The mistle thrush (Turdus viscivorus) is a common bird found in much of Europe, temperate Asia, and North Africa. It lives year-round in many places, but some populations in the north and east migrate south for the winter, usually in small groups. This is a large thrush with pale grey-brown feathers on its back, a greyish-white chin and throat, and black spots on its pale yellow and off-white belly. Males and females look alike, and the three subspecies differ only slightly. The male has a loud song that can be heard even in bad weather, earning it the nickname “stormcock.” The name was also spelled “missel thrush” in the past.
Mistle thrushes are found in open woods, parks, hedges, and farmland, and they eat various invertebrates, seeds, and berries. They especially like mistletoe, holly, rowan, and yew. Mistletoe is preferred when available because the bird helps to spread the plant’s seeds, allowing them to germinate. In winter, mistle thrushes will defend clumps of mistletoe or other fruit-bearing trees from other birds, such as waxwings, to keep them as food reserves for harder times.
Mistle thrushes build open cup nests against tree trunks or in forked branches, which they protect fiercely, even from potential predators like humans or cats. They usually lay three to five eggs, which the female incubates for 12 to 15 days. The chicks leave the nest about 14 to 16 days after hatching, and there are typically two broods each season. There was an increase in their range in the 18th and early 19th centuries, but in recent decades their numbers have declined, possibly due to changes in farming practices. Despite this, they are still classified as of least concern by the International Union for Conservation of Nature.
The mistle thrush is the largest thrush in Europe. The nominate subspecies is 27-28 cm long with a wingspan of 45 cm and weighs between 93 to 167 g, averaging around 130 g. It has a stocky posture on the ground. The chin and throat are greyish-white, while the yellow-buff breast and off-white belly have round black spots that become denser on the lower chest. Its long tail has white tips on the outer feathers, and the underwing coverts are white. The eyes are dark brown, and the bill is blackish with a yellowish base on the lower mandible. The legs and feet are yellowish-brown. Both sexes have the same plumage. Juveniles look similar to adults but are paler on top and have smaller spots on the yellowish underbelly. By their first winter, they closely resemble adults but are generally more buff-colored underneath.
There is some variation among the nominate T. v. viscivorus, with the darkest birds found in western Europe and the palest in Siberia and Turkey. The southeastern subspecies T. v. bonapartei measures about 30 cm in length, making it slightly larger than the nominate form. It is paler grey above and whiter below, with fewer black spots. The southwestern subspecies T. v. deichleri looks like T. v. bonapartei but is about the same size as T. v. viscivorus and has a more slender bill.
Adults undergo a complete molt after breeding, starting from late May to the end of June, and finishing by early October. Juveniles have a partial molt, changing their head, body, and covert feathers, which is complete by October, depending on when they hatched.
The mistle thrush is larger, paler, and has a longer tail than the related song thrush. In the western Himalayas, it may be confused with the plain-backed and long-tailed thrushes. The plain-backed thrush has no obvious wing bars, is more rufous above, and has bars on its belly instead of spots. The long-tailed thrush has olive-toned feathers, bars on its breast, and two wing bars. Juvenile mistle thrushes can be confused with White’s thrush, but that species has golden-yellow feathers and a distinctive pattern on its underwings.
The male mistle thrush sings a loud, melodious song with fluted whistles, sounding like “chewee-trewuu … trureetruuruu.” He repeats this three to six times to mark his territory, attract a mate, and strengthen the pair bond. His song is similar to that of the song thrush or blackbird but is louder and less varied, often heard up to 2 km away. Males mainly sing from treetops or other high spots from November to early June, especially being most vocal in the breeding season.
