The grey hypocolius[3] or simply hypocolius (Hypocolius ampelinus) is a small passerine bird species. It is the sole member of the genus Hypocolius and it is placed in a family of its own, the Hypocoliidae. This slender and long tailed bird is found in the dry semi-desert region of northern Africa, Arabia, Afghanistan, Pakistan, and western India. They fly in flocks and forage mainly on fruits, migrating south in winter.
The grey hypocolius is a slim bird with a long tail, slight crest and thick, short hook-tipped bill. Its shape and soft, satiny plumage resembles that of the waxwing. Birds are mainly a uniform grey or brownish-grey colour, with males having a black triangular mask around the eyes. They have white-tipped black primary wing feathers and a black terminal band on the tail. Adults are about 19–21 cm in length.[4]
The head feathers are raised when the bird is excited. They fly in a straight non-undulating style and when hopping in shrubbery, can appear like a babbler. The tarsus is short and sturdy with coarse scales. There are rictal bristles visible at the base of the bill and the nostrils are exposed, small and oval.[5]
The relationships of the species were formerly unclear. Earlier authors had suggested that they were related to the bulbuls[6] or shrikes.[7][8] They appear to be related to the waxwings, and at least one study based on molecular sequences suggests that it belongs to the same group.[9][10] A 2019 study found them to be in a clade containing the palmchat (Dulidae), waxwings (Bombycillidae), silky-flycatchers (Ptiliogonatidae), hylocitrea (Hylocitreidae), and the extinct Hawaiian honeyeaters (Mohoidae), with Hypocoliidae being a sister group to the Mohoidae (with both diverging about 15-20 mya during the early-mid Miocene), and the clade containing Mohoidae and Hypocoliidae being sister to Hylocitreidae, which diverged slightly earlier in the Miocene.[11]
The grey hypocolius ranges through the Middle East, breeding in the Iraq, Iran, Afghanistan, Pakistan, Turkmenistan area,[12] and wintering mostly near the Red Sea and Persian Gulf coasts of Arabia, including Bahrain. It is a vagrant to Turkey, Israel, Egypt and Oman. They are regular winter visitors to the Kutch region of western India[13][14] and vagrants have been noted as far south as Kihim near Bombay.[15] It is found in woodland and scrub in arid and semiarid regions, especially river valleys near deserts, as well as in irrigated and cultivated areas with trees, such as palm groves and gardens.[6][16]
The grey hypocolius is a shy and unobtrusive, even cryptic, bird which will fly to thick cover when disturbed, where it will remain motionless until the perceived danger has passed. Its flight is strong and direct (without undulations).[4] It will form flocks, especially in winter, and roost communally.[16]