Pine Grosbeak Life History

Habitat

Pine Grosbeaks live in open evergreen forests with spruce, pine, or fir across Canada, in mountainous regions in the West, and in subalpine forests in Eurasia. In the Sierra Nevada in California they occur in open red fir and lodgepole pine forests usually higher than 6,000 feet. In the Rocky Mountains they are most common in valleys near timberline (above 9,000 feet). In the winter they either stay in similar habitat, move to lower elevations, or to areas with abundant mountain ash, maple, and ash fruits and seeds. Back to top

Food

Nearly 100% of their diet is made up of buds, seeds, and fruits from spruce, pine, juniper, birch, mountain ash, maple, box elder, crabapple, blackberry, ragweed, and burdock. They forage on the ground or in trees, grabbing seeds and fruits or nipping fresh buds and needles from the tips of branches. Though they are primarily vegetarian they catch insects and spiders in the summer. These protein-rich items are often fed to their growing young along with mixed plant foods. In the winter they also eat grit and salt along roadsides. They frequently visit feeders with black oil sunflower seeds or suet. Grosbeaks drink water or eat snow daily.Back to top

Nesting

Nest Placement

Pine Grosbeaks nest in evergreen trees often near the trunk where the nest is well concealed by dense vegetation. They tend to nest between six and 16 feet above the ground.

Nest Description

The female builds a loose foundation of evergreen twigs into which she weaves roots and smaller twigs. She then builds the inner cup of the nest with rootlets, twigs, and grass. She lines it with lichen, evergreen needles, soft grasses, and feathers. The nest is around 6–9 inches across and 3–4 inches deep on the outside with an inner cup around 2.5–3 inches across.

Nesting Facts

Behavior

In trees Pine Grosbeaks sluggishly hop between braches nipping off the new growth of trees or snatching seeds and fruits. They also hop or walk along the ground when they are searching for fallen seeds or fruits. When boreal tree species produce larger seed crops Pine Grosbeaks often raise more young and are more likely to survive the winter. But when those trees fail to produce seed crops the next season, the now larger population of grosbeaks wanders or irrupts outside of the normal breeding range to find food. During these irruptions they often turn up at bird feeders farther south than normal. In the winter, they forage in groups from 5–15 individuals. In areas where different call types exist, individuals with the same song type stick together; they do not forage with other groups with different flight calls. During the breeding season, they form monogamous pairs. Males sing from treetops to defend their breeding territory. Mated pairs have identical flight calls, which may indicate that they form strong bonds with each other. Back to top

Conservation

Pine Grosbeaks are fairly uncommon in the United States as they only breed in small pockets of forest in western mountains, and they are easy to overlook. Much of their far-northern breeding range lies outside of the area covered by the North American Breeding Bird Survey, making it hard to estimate population trends precisely. Nevertheless, North American Breeding Bird Survey data suggest that populations of Pine Grosbeaks held steady between 1966 and 2019. Partners in Flight estimates a global breeding population of 11 million and rates them 10 out of 20 on the Continental Concern Score, indicating a species of low conservation concern. Research modeling the projected impacts of climate change on birds in the Sierra Nevada suggests that, at least in California, Pine Grosbeaks are vulnerable to climate change.

Credits

Adkisson, Curtis S. (1999). Pine Grosbeak (Pinicola enucleator), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA.

Dunne, P. (2006). Pete Dunne's essential field guide companion. Houghton Mifflin Harcourt, New York, USA.

Ehrlich, P. R., D. S. Dobkin, and D. Wheye (1988). The Birder's Handbook. A Field Guide to the Natural History of North American Birds, Including All Species That Regularly Breed North of Mexico. Simon and Schuster Inc., New York, NY, USA.

Koenig, W. D., and J. M. H. Knops. (2001). Seed-crop size and eruptions of North American boreal seed-eating birds. Journal of Animal Ecology 70:609-620.

Lutmerding, J. A. and A. S. Love. (2020). Longevity records of North American birds. Version 2020. Patuxent Wildlife Research Center, Bird Banding Laboratory 2020.

Partners in Flight. (2020). Avian Conservation Assessment Database, version 2020.

Sauer, J. R., D. K. Niven, J. E. Hines, D. J. Ziolkowski Jr., K. L. Pardieck, J. E. Fallon, and W. A. Link (2019). The North American Breeding Bird Survey, Results and Analysis 1966–2019. Version 2.07.2019. USGS Patuxent Wildlife Research Center, Laurel, MD, USA.

Sibley, D. A. (2014). The Sibley Guide to Birds, second edition. Alfred A. Knopf, New York, NY, USA.

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