The manner of occurrence was usually as small flocks of six or eight or even twenty or more birds. These combined with several other species to make up larger flocks which worked ceaselessly through the crown foliage of low, semi-open woodland. However, many were found even in the tall, dense swamp forests along the coast and also in the oak woods on Mt. Cacaguatique. _Winter._--Dr. A. F. Skutch has contributed the following account: "The Tennessee warbler winters in Central America in vast numbers. Coming later than many other members of the family, the first individuals appear in mid-September; but the species is not abundant or widely distributed until October. During the year I passed on the Sierra de Tecpán in west-central Guatemala a single Tennessee warbler appeared in the garden of the house, at 8,500 feet, on November 7 and despite frosty nights lingered into December. On November 19, 1935, I saw one on the Volcán Irazú in Costa Rica at 9,200 feet--the highest point at which I have a record of the species. At the other extreme I found a few of these adaptable birds among the low trees on the arid coast of El Salvador in February and among the royal palms at Puerto Limón, on the humid coast of Costa Rica, in March. But Tennessee warblers are most abundant as winter residents at intermediate altitudes, chiefly between 2,000 and 6,000 feet above sea-level. From 3,000 to 5,000 feet they often seem to be the most abundant of all birds during the period of their sojourn. They travel in straggling flocks and form the nucleus of many of the mixed companies of small, arboreal birds. At times 'myriads' is the only term that seems apt to describe their multitudes.