The tufted tit-tyrant (Anairetes parulus) is a species of bird in the tyrant flycatcher family Tyrannidae. This species is found in western South America; its range stretches from southern Colombia south along the Andes mountains to Tierra del Fuego. It prefers to live in upper montane forests and shrublands; however, it is a habitat generalist and can be found across a wide range of ecosystems. The tufted tit-tyrant has three subspecies, including the nominate subspecies Anairetes parulus parulus, A. p. aequatorialis, and A. p. patagonicus, and is very closely related to the Juan Fernández tit-tyrant. It is very small with a distinctive and conspicuous crest. The bird's head is black overall with white supraloral and postocular stripes. Its dull grayish-brown back contrasts with its white throat and breast that are covered with black streaks and pale, unmarked yellow underbelly. There are few noticeable differences in plumage between the subspecies. It is a vocal flycatcher with a broad repertoire of songs. This tit-tyrant defends its territory only against other tit-tyrants and, except for the southernmost population, is non-migratory. The tufted tit-tyrant feeds mainly on a variety of insects that it hunts on or from small shrubs, typically by perch gleaning. It normally hunts in pairs. The breeding season varies for this bird depending on its geographical location. Two to three eggs are normally laid twice a year in a cup-shaped nest made of root fibers, grasses, and lichens and lined with small feathers. The tufted tit-tyrant is listed as a species of least concern due to its large range and population. German explorer Heinrich von Kittlitz described the tufted tit-tyrant in 1830. The tufted tit-tyrant's genus, Anairetes, is in the tyrant flycatcher family Tyrannidae and is believed to be most closely related to the tyrannulet genera Mecocerculus and Serpophaga; however, there is no definitive evidence supporting this claim. The tufted tit-tyrant was described as Muscicapa parulus by Heinrich von Kittlitz in 1830 from a specimen collected near Valparaíso, Chile. It was later moved from the genus Muscicapa, which today solely contains Old World flycatchers, to Anairetes; however, this genus was too similar to the pre-existing genus Anaeretes, so Harry Church Oberholser erected the genus Spitzitornis for it and the other tit-tyrants. However, Spitzitornis was eventually abolished and the tit-tyrants were returned to Anairetes. The tufted tit-tyrant is believed to form a superspecies with the Juan Fernández tit-tyrant. Members of the genus Anairetes are commonly known as tit-tyrants because their active foraging behavior and crests are reminiscent of the true tits in the family Paridae, while the genus itself is part of the tyrant flycatcher family. The tufted tit-tyrant is known in Spanish as the Cachudito, which means 'little longhorn' in reference to the bird's crest. The tufted tit-tyrant has three described subspecies. Anairetes parulus aequatorialis is the northernmost subspecies and is found in the Andes from southern Colombia to western Bolivia and northern Argentina. It was described by Hans von Berlepsch and Władysław Taczanowski in 1884. The nominate subspecies, A. p. parulus, is found in western Chile and in southwest Argentina south to Tierra del Fuego and was described by Kittlitz in 1830. The third subspecies, A. p. patagonicus, is found in western Argentina and was described by Austrian ornithologist Carl Eduard Hellmayr in 1920. The tufted tit-tyrant is a small bird, averaging 9.5 to 11 centimeters (3.7 to 4.3 in) in length and weighing about 6 grams (0.21 oz). Its long, recurved crest is typically conspicuous and is often parted, giving the impression that the bird has two crests. The crest's feathers are black and emerge from the center of the bird's black crown, although occasionally there is a small patch of white hidden by the crest. The head is black overall with a white supraloral and postocular stripe. The bird's iris is creamy white to pale yellow and the bill is black. This tit-tyrant's back is a dull, grayish brown, and the wings and tail are a duskier shade of this color. The wings also feature two narrow white wingbars, while the outer tail feathers are white. The throat and breast are white and covered in dark gray to black streaks, which thin out further down the breast and along the sides. The belly is a pale yellow which fades as the plumage becomes more worn, while the bird's legs are black. Males and females are similar in appearance, although females are typically smaller and may have smaller crests. Juvenile tufted tit-tyrants are duller in coloration and have a shorter crest; the juvenile's wingbars are also buffy and there is no hidden white spot on the crown. There are few variations in plumage between the three subspecies. Anairetes parulus aequatorialis tends to be browner than the nominate subspecies in its upperparts, with broader and more extensive breast streaks and broader and more distinct white wingbars. A. p. patagonicus has more variation from the nominate subspecies as it is paler gray overall, particularly on the crown, and the wingbars and breast streaks are broader and more distinct. A. p. patagonicus's underbelly is also a paler yellow to white. This flycatcher has a loud, high-pitched song. It is also known to give a fast chuit-chuit-chuit-chuit-chuit-chidi-didi song, and occasionally single notes of chuit are made in a slow series of calls. When foraging in pairs, tufted tit-tyrants have been observed using a perr-reet call to stay in contact with each other. The species' contact call has been described as a pluit-pluit. The tufted tit-tyrant is also known to give a long, weak trill.