Rose-breasted Grosbeak - Range and Ecology

Range and Ecology

The Rose-breasted Grosbeak's breeding habitat is open deciduous woods across most of Canada and the northeastern USA. In particular the northern birds migrate south through the United States east of the Rocky Mountains, to winter from central-southern Mexico through Central America and the Caribbean to Peru and Venezuela. The southern limit of its wintering range is not well known; it was for example only recorded in the Serranía de las Quinchas (Colombia) in the 1990s. In winter, they prefer more open woodland, or similar habitat with a loose growth of trees, such as forest edges, parks, gardens and plantations, ranging from sea level into the hills, e.g. up to 5,000 ft (1,500 m) ASL in Costa Rica.

The first birds leave the breeding grounds as early as August, while the last ones do not return until mid-late May. In general, however, they migrate south in late September or in October, and return in late April or early May. It appears as if they remain on their breeding grounds longer today than they did in the early 20th century, when migrants were more commonly seen in May and August than in April or September. The Rose-breasted Grosbeak occurs as a very rare vagrant in western Europe.

It builds a twig nest in a tree or large shrub. The Rose-breasted Grosbeak forages in shrubs or trees for insects, seeds and berries, also catching insects in flight and occasionally eating nectar. It usually keeps to the treetops, and only rarely can be seen on the ground. During breeding it is fairly territorial; in winter, it roams the lands in groups of about a handful of birds, and sometimes in larger flocks of a dozen or more. In the winter quarters, they can be attracted into parks, gardens, and possibly even to bird feeders by fruit like Trophis racemosa. Other notable winter food includes Jacaranda seeds and the fruits of the introduced Busy Lizzy (Impatiens walleriana).

Fires are necessary to maintain many kinds of grassland (see Fire ecology). Fire suppression in the late 20th century allowed forests to spread on the Great Plains into areas where recurring fire would otherwise have maintained grassland. This allowed hybridization with the Black-headed Grosbeak subspecies P. melanocephalus papago Range expansions also seem also to have occurred elsewhere, for example in northern Ohio where it bred rarely if at all in the 1900s (decade), but it by no means an uncommon breeder today. In general, though it requires mature woodland to breed and is occasionally caught as a cage bird, the Rose-breasted Grosbeak is not at all rare, and not considered a threatened species by the IUCN.