Noisy and conspicuous (4), the sulphur-crested cockatoo forms large flocks of up to several hundred birds (2). As the famous naturalist Charles Darwin observed during his visit to Australia, these flocks are commonly found feeding in wheat fields, and are considered to be pests by many Australian wheat farmers (5). During feeding some members of the flock stand guard on a nearby perch, alerting the rest of the group to any danger by making a raucous alarm call (2) (4). When not feeding, the sulphur-crested cockatoo will frequently bite off smaller branches and leaves, which helps prevent the bill from growing too large. A similar behaviour is also employed by this species in urban environment, causing widespread damage to wooden panelling and timber decking (4). Flocks spend the night at a permanent roosting site, usually in trees, but may travel over several kilometres during the day in search of food (2) (6). The sulphur-crested cockatoo's breeding season varies according to location, with populations in southern Australia breeding between August and January, and populations in northern Australia breeding from May to September. Once formed, each breeding pair constructs a nest well apart from the other pairs, which usually comprises a bed of woodchips in a tree hollow. A clutch of two to three eggs is laid, which are incubated by both parent birds, with hatching taking place after 25 to 27 days. Nestlings remain in the hollow for 9 to 12 weeks and are fed by both adults, before fledging and joining a feeding flock (2).