Pine grosbeak

Appearance

This species is one of the largest species in the true finch family. It measures from 20 to 25.5 cm in length and weighs from 52 to 78 g , with an average mass of 56.4 g . Among standard measurements, the wing chord is 10.2 to 11.6 cm , the tail is 7.8 to 9.5 cm , the bill is 1.4 to 1.65 cm and the tarsus is 1.9 to 2.3 cm . Adults have a long forked black tail, black wings with white wing bars and a large bill. Adult males have a rose-red head, back and rump. Adult females are olive-yellow on the head and rump and grey on the back and underparts. Young birds have a less contrasting plumage overall, appearing shaggy when they moult their colored head plumage.

Its voice is geographically variable, and includes a whistled ''pui pui pui'' or ''chii-vli''. The song is a short musical warble.

Habitat

The breeding habitat of the pine grosbeak is coniferous forests. They nest on a horizontal branch or in a fork of a conifer. This bird is a permanent resident through most of its range; in the extreme north or when food sources are scarce, they may migrate farther south.

Pine grosbeaks forage in trees and bushes. They mainly eat seeds, buds, berries, and insects. Outside of the nesting season, they often feed in flocks.

Evolution

The pine grosbeak, together with its Himalayan relative the crimson-browed finch , represents an ancient divergence from the same stock that also gave rise to the true bullfinches . The ''Pinicola'' lineage diverged from its relatives perhaps a dozen million years ago, during the Clarendonian faunal stage of the mid-Miocene. Across the species' range, nine subspecies have been described, with the five New World forms having differing plumages and vocalizations, suggesting genetic divergence within the New World, perhaps to species level.

At the same time, the evolutionary radiation of ''Pyrrhula'' throughout Eurasia and the Holarctic expansion of the closely related ''Leucosticte'' mountain finches and relatives began. These genera evolved in the interior of Asia, and thus the original ''Pinicola'' stock was probably already a conifer forest bird living to the north of the Himalayas. The separation of the modern species is likely the result of climate change which displaced ''Pinicola'' habitat to subarctic northern and subalpine Himalayan regions. Possibly, the ancestors of the North American pine grosbeaks were wind-blown individuals which arrived via the northern Pacific, as the Bering Land Bridge was generally submerged in the Late Miocene.

According to studies by Arnaiz-Villena et al., all birds belonging to the genus ''Pyrrhula'' have a common ancestor: ''Pinicola enucleator''.