered in this paper, since behavior is inherent, and probably can be cited as evidence of close relationship or the opposite. All that I have been able to learn is that _Phainopepla_ has a nuptial flight in which the male chases the female, and that _Dulus_ (Wetmore and Swales, 1931:347) seeks the company of others of its kind at all times, and that two birds, presumably paired, will sidle up to one another when they are perched. NEST BUILDING There are numerous papers concerning the nesting of waxwings. _B. garrula_, owing to its nesting in the far north, where observers are few, has received less attention than _B. cedrorum_. There is, on the other hand, no literature that deals with the nesting habits of the majority of the Ptilogonatines, with the exception of _Phainopepla_, on which there is considerable literature (Merriam, 1896; Myers, 1907, 1908). No detailed study of the nesting of _Dulus_ has been reported, although Wetmore and Swales (1931) have described carefully the large communal nest of this genus. In _Bombycilla_, both members of a pair apparently aid in the construction of the nest (Crouch, 1936; Swarth, 1932). Although the sexes are alike in plumage and general appearance, most students of the nesting of waxwings agree that one bird, assumed to be the female, does most of the arranging of the material, and does the shaping of the nest, whereas both birds carry materials to the nest site. As is characteristic of many passerine birds, both members of the pair gather materials and fly back to the nest site, where the female takes the more active part in the construction of the nest itself. Both species of American waxwings build bulky nests, with the base or platform composed of a large amount of twigs and sticks, from which there often trails a mass of sticks and moss or string. Softer materials such as moss, plant fibers, and string, are placed inside the platform; moss is readily available to, and preferred by, _B. garrula_ according to Swarth (_op. cit._:271), and various plant fibers and string are used by _B. cedrorum_. The inner lining consists of soft plant fibers or down, dry grasses, and feathers. The nest is usually unconcealed in a tree either adjacent to a trunk or on a main side branch, but sometimes in a fork. Nest building by both Cedar and Bohemian waxwings is rapid, taking from three to five days, and is followed immediately by egg laying.