Lesser Goldfinch

This species is not only the smallest North American Spinus finch, it may be the smallest true finch in the world. Some sources list more subtropical Spinus species as slightly smaller on average, including the Andean siskin (Spinus spinescens). This species ranges from 9 to 12 cm (3.5 to 4.7 in) in length and can weigh from 8 to 11.5 g (0.28 to 0.41 oz). Among standard measurements, the wing chord is 5.5 to 7 cm (2.2 to 2.8 in), the tail is 3.9 to 4.7 cm (1.5 to 1.9 in), the bill is 0.9 to 1.1 cm (0.35 to 0.43 in) and the tarsus is 1.1 to 1.2 cm (0.43 to 0.47 in). There is a slight northwest-southeast cline in size, with the largest birds from Mexico and further south being up to one-fifth larger than the smallest from the extreme northwest of its range; this effect is more pronounced in females. There is also considerable variation in the amount of black on the head and back in males and thus five subspecies have been proposed. But this variation, too, seems to be simple and clinal changes in allele frequency and thus the "subspecies" might be better considered color morphs or geographic forms. Males are easily recognized by their bright yellow underparts and big white patches in the tail (outer rectrices) and on the wings (the base of the primaries). …

This goldfinch ranges from the southwestern United States to as far north as the Columbia River in Washington and south to Venezuela and Peru. It seasonally migrates out of parts of its U.S. range, but is resident year-round in others, and has rapidly expanded across much of the Pacific Northwest in recent decades as a year-round resident. The lesser goldfinch often occurs in flocks or at least loose associations. It utilizes almost any habitat with trees or shrubs except for dense forest, and is common and conspicuous in many areas, often coming near houses. It is common at feeders in the Southwest United States and will come almost anywhere with thistle sock feeders. Flocks of at least six birds will often be seen at feeders. It feeds mostly on tree buds and weed seeds; geophagy has been observed in this species. The nesting season is in summer in the temperate parts of its range; in the tropics it apparently breeds all-year round, perhaps less often in September and October. It lays three to six bluish white eggs in a cup nest made of fine plant materials such as lichens, rootlets, and strips of bark, placed in a bush or at low or middle levels in a tree, around 4 to 8 ft (1.2 to 2.4 m) or higher off the ground. …