The Eurasian siskin (Spinus spinus) is a small passerine bird in the finch family Fringillidae. It is also called the European siskin, common siskin or just siskin. It is very common throughout Europe and Asia. It is found in forested areas, both coniferous and mixed woodland where it feeds on seeds of all kinds, especially of alder and conifers.
It can be distinguished from other similar finches by the color of the plumage. The upper parts are greyish green and the under parts grey-streaked white. Its wings are black with a conspicuous yellow wing bar, and the tail is black with yellow sides. The male has a mainly yellow face and breast, with a neat black cap. Female and young birds have a greyish green head and no cap. It is a trusting, sociable and active bird. The song of this bird is a pleasant mix of twitters and trills. For these reasons it is often raised in captivity.
These birds have an unusual migration pattern as every few years in winter they migrate southwards in large numbers. The reasons for this behaviour are not known but may be related to climatic factors and above all the availability of food. In this way overwintering populations can thrive where food is abundant. This small finch is an acrobatic feeder, often hanging upside-down like a tit. It will visit garden bird feeding stations.