Pittas are a family, Pittidae, of passerine birds found in Asia, Australasia and Africa. There are 44 species of pittas, all similar in general appearance and habits. The pittas are Old World suboscines, and their closest relatives among other birds are in the genera Smithornis and Calyptomena. Initially placed in a single genus, as of 2009 they have been split into three genera: Pitta, Erythropitta and Hydrornis. Pittas are medium-sized by passerine standards, at in length, and stocky, with strong, longish legs and long feet. They have very short tails and stout, slightly decurved bills. Many have brightly coloured plumage.
Most pitta species are tropical; a few species can be found in temperate climates. They are mostly found in forests, but some live in scrub and mangroves. They are highly terrestrial and mostly solitary, and usually forage on wet forest floors in areas with good ground cover. They eat earthworms, snails, insects and similar invertebrate prey, as well as small vertebrates. Pittas are monogamous and females lay up to six eggs in a large domed nest in a tree or shrub, or sometimes on the ground. Both parents care for the young. Four species of pittas are fully migratory, and several more are partially so, though their migrations are poorly understood.
Four species of pitta are listed as endangered by the International Union for Conservation of Nature; a further nine species are listed as vulnerable and several more are near-threatened. The main threat to pittas is habitat loss in the form of rapid deforestation, but they are also targeted by the cage-bird trade. They are popular with birdwatchers because of their bright plumage and the difficulty in seeing them.
Taxonomy and systematics
thumb|alt= stout dull coloured bird hunched over mossy rock|The [[rusty-naped pitta was once placed in the genus Pitta but is now in Hydrornis.]]
The first pitta to be described scientifically was the Indian pitta, which was described and illustrated by George Edwards in 1764. Carl Linnaeus included the species in his revised 12th edition (1766–1768) of the Systema Naturae based on Edwards' descriptions and illustrations as well as other accounts, placing it with the Corvidae as Corvus brachyurus. Ten years later Statius Müller moved it and three other pittas to the thrush family Turdidae and the genus Turdus, due to similarities of morphology and behaviour. In 1816 Louis Pierre Vieillot moved it to the new genus Pitta. The name is derived from the word (pitta) in the Telugu language of South India meaning "small bird".
The family's closest relatives have for a long time been assumed to be the other suboscine birds (suborder Tyranni), and particularly the Old World suboscines; the broadbills, asities and the New World sapayoa. These arboreal relatives were formerly treated as two families, and are now either combined into a single taxon or split into four. A 2006 study confirmed that these were indeed the closest relatives of the pittas. The clade they form, the Eurylaimides, is one of the two infraorders of suboscines, which is one of three suborders of the passerine birds. With regards to their relationship within the Eurylaimides, another 2006 study placed the pittas as a sister clade to two clades of broadbills and asities. This same study postulated an Asian origin for the Eurylaimides and therefore the pittas.
Two DNA studies, from 2015 and 2016, came to a different conclusion, finding that the Eurylaimides were divided into two clades and that the pittas formed a clade with the broadbills of the genera Smithornis and Calyptomena, with the remaining broadbills and asities in the other clade.
The number of pitta genera has varied considerably since Vieillot, ranging from one to as many as nine. In his 1863 work A Monograph of the Pittidae, Daniel Elliot split the pittas into two genera, Pitta for the species with comparatively long tails and (the now abandoned) Brachyurus for the shorter-tailed species. Barely two decades later, in 1880/81, John Gould split the family into nine genera, in which he also included the lesser melampitta (in the genus Melampitta) of New Guinea, where it was kept until 1931 when Ernst Mayr demonstrated that it had the syrinx of an oscine bird. Philip Sclater's Catalogue of the Birds of the British Museum (1888) brought the number back down to four – Anthocincla, Pitta, Eucichla, and Coracopitta.
Modern treatments of taxa within the family vary as well. A 1975 checklist included six genera, whereas the 2003 volume of the Handbook of the Birds of the World, which covered the family, placed all the pittas in a single genus. Writing in 1998, Johannes Erritzoe stated that most contemporary authors considered the family to contain a single genus. Before 2006 the family was not well studied using modern anatomical or phylogenetic techniques; two studies, in 1987 and 1990, each used only four species, and comparisons amongst the family as a whole had relied mostly on external features and appearances. the Handbook of the Birds of the Worlds HBW Alive checklist, and the International Union for Conservation of Nature (which follows the HBW Alive checklist). A 2013 study found that the red-bellied pitta, a widespread species found from Sulawesi to Australia, was actually a species complex. The study divided it into 17 new species; some authorities have recognised fewer, for example the IOC have recognised only 10. The syrinx is tracheo-bronchial and lacks a pessulus or intrinsic muscles. Pittas are behaviourally reluctant to fly, but are capable and even strong fliers. The tails range from being short to very short, and are composed of twelve feathers.
Unlike most other forest-floor bird species, the plumage of pittas is often bright and colourful. Only one species, the eared pitta, has entirely cryptic colours in the adults of both sexes. In the same genus, Hydrornis, are three further species with drabber than average plumage, the blue-naped pitta, blue-rumped pitta and rusty-naped pitta. Like the other Hydrornis pittas they are sexually dimorphic in their plumage, the females tending towards being drabber and more cryptic than the males. In general the sexes in the family tend to be very similar if not identical. Across most of the family the brighter colours tend to be on the undersides, with patches or areas of bright colours on the rump, wings and uppertail coverts being concealable. Being able to conceal bright colours from above is important as most predators approach from above; four species have brighter upperparts. Several species are lowland forest specialists. For example, the rainbow pitta is not found above . Other species may occur at much higher elevations, including, for example, the rusty-naped pitta, which has been found up to . The altitudinal preferences varies in the fairy pitta across its range, it can be found up to in Taiwan but stays at lower altitudes in Japan.
The movements of pittas are poorly known and notoriously difficult to study. Bird ringing studies have not shed much light on this. One study in the Philippines ringed 2000 red-bellied pittas but only recaptured ten birds, and only one of these recaptures was more than two months after the initial capture. Only four species of pitta are fully or mostly migratory, all in the genus Pitta: the Indian pitta, the African pitta, the fairy pitta and the blue-winged pitta. As well as these four, the northern subspecies of the hooded pitta is a full migrant. Other species make smaller or more local, and poorly understood, movements across small parts of their range,
The pittas are strongly territorial, with territories varying in size from in the African pitta to in the rainbow pitta. They have also been found to be highly aggressive in captivity, attacking other species and even their own; such behaviour has not been observed in the wild. Pittas will perform territory-defence displays on the edges of their territories; fights between rivals have only been recorded once. One such territorial display is given by the rainbow pitta, which holds its legs straight and bows to a rival on the edge of its territory, while making a purring call. Displays like this are paired with calls made out of sight of potential rivals; these territorial calls are frequent and can account for up to 12% of a bird's daylight activity. Migratory species will defend non-breeding feeding territories as well as their breeding ones.
Diet and feeding
upright|thumb|alt= Small collection of broken snail shells next to large root on leafy forest floor|The anvil of a [[noisy pitta, used to smash snails against to remove the shells]]
Earthworms form the major part of the diet of pittas, followed by snails. Earthworms can become seasonally unavailable in dry conditions when the worms move deeper into the soil, and pittas also take a wide range of other invertebrate prey, including many insects groups such as termites, ants, beetles, true bugs, and lepidopterans. Freshwater crabs, centipedes, millipedes, and spiders are also taken. Eight species have been recorded using stones as anvils on which to smash open snails to eat,
Breeding
Like most birds, pittas are monogamous breeders, and defend breeding territories. Most species are seasonal breeders, timing their breeding to occur at the onset of the rainy season.) by the entrance. The nests can either be placed on the ground or in trees. Some species always nest in trees, like both African species, others nest only on the ground, and others show considerable variation. Both sexes help to build the nest, but the male does most of the work. It takes around two to eight days to build a new nest; this probably varies depending on the experience of the birds involved. A new nest is constructed for each nesting attempt, Clutch size may vary within a species depending on latitude. A study of noisy pittas found that birds in the tropics had smaller clutch sizes than those in more temperate environments. The eggs of pittas are slightly pointed at one end, and generally smooth (the deeply pitted eggs of the superb pitta being the exception to this). The size of eggs varies by species, smaller-sized species laying smaller eggs. There is also some variation in egg size within a species in species with large ranges. For example, the eggs of noisy pittas are smaller closer to the tropics. The males and females make regular feeding trips to the chicks; When the chicks are small, prey may be broken up before being fed to the chicks,
Status and conservation
thumb|alt=Illustration of two birds with different plumage|[[Blue-headed pittas (male left, female right) are threatened by rapid deforestation in Borneo]]
Pittas are generally forest birds and, as such, are vulnerable to habitat loss caused by rapid deforestation.
The Gurney's pitta was not seen for 34 years between 1952 and 1986, before a small population was discovered in southern Thailand. This small population declined after its rediscovery, and, by 2000, it had reached a low of 10 pairs, and was listed as critically endangered. In 2003, the species was found in Burma for the first time since 1914, and in large numbers, between nine and thirty five thousand pairs. The species was considerably less threatened than thought, but it is still of considerable conservation concern, as deforestation of the habitat in Burma continues. The rapid rate of deforestation in Borneo has pushed the blue-headed pitta, considered common and secure as recently as 1996, into the list of species considered vulnerable.
Pittas have been targeted by poachers for the illegal wild-bird trade. They are not targeted because of their song, as many songbirds are, and may simply be captured as bycatch from collecting other species, and because of their attractive plumage. According to some trappers, they also may end up being eaten for food. On Manus, locals report that predation by snakes, including the brown tree snake, is responsible for the rarity of the endangered superb pitta, but the snake, the introduction of which is responsible for several extinctions of island birds across the Pacific, is native to the island, and is therefore likely a natural threat.