The Cape parrot (Poicephalus robustus) is recognized as Critically Endangered in South Africa, and there are only about 1,000 to1,500 birds in the wild today, representing the entire global population. Their numbers have decreased historically, and their habitat has been fragmented or lost. This is particularly significant because they are habitat specialists, dependent on Yellowwood (Podocarpus) Afromontane forests for both their food and nest sites.
Cape parrots mature late, might not breed each year and raise few chicks to adulthood, so recovery from any further natural or artificial disaster is questionable. Because Yellowwood forests in key areas of the parrot? distribution are sparse and have a young age structure, there will be little natural regeneration to climax forest communities for many decades.
Without habitat preservation, the Cape parrot is doomed to extinction in the wild and, being a mobile species, protecting a single or few local Yellowwood forests is inadequate; a large mosaic of areas supporting a meta-population is necessary. Such forest reserves would conserve many other species of animals and plants and aid ecotourism, education and the sustainable use of natural products.
Many natural nest sites are essential because Cape parrots rarely nest in artificial nest boxes, thus the preservation of old Yellowwood trees, where the birds nest naturally, is critical.
Natural predation appears to be low on adult Cape parrots but this is difficult to quantify. Nevertheless, it is essential that human predation (poaching) be eliminated and illegal trade stopped. The prevalence of psittacine (parrot) beak and feather disease (PBFD) in captive and wild Cape parrot populations has to be assessed rigorously because PBFD might be the single most critical factor threatening the survival of the species. Research into a vaccine against PBFD is ongoing but expensive.
Cape Parrot Behaviors
Cape parrots are diurnal with activity commencing at sunrise and lasting for a few hours before rest at midday. Activity then recommences for a few hours until sunset. Its timing changes seasonally with day length; however, bad weather, including snow, mist or hot berg winds, does not prevent activity. The birds are more active on cool, misty days.
These parrots are characterized by their monogamous pairing, but gregarious flocking behaviors, and most are very vocal. They have a distinctive vocal repertoire comprising five elements described as tzu-wee, zu-wee, zeu-wee, zz-keek and a nasal zeek. A raucous alarm call, which has a rasping tone with many harmonics, is given by startled/threatened birds. Adult and juvenile birds threatened in the nest give an aggressive succession of zeeks, which become a continuous growl.
Individuals occasionally chirp when settling on a snag or canopy tree while sunning, preening or feeding. Male-female pairs at the nest are usually quiet, chirping infrequently. In flight, however, Cape parrots are quite vocal; calling before taking off and calling continuously while flying.
Cape parrots preen during drizzle or sun in the early morning before and after sunrise. Birds usually preen for a few minutes when perched on exposed branches near snags. Allopreening, particularly around the crown, neck and throat, is sometimes followed by bill-rubbing.
Preening birds might vocalize with small chirps, rattle their feathers and then stretch their shoulders back before scratching the head, especially below and behind the eye. The backward extension of the shoulders and wings is referred to as the archangel display. A high-pitched screech can be associated with the display. Stretching behavior is accompanied by wing flaps and tail wags, which are also included in male-female courtship displays.
A typical Cape parrot male sequence comprises a quick wing raise on arrival at a snag, then stretching of the wing (right then left) over a tail extension, followed by stretching of the leg, rattling of the feathers, then looking around before half wing raising along with a tail wag.
Alternatively, males will give a tail-wag with the wings back then do a wing extension followed by a head bob and a mandible rattle. The female responds with a wing stretch followed by a right-wing or tail stretch, in which the wing is extended over the tail, and then the wing is placed on the bird? back facing. The male responds with a wing flap, a tail wag, and then a wing extension.
Cape parrots perch on the top branches of snags or in the crowns of emergent forest trees, particularly Yellowwoods. Yellowwood trees are important for breeding, feeding and social interactions. Roost sites are usually emergent snags or trees in the forest.
During the middle of the day, parrots sleep or rest in Yellowwood or stinkwood trees just below the canopy. They sleep with their feathers fluffed out, especially on the neck, the eyes closed and the head turned and tucked into the shoulder. When not resting, they walk along branches with the aid of the beak, hanging upside down from a branch, holding on with a leg, or hopping among branches.
Social behaviors include chasing, snapping, diving, tussling with beaks, regurgitating and feeding one another, perching and playing or vocalizing. Family groups fly and move about in the trees, with juveniles chirping; they then might hang upside from branches, chew branches and move between them. Birds appear and then disappear in the foliage.Typically, in the early morning after sunrise, a Yellowwood tree can contain a flock of 15 parrots in its crown, layered throughout the canopy. Occasionally, a single bird displaces another bird of the same sex, and juveniles duel with their beaks, chasing others off branches until the other bird retreats or flies away.
Cape parrots are strong fliers. When flying between forest patches, they fly high in small flocks or in pairs, and occasionally as singletons. Above the forest canopy, they wheel and swerve before slowing to settle, feed or socialize. Circling is the most common flight pattern, with birds flying out from snags or trees before returning to perch. When startled, birds take flight, sometimes darting through trees while squawking or screeching loudly.
Cape parrots interact with Rameron pigeons whose movements and foraging behaviors are closely matched.They occasionally interact with Knysna Louries or Trumpeter Hornbills foraging in fruiting trees. African Goshawks sometimes chase Cape parrots; Lanner falcons, too, but less so. The parrots, however, are evasive, and shriek and squawk loudly.
Feeding Biology Of The Cape Parrot
Cape parrots are food nomadics, moving between forest patches in search of food, occasionally making longer foraging forays to coastal forest. Fruiting of trees in Afromontane forests shows that there are a few dominant species (e.g. Outeniqua Yellowwood, the True Yellowwood and the Corkwood), and that fruiting unpredictably results in patchy production, particularly during late spring and summer.
Cape parrots feed on the kernels or endocarps of a variety of forest fruit but primarily eat the fruits of Yellowwood species. Dietary diversity is always low, and Outeniqua and True Yellowwoods are the major food items. The parrots are very efficient at accessing the kernels of Yellowwood fruits. Seasonal changes in diet reflect the changing availability of Yellowwood species, when other fruits are eaten because Yellowwoods are unavailable. Cape parrots occasionally feed on the fruits of introduced species, including some exotic and commercial tree species.
The parrots usually feed in single-species flocks, often in one Yellowwood tree, for extended periods. Cape parrots are specialized for exploiting Yellowwood fruits, using their heavy, robust bill for extracting kernels from the fruits. They access them while still unripe and unused by other frugivores. Benefits of these fruits, particularly those of the Outeniqua Yellowwood, include extended fruiting periods, high fruit yield and high-energy and fat content. Kernels of Outeniqua Yellowwood have the largest and most rewarding fruits and are four times heavier than the next most profitable fruit.
Birds drink during the morning activity period often at a regular drinking site. Several birds might drink together, but each drinking session is brief, with birds flying down to drink for no longer than one minute before returning to perch in cover. Occasionally, the parrots drink from hollows in a Yellowwood tree. Beak wiping or cleaning by rubbing the beak on a branch is observed regularly.
Breeding Biology Of Cape Parrots
Cape parrots are secondary cavity nesters, showing striking hatching asynchronies (the staggering of development between chicks within a clutch). They are also characterized by delayed maturity, small clutches, high parental investment and fledging only a few offspring. Breeding success of Cape parrots is affected by the availability of very old trees, especially those showing signs of senescence, which provide nesting sites. These trees are increasingly scarce with continued exploitation of Yellowwood forests.
From March to December, Cape parrot pairs show socio-sexual behavior. This includes allopreening (preening the mate, particularly the head), courtship with a wing display, courtship feeding and mating attempts. Copulation is a highly ritualized behavior pattern occurring well before and long after egg laying, which maintains the pair bond.
Courtship prior to copulation involves several behaviors including switch-sidling displays, wing displays, head bobbing, similar to the behavior used when regurgitating food and courtship feeding. There are intermittent archangel displays in which the orange-red of the underwing is displayed by both sexes, with duetting between the pair. The male Cape parrot usually regurgitates food to the female. Pairs nibble at one another? beaks, rub shoulders and sometimes copulate. Pairs are very affectionate.
Until 1994, there were only two nest records for Cape parrots; now there are many, predominantly in natural holes or snags in dead emergent canopy trees. The primary function of the nest site is to provide safety from predators, but it also contributes to the insulation of eggs and warmth for chicks. Most are in Yellowwood trees, which remain standing long after death and often have holes in the trunk where branches have broken away and are occupied on consecutive years. Suitable nest sites are limiting because of the relatively low abundance of primary cavity-nesting species (e.g. olive woodpeckers) and because of competition with Trumpeter Hornbills. No known nest sites have been located less than 1 kilometer of Afromontane forests.
Usually three or four eggs are laid between April and August (although eggs have been laid in other months), and they incubated for 28 to 30 days. Chicks solicit food by chirping continually and are fed by both parents. Nestlings have a distinct egg tooth and are soon covered with a sparse white down, which later turns to yellow. At 15 days, pin feathers appear on the chick? foreheads, and at 35 days green tail feathers brake free of the quills. When chicks emerge from the nest, each resembles an adult female in coloring, except for a coral pink forehead, which develops later. Changes in juvenile plumage include the appearance of a brick-red color on the forehead, which disappears at about five months and is replaced by bright red in females.
The parents are cautious and vigilant when flying off from the nest site, and as the chicks grow they appear at the cavity entrance giving zeek-zeek calls. Pairs usually give loud squawk calls when returning to the nest, and both may enter the nest hole to feed chicks.
The first nestling fledges at nine to 10 weeks, and the first molt begins at five to seven months. After fledging, chicks remain together with their parents and continue to be fed, playing with siblings and nibbling at fruit. Fledglings and adults communicate vocally. Young Cape parrots are fed almost entirely on Outeniqua Yellowwood fruits since the kernels of the fruits are high in fat and energy compared with other available forest fruits, which may restrict the duration of the breeding season. Juvenile Cape parrots remain in their nest locality for a few months following fledging but then integrate with adult flocks and participate in inter-forest movements.
Captive Cape Parrot Breeding
Captive breeding of Cape parrots is necessary to prevent pressure on the natural population from illegal trade, and it aids in education. It has been facilitated by advances in nutrition, disease prevention and hygiene. The captive population is small because there are few compatible and productive pairs and due to the mortality caused by PBFD.
The captive breeding program should not, however, be relied on to guarantee the viability of the wild population. Indeed, one should question the principle, purpose and morality of conserving a species entirely in captivity. Nevertheless, the Cape parrot stud book should be mandatory to facilitate productivity and outbreeding while preventing hybridization and disease transmission.
Cape Parrot Numbers
The numbers of the Cape parrot have declined greatly in the past 50 years, particularly in the Eastern Cape, including Transkei, less so in KwaZulu-Natal (KZN) and little in the Mpumalang-Northern Province, where the species has always been scarce. Absolute densities using total mapping provide the most reliable indicators of population abundance. All Afromontane and coastal forest patches in the range of the Cape parrot have now been monitored for 10 years. There are about 1,000 Cape parrots in the wild, but not all of these comprise compatible breeding pairs.
At most forests, the presence and numbers of Cape parrots is unpredictable, however, regular sightings of pairs are associated with a nest locality or a seasonal fruit supply. In optimal habitat, total numbers are highest in winter and represent the resident breeding group, and lowest in spring and early summer, when the birds are dispersed. Groups of two to four birds are observed most, probably pairs or family groups, and larger flocks (of less than 10) are usually concentrated at roost sites, water points or fruiting trees and represent aggregations of smaller groups.
Annual variations in the numbers of Cape parrots reflect environmental changes caused by weather conditions and food availability. Distributional data show that the population is contracting in its range and that numbers are probably too low to recolonize peripheral forest patches of suitable habitat. Although Cape parrots have good dispersal abilities, the nature of the matrix surrounding the forest fragments, and the probable need for social learning of the temporal and spatial scales of food availability, further reduces the likelihood and efficacy of re-colonization.
For more information, go to the Cape Parrot Project website.