Rose-breasted grosbeak males and females have different color patterns. Rose-breasted grosbeaks are 18 to 21.5 cm long and from 39 to 49 grams. Males have a black head, white bill, are black and white dorsally and have a white belly and breast, topped with their rosy throat. Females are brown with white markings above and buffy with brown streaks on the belly, breast, and throat.
Rose-breasted grosbeaks breed in northern North America, from British Columbia in the west to the Atlantic coast of Canada in the east and as far south as New Jersey, the Appalachian Mountains through South Carolina, west to eastern Kansas, Nebraska, and the Dakotas. In winter they are found in the greater Antilles, coastal Mexico, and throughout Central America and northern South America to eastern Peru and Guyana.
Rose-breasted grosbeaks are found in a wide variety of wooded habitats, including swamp or wet forests, forests along rivers and streams, and forest edges. They prefer mixed or deciduous woodlands with an open structure, such as second-growth habitats. They seem to avoid dry woodlands and grasslands.
Rose-breasted grosbeaks form mated pairs during breeding season. Pair bonds form in spring on the breeding grounds, when females approach territorial, singing males. Males use several kinds of courtship displays with females: the rapid warble flight and wing-fluff, both of which are accompanied by a warbling song. Warble flight involves the male flying slowly with his tail spread and with small movements of the wings, the wing-fluff involves the male holding his wings out to the side with his tail spread and moving his head and body from side to side as he hops on a branch.
Rose-breasted grosbeaks begin building nests in May and lay from 1 to 5 (usually 4) pale, bluish-green eggs speckled with darker colors. Nests are constructed in trees, shrubs, or vines and are made of loosely woven grass and twigs formed into cup-shapes. Generally 1 set of young is laid each year. Eggs hatch from 11 to 14 days after the beginning of incubation and young can fly after 9 to 12 days. The young are dependent on their parents for another 3 weeks after fledging and remain with the parents throughout the summer until migration. Young are able to breed in their first year after hatching.
Both females and males incubate the eggs, keep the young warm once hatched, and feed the young. Young are naked and helpless at hatching, with light down and weighing about 4.5 g. Parents feed nestlings up to 75% crushed insects. Young still depend on their parents for 3 weeks after they can fly and remain with them through their first summer.
The oldest reported wild bird was captured at almost 13 years old. Captive birds have lived up to 24 years.
Rose-breasted grosbeaks are migratory, with no overlap in breeding and wintering ranges. They migrate at night, usually in small flocks or alone. Rose-breasted grosbeaks hop on the ground and have an undulating flight pattern. When startled they often freeze and they will flick their wings, spread their tails, raise their head feathers, and give chase towards a threat. Pairs chase away others of the species during the breeding season.
Rose-breasted grosbeaks often return to the same breeding area year after year. There is no published information on home range size.
Rose-breasted grosbeaks are known for their lovely, melodic song. Males sing to advertise breeding territories, up to 689 songs in a day. Females may also sing when they are building nests. Other calls used include a sharp "chink" contact call and various squawks, chuks, and hurrrs. Young first make sounds at 6 days after hatching and young males sing their first songs at about 30 days old. Songs seems to be learned.
Rose-breasted grosbeaks eat seeds, fruit, and insects, with proportions varying seasonally. During the breeding season they eat approximately 52% insects and 48% seeds and fruit. During migration they eat mostly fruits. Rose-breasted grosbeaks forage in tree branches or on the ground. They take insects from leaves or capture them in the air. Insects eaten include beetles, including Colorado potato beetles, bees and ants, bugs, and butterfly larvae. They prey heavily on wild berries, weed seeds, and will sometimes eat domestic crops like peas, corn, oats, and wheat.
Most predation is on eggs and nestlings. Rose-breasted grosbeak pairs will attack predators near their nests. Reported nest predators are blue jays, common grackles, grey squirrels, and red squirrels. Adults may be preyed on by Cooper's hawks and sharp-shinned hawks.
Rose-breasted grosbeaks may help disperse fruit seeds and control insect populations in the ecosystems they live in. Their nests are parasitized by brown-headed cowbirds, but parents usually keep cowbirds away. Other parasites are lice and parasitic flies.
Rose-breasted grosbeaks occasionally take domestic crops, such as peas, corn, oats, and wheat. (Wyatt and Francis, 2002)
Rose-breasted grosbeaks are appreciated for their lovely song and the bright colors of the males. They are frequent visitors at bird-feeders.
Rose-breasted grosbeaks populations seem to be stable and they are not considered threatened at this point.
Tanya Dewey (author), Animal Diversity Web.
Wyatt, V., C. Francis. 2002. Rose-breasted grosbeak (Pheucticus ludovicianus). Birds of North America, 692: 1-20. Accessed April 29, 2009 at http://bna.birds.cornell.edu/bna/species/692.