A guide to nestling development and aging in altricial passerines

This is a guide to altricial passerines. It has an explanation of variables used for aging birds and an explanation of methodology employed, and provides information obtained while recording the early aging of the Dusky Flycatcher, the Carolina Wren, the Wrentit, Sprague’s Pipit, the Song Sparrow, the Chestnut-collared Longspur and the American Goldfinch.