They forage on wet ground or in shallow water, mainly eating insects, small fish and some seeds. Their most common mode of foraging is to vigorously flip leaves and rip at submerged aquatic vegetation. The mast of small-acorn producing oaks, such as Willow Oak, is also important. In some areas, the nuts of planted pecans are heavily used. They very rarely will attack small passerine birds, and have been known to kill species as large as Common Snipe. They feed in flocks during migration and on the wintering grounds, sometimes joining other blackbirds, both often occurring in single species flocks. They more often roost with other blackbirds; some small roosts are in brushy vegetation in old fields and others are in massive mixed flocks—sometimes in the urban areas.
The species nests relatively early for a boreal forest bird. They linger in the boreal zone to complete their molt. Their autumn migration is slow, with birds often remaining in the northern states well into December; spring migration is much more rapid. The largest wintering concentrations are found in the lower Mississippi Valley, with smaller concentrations in the Piedmont and south Atlantic coastal plain.
Fairly quiet in fall migration and most of the winter, both males and females will sing (particularly on warm days) in the late winter and spring. The song consists of gurgling and high-pitched squeaks.