Of the minor notes Andrew Allison (1907) says: "I know of no other warbler except the Chat that can produce so great a variety of sounds; and since nearly all of the notes resemble those of other warblers, this is a most confusing bird to deal with during the busy season of 'waves'." The call note often has a buzzing quality, and often runs into a long chatter (also characteristic of the young bird), but it may be given so sharply enunciated that it suggests the _chip_ of the black-poll. Allen (MS.) writes it _chi_, "like pebbles struck together," and Cordelia J. Stanwood (1910) renders it _sptz_, saying "the sound resembled the noise made by a drop of syrup sputtering on a hot stove." _Field marks._--The black-poll, in its spring plumage, and the black-and-white warbler resemble each other in coloration, but the latter bird may be readily distinguished by its white stripe down the center of the crown and the white line over the eye. The contrast in the behavior of the two birds separates them at a glance. _Enemies._--Like other birds which build on the ground, the black-and-white is subject, during the nesting season, to attacks by snakes and predatory mammals. A. D. DuBois (MS.) cites a case in which maggots destroyed a nestful of young birds. Harold S. Peters (1936) reports that a fly, _Ornithoica confluens_ Say, and a louse, _Myrsidea incerta_ (Kellogg), have been found in the plumage of the black-and-white warbler. Herbert Friedmann (1929) says: "This aberrant warbler is a rather uncommon victim of the Cowbird, only a couple dozen definite instances having come to my notice. * * * The largest number of Cowbirds' eggs found in a single nest of this Warbler is five, together with three eggs of the owner." George W. Byers (1950) reports a nest of this warbler, in Michigan, that held two eggs of the warbler and eight of the cowbird, on which the warbler was incubating. His photograph of the eggs suggests that they were probably laid by four different cowbirds. _Fall._--Several of the warblers show a tendency to stray from their breeding grounds soon after their young are able to care for themselves, perhaps even before the postnuptial molt is completed and long before the birds gather into the mixed autumn flocks. Among these early wandering birds the black-and-white warbler is a very conspicuous species, perhaps because it is one of our commoner birds or, more probably, because of its habit of feeding in plain sight on the trunks and low branches of dead or dying trees and shrubs instead of hiding, like other warblers, high up in the foliage. It may be that the warblers we see at some distance from their breeding grounds thus early in the season have already begun their migration toward the south: they often appear to be migrating.