Filling in the Gaps the Breeding Biology of Palm Cockatoos on Cape

PsittaScene, May 2001 2/1/02 12:50 PM Page 2

Filling in the gaps The breeding biology of Palm Editor Rosemary Low, Cockatoos on Cape York Peninsula P.O. Box 100, by STEVE MURPHY Mansfield, Notts., United Kingdom As I sat in the tropical savanna of Palm Cockatoos, breeding involves actually started with the first NG20 9NZ far northern Queensland, sweat an extremely long lead up time of rains of the wet season. I think beading on my brow, I knew it complex courtship displays and that this lack of concordance is wouldn't be long before the show never-ending vigilance for due to a small number of CONTENTS would start. Even though I'd been potential rivals. Even then, after all observations of what can be a protracted breeding season. This Palm Cockatoo...... 2-3 working in the area since mid- the lead-up time, it seems that the morning, I hadn't yet heard so odds are stacked against them.... arises from a long incubation and Echo Parakeet...... 4-5 much as a peep. But then, right on Our knowledge about Palm nestling period (about four Golden Conure Fund...... 6 time, something went whooshing Cockatoos in the wild has months) and the ability of pairs to by above my head. Something that lay again after a failed attempt. I Buffon’s Macaw Fund...... 7 suffered from a large and sounded like someone narrowly enigmatic void for a long time. have found that Palm Cockatoos Grey Parrots...... 8-10 missing me with a big leafy Even the most basic biological are loosely seasonal breeders, Palm Cockatoo Fund branch. And then, there in front information, vital to our with most laying occurring Launch...... 11 of me, on the rim of a hollow in a understanding and future around August, but because huge paperbark, landed a management of these threatened individuals can re-attempt after Breeding for magnificent male Palm Cockatoo. I nest failure, breeding can trickle Conservation ...... 12-13 birds, is surprisingly poor. Take had been watching this particular the question of breeding season. on throughout the year. This Carnaby’s Black Cockatoo13 tree hollow for the past week in In the past nobody could agree on accounts for the fact that I have Lilac-crowned Parrot ..14-15 an attempt to piece together the exactly when these cockatoos detected breeding in every month behaviour leading up to a of the year on Cape York. Psitta News...... 16-17 breed in the wild. Some thought breeding attempt. The male sat that young usually left the nest by Like breeding seasonality, the Members List...... 18 there whistling, wing spreading the beginning of the wet season preferred breeding habitat of WPT Info Page...... 19 and stomping his left foot. Shortly (around December). By contrast, these cockatoos was also debated. after, a female arrived and the others suggested that breeding Some thought that breeding Parrots in the Wild ...... 20 pair bowed their heads to one another, presented their brilliant scarlet cheek patches and synchronised their calls in an impressive courtship display. Within the next few minutes, several more males arrived in the area and all started trying to out- do one another with more ear- splitting calling. This was obviously too much for the resident male who promptly attempted to round up all his Cover Picture rivals. One clash with a Once again we are indebted to Roland and Julia Seitre for an particularly stubborn interloper outstanding photo on our front ended in a cloud of black feathers cover. We had thought there as the two males tumbled to the were simply no good shots of ground. Once the last of the Palm Cockatoos in the wild, intruders was seen off, the but the Seitres had it covered! resident rejoined his female and The World Parrot Trust does not got down to business again. necessarily endorse any views or statements made by contributors Although I had seen male-male to PsittaScene. conflict before, this particular It will consider articles or letters afternoon turned out to be one of from any contributors on their the most impressive of these merits. displays that I have ever seen. Anyone wishing to reprint articles And yet despite the amount of will need permission from the activity that went on, it could be author, must state that it was copied from PsittaScene, and another year or so before an egg notify WPT. appeared in the nest hollow. These All contents © World Parrot Trust are the sort of encounters that reinforce my suspicions that, for A pair of Palm Cockatoos in full display. Photo: Roland Seitre

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Could scrub pythons be responsible for Palm Cockatoo nest failures? Here, a large and Bamaga chick. Even at this quite advanced age Palm Cockatoo chicks can be bulging python is caught inside a Sulphur-crested Cockatoo nest. Photo: Steve Murphy predated. Photo: Steve Murphy occurred in the rainforest while Palm Cockatoo prefer, those that snug 18x20cm! A tight squeeze amethistina. This is especially birds foraged in the savanna, have openings that face upwards for a bird that can weigh up to likely given the fate of some of while others suggested that it was seem to be the norm. But don't be 1kg, is 56cm long and has a the local Eclectus Parrot and the exact opposite. The truth is, fooled into thinking that large wingspan of over 1m. Compare Sulphur-crested Cockatoo chicks. that on Cape York, breeding bird equals a large nesting hollow. this to the largest active nest For example, in one Eclectus nest occurs in the savanna as well as While it is true that some pairs found so far, a spacious 80x35cm, that researchers Rob Heinsohn the rainforest, although most of don't like to feel cramped and and you begin to get some idea of and Sarah Legge were monitoring, the breeding that has been crowded while incubating and the variation. Equally varied is the a disastrous exchange of hollow detected has been in the savanna. brooding (which is depth of the nest from the rim of occupancy occurred. One day, This more reflects observer bias understandable with incubating the hollow to the nesting instead of finding two healthy and (i.e. nests are easier to find in the shifts that can exceed ten hours!), platform, which can be anything quite advanced chicks, the hollow more open savanna), although others obviously prefer that cosy from 43cm to over 2m. was full of coiled up and nest hollows superficially seem to feeling. In fact, the record for contented serpent. Several days The nesting platform is very later the snake moved on, only to be more common in the savanna. smallest internal dimensions of an interesting, as Palm Cockatoos ar e leave a couple of large scats As for the type of tree hollows active nest so far is a remarkably the only parrots that go to such which contained the leg bands of extraordinary lengths to ensure the nestlings. Sure proof if ever that their chicks and eggs remain there was any doubt! high and dry during the long wet season of tropical Australia. Although this gives me some idea Throughout the year, pairs of what might be happening to all maintain several hollows in their those Palm Cockatoo chicks and territory and build platforms of eggs, I have a sneaking suspicion splintered twigs which can be that sometimes it can be a lot more anything from a few centimetres sinister. A couple of times I have to well over two metres deep. found eggs crushed but uneaten Given the huge amount of effort in the nest. This seems unlikely that goes into preparing each site, behaviour for a predator. Maybe there should be little wonder why rival pairs are responsible? Birds males don't tolerate each other fight tooth and nail (or beak and near their nest hollows. It may claw?) to chase off rivals during have also been the mechanism courtship. But what would happen that drove the evolution of the if rivals visited an active nest and flamboyant wing spreading and they couldn't be chased off? drumming displays for which More and more the gaps in our these Cockatoos are renowned. understanding of Palm Cockatoo Perhaps the most alarming statistic biology are being filled. It's to emerge from the study to date challenging work and it's far from is the high rate of nest failure. Over over. There are still a few big the past two breeding seasons I have questions that need to be monitored 21 active nests, and of answered, like how often do pairs these only 4 have successfully attempt to breed, and what really fledged young cockatoos. Eggs is happening to all those missing and chicks seem equally likely to chicks and eggs? I'm also trying to go missing, and even quite find out what defines good advanced chicks have breeding habitat, and then there's mysteriously vanished. The the question of whether birds culprits are likely to be large move between the different sub- varanid lizards, like Gould's populations in Australia, and Steve and Paul Igag (par rot researcher from Papua New Guinea) prepare to climb monitors Varanus gouldii, and .....well, let's just say that an active nest tree. Photo: Sarah Legge scrub pythons Morelia I'd better get back to it...

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