National Geographic Magazine/Volume 31/Number 4/Friends of Our Forests/Northern Parula Warbler
The Warblers of North America
Range: Breeds mainly in Transition and Austral Zones, from eastern Nebraska, northern Minnesota, central Ontario, and Anticosti and Cape Breton Islands south to central southern Texas, southern Louisiana, Alabama, Virginia, and Maryland; winters probably in the Bahamas and West Indies to Barbados, and from Vera Cruz and Oaxaca to Nicaragua.
The northern parula, smallest of our warblers, with prevailing colors blue and yellow, is generally distributed during migration and usually found in company with other warblers in leafy trees, which it explores from the lower to the topmost branches. It is one of the most active of the tribe, and is untiring in its pursuit of the minute insects which form its food. Its habit of hanging head downward as it explores a cluster of blossoms suggests a chickadee, and the little fellow is a combination of warbler, kinglet, and chickadee. It is very partial to nesting in usnea moss and so is found in summer along streams or in swampy localities where long streamers of the usnea festoon the trees. The preference of the parula for this moss as a site for its nest is exemplified by a nest I once found in Maryland on the bank of the Potomac, which had been built in the frayed end of an old rope hanging to a sapling and which a short distance away looked to me—and no doubt to the bird—exactly like a clump of usnea. As no usnea occurred in this locality, the bird accepted the frayed rope as a satisfactory substitute, and in so doing followed the spirit if not the letter of family tradition. However, the parula is not strictly limited to usnea for a nesting site and I once saw a pair carrying shreds of bark into a juniper on an island in the Potomac River, the nest being already far advanced toward completion. The parula has a short, buzzing song of which it is prodigal enough, but it is weak and can be heard at no great distance.