Although the Pine siskin (Spinus pinus) is patterned like a sparrow, its shape, actions, and callnotes all reveal that this bird is really a goldfinch in disguise. After nesting in the conifer woods, Pine Siskins move out into semi-open country, where they roam in twittering flocks. They often descend on fields of thistles or wild sunflowers, where they cling to the dried flower heads, eating seeds. In winter they sometimes invade southward in big numbers, with flocks coming to feeders along with American Goldfinches.
Pine siskin’s breeding range often changes from year to year. May nest in loose colonies or in isolated pairs. Courtship and formation of pairs may begin in winter flocks; male displays by flying in circle above female, with wings and tail spread widely, while singing. Male often feeds female during courtship. Nest site is well hidden in tree (usually in conifer), on horizontal branch well out from trunk. Typically 10-40′ above ground, can be lower or higher. Nest (built by female) is a rather large but shallow open cup of twigs, grass, strips of bark, rootlets, lined with moss, animal hair, feathers.
Pine siskin’s have a erratic migration pattern especially in its winter occurrence, coming south in huge numbers some years, very scarce in others. After big invasion winters, a few may remain to nest south of normal range. Pine siskin’s migrate by day, in flocks.