Cape May and bay-breasted warblers' nests were enough of a prize that it is quite certain that all found were kept and that the collections do not reflect any bias. There is a possibility of slight bias, collectors perhaps prizing larger clutches,in the other three species in the museum collections, but their clutch sizes are so constant that this seems improbable. The data of Harlow are not subject to his criticism, since he recorded all
nests found.