PSITTACIDAE Parrots and Parakeets FAUNA PARAGUAY

PSITTACIDAE - PARROTS AND PARAKEETS
Twenty-one species in this pantropical family reach Paraguay, like all Neotropical Parrots they belong to the tribe Arini in the subfamily Psittacinae. The earliest known fossil parrots date back 40 million years to the Lower to Middle Eocene. Taxonomically the parrots are usually placed between the pigeons and the cuckoos but DNA ecidence suggests that they have no close living relatives and similarity of characteristics to other groups may be a result of convergence. Parrots are a relatively homogeneous group with a large number of species for a non-passerine family. It has proved difficult in the past to produce a meaningful classification below family level but the monophyly of the Neotropical parrots is however indicated by common behavioural and morphological characters. The terms "parrot" and "parakeet" are widely understood but of little taxonomic value. In general "parrot" is used for large, short-tailed species and "parakeet" for smaller, longer-tailed species, though in some cases the terms are interchangeable, and for simplicity the generic term "parrot" is used throughout the rest of this account.
Parrots have large heads, short necks and short legs. The skull is broad with a large brain case and the large orbit is either completely or nearly completely ringed with bone. All species have a fleshy cere (though it is sometimes hidden by feathers) which enables the bill to articulate with the skull. Their most distinctive character is the comparatively large, broad-based bill with a steeply downcurved upper mandible, hooked tip and "toothed" cutting edge to the lower mandible. The tongue is fleshy and thick, with a horny epithelium, and well-developed jaw musculature allows gentle manipulation of items in the bill as well as providing impressive crushing power when required. Parrots feed mainly on plant material, some species being highly specialist feeders (eg Anodorhynchus macaws) and others more generalist. The crop is well-developed and the crop muscular. Though many species appear to eat fruit, the flesh is usually discarded and the seed is crushed and eaten, the origin of their description as "seed predators". The tibia is short and feathered and the tarsus is long in comparison covered with granular scales. The feet are zygodactyl, two toes facing forwards and two facing backwards, this giving a powerful grip and enables "hand-like" manipulation of food items. Parrots walk on land with a swaggering gait, in the trees they use the strong feet and bill to climb. There is great diversity in size between the largest and smallest species and in tail and wing length. In general longer-winged, longer-tailed species make longer daily movements than shorter-winged, shorter-tailed species. Parrots in general fly rapidly with fast, shallow wing beats and most species are gregarious. Indeed much behaviour appears to be learned from flock members rather than instinctive and parrots are considered to be amongst the most intelligent of avian families. In some species large flocks may gather at dawn and dusk prior to arriving at and leaving the roost. They usually engage in social activity before settling down to roost with the bill tucked under the wing.
The dominant colour in Paraguayan parrots is green which provides surprisingly effective camouflage in the tree canopy where most parrots feed. The plumage is stiff and sparse, with notable areas of apteria. Some species possess powder down. There is a complete annual moult usually just after breeding. The primaries moult from the centre, starting with the sixth primary and proceeding inwards and outwards simultaneously. The secondaries moult from the outermost to the innermost. Juveniles replace all their feathers in the first year. Vocally parrot calls are harsh, grating and unmusical, producing an unpleasant cacophony of sound when several flock members call at once. Vocalisations are clearly designed for communication over large distances, and most species call mainly when in flight. The peak of vocalisations are in the morning and evening, they are quieter during the day when resting or feeding. Despite their apparent lack of form, vocalisations are species specific.
Parrots have monogamous breeding systems, with larger species pairing for life. Pair bonds are reinforced by frequent allopreening, mutual feeding and other social interactions. The vast majority of parrots are cavity nesters, usually in tree holes, but sometimes burrowing into termite mounds etc. Myiopsitta is unique in the family in building its communal stick nests. No territoriality is shown in this family, though the area immediately around the nest may be defended. Eggs are white, cavity nesters having no need for cryptic colouration. Young are altricial and born naked or with sparse down. Prolonged incubation and fledging periods, delayed maturity and slow growth all add up to a long lifespan. Adult plumage is attained in 1 to 3 years.
The characteristics of the twelve Paraguayan genera are summarised below.

Anodorhynchus "Blue Macaws" - Large to huge with long graduated tail and predominately blue plumage. Naked orbital skin and variable area at base of lower mandible. Incomplete bony orbital ring. Dietary specialists feeding on palm nuts. No sexual dimorphism.

Ara "Typical Macaws" - Large with bare white facial skin showing lines of bristly feathers. Long graduated tails. Bright plumage. Complete bony orbital ring flattened posteriorly. No sexual dimorphism.

Primolius "Maracanas" - Similar to Ara and once included within that genus. Primolius is distinguished by reduced bare facial skin, smaller size and mostly green plumage. No sexual dimorphism.

Aratinga "Aratinga Parakeets" - Medium-sized parakeets with long, graduated tails and broad, heavy bills. Naked orbital ring but rest of head feathered. Bony orbital ring slightly incomplete, the prefrontal process extending back to the postfrontal. No sexual dimorphism.

Nandayus "Nanday Parakeet" - Monotypic genus superficially Aratinga-like. Bill longer than it is deep with notched upper mandible. Cere partly feathered but nostrils exposed. Extensive black on plumage. No sexual dimorphism.

Pyrrhura "Conures" - Small parakeets with long, graduated tails. Bill broad with notched upper mandible. Prominent naked cere and orbital ring. Complete bony orbital ring. Flight extremely rapid and agile, torpedo-like with sudden changes of direction. No sexual dimorphism.

Myiopsitta "Monk Parakeet" - Monotypic genus. Medium-sized with long, graduated tail. Large head with rounded forehead, heavy bill and rounded tip to notched upper mandible. Cere feathered. Incomplete bony orbital ring and narrow auditory meatus. Unique breeding system in parrots, building huge, conspicuous, stick nests. No sexual dimorphism.

Forpus "Parrotlets" - Tiny, stocky and with very short, wedge-shaped tail. Bill large with notched upper mandible. Sexually dimorphic.

Brotogeris "Tui Parakeets" - Small parakeets with a narrow, protruding bill. Long, rounded notch on upper mandible and steeply curved lower mandible. Tail graduated, the Paraguayan species with elongated central tail feathers. Bony orbital ring incomplete with tiny postfrontal process, large squamosal and large mandibular foramen. Powder down and no uropygial gland. No sexual dimorphism.

Pionopsitta "Pileated Parrot" - The Paraguayan species is atypical of the genus and its characteristics are given here. Small to medium-sized, stocky and with short, slightly rounded tails. Wings narrow and pointed (compared with other members of the genus). Bill with inflated base and notch on upper mandible. Prominent naked cere. Sexually dimorphic.

Pionus "Pionus Parrots" - Medium-sized, stocky parrots with short, squarish tails. Robust bill with notched upper mandible and naked cere. Complete bony orbital ring, the prefrontal and postfrontal processes being fused by a strong bar with an abruptly angular lower edge. Powder down and no uropygial gland. Flight flappy and fast, with wings apparently being flapped at the wrist. No sexual dimorphism.

Amazona "Amazon Parrots" - Stereotypical parrots. Large, stocky with robust bills and short, rounded tails. Prominent notch on upper mandible and conspicuous naked cere. Bony orbital ring complete and skull features similar to those of Pionus. Powder down and no uropygial gland. Flight with characteristic rapid, shallow wingbeats of almost straight wings. No sexual dimorphism.

REFERENCES
Campbell B & Lack E 1985 - A Dictionary of Birds - T & AD Poyser.
Collar NJ 1997 - Psittacidae Handbook of the Birds of the World Volume 4 - Lynx Ediciones.
Forshaw JM, Cooper WT 1989 - Parrots of the World 3rd Revised Edition - Landsdowne Editions.
Juniper T, Parr M 1998 - Parrots: A Guide to the Parrots of the World - Pica Press.