Pittas

(Pittidae)

Size

Number of genera, species

1 genus; approximately 30 species

Feeding Ecology

Distribution

Primarily southeastern Asia, including Indonesia, China, Japan, and India; Australia; West and East Africa

Distribution

Primarily southeastern Asia, including Indonesia, China, Japan, and India; Australia; West and East Africa

Evolution and systematics

Original taxonomic treatments of the pittas led to their inclusion in the crow family, and subsequently in the thrush family. It was not until the early 1800s that the pittas were designated as a distinct family and correctly classified as sub-oscines. More recently, DNA hybridization and morphological analyses have convincingly demonstrated Pittidae is monophyletic and a sister taxon to the broadbills of Africa and Asia.

Although classification at the family level is widely accepted, there are conflicting opinions regarding the appropriate number of genera and species. Although as many as six genera have been proposed, and preliminary estimates of genetic divergence support these distinctions, most authors have chosen to recognize only the genus Pitta. Recent taxonomic treatments recognize 29-31 species. This number will undoubtedly change as molecular methods generate a better understanding of the evolutionary history of the Pittidae.

Physical characteristics

Secretive and rarely seen, pittas are often described as "jewels of the forest" on account of their brilliant plumage coloration. Many species are characterized by patches of red, green, purple, black, white, chestnut, and turquoise, often adjacent and sharply contrasting. In many cases these colors are on the breast, chin, or on areas of the body that can be con cealed by more drab-colored wing feathers, presumably in an attempt to avoid detection by predators. In most species, females and males share these brilliant colors. Cryptically colored females occur in 11 species, and in only a single species is cryptic coloration shared by males and females. In contrast, nearly all juvenile and immature birds are cryptic.

Pittas have round bodies, large heads, long legs, and short tails. These features reflect the terrestrial habits shared by all pittas. The pittas are also strikingly similar in size, with most species measuring about 8 in (20 cm) in length. Pittas have stout bills, often hooked at the tip, not unlike the bills of many thrushes (Turdidae).

Distribution

Pittas occur in Asia, Indonesia, Australia, and Africa. The greatest diversity of species is found in peninsular Malaysia, Borneo, Sumatra, and Java. Only a single species is found throughout most of India, two species occur in Africa, and only two species occur regularly in Australia.

Habitat

Most pittas are found on the ground in tropical rainforests. In many cases they appear to prefer areas that are moist, often near rivers or streams or in shaded ravines, with a rich layer of leaf litter in which to forage. Some species occur in

Pitta nest. (Illustration by Michelle Meneghini)

moist, montane forest up to elevations of 8,200 ft (2,500 m), but the majority of species are found near sea level. In Australia these birds use monsoon and eucalypt forest, and in Africa they inhabit rainforest and drier bush and woodlands. Although they avoid open habitats, a number of species are relatively tolerant of habitat modification, persisting in degraded forest, forest fragments, and secondary forest.

Behavior

Pittas are secretive birds, uncommonly encountered, and difficult to observe in the poor light and dense vegetation of the forest understory. As a result, there are few behavioral observations for the majority of species. With the publication of Pittas, Broadbills, and Asities, by Frank Lambert and Martin Woodcock in 1996 and Pittas of the World, by Johannes Errit-zoe and Helga Boullet Erritzoe in 1998, there is now a solid foundation synthesizing the information from what few species have been studied and highlighting the large gaps in our knowledge that remain.

Pittas are found alone or in pairs and are territorial. Territories may vary widely in size depending on the species and habitat; African pitta (Pitta angolensis) territories may be as small as 0.75 acre (0.3 ha), rainbow pittas (Pitta iris) defend areas larger than 2.5 acres (1 ha), and for some species only a single pair may be found in an area as large as 50 acres (20 ha).

Pittas give short calls, usually one, two, or occasionally three syllables, which can be either whistled or buzzy. The role that these calls play in territorial defense is evidenced by the fact that many species can be drawn out of dense vegetation by playing a recording of their call. In a natural setting, such a response may lead to encounters between males on adjacent territories. For rainbow pittas and elegant pittas (Pitta elegans) biologists have described displays in which males from adjacent territories face off and perform bowing displays sometimes in conjunction with "purring" vocalizations.

When approached, a number of species give alarm calls in conjunction with distraction displays, such as flashing a conspicuous white patch of the wing, spreading the tail, or fanning out the bright feathers of the breast. In other cases threats are responded to with behaviors that may reduce con-spicuousness, in which species lower their brightly colored breasts to the ground and remain motionless.

Most pittas are nonmigratory or make local movements outside the breeding season. However, Indian pittas (Pitta brachyura), blue-winged pittas (P. moluccensis), and fairy pittas (P. nympha), as well as a subspecies of the African pitta (P. a. longipennis) and populations of hooded pittas (P. sordida) and red-bellied pittas (P. erythrogaster) are migrants. Although most species migrate over land, it is believed that the fairy pitta may fly nonstop from Vietnam across the ocean to Borneo, a flight of approximately 620 mi (1,000 km)! Given the short, rounded wings of pittas, it is somewhat surprising these birds make long migratory flights.

Feeding ecology and diet

Pittas forage terrestrially, hopping along the forest floor, sometimes remaining motionless to search for exposed invertebrates, sometimes searching noisily through the leaf-litter or digging in the soil for earthworms. The primary food items are invertebrates, including spiders, a wide variety of insects, snails and slugs, and annelid worms. Some of the larger species may also take small vertebrates, including small frogs, snakes, and even mice. Seeds have also been found in the stomachs of several species, but whether fruit is regularly consumed or simply eaten from the forest floor after it is infested with insects remains unknown. Using stone "anvils" for smashing snails to remove the shells has been observed in at least six species.

Earthworms figure prominently in the diets of many pittas, especially during the nesting season. In Australia, the diet of the rainbow pitta varies seasonally; earthworms comprise most of the diet during the wet season, while other invertebrates are more important during the dry season.

Reproductive biology

Almost all pittas breed seasonally, with breeding timed to coincide with the onset of the rainy season. An exception to this pattern is the superb pitta (Pitta superba), which apparently nests throughout the year on the island of Manus. In most species there are relatively few unique displays prior to copulation, and most pittas probably are monogamous. However, the African pitta performs a unique display prior to the breeding season. During display bouts, this species repeatedly jumps about 10 in (25 cm) into the air, parachuting back to the perch with several shallow wing-beats. During this display the red belly is prominently displayed and the birds often give a "prrt-wheet" vocalization.

The domed nest typical of the pitta family is the size and shape of a "rugby football." Both the male and female par-

Pitta Moluccensis
A blue-winged pitta (Pitta moluccensis) suns itself. (Photo by R. & N. Bowers/VIREO. Reproduced by permission.)

ticipate in the construction of this bulky nest, which is loosely built leaves and twigs, often on top of a platform constructed of larger sticks. Although this "sloppy" construction may decrease the durability of the nests, it has been hypothesized that it may also decrease the ease with which they are detected by predators. The entrance to the nest is through a hole in the side, often facing out onto a path or other opening in the vegetation. The interior of the nest is lined with fibers or finer leaves. The nest may be located on the ground or 3-50 ft (1-15 m) above the ground in a tree or small bush. Ground nesting species often build a "door mat" of fine twigs, but the door mat built by the rainbow pitta is often constructed of mammal dung.

Clutch size varies from two to six eggs; most species lay three to four eggs. The incubation period lasts 14-16 days. For most species that have been observed, both the male and female share the task of incubation. The eggs apparently hatch asynchronously. The altricial young hatch naked, blind, and with limited mobility. The male and female share the tasks of brooding and feeding the young.

The young fledge from the nest after only 11-17 days, at which time they are usually already able to fly. They continue to be fed by the adults, usually for a week to ten days, but this period may last up to a month.

Conservation status

Many pittas have restricted ranges and depend on forested habitats that are rapidly being cleared. Additionally, the bright colors of these birds have made them popular cage birds and they are also popular targets of hunters in many parts of the world. As a result, there is considerable concern about the population viability of many pitta species. The most seriously threatened species is Gurney's pitta (Pitta gurneyi), which is considered Critically Endangered. It was added to Appendix I of CITES in 1995. Additionally, eight other species have been recognized by the IUCN and BirdLife International as Vulnerable: Schneider's pitta (Pitta schneideri), superb pitta, azure-breasted pitta (P. steerii), whiskered pitta (P. kochi), fairy pitta, black-faced pitta (P. anerythra), graceful pitta (P. venusta), and blue-headed pitta (P. baudii). Of these, whiskered pittas are listed in Appendix I of CITES and fairy pittas and banded pittas (P. guajana) are listed in Appendix II. Four species are designated as Near Threatened—the giant pitta (P. caerulea), Sula pitta (P. dohertyi), garnet pitta (P. granatina), and mangrove pitta (P. megarhyncha). Effective conservation of these species depends on habitat preservation and protection from hunting and trapping. Although this may seem an impossible task, an increasing awareness of the shrinking population of Gurney's pitta has begun to shift the economic value of this species away from illegal trade toward conservation-based ecotourism that relies on habitat preservation. Perhaps this widely publicized project can serve as a model for the protection of other threatened pittas.

Significance to humans

Their bright colors have made pittas popular birds in the wild bird trade. Pittas have also been hunted for food. This has probably been most extensive along migratory routes where pittas can be captured in large numbers, often with snares that are set in the vegetation. More recently, the growing popularity of bird-watching and ecotourism has lead to an increased interest in these species.

Indian Pitta Cage

1. Hooded pitta (Pitta sordida); 2. Indian pitta (Pitta brachyura); 3. Superb pitta (Pitta superba); 4. Graceful pitta (Pitta venusta); 5. Gurney's pitta (Pitta gurneyi); 6. African pitta (Pitta angolensis); 7. Rainbow pitta (Pitta iris). (Illustration by Michelle Meneghini)

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