White-naped xenopsaris

The white-naped xenopsaris was described in 1869 by the German-Argentine scientist Hermann Burmeister, based on a specimen collected near Buenos Aires. Burmeister originally placed it in the becard genus, Pachyramphus. It was moved to the monotypic genus Xenopsaris by Robert Ridgway in 1891, but was still known to be closely related to Pachyramphus. A 1989 study of anatomy identified Pachyramphus as a sister taxon to Xenopsaris, but the white-naped xenopsaris was kept in its own genus due to several morphological and behavioural differences, namely its smaller size, the shape of its legs, the length of its primary flight feathers, the lack of strong sexual dimorphism (differences between the sexes) and the construction of the nest. When placed with the tyrant-flycatchers, Tyrannidae, it was considered closely related to the genera Suiriri, Serpophaga and Knipolegus. The uncertainty was not confined to this species, as there was a general confusion about where to draw the lines between the cotingas, tyrant-flycatchers and manakins. Resolution was provided by the same 1989 study that confirmed the link between Xenopsaris and Pachyramphus. In it, Xenopsaris and six other genera previously held in the three families were found to actually form a fourth family, later named Tityridae. A 2007 study of mitochondrial DNA confirmed the white-naped xenopsaris' place in the Tityridae, and its close relationship to Pachyramphus, as well as the genus Tityra. These three genera were found to be more distantly related to a fourth genus Iodopleura (the purpletufts), although further studies are needed to understand the complete relationship between these four genera. described by Georges Cuvier in 1817. The specific name albinucha is from Latin and refers to the bird's white () nape (''''). The species is also known as the reed becard, and simply xenopsaris. There are two subspecies of white-naped xenopsaris; the widespread nominate subspecies, and the more restricted X. a. minor of Venezuela, which was described by Carl Eduard Hellmayr in 1920. ==Description==

The white-naped xenopsaris is smaller than the closely related becards and tityras, measuring in length and weighing around . The subspecies X. a. minor has the same plumage as the nominate subspecies, but is smaller; the wing-chord (measurement from the wrist-joint to the end of the wing) length of the nominate subspecies, for example, is compared to in X. a. minor. The song of this species is delicate, and does not carry far. It is most commonly heard during the rainy season, but can be heard at any time of the day. The call is described as a thin, high-pitched and hesitant "teep, tre'e'e'e'e'a eea wu'u'u'e'e'e-e-e-e-e-p" or a "twip, tsiweeé, tseee, ti-ti-ti-ti", according to the Handbook of the Birds of the World. The initial trill is described as rising and then falling, and the last trill is described as long. Birds may sometimes vary the pattern and only use part of the song. The species is also described as making a squeaky and undulating screech, The white-naped xenopsaris looks somewhat similar to the cinereous becard, which overlaps its range in Venezuela. The white-naped xenopsaris is smaller, with a longer tail, thinner bill, whiter underparts (instead of grey) and browner upperparts (rather than greyish) . == Distribution and habitat ==

, one of the habitats used by this species The white-naped xenopsaris has a disjunct distribution. The southern population of the nominate subspecies is widespread from north-eastern Brazil through to Bolivia, Paraguay and northern Argentina and Uruguay. A separate population of the nominate is found in Guyana. The subspecies X. a. minor is found in west and central Venezuela, and probably extends into north-eastern Colombia. They occupy a variety of habitats across their range, including Caatinga scrubland, riparian (river) woodland, lightly wooded areas, the borders of open gallery forest and open areas with scattered trees. They usually live near water or damp areas, and range from sea-level to . ==Behaviour==

Diet and feeding The white-naped xenopsaris feeds on insects, but no studies have yet been done on the diet of adults. Chicks in the nest are fed grasshoppers from the family Acrididae, mantidflies, praying mantises and mosquitoes. Chicks hatch within 24 hours of each other. Six days after hatching, the chicks' eyes have opened and after eight days they are covered in whitish down. Chicks defecate outside of the nest by raising their tail to the side of the nest, so nests with older chicks are surrounded by faecal matter. Both parents feed and brood the chicks, taking it in turns. When one parent returns with food, it takes over brooding duties while the other leaves to hunt. The chicks are fed by the parents for several days after fledging. The family may travel as a group or the parents may divide the brood, taking one or two chicks each. ==Conservation status==

Across its range, the white-naped xenopsaris is uncommon and patchily distributed. It has not been evaluated as threatened by the IUCN Red List, as it does not meet any of the criteria. The population is evaluated as being stable, as there is no evidence of any decline or extreme fluctuations. It also occupies an enormous range, estimated to be . For these reasons, it is evaluated as a species of least concern. ==References==