Male Cockatoos Create Tools to Drum Up A Lover

Wild Australian palm cockatoos are the first animals filmed using tools that they created to produce sounds

by GrrlScientist for Forbes | @GrrlScientist

Palm cockatoo (Probosciger aterrimus).
(Credit: Doug Janson / CC BY-SA 3.0)

For the first time ever, an animal has been documented making tools to create music. Male palm cockatoos, Probosciger aterrimus, use their enormous beaks to break off sizable sticks from trees and fashion them into a shorter and smoother drumstick that they clutch in their left foot to beat on a tree hollow. Other palm cockatoos instead choose seed pods that they specifically alter for the task.

“The large smoky-grey parrots fashion thick sticks from branches, grip them with their feet and bang them on trunks and tree hollows, all the while displaying to females,” said conservation biologist and evolutionary ecologist, Robert Heinsohn, a professor at Australian National University, and lead author of the study.

Most animals that make or use tools do so to hunt or to forage more effectively (for example, read this), but these cockatoos use their tools specifically to create a rhythmic beat that is designed to impress females. Indeed, according to the study, 70% of males who were observed drumming did so when a female was present (ref).

Rockatoos: A male palm cockatoo, Probosciger aterrimus (right), woos a female with loud whistles, blushing red cheek patches, erect head crest feathers — and with his unique rhythmic drum performances in trees, using a drumstick that he made himself.
(Credit: Cristina Zdenek / doi:10.1126/sciadv.1602399)

Drumming is part of an intricate courtship display where male palm cockatoos sway their bodies and erect their long slender crest feathers, whilst producing loud, high pitched whistles and “blushing”, which is where their featherless cheek patches turn bright red, contrasting brilliantly with their all-black plumage. As the display continues, the male spreads his large black wings, pirouettes on his branch and bobs his head.

If the watching female is impressed, she will join the courting male on his branch and imitate his movements by erecting her crest, and swaying, bobbing and whistling alongside him as he drums. As they establish their pair bond, they sometimes stop to preen each other’s feathers gently.

Palm cockatoos are monogamous, and the female produces just a single egg every two years, on average, so such displays are important to these birds.

Although tool-making and drumming was first mentioned in the literature in 1984 (ref), wild palm cockatoos are extremely shy and elusive, so this behavior was difficult to study.

“In order to capture and study this rare behavior, we had to carefully stalk these birds through the woodland and covertly film them,” said study co-author, sensory ecologist, Christina Zdenek, a PhD candidate at The University of Queensland, who did most of the field work and filming.

“The success rate of recoding these drumming events worked out to be one drumming event every one hundred hours,” Ms. Zdenek said.

In total, she managed to film 18 wild male palm cockatoos over a period of seven years and ended up with a total of 131 recorded drumming sequences.

“Now that was hard work!”

Palm cockatoo tapping sounds are non-random, rhythmic, and individual

Analysis of the 131 drumming sequences by 18 wild male palm cockatoos reveals that they have a predictable beat, they incorporated repeated elements into their performances, and they all had recognizable individual styles and cadences (Figure 1):

Fig.1. Palm cockatoos use sound tools to produce a rhythmic beat
(A) Male palm cockatoo drumming on a hollow tree with a manufactured “drumstick.” Photo: C.N.Z. (B)Distribution of variances for intertap intervals (seconds) over 131 sequences of drumming by 18 male palm cockatoos. (C to H) Examples of drumming sequences of varying length showing time on x axis (seconds). Temporal spacing of drumming taps is shown in the top row of each figure and is compared to a randomly generated sequence in the lower row. Sample sizes, mean intertap intervals, coefficients of variation (cv), and shape parameters are given above each sequence. (doi:10.1126/sciadv.1602399)

Each male’s drumming beat was unique, so specific individuals could be recognized from that sound alone.

“Some males were consistently fast, some were slow, while others loved a little flourish at the beginning,” Professor Heinsohn said. “Such individual styles might allow other birds to recognise who it is drumming from a long way away.”

According to Professor Heinsohn, the females watch performing males closely and presumably, a female will select her mate based on his particular drumming skills and courtship display.

There is an important distinction from human drumming: although the sounds do carry for quite a distance, drumming is not a social activity for cockatoos as it is for humans. People often use drumming in conjunction with or as the basis for group activities, such as drum circles, and people may respond by dancing to drum beats produced by others. Which raises the question: did human rhythmic drumming start as a courtship display?

Interestingly, the researchers found no evidence that wild palm cockatoos respond similarly to rhythms produced by male cockatoos during their drumming displays, although many birds, such as birds of paradise (video) and manakins (video), have intricate courtship dances.

Palm cockatoos’ lack of dancing also differs from another cockatoo species, the Eleonora cockatoo, Cacatua galerita eleonora. These cockatoos are well-represented by Snowball, who took the world by storm a few years ago when a YouTube video captured him spontaneously dancing to music with a powerful rhythmic beat (video). Subsequent studies confirmed that Snowball keeps time with the beat, slowing down or speeding up with the music (ref).

Although there are a few observations of male palm cockatoos in New Guinea using a clenched foot for drumming, creating tools for drumming has only been reported for palm cockatoos living in Australia, suggesting this behavior is cultural.

Christina Zdenek stalks drumming wild palm cockatoos (Probosciger aterrimus) on her field site in the Iron Range NP on Cape York, Queensland.
(Image courtesy of Christina Zdenek.)

How did drumming get started in Australian palm cockatoos? Since the male uses sticks to construct a nest in a tree cavity, it is possible this behavior started when a male successfully used a stick to advertise his nest by tapping on the entrance to the hollow.

Already, studies are underway to test whether drumming improves breeding success and to determine why only some male cockatoos use drumming in their courtship displays.

But important questions remain. For example: do male cockatoos always use the same sort drumming tool — stick or seed pod — that their fathers use? do male cockatoos learn their cadences — slow and steady or faster and more variable — from their fathers? do female cockatoos prefer a particular drumming rhythm? do single male cockatoos incorporate drumming rhythms into their own performances from paired males? how do cockatoos respond to rhythmic versus non-rhythmic cadences? Occasionally, drumming is performed for long periods of time in the absence of other display behaviors — is the male is practicing?

Considering these birds’ elusiveness, it may take a very long time to answer these questions convincingly.

A wild male palm cockatoo (Probosciger aterrimus) poses with his drum stick.
(Credit: Christina Zdenek / doi:10.1126/sciadv.1602399)

Although they are not endangered, wild palm cockatoos in Australia are threatened by habitat destruction as the direct result of bauxite mining by the aluminum industry. This has inspired researchers to begin researching the conservation needs of palm cockatoos living on Australia’s Cape York peninsula, and this study was part of that larger effort.

Source:

Robert Heinsohn, Christina N. Zdenek, Ross B. Cunningham, John A. Endler, and Naomi E. Langmore (2017). Tool-assisted rhythmic drumming in palm cockatoos shares key elements of human instrumental music, Science Advances, published online on 28 June 2017 ahead of print | doi:10.1126/sciadv.1602399

Also mentioned:

Polly gets his own cracker: clever cockatoo manufactures, uses tools.

GA Wood (1984). Tool use by the palm cockatoo Probosciger aterrimus during display, Corella, 8:94–95 (link)

Aniruddh D. Patel, John R. Iversen, Micah R. Bregman, and Irena Schulz (2009). Experimental Evidence for Synchronization to a Musical Beat in a Nonhuman Animal, Current Biology, 19(10):827–830 | doi:10.1016/j.cub.2009.03.038

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Originally published at Forbes on 29 June 2017.