ABSTRACT
Bay-breasted warblers nest in coniferous and coniferous-deciduous forests of the northern US and Canada, especially in forests undergoing outbreaks of the spruce bud worm. One major basis for these censuses was to compare populations of bay-breasted warblers and other species simultaneously in two adjacent habitats. Densities of bay-breasted warblers and other bird species were measured in two square plots laid out with compass and tape, both 3.3 ha (8.2 acres) in size and surrounded by similar habitat. Record on maps of the plots all individuals seen or heard during censuses. It was not possible to conduct tests of the accuracy of these censuses. In a study of two plots containing coniferous-dwelling congeners of the bay-breasted warbler, ten censuses were randomly chosen from both sites, out of a much more extensive series of census conducted during a breeding season.
