WHAT IS A PARROT?

Parrots form one of the most distinctive groups of birds despite their variation in size, colour, form and distribution. Their diversity is exhibited by more than 300 species, most of which, including all of the African species, are tropical or subtropical. Perhaps their most distinctive feature is the shape of the bill, with the curved upper extended portion (upper mandible or maxilla) fitting over the lower part (lower mandible). The bill is powerful and has a wide gape with strong musculature, associated with a hinge in the skull. This produces cranial kinesis, a slight flexing movement of the skull, which optimises leverage, for example, when cracking hard nuts. The bill is short and broad-based with a cere around its base. The tongue and jaw muscle structure is complex, variable and highly developed, to extend the great power and control needed in the handling and ingestion of food items. The gizzard is highly developed and muscular to macerate hard plant material.

Another feature characteristic of parrots is their perching grip. The legs are short with granular scales and parrots rest with two toes holding in front of a perch, and two providing support behind (termed zygodactyly). This is in contrast with most birds, which have three toes forward and one back (anisodactyly). Zygodactyly increases parrot mobility, enabling them to climb well in treetops and walk on the ground, as well as to hold and manipulate food proficiently. In trees, parrots move with slow deliberate movements, alternately turning each foot inward to grasp a branch as they move along it, shifting body mass from side to side with each step. During terminal branch feeding in the canopy, they use their bills as an extra foot. Lovebirds are the only African parrots to forage routinely on the ground.

Parrots are often brightly coloured although some are cryptic. The forehead or frons and cheeks (ear coverts) are often conspicuously coloured, particularly in the lovebirds, whereas several of the African (Poicephalus) parrots have colourful epaulettes (lesser wingcoverts) on the angle of the wing and shoulder. A white periopthalmic eye-ring is well developed in several of the lovebirds (Agapornis species) (Figure 1.1). The rump and tail feathers are colourful and conspicuous in many Agapornis and Poicephalus species (Figure 1.2).