The pine siskin was formally described in 1810 by the American ornithologist Alexander Wilson under the binomial name Fringilla pinus.

Although they can be confused by the more inexperienced for other finches or even American sparrows, pine siskins are distinguished by their heavy streaking, relatively slender bills, notched tail, yellow or whitish patches on the wings and smallish size.

Adult pine siskins of the typical morph do not have green and yellow tones, although juveniles can have a yellowish-buff wash on their underparts and buff-toned wingbars, for a short period prior to their autumn migration.

[9] Their breeding range spreads across almost the entirety of Canada, Alaska and, to a more variable degree, across the western mountains and northern parts of the United States.

However, stands of ornamental conifers or deciduous trees may support nesting birds in partially developed parks, cemeteries, and suburban woodlands.

Mineral deposits can lure them to otherwise unattractive habitats like winter road beds that are salted to melt snow and ice.

In a part of their esophagus called the crop, the species can store up to 10% of their body weight in seeds overnight, providing extra food on cold days.

In summer, they will eat many insects, especially aphids, as well as a few spiders and grubs, which they then feed to the young as a protein-rich food that contributes to their growth.

Nests are often heavily insulated with thick plant materials and females may literally never cease incubating their eggs and hatchlings, while being fed by their male mate.

[7] Although considered Washington's most common finch, the pine siskin has suffered a significant annual decline in population since 1966, according to the Breeding Bird Survey.