VOL. 19 (4) DECEMBER 2001 127 AUSTRALIAN BIRD WATCHER 2001, 19, 127-128
Water-begging in the Juvenile Gang-gang Cockatoo Callocephalon fimbriatum
IAN ENDERSBY and MARGARET ENDERSBY 56 Looker Road, Montmorency, Victoria 3094
Introduction The breeding season of the Gang-gang Cockatoo Callocephalon fimbriatum is usually October to January although some records extend the season a little earlier or later (Higgins 1999). In the wild, the young leave the nest about eight weeks after hatching and are fed by the parents for a further four to six weeks (Forshaw 1991). The only published exception to this pattern is an observation by Metcalf (1984) of a young bird being fed in July and August in Canberra. Metcalf attributed this to either an out-of-season breeding event or to the young being taught to forage in species of exotics. Gang-gang feeding is predominantly arboreal with birds coming to ground only to drink or to examine fallen nuts or cones (Frith 1976). Both male and female feed nestlings and fledglings by regurgitation (Higgins 1999). Young Gang-gangs bob their heads up and down in an irregular fashion, on outstretched necks, when soliciting food (Courtney 1996) and give a food begging call and a food-swallowing vocalisation (Higgins 1999). Typical Gang gang begging calls have been recorded by Buckingham & Jackson (1988).
Methods Water-begging in the juvenile Gang-gang Cockatoo was recorded during regular observations in a suburban garden in Montmorency, Victoria, between 7 July and 2 August 2000. On each occasion we were alerted to the activity by the begging calls of the young. Birds were watched through a window at distances of less than 5 metres, and lighting was good in each case. Begging and response occupied less than 15 minutes. Birds feeding 10 metres above the ground in the canopy of a eucalypt were observed with 7x50 binoculars and checked regularly over a four-hour period.
Observations
7 July A male and a female Gang-gang Cockatoo drank from a bowl at ground level, alternately dipping and then raising their heads. A young bird, with a red crest starting to emerge, was on a branch above the bowl. It begged by pumping its wings up and down while squawking rhythmically. The female fed it by regurgitating material that was, most likely, water.
1 August 1620 h. A male Gang-gang drank water from the ground-level bowl and then regurgitated the contents of his crop to a begging juvenile in the tree above. The female then drank from the bowl and she also provided the contents of her crop to the begging young bird. ENDERSBY & ENDERSBY: AUSTRALIAN 128 Water-begging in Juvenile Gang-Gang BIRD WATCHER
2 August 1230 h. Three Gang-gangs were once again observed and were presumed to be the family group seen on the previous two occasions. They commenced feeding on the fruit capsules of a Sugar Gum Eucalyptus cladocalyx, and were observed for over four hours; no begging calls were heard during that time, and all three birds continued to f~ed individually.
Discussion The young male Gang-gang was well-fledged and quite capable of feeding by himself. He was observed feeding on the fruit or seeds of a eucalypt for several hours without seeking food from his parents by begging behaviour. However, he did, on more than one occasion, solicit and was given water by each parent. Careful attention to Metcalf's (1984) account suggests that this late-season feeding event may have been regurgitation of water rather than of food: ... she flew to the bath, drank, and then went to sit close to the juvenile. The juvenile began a grumbling begging call and sidled up to the female, opened its beak over hers and, still calling, began to receive food from her for five seconds. The female appeared to terminate this exercise. They sat apart for two minutes before beginning the whole process again and again until the fourth occasion when the young was rebuked. This description implies that the young received water from the parent even though Metcalf used the word 'food'. Our observations, and those of Metcalf (1984), are consistent with juvenile Gang-gang Cockatoos becoming independent of their parents for arboreal feeding within a few weeks of fledging. However, the much more risk-prone activity of coming to the ground to drink could well be delayed until the birds are more experienced. Hewish (1986) noted a family of two adults and a juvenile male coming to a garden pond to drink late in the day in late April and described the approach of the juvenile as 'cautious'. Additional observations of the feeding and drinking behaviour of Gang-gang family groups between April and September are needed to determine whether late-season begging is primarily for food or water, and whether juveniles avoid the risk of feeding or drinking on the ground in their first season.
References Buckingham, R. & Jackson, L. (Eds) (1988), A Field Guide to Australian Bird Song, Cassette 4, Sooty Tern to Superb Parrot, Bird Observers Club of Australia, Melbourne. Courtney, J. (1996), 'The juvenile food-begging calls, food-swallowing vocalisation and begging postures in Australian cockatoos', Australian Bird Watcher 16, 236-249. Forshaw, J.M. (1991), Australian Parrots, 2nd edn, Ure Smith, Sydney. Frith, H.S. (Ed.) (1976), Reader's Digest Complete Book of Australian Birds, 1st edn, Reader's Digest Semces, Sydney. Hewish, M. (1986), 'Records of Gang-gang Cockatoos in Bacchus Marsh in 1985/6', Geelong Naturalist 23, 16-19. Higgins, P.J. (Ed.) (1999), Handbook of Australian, New Zealand and Antarctic Birds, vol. 4, Oxford Vnivers1ty Press, Melbourne. Metcalf, E.C. (1984), 'Gang-gang Cockatoos', Canberra Bird Notes 9, 29-30. Received 12 June 2001 •