Palm cockatoo drums with self-fashioned drumstick
With a female listening, palm cockatoo males may repeatedly strike a hollow branch or trunk with a stick. Robert Heinsohn and colleagues heard that the birds have good rhythm and that every male has his individual drumming style.
A palm cockatoo male from North Australia can produce different sounds while erecting its crest. That is impressive, but there is something that really stands out: it may start drumming.
When a male is going to perform, it breaks off a twig, removes the leaves, trims it to approximately 20 centimetres, grasps it in one of both foots and starts beating repeatedly on a hollow branch or trunk. Instead of a stick, it may use a seed pod of a particular tree (Grevillea glauca, the bushman’s clothes peg) after adjusting the shape with its beak. It may continue drumming for a while, producing a sequence of up to 90 taps.
It is remarkable that the intervals between the taps don’t occur at random intervals; instead, the cockatoos produce a regular pulse, as Robert Heinsohn and colleagues assessed. They also noticed that each male has its individual, consistent style; some males have slow drumming rates, whereas others drum at a faster rate, or insert short sequences of faster drumming in the performance occasionally.
It is not known yet which function the performance might have. Palm cockatoos form monogamous pairs which occupy a large territory. The sound does not travel far enough to be heard by the neighbours, so a male cannot communicate with them by drumming; he always is playing solo. As most performances are attended by the female, the music probably is meant for her, and it may be a male’s way to inform its partner about its condition or age; the birds may live more than 50 years. We don’t know whether the females like the percussion and what rhythm they prefer.
Willy van Strien
Photo: Christoph Lorse (Via Flickr. Creative Commons CC BY-NC-SA 2.0)
Heinsohn, R., C.N. Zdenek, R.B. Cunningham, J.A. Endler & N.E. Langmore, 2017. Tool-assisted rhythmic drumming in palm cockatoos shares key elements of human instrumental music. Science Advances 3: e1602399. Doi: 10.1126/sciadv.1602399