VOL. 17 (4) DECEMBER 1997 185 AUSTRALIAN BIRD WATCHER 1997, 17, 185-191 Age-Related Colour Changes and Behaviour in the Ground Parrot Pezoporus wallicus by JOHN COURTNEY, 'Ashgrove' , Swan Vale, via Glen Innes, N.S.W. 2370 Summary Three chicks of the Ground Parrot Pezoporus wallicus, from northern New South Wales, were hand-reared in 1977 as part of a larger project on Australian parrots. These juveniles began to acquire the red frontal band when aged 3 months 1 week, and this process was completed by 4 months. The pink bill and cere of chicks began to grey at 2 months, gradually darkening to the grey of adults at 6 months. Chicks had dark brown irides which gradually lightened to pale brownish white at 6 months. By 3 years of age, the two birds presumed to be males exhibited slight sexual dimorphism in having plain green unstreaked feathers on the throat/upper breast; in contrast, these feathers in females (and juveniles) had a black blotch in the centre. Males had plain pale blue feathers on the underside of the carpus (not examined in a presumed female). These feathers were also plain pale blue on two unsexed nestlings. Males performed a 'shoulder-squaring' courtship display typical of platycercine parrots, but did so on the ground. They also performed a vigorous 'body-bouncing' display while perched. The species is partial to water-bathing and sun-basking. Courtship-feeding was confirmed. The method of head-scratching is 'over the wing'. Males also had an unusual ritualised fighting method. Except for courtship-feeding, no physical contact between individual Ground Parrots was observed. The birds roosted apart at night, usually on the ground, but sometimes perched. All activity was diurnal. Introduction Although the Ground Parrot Pezoporus wallicus is difficult to observe in the field because of its shy behaviour, cryptic plumage and preference for dense ground cover (Gosper 1995), its basic biology is now well known (e.g. Meredith et al. 1984; Jordan 1987, 1988; McFarland 1988, 1991a,b). However, many aspects of colour changes and behaviour from chick to adult have remained unrecorded because of the difficulty of observation in the field. This study, using hand-reared captive birds, attempts to redress these deficiencies. Lendon (1973) observed that data are non-existent on courtship-feeding, water-bathing, age of acquisition of red frontal band, and method of head-scratching. As much of this previously unknown information was obtained when observing the individuals in this study, the results are presented to supplement information on the life-history of the species. Methods The three young Ground Parrots of this study originated from the north coast of New South Wales, and thus belonged to the nominate race wallicus of the eastern Australian mainland. When hand­ rearing began on 18 September 1977, the chicks' remiges (secondaries) were 10 mm long. On the evidence of Hodges (1961) they were estimated to be 12 days old. Rearing of an unrelated fourth young, estimated to be two days older than the other chicks, began on 3 October 1977, and a further two wild nestlings were subsequently examined. This study was the continuation of the project outlined in Courtney (1974), and was an extension of the study by Courtney (1997). Results Colour The nestlings in this study (see photo in Low 1986) and those observed by Hodges (1961) had pink bills. Their bills began to darken at about 58 days old, and gradually became the grey of adults at six months old. Initially their ceres were also pink. This paled to creamy white as their beaks began to darken, then gradually became grey over the same period as the mandibles darkened. AUSTRALIAN 186 COURTNEY BIRD WATCHER The nestlings had dark brown irides that gradually paled, becoming pale brown with underlying white, at six months of age. The flesh-coloured feet and legs of juveniles and adults were faintly tinged with grey, a feature previously noted by Serventy & Whittell (1962). This is a condition considered unusual in parrots (Smith 1975). The usual brown appearance oflegs (e.g. Forshaw 1981) seems to be an illusion created by dust and dirt, for their legs appear almost flesh-coloured after bathing in water. At about 100 days" old, all three young remaining (one of the original brood died) had acquired a small (c. 1-1.5 mm diameter) patch of red feathers immediately above the natural division in the centre of the cere. Previously, the feathers in this region were green and black. Twenty days later their red frontal bands appeared complete, having spread outwards from the centre. By three years of age, when they started performing courtship behaviour, two of the three Ground Parrots (thought to be males) differed by having the throat and upper breast plain green. The age of acquisition of the plain green feathers was not determined precisely. In contrast, the third individual (thought to be female) had the feathers of the throat and upper breast green with narrow black centres along the shafts, giving them a streaked appearance; this condition persisted until the bird died at about four years old. These feathers closely resembled those evident in a photograph by J. Gray (in DeJose 1989) of a presumed female brooding nestlings in the wild. A Ground Parrot incubating eggs (Evans Heac!, N.S.W.) that was killed and eaten on the nest by a Grass Owl Tyto capensis, leaving only the head and throat, also had green feathers with black shaft-streaking on the throat (pers. obs.). Two unsexed nestlings had black­ blotched throat/upper-breast feathers; the black was more pronounced than on the presumed adult females discussed above. In the two adult males, most feathers on the undersurface of the carpal joint were pale blue, along with a few scattered green feathers. This was discovered when one individual was observed making the typical platycercine 'shoulder-squaring' courtship display, which is thought to display the blue colour-patch beneath the carpus (e.g. Lendon 1973, Smith 1975). Two wild nestlings, subsequently examined, had similar plain pale blue feathering beneath the carpus. The feathering in this region was not recorded for the presumed adult female. Nestlings have remiges resembling those of adult Ground Parrots. The secondaries have two yellow spots, and sometimes a small third spot is present on the rear vane. The primaries have a single spot on the rear vane, corresponding to the 'wing-stripe' of most platycercines. In most primaries, and some secondaries, a pale triangular patch ('toothing') is present on the frontal vane (Schodde & Mason 1980). Some secondaries closest to the body have multiple 'toothing'. Behaviour Unlike most other parrots, Ground Parrots can run at varying speeds, at least as quickly as gamebirds of similar size, and appear not to bound like many platycercine parrots do. When running at top speed around an aviary, their legs become a blur to the human eye. They readily climb aviary netting (contra Lendon 1973), grasping alternately with beak and feet, moving up or down at an angle, and descending tail­ first. They also climb into bushes and tangles of fine branches, perching competently. When large bunches of green seeding grass were placed in the aviary, the parrots usually clambered up onto the unstable mass, rather than standing on the ground to feed . When climbing about, their long claws appeared to act as extensions to the toes, helping to prevent their feet from falling through between the stems. Their long legs VOL. 17 (4) DECEMBER 1997 Morphology and Behaviour of Ground Parrot 187 enabled them to step up onto tussocks with minimal effort. Sometimes when feeding on the ground, they reached above their heads with one foot to pull down seeding grass within reach of the bill. They held entire seed-heads in the foot while eating, never single large seeds as other parrots often do. These parrots were ambidextrous, an unusual trait in parrots. Close observation showed that the foot chosen to pick up a fallen seed-head happened by chance: it was simply the foot not supporting the body weight at the time of nearest approach to the object. When the parrots were eating, their pupils suddenly contracted greatly when the tip of the bill approached within 1 em or so of the food item. This action appeared to be connected with close focusing of the eyes. Courtship-feeding was confirmed in the Ground Parrot when, at the age of almost three years, one presumed male was seen to make preliminary head-bobs, then regurgitate with gentle head-bobbing into the slightly up-turned beak of the presumed female. No food-soliciting call was uttered, in contrast with the behaviour of adult female Budgerigars Melopsittacus undulatus which vocalise like juveniles when food­ soliciting (Wyndham 1980). Ground Parrots drink unhurriedly by immersing the partly opened but immobile mandibles and rapidly pumping the contained tongue up and down. The head is lifted up and down from the water a number of times, but never tilted back like cockatoos. In comparison, Budgerigars drink in a different way by immersing the bill once only and rapidly opening and closing the mandibles, then flying off (pers. obs.). The Ground Parrots were observed water-bathing at least daily, during which they squatted deeply in the water, dunked the head and vigorously flapped the wings in similar fashion to rosellas Platycercus. The species also sun-basks, and is extraordinarily partial to and tolerant of solar radiant heat, more so than any other parrot encountered in this and related studies (Courtney 1997 and relevant references). The Ground Parrots were frequently observed lying stretched out on one side, with uppermost wing fully extended over the legs in typical platycercine posture, in high midday summer temperatures which caused stress to other parrots in aviaries nearby.