Rose-breasted Grosbeak Life History

Habitat

Habitat ForestsRose-breasted Grosbeaks breed in moist deciduous forests, deciduous-coniferous forests, thickets, and semiopen habitats across the northeastern United States, ranging into southeastern and central Canada. They gravitate toward second-growth woods, suburban areas, parks, gardens, and orchards, as well as shrubby forest edges next to streams, ponds, marshes, roads, or pastures. During migration, grosbeaks stop in a wide variety of habitats including primary and secondary forest, wet and dry forest, shrub thickets, pine woods, shrubby dune ridges, scrub, urban areas, and wetlands. They spend the winter in forests and semiopen habitats in Central and South America, often in middle elevations and highlands (up to about 11,000 feet in Colombia).Back to top

Food

Food InsectsDuring the breeding season Rose-breasted Grosbeaks eat a lot of insects, as well as wild fruit and seeds. They mostly feed on berries during fall migration, and on their wintering grounds they have a varied diet of invertebrates and plant material. Grosbeaks usually glean their food from dense foliage and branches. They also snag food while hovering, and sometimes fly out to hawk for insects in midair. The animal portion of their diet includes beetles, bees, ants, sawflies, bugs, butterflies, and moths. Their vegetarian fare includes elderberries, blackberries, raspberries, mulberries, juneberries, and seeds of smartweed, pigweed, foxtail, milkweed, plus sunflower seeds, garden peas, oats, wheat, tree flowers, tree buds, and cultivated fruit.Back to top

Nesting

Nest Placement

Nest TreeThe male may help the female choose a nest site, which is usually in a vertical fork or crotch of a sapling. Nesting plants include maple, red-berried elder, balsam fir, eastern hemlock, and spruce, and may be in wet or dry areas. They are usually in forest openings, overgrown field edges, old pastures, shrubby roads, railroad rights-of-way, gardens, parks, or residential areas. The male and female each may test the nest site’s suitability by settling into it and turning around several times.

Nest Description

The male and female build the nest together in 4–9 days, working from dawn to dusk. They construct a loose, open cup of coarse sticks, twigs, grasses, weed stems, decayed leaves, or straw, and line it with fine twigs, rootlets, or hair. Sometimes the nest is so flimsy that you can see the outline of the eggs through it. The birds’ habit of using forked twigs may help hold the nest together despite its thin construction. The finished nest measures about 3.5–9 inches across and 1.5–5 inches high on the outside, while the inner cup is about 3–6 inches across and 1–3.5 inches deep.

Nesting Facts
Clutch Size:1-5 eggs
Number of Broods:1-2 broods
Egg Length:0.8-1.1 in (2-2.7 cm)
Egg Width:0.6-0.8 in (1.6-1.9 cm)
Incubation Period:11-14 days
Nestling Period:9-12 days
Egg Description:Pale green to blue, with reddish brown or purplish speckles.
Condition at Hatching:Helpless, with sparse white down and closed eyes.
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Behavior

Behavior Foliage GleanerMales sing to establish territories and attract females. When a female approaches, the male rebuffs her for a day or two before accepting her as a mate. Once mated, Rose-breasted Grosbeaks appear to be monogamous. A breeding pair will tolerate migrant males in their territory if the intruder is silent. Otherwise, territorial males ward off male intruders by spreading their tails, flicking their wings, raising their crown feathers, and often chasing the intruder away. Males respond strongly to recordings of Rose-breasted Grosbeak songs and Black-headed Grosbeak songs, but they attack mounted specimens of their own species 5 times more often than they attack specimens of the other species. Females drive off other females that approach their mate. Both male and female Rose-breasted Grosbeaks share incubation, brooding, and feeding duties at the nest. Nest predators include Blue Jays and Common Grackles—which breeding grosbeaks will mob noisily and aggressively near the nest—along with red and gray squirrels. Adult grosbeaks are hunted by predators such as Cooper’s Hawks and Sharp-shinned Hawks. During migration and winter Rose-breasted Grosbeaks are found individually, in pairs, or in loose flocks, sometimes with other species.Back to top

Conservation

Conservation Low ConcernRose-breasted Grosbeaks are common forest birds but their populations experienced a slow decline from 1966 to 2015, resulting in a cumulative loss of about 35% during that time, according to the North American Breeding Bird Survey. Partners in Flight estimates a global breeding population of 4.1 million, with 46% spending some part of the year in the U.S., 21% in Mexico, and 54% breeding in Canada. The species rates an 11 out of 20 on the Continental Concern Score. Rose-breasted Grosbeak is not on the 2016 State of North America's Birds' Watch List. These birds nest in saplings, so their numbers could be dropping as forests start to mature over the eastern United States. Because they look and sound pretty, Rose-breasted Grosbeaks are commonly trapped for sale as cage birds in their wintering range, and this has an unknown impact on their population. Back to top

Backyard Tips

Rose-breasted Grosbeaks often visit bird feeders, where they eat sunflower seeds as well as safflower seeds and raw peanuts. Even if you live outside their summer range you may still catch one visiting during spring or fall migration if you keep your feeders stocked.

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Credits

Lutmerding, J. A. and A. S. Love. Longevity records of North American birds. Version 2015.2. Patuxent Wildlife Research Center, Bird Banding Laboratory 2015.

Partners in Flight (2017). Avian Conservation Assessment Database. 2017.

Sauer, J. R., D. K. Niven, J. E. Hines, D. J. Ziolkowski, Jr., K. L. Pardieck, J. E. Fallon, and W. A. Link (2017). The North American Breeding Bird Survey, Results and Analysis 1966–2015. Version 2.07.2017. USGS Patuxent Wildlife Research Center, Laurel, MD, USA.

Sibley, D. A. (2014). The Sibley guide to birds, second edition. Alfred A. Knopf, New York, USA.

Wyatt, Valerie E. and Charles M. Francis. 2002. Rose-breasted Grosbeak (Pheucticus ludovicianus), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA.

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