Small, sparrow-like bird. Male has mostly black head with large white whisker mark; female is olive-brown on back and pale yellowish below with a dull yellow bill. Found in open marshlands and disturbed habitats with long grass, especially near water; often seen in flocks, feeding on grass seeds. Song is a staccato series of about 10 notes on one pitch. Most similar to Lined Seedeater, but male Lesson’s lacks a white stripe on crown; females of the two species are identical and not safely identified unless accompanied by males. Females are best told from other seedeaters (except Lined) by strong yellowish wash on underparts and relatively small, dull yellow bill.