Sulphur-crested
Cockatoo - Cacatua galerita
There are two extraordinary aspects
of
sulphur-crested cockatoo behaviour. The first is the awesome volume of
the sulphur-crested cockatoo's call. Sitting quietly in the Atherton
rainforests,
waiting to record the sounds of the more timid birds, I was often
scared
out of my wits when a sulphur-crested cockatoo began screaming in the
canopy
high above me. After three weeks in the Atherton rainforests I had
still
not grown accustomed to this vocalization, and I still jumped each time
I heard one of these impressive birds scream. The volume of these
birds'
calls must pose an obstacle for all other animals who try to
communicate
using the same airspace; even from their songposts high in the canopy,
the sulphur-crested cockatoo’s calls mask the vocalizations of birds on
the forest floor.
The second extraordinary aspect
of sulphur-crested
cockatoo behaviour is the tremendous distances these social animals
cover
in their daily routine. I have seen noisy flocks of more than fifty
cockatoos
fly from one forested mountaintop to another. I have heard these birds
travel the canopy alighting in the valleys and peaks that form the
landscape
above the Atherton rainforest canopy. Clearly sulphur-crested cockatoos
are animals that do not belong as isolated individuals confined to bird
cages or pet stores.
An intriguing recent analysis of
sulphur-crested
cockatoo vocalizations found that the calls of these birds appear to be
governed by fundamentally different processes than the songs of other
birds.
Whereas most bird vocalizations are composed of pure whistled notes or
layers of harmonic sounds, sulfur-crested cockatoo vocalizations appear
to have chaotic, non-harmonic properties. Chaotic acoustic structures
also
appear in the vocalizations of Australia’s gang-gang cockatoos,
Callocephalon
fimbriatum, and zebra finches, Taeniopygia guttata .
Habitat.
Sulphur-crested cockatoos occupy
a wide
variety of habitats, and appear to be equally adept at finding food in
the heart of rainforests as in grassy fields next to beachside cabanas
Range.
Sulphur-crested cockatoos can be
found
in many parts of Australia, especially in the coastal areas of northern
and eastern Australia, Papua New Guinea, and New Zealand.
Further
Reading.
M. S. Fee, B. Shraiman, B.
Pesaran, &
P. P. Mitra. 1999. The role of nonlinear dynamics of the surinx in the
vocalizations of a songbird. Nature. 395:67-71.
N. H. Fletcher. 2000. A class of
chaotic
bird calls? Journal of the Acoustical Society of America. 108:821-826.
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