Cliff Frith shares the latest Tooth-billed Bowerbird amazing story
- Peter Valentine
- 2 days ago
- 6 min read
Peter Valentine | Conservation Officer
On Thursday 23 April, renowned ornithologist Cliff Frith presented a much-appreciated talk in the Malanda Hotel. The capacity crowd of BirdLife Northern Queensland members and supporters (and other interested parties) were offered an insightful elaboration about this unique species within a distinctive group of birds, the lives of which are still being studied.
One of the reasons I love living on the Atherton Tableland is that virtually every month we can enjoy a presentation in the ballroom of the Malanda Hotel, usually on somewhat esoteric natural history content, often given by a global expert in the field. This time over 100 people gathered (many after a sociable meal) and were informed and entertained by Cliff. Of course, most knew that Cliff and his late beloved partner Dawn Frith were the acknowledged research experts on bowerbirds and so expectations were high. It is not as though there has been little written about bowerbirds as Cliff shared the titles and covers of many books written about bowerbirds from the late nineteenth century on. Many more strictly scientific contributions, a host of peer-reviewed journal articles, have helped us gain better understanding of a diverse and complex group.
One of the fascinating early photographs in the presentation showed the technique used by Cliff and Dawn to gain the first and only photograph of a Tooth-billed Bowerbird on its nest. High in a tangle of vines it required cutting a very long solid pole, inserting the base in a deep hole and guying the pole to the ground. Then the pole was climbed and two cross bars at the top fastened to support a cover as the hide and a perch for the photographer (Cliff). Dawn would then haul up the photographic equipment for Cliff and he would spend many hours awaiting the chance of a photo. Quite a scary exercise. But it did result in the image of a female Tooth-billed Bowerbird on its nest. Remarkable.
The behaviour of Tooth-billed Bowerbirds has been studied over a long time but sometimes interpretations have been off the mark. Cliff carefully assembled what is known, and separated that from what may have been believed and said. The peculiarly designed bill with teeth-like projections is known to be used to cut leaves, but more significantly perform a role to support a seasonal diet of leaves, not just to cut leaves to decorate the male court. The process of clearing and decorating a court, undertaken by the male Tooth-billed Bowerbird, is fascinating with leaf species selection variable from place to place and from individual to individual. Each court has the important tree trunk incorporated to provide a hiding element for the male display. And a perch to sing from.
And what a display. The vocal elements are well known and it is by mapping male Tooth-billed Bowerbird courts (identified by the male songs) that Dominic Chaplin and his assistants have been able to monitor the presence of this species for the past 20 years. As Cliff made clear, males are extremely site faithful and courts exist in the same location over many decades. Cliff revealed Tooth-billed Bowerbirds are long-lived with much to learn before successful breeding. Hence the extended adolescence (perhaps 6 years or so) before assuming adult features (including a pitch black gape). One banded male that Cliff and Dawn monitored used the same court for 22 years. But possessing a court is no guarantee of successful breeding.
Another fascinating outcome of Cliff and Dawn’s work was the potential habitat modification by male Tooth-billed Bowerbirds. For much of the year fruit is the dominant food source and because so much time is spent at the court, the seeds of these fruits get deposited beneath the song perch. Cliff employed a “crap-catcher” to elucidate what fruit species are favoured and noted that over the many decades of such seed concentration, trees of the favoured fruits would become more abundant near the courts. Perhaps this adds to the locational fidelity by the males?
The role of female sexual selection is paramount in influencing appearance and behaviour. Although there is little sexual dimorphism in plumage, the females are apparently extremely fussy about the quality of a male’s plumage, and indeed of everything that a male does. It appears that the remarkable mimicry by the male, of other bird species calls used as part of his display, has been fine-tuned to be virtually identical calls to the mimicked species. Comparisons of sonograms shared by Cliff help reveal this. We were shown some images of a male display that was most revealing and the various elements were nicely captured, from hiding behind the tree trunk, the exposure of the black gape, the soft whisper calls and the bold approach.
The finale of Cliff’s presentation was a marvellous video, captured by a trail camera of Graham Harrington, that has been accessed and shared with Cliff by Amanda Freeman who was an ongoing research colleague with Graham and a co-author with Cliff on this unique behaviour revealed by the videos. Cliff’s presentation included a great deal of description about the mating behaviour of birds and some anatomical gems including the absence of penises in most male bird species, with exceptions including Emus, Cassowaries and ducks. Instead, most birds mate with a “cloacal kiss”, which is a fast direct contact between male and female cloaca with rapid transfer of sperm. The mating ritual in the Tooth-billed Bowerbird involves a great deal of display activity, enabling assessment by each fussy female, and often ends in rejection by the female who heads off to find a more fit partner. Only a few males in an area will be chosen mates; most will fail.
But the video also showed us another active element, unanticipated by most of us. Following acceptance by the female (a submissive posture presented to the displaying male), there was the rapid cloacal kiss and then a separation of the two cloaca BUT not of the two birds, for the male firmly held on to his strong grip of her nape despite her obvious struggles to get free. She had clearly been inseminated and wished to get on with her life, whereas the male was holding her down with his body and his powerful bill gripped on her nape. She, in the meantime, was trying hard to attack him with her bill, at times gripping his plumage and even his wing. Feathers flew and there was a concern from observers that one or both may be injured in the struggle. The battle continued for quite a while until finally, with more feathers flying, she escaped and flew off. This amazing footage revealed a hitherto unimagined behaviour which Cliff humorously called “rough sex”. Cliff mentioned that there is nothing like this behaviour known in any other passerine species in the world.
It turns out that Cliff and Dawn had seen this behaviour once or twice during their long study of the species at Paluma, but decided against reporting it as they assumed it was aberrant behaviour. But now decades later Cliff had evidence that this might actually be normal. A total of 12 separate videos captured by Graham Harrington’s trail cameras, showed the behaviour consistent at different courts. Quite astonishing to all of us.
As one might have imagined there was a great deal of interest and many questions followed with much time devoted to attempted explanations or better understanding of the behaviour of the male. The concept of sperm competition, expressed in various ways, was considered as part of the explanation. This recalled for me the fascinating example of Glasswing Butterflies, the males of which produce a wax like substance with which they seal the female vulva post copulation to ensure she will not mate again. This might be seen as the Lepidopteran equivalent of the human “chastity belt” of mediaeval times. Does this action by the male Tooth-billed Bowerbird have the same effect – to ensure that this male remains the sole source of sperm? There is much scope for expanded interpretation of what has been recorded by Cliff and Amanda and that will no doubt be a topic for future research. Unfortunately, nests of Tooth-billed Bowerbirds are extremely difficult to find and any study involving nests and young face a significant challenge. Many ideas from the audience were shared. Despite Cliff’s encouragement, no questions were raised about “ducks”. That will have to await another presentation.
The audience expressed their great appreciation for Cliff’s presentation and the time he devoted to preparing and sharing this unique material. I suspect everyone will appreciate even more this wonderful Wet Tropics endemic bird, perhaps paying even more attention when next encountering the bird or the song. Thanks were expressed to all for attending and for the hotel for providing the excellent venue. More talks are planned by BirdLife Northern Queensland for future months.
The original article just published in EMU – Austral Ornithology can be read here:
