Denise Cullen
Do women prefer drummers? Among a population of rare bird drummers in relict rainforest in Far North Queensland, the debate is settled: they most definitely do.
Male Palm Cockatoos (Probosciger aterrimus) of Kutini-Payamu (Iron Range) National Park manufacture percussion instruments which they use to drum on trees to impress potential mates, says Professor Robert Heinsohn from the Australian National University, who has studied the birds for more than two decades.
The birds would be at home with Motley Crue’s Tommy Lee; Blink 182’s Travis Barker, or for older afficionados, perhaps John Bonham.
The avian drummers, a population that’s genetically distinct from others on Cape York Peninsula, “show off and put their heart and soul into the performance,” Heinsohn says.
While other birds do use tools – the New Caledonian crow, for instance, is renowned for using twigs to skewer grubs – palm cockatoos are unique in using tools to enhance their courtship displays rather than for foraging or self-maintenance, Heinsohn and colleagues note in an article published late last year in the Proceedings of the Royal Society B.
More remarkable still is that they fashion their “drumsticks” out of trimmed tree branches or by modifying the large seed pods of Grevillea glauca (bushman’s clothes peg), according to their own unique designs.
“They have different styles,” Heinsohn told me during an interview.
“Some like to make short, fat drumsticks, others like to make long, skinny ones – and they’re highly consistent in terms of what they prefer.
“They’re all very rhythmic but they all have different styles in terms of how they tap – some develop a display where it’s very fast, some tap quite slowly, and others have little flourishes in between.”
While the drumsticks made from tree branches make a blunt, tapping sound, the percussion instruments shaped from seed pods tend to be more resonant and echoey.
Further research is needed to unravel the meaning behind palm cockatoos’ different drumming preferences, why some master craftsmen are equally adept at whittling both branches and seed pods, and to what extent their skills evolve with practice.
“(The male) seems to be very consistent, but we haven’t (explored) these sequences over too many years yet, so we don’t know if they change over long periods of time,” Heinsohn says.
“It’s possible that he might just keep getting better and better, or adding things to his repertoire.”
Parrots in peril
Heinsohn, who presented his research at the Australasian Ornithological Conference in Brisbane ,holds grave concerns for the future of what he acknowledges is his favourite bird.
Weighing in at around one kilogram, palm cockatoos are the largest cockatoos, boast one of the biggest brains for body size of all the other parrots, and are the most ancient cockatoos on the evolutionary tree, he points out.
Three years ago, Heinsohn was part of a team of researchers which sounded the alarm about the “steep decline” in the number of Australian palm cockatoos and successfully called for a change in their conservation status from “vulnerable” to “endangered” under the International Union for Conservation of Nature (IUCN).
(Palm cockatoos are also found in New Guinea (West Papua, Indonesia and Papua New Guinea) where they are listed as “near threatened”.)
Writing in Biological Conservation, the researchers noted that the Australian population of palm cockatoos comprised an estimated 2500 individuals at most, with their survival hanging in the balance due to low reproductive rates and habitat destruction.
Heinsohn explains that female palm cockatoos lay an egg only once every two years – and that single egg has a very low chance of becoming a fledgling.
“There’s a lot of predation … from pythons and goannas to the point where, on average, a female is only producing a surviving chick about every 10 years or so,” he says.
Also complicating the picture is that these birds require spacious nest hollows in which to breed – and these can only be found in mature eucalyptus trees.
More: the bird drummers
Changed fire regimes since European settlement means that fires tend to burn too hot, too big, too frequently, or at the wrong time of year.
“Often the problem is that these trees that have nest hollows in them get burned down … or the seedlings never get a chance to grow into large trees,” Heinsohn notes.
“Rarely is the burning at just the right level to maintain a healthy woodland, and so the birds have fewer and fewer nests.”
Bauxite mining taking place on the west coast of Cape York Peninsula is also taking its toll on the population.
“It’s a very destructive form of land use, because they’re after the topsoil, and so the mining companies are literally bowling over tens of thousands of hectares in one go, which is terrible for all our wildlife”
Robert Heinsohn
“So, between those three things, the birds’ numbers are going down, and quite quickly.”
Heinsohn and other researchers are trying to fathom the reasons behind the slow reproduction rate, seeking to restore traditional burning practices, and consult with mining companies to find better ways to protect the palm cockatoos’ habitat.
“That means protecting the strips of rainforest around creek beds and having more of a buffer of woodland trees, before they hit the parts where they’re going to be mining intensively,” he says.
“They’re three constructive things that we’re trying to do, but we haven’t succeeded yet, of course.
“In the meantime, we’re very worried.”
Unparalleled wilderness
Heinsohn would ideally like to see greater public awareness and appreciation for how special Cape York Peninsula is.
“It’s got a whole lot of animal and plant varieties that are found nowhere else in Australia … it’s like having a little piece of New Guinea on our own soil,” he adds.
When Heinsohn first started conducting research there in the late 1990s, he’d spend six to eight months of the year in the area, sleeping in a two-walled shack he dubbed “the humpy”, with not much more than a single bed, hammock and small gas cooker.
Despite the ravages of the wet season, when his four-wheel drive sometimes stalled in flooded, crocodile-infested creek crossings, he loved the adventure.
“Every morning you’d be woken by the cacophony of rainforest birds and the palm cockatoos would fly over, only about 15 to 20 metres off the ground, and they’d swivel their heads and look down at you and would go, ‘Hurroo’,” he says, mimicking the birds’ unique human-like hello call.
“I just loved the magic of that … obviously I’m anthropomorphising but I really felt like they were saying ‘good morning’ to me, and it was just a great way of kicking off every day.”
Robert Heinsohn
Palm cockatoos generally mate for life.
“There’s the occasional divorce – we don’t know why – but most of the time, (mating pairs) have a long-term relationship,” he explains.
Every breeding season, the male bird will build a new nest and whittle a fresh set of drumsticks or seed pods with which to woo his mate all over again.
“The male keeps trying really hard with his existing female, sort of like he can’t take her for granted,” Heinsohn explains.
“He has to get her in the mood for mating, so she’ll lay her eggs in the nest, and the breeding will go on.
“It’s not like he can never relax. He’s having to work very hard, even if (the relationship) is for life.”
