the rusty blackbird (euphagus carolinus) is a medium-sized blackbird , closely related to grackles ("rusty grackle" is an older name for the species) .
it is a bird that prefers wet forested areas , breeding in the boreal forest and muskeg across northern canada , and migrating southeast to the united states during winter .
formerly abundant , the rusty blackbird has undergone one of the most rapid declines of any abundant bird species in north america in recent years , for reasons that are not well understood .
adults have a pointed bill and a pale yellow eye .
they have black plumage; the female is greyer .
"rusty" refers to the brownish winter plumage .
they resemble the western member of the same genus , the brewer's blackbird; however , this bird has a longer bill and the male's head is iridescent green .
their breeding habitat is wet temperate coniferous forests and muskeg across canada and alaska .
the cup nest is located in a tree or dense shrub , usually over water .
birds often nest at the edge of ponds/wetland complexes and travel large distances to feed at the waters edge .
emerging dragonflies and their larvae are important food items during the summer .
these birds migrate to the eastern and southeastern united states , into parts of the grain belt , sometimes straying into mexico .
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 flockssometimes 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 .
