Longspurs, Snow Buntings

The Calcariidae family consists of six species of small passerine birds, including longspurs and snow buntings, divided across three genera: Calcarius, Plectrophenax, and Rhynchophanes. Ranging from 20 grams for the Chestnut-collared longspur to 42 grams for McKay's bunting, these birds have brown, grey, and white plumage and live across North America and Eurasia. They are known for their migratory behavior, adapting to environments such as grasslands, tundra, mountains, and beaches. Formerly grouped with Emberizidae, Calcariidae are now a separate family due to their genetic distinctness, with their evolutionary divergence estimated around 4.2–6.2 million years ago. While some species, such as McKay's bunting and the snow bunting, have been known to hybridize, substantial differences support their classification as distinct species. These birds, which forage for insects, seeds, and grasses during the day, inhabit open areas like prairies and beaches and have extensive ranges, with some species breeding in very northern or prairie regions and wintering across temperate zones.