Australian blue Cockatoos corellas demonstrative destructive docile flock garden pest grazing Noisy pet root eater show-off talker vocal white yellow tail feathers pest beaks birds branches eucalyptus-tree fauna gum-tree native tree wildlife electrical-supply electricity falconiformes feathers garden-pest iconic overhead-power-lines perch perching perching-birds powerlines powerpoles root-eater sky suburban tail wires