The chief difference between other members of the parrot family and cockatoos is, of course, that the latter possess crests, and these vary considerably in shape and size.

Many of them have fan-shaped crests and far the most beautiful as well as the largest of these adorns Leadbeater's Cockatoo. The Roseate's is rather the shape of a Roman helmet, while that of the quaint but attractive little Gang-Gang resembles a lady's feathered toque.

Cockatoos are not round at all in the New World, their habitat being exclusively the continent of Australia and the neighboring islands.

Generally speaking, they are gregarious, some of them remaining in large flocks even during the breeding season - a period when many birds tend to leave the flock and go off separately in pairs.

Like most things, cockatoos have their advantages and their disadvantages. Among the latter must be listed their powerful and destructive beaks and their loud and harsh voices; and among the former the delightfully charming and affectionate dispositions of really tame specimens, which I think are even more demonstrative to their human friends than are tame parrots.

A tame cockatoo in a cage should be taken a lot of notice of and let out as often as possible. It should also be given plenty to occupy it and exercise its beak upon - an empty cotton-reel being excellent for this purpose. Its owner should realize when he buys a bird that he is taking on an obligation, which goes far beyond simply keeping it supplied with food and water.

These are mere essentials, and any bird-keeper worth his salt will give his pet plenty of affection and use his imagination to supply those small extra attentions which make all the difference between a bored, bedraggled captive and a really happy, healthy and contented pet. This, of course, entails a certain amount of trouble for the owner, but I know of few ways of expending energy that are so infinitely rewarding.

One thing that must be avoided at all costs and which is rather a temptation to children, is teasing a cockatoo in order to make it raise its crest and screech. Such treatment is completely ruinous to the temper of a pet bird. Cockatoos in an aviary revel in a rain bath, and caged specimens should either be put out in their cage in a light summer shower, or, if this is impossible, be sprayed indoors with a fine spray of tepid rainwater.

A cockatoo's cage should be as large as possible, and care should be taken to ensure that the bird's crest when fully spread does not come in contact with the top of the cage, otherwise its appearance will be spoiled..

Cockatoos should be fed chiefly upon sunflower seed and monkey-nuts, with small quantities of canary seed and oats or groats as well as a pinch of hemp every other day; when they are breeding, the latter should be given daily and the amount considerably increased as it is a valuable rearing food.

Wheat can also be offered, particularly to the larger species, and most cockatoos appreciate a piece of stale bread soaked in sweetened milk and this can be given occasionally as a titbit. In my experience the majority of cockatoos are not particularly keen on fruit but are very fond of the usual wild green-foods, also the leaves of cultivated spinach-beet and particularly the midribs of seakale-beet.

Spend time with your pet, feed him well and you will have a delightful companion which will live many long years. Enjoy him!