Columbia subject headings:
Molting.
Passeriformes--Age determination--North America.
Passeriformes--Physiology--North America.
Harvard subject headings:
Molting.
Passeriformes--Age determination--North America.
Passeriformes--Physiology--North America.
Princeton subject headings:
Molting.
Passeriformes--Age determination--North America.
Passeriformes--Physiology--North America.