A quest for riflebirds
Contact Call | Volume 11 Number 4 | December 2022
The Birds-of-Paradise of New Guinea and tropical Australia represent some of the most staggeringly beautiful and unusual birds on our planet. While the ornate plumes of the males have been collected and treasured by Europeans since as early as the 16th century, and possibly as early as 50,000 years ago by native Papuans, it wasn’t until the mid-19th century that Western naturalists were able to observe their spectacular courtships in the wild.
Perhaps the most notable of these Western naturalists was Alfred Russel Wallace, who spent many years observing and collecting Birds-of-Paradise in Australasia, and was instrumental in developing early evolutionary theory alongside Charles Darwin. It is without doubt that Darwin, too – despite never having seen a living Bird-of-Paradise – was greatly inspired by their beauty, which helped form what I consider to be his most unique contribution to science: the theory of sexual selection through female choice.
However, despite a long history of scientific interest in the Birds-of-Paradise, their remoteness has prevented all but a few dedicated researchers from conducting detailed studies on their courtship displays, leaving many questions about the behaviour and evolution of these spectacular birds unanswered.
In an attempt to remedy this, my PhD thesis focuses on the courtship behaviour of Victoria’s Riflebird, a Bird-of-Paradise common in the Atherton Tablelands.
The first European to discover this species was John MacGillivray, who worked as a collector for the esteemed ornithologist John Gould in his famous expedition to Australia in the 1840s. Gould formally described the species in 1850, naming it Ptiloris victoriae in honour of Queen Victoria, thus beginning the tradition of naming Birds-of-Paradise after European monarchs.
The last scientific paper to be published on the courtships of Victoria’s Riflebird was authored by none other than Cliff Frith in 1996, and illustrated by the renowned painter William (Bill) Cooper. Bill was even known to train the birds in his back garden to feed from his hand and enter his shirt pockets, a practice not uncommon among people living in the rainforests. This means that, to the envy of many a European, North Queensland is one of the few places in the world where Birds-of-Paradise may be included in one’s garden birds checklist (though it should be noted that the feeding of wild birds is best avoided).
In their paper, Cliff and Bill described the basic elements of the courtship displays of Victoria’s Riflebird, comparing it with the other riflebird species. The courts (sites where courtship happens) of these birds are typically vertical dead tree stumps, though I have seen many birds also displaying on horizontal branches and vines. On one occasion, an adult male was even seen displaying to a female on the shoulder of a person who was feeding them! While males call throughout their territories, one can often find them at their courts by following their harsh, hissing yaass! calls, which is somewhat infrequently followed by a second syllable.
Once a male spots a potential mate, he raises his wings above his head, forming what resembles a living satellite dish, during which he may also display his bright yellow gape. This has been referred to as the circular wings posture.
Anticipation then builds as the male slowly extends and flexes his legs until a potential mate finally lands on his display perch, at which point he will begin the more dynamic phase of his routine called the alternating wing-clap display, where he jerks his wings and head from side-to-side in alternating motions.
One can only try to imagine what this looks like from a female’s perspective; a rustling blur of black and shining sapphire, complete with a sheen of sparkling blue-green which – owing to their more elaborate visual systems – must appear all the more spectacular when viewed through a bird’s eyes.
One can also try to imagine what it is like for the male to produce this display. Any time I tried to re-enact it myself, I quickly became quite disoriented and dizzy. It is an impressive feat of motor coordination that males don’t only perform such a display, but also do so in a way that accounts for the position of the female, all the while remaining balanced on a narrow perch.
Anyone who has seen an adult male Victoria’s Riflebird display to a female may have noticed how carefully they adjust not only their position, but also their effort in response to their audience. Males appear to reduce the rate at which they clap their wings when females look away from them, but increase in tempo when they see that the female is paying attention.
This may seem obvious, but the ability of animals to flexibly adjust their behaviour according to what they think another individual is experiencing, seems to evolve only under certain ecological and social circumstances. In this case, it’s certainly beneficial for a courting male to have a feel for what a visiting female is experiencing, as his reproductive success depends almost entirely on whether or not she finds him attractive enough to mate with.
Indeed, wooing a female requires considerable social and motor skills, which require prolonged periods of dedicated practice. This may – at least in part – explain why male birds-of-paradise, bowerbirds, and mannikins, to name a few, spend many years in drab plumage, looking very much like females, after which they grow their characteristic adult feathers.
Amazingly, to offset the reproductive costs of these long immature periods, young males may produce viable sperm and “sneak” copulations at the courts of adults!
While the immature males of some species spend at least some of their time cheekily stealing copulations from adults, much of their time is spent practicing their displays, and in a handful of species, immature males practice with each other. In the Victoria’s Riflebird, for instance, drab-coloured young males are often seen practicing in pairs, and less frequently in groups of three or four.
Interestingly, when John MacGillivray first described the habits of immature male Victoria’s Riflebirds in the 1800s, he thought they were fighting. He even mentioned that he managed to shoot three birds with one shot of his hunting rifle as they were so occupied with their “pugnacious” habits. While no scientific studies have been conducted on the topic, I am convinced what MacGillivray saw were practice displays, not acts of violence.
There may, however, be some truth to his original description. While young males may indeed cooperate to some extent to hone their skills, they may also compete with each other for practice time.
To test between these hypotheses, I am interested in applying methods originally designed for the analysis of human speech to the displays of immature male riflebirds. For instance, just like during conversations, humans take turns in speaking, though we may occasionally interrupt one another. Sometimes, a conversation may represent an exemplary bout of turn-taking, while at other times – during a heated argument, for instance – conversations are plagued by interruptions. Applying this to riflebirds, evidence of turn-taking suggests that males cooperate, while significant interruptions during practice courtships would suggest that males compete for practice time.
This latter outcome may lead one to question why males practice together at all. My hypothesis is that, since males presumably benefit from practicing with a “dummy” female – much like how boxers practice with a sparring partner – some social interaction between males should persist, as young males search for their dance partners, even when they refuse to take fair turns.
While there is still much to be learned about the Victoria’s Riflebird, I worry about the future of this species, as it is currently classified as “Vulnerable” in the IUCN Red List of Threatened Species.
The decline in populations of riflebirds is almost entirely due to the extensive clearing of their rainforest habitat. With the vast majority of birds occurring in old growth and 25-year regrowth forest, it is imperative to stop any further deforestation in the Wet Tropics and restore the areas that have been converted to pastures. If this doesn’t happen, it won’t be long before many of the Wet Tropics’ beloved endemic animals will have vanished from the planet forever – the main culprit being the world’s ravenous desire for beef.
Certainly, we must ask ourselves: is it worth wasting the world’s natural beauty for a luxury food we don’t need?
During my PhD, I hope to answer at least some questions about the courtship displays of these marvellous birds. However, I would consider much of this time wasted if I don’t manage to inspire people along the way to better appreciate nature, and strive for its conservation.
As the influential primatologist and conservationist Jane Goodall once said:
“You cannot get through a single day without having an impact on the world around you. What you do makes a difference, and you have to decide what kind of difference you want to make.”
Story and images by Thomas MacGillavry.
Thomas MacGillavry is a Ph.D. candidate at the Konrad Lorenz Institute of Ethology with the University of Veterinary Medicine in Vienna, Austria. This work is funded by the Austrian Science Fund (FWF).
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