Sulphur-crested cockatoos' distinctive raucous calls can be very loud. They are naturally curious, as well as very intelligent. They have adapted very well to European settlement in Australia and live in many urban areas.
Species that feed on the ground are very vulnerable to predator attacks. The cockatoo has evolved a behavioural adaptation to protect against this: whenever there is a flock on the ground, there is at least one high up in a tree (usually a dead tree), keeping guard. This is so well-known that it has even entered Australian slang: a person keeping guard for sudden police raids on illegal gambling gatherings is referred to as a cockatoo or cocky for short.
On one walk, I was surprised by black shapes moving within the green leaves of a front garden tree. The moving shapes were three yellow-tailed cockatoos, doing what yellow-tailed cockatoo do – pulling bark of tree limbs, looking for wood borers and tree grubs. It was delightful to watch them. Not sulphur crested, but cousins.