"Wintering throughout the length of Central America, from near sea level up to 9,000 feet and rarely higher, the black-and-white warbler is somewhat more abundant in that portion of its altitudinal range comprised between 2,000 or 3,000 and 7,000 or 8,000 feet above sea level. It is found in the heavy forest, in the more open types of woodland, among the shade trees of the coffee plantations, and even amid low second-growth with scattered trees. It creeps along the branches in exactly the same fashion in its winter as in its summer home. Solitary in its disposition, two of the kind are almost never seen together. The only time I have heard this warbler sing in Central America was also one of the very few occasions when I found two together. Early on the bright morning of September 1, 1933, when the warblers were arriving from the north, I heard the black-and-white's weak little song repeated several times among the trees at the edge of an oak wood, at an altitude of 8,500 feet in the Guatemalan highlands. Looking into the tree tops, I saw two of these birds together. Apparently they were singing in rivalry, as red-faced warblers, Kaup's redstarts, yellow warblers, and other members of the family solitary during the winter months will sing in the face of another of their kind, at seasons when they are usually silent. Often such songs lead to a pursuit or even a fight; but I have never seen black-and-white warblers actually engaged in a conflict in their winter home. "Although intolerant of their own kind, the black-and-white warblers are not entirely hermits; for often a single one will attach itself to a mixed flock of small birds. In the Guatemalan highlands, during the winter months, such flocks are composed chiefly of Townsend's warblers; and each flock, in addition to numbers of the truly gregarious birds, will contain single representatives of various species of more solitary disposition, among them often a lone black-and-white, so different in appearance and habits from any of its associates. "This warbler arrives and departs early. It has been recorded during the first week of August in Guatemala, and by the latter part of the month in Costa Rica and Panamá. In Costa Rica, it appears not to linger beyond the middle or more rarely the end of March; while for northern Central America my latest date is April 22. "Early dates of fall arrival in Central America are: Guatemala--passim (Griscom), August 3; Sierra de Tecpán, August 23, 1933; Santa María de Jesús, August 6, 1934; Huehuetenango, August 14, 1934. Honduras--Tela, August 19, 1930. Costa Rica--San José (Cherrie), August 20; Carrillo (Carriker), September 1; San Isidro de Coronado, September 8, 1935; Basin of El General, September 19, 1936; Vara Blanca, September 5, 1937; Murcia, September 11, 1941. Panamá--Canal Zone (Arbib and Loetscher), August 24, 1933, and August 29, 1934. Ecuador--Pastaza Valley, below Baños, October 17, 1939.