In Michigan from 1930 through 1940, 121 nests of the Prothonotary Warbler were observed. Only 28, or 23.14 per cent, were successful. Out of 413 eggs, 159 (38.47 per cent) hatched and 100 young were fledged (.87 per total nest; 3.78 per successful nest). The fledgling success was 25.66 per cent of eggs laid. More failures in Michigan resulted in more nestings by individual birds. In Tennessee during 1939, 30 nests were observed until terminated or successful; 19 were successful (63.33 per cent) while out of 139 eggs, 78 hatched and all the young lived to leave the nest or 56.11 per cent fledging success of eggs laid; 2.6 young were fledged per total nest; 4.1 per successful nest. He also notes that in Michigan the species is typically single-brooded if the first nesting is successful, but that in Tennessee it is typically double-brooded. _Plumages._--According to Dr. Dwight (1900) the natal down, located as indicated above, is brownish mouse-gray. Ridgway (1902) gives rather the best description of the juvenal plumage as follows: "Pileum, hindneck, back, and scapulars dull olive-greenish; wing-coverts, tertials, rump, and upper tail-coverts slate-gray, tinged with olive, the middle and greater wing-coverts narrowly tipped with light olive-greenish, producing two very indistinct bands; secondaries, primaries, and rectrices as in adults; sides of head pale yellowish olive; chin, throat, and chest dull light grayish olive, darkest on chest rest of under parts dull white, passing on sides and flanks into olive-grayish." In very young birds, according to Dr. Dwight, there is a variable amount of brownish wash on the back, which fades out to gray. And Dr. Chapman (1907) says that the white on the inner webs of the tail feathers is more restricted than in adults and more or less mottled with blackish. This first plumage is followed in June and July by a partial postjuvenal molt involving all the contour plumage and the wing coverts but not the rest of the wings or the tail. The young bird now becomes a golden swamp warbler, the young being nearly like the adults, the females being considerably duller in color than the males and having less white in the tail. The crown and hind neck in both sexes, both old and young, are washed with dusky or olive in the fall. Spring plumages are produced by very slight wear without molt. There is one complete, annual molt in late summer. _Food._--Very little seems to have been recorded on the food of the prothonotary warbler. It is evidently highly insectivorous, obtaining most of its food from the trunks and branches of trees and shrubs and from fallen logs. Brewster (1878) says: "This Warbler usually seeks its food low down among thickets, moss-grown logs, or floating débris, and always about water. Sometimes it ascends tree-trunks for a little way like the Black-and-White Creeper, winding about with the same peculiar motion."