Many collections of parrots com­prise widely differing species, yet the food offered to them tends to become standardised. The birds would benefit if a little less routine and rather more thought was introduced into their diets.

At San Diego, one of the most im­portant and progressive of the world's zoos, medical staff examine diets of various species from several aspects, including reported food preferences in the wild, occupational therapy of food items (not necessarily related to nut­ritional value) and practical consider­ations of foodstuff availability, perish­ability and economy.

The subject of occupational therapy is especially important in the case of caged parrots which seldom have enough with which to occupy their minds and beaks. Such foods as spray millet and corn-on-the-cob, wheat or grasses in the ear, will provide great enjoyment and occupation. And a suitable bone will provide hours and even days of activity.

Similarly, it is of value to provide, in a separate container, such seeds as canary and white millet, which some large parrots like, for it takes them longer to eat the same weight in these seeds than in sunflower because of the time spent husking them. Parrots enjoy peanuts in the shell because of the attraction of crunching up the shell. However, if the peanuts are then dis­carded, as sometimes happens, this becomes an expensive item.

San Diego's list of considerations for feeding is useful only up to a point with parrots. Most, such as Pesquet's Parrot, are known to take large quan­tities of fruits and that species will not eat seed at all in captivity but only fruits and various soft foods. The diet of most parrots, however, is quite varied in the wild, consisting of fruits, buds, leaves, seeds, insects, nectar and nuts. While seed forms only a small part of their diet, or may never be encountered, many parrots could exist on little else in captivity. They are extremely adaptable in the matter of diet and, in the wild, parrots often raid cultivated crops; however, this adapta­bility must not be abused and every effort should be made to provide a varied diet.

This will result in healthier birds and will also add interest to their lives; bored parrots and those which are incorrectly fed all too often acquire the habit of feather plucking which is usu­ally only curable if the diet and con­ditions under which they are kept are altered.

Diet also influences the desire and ability of birds to breed and it is of vital importance in the case of laying females. The egg must contain all the nutrients required by the embryo before hatching and, if its contents are deficient, the embryo or the chick will die in the shell. Even a minor defici­ency of a certain vitamin or mineral could result in the death of the chick, before or after hatching. As it is almost impossible to know in which area the diet is deficient, a balanced diet is essential.

The most likely deficiencies are of the amino acid lysine, Vitamins A and D and Bz (riboflavin), calcium and certain trace minerals. especially manganese. Lysine is found in the oily seeds - niger, hemp and maw - and deficiency is likely - indeed common - in birds fed mainly on millet and sun­flower. It can manifest itself as patches of yellow in the plumage of a predomi­nantly green bird. Breeders sometimes become excited at the appearance of such a bird, believing that it may lead to a pied mutation, but this is not the case and if the diet is corrected the plumage will become normal at the next moult. Cuttlefish bone, which is taken readily by all parrots, is the main source of calcium. Old mortar rubble is equally valuable.

Trace elements will be obtained from a mineral grit specially formu­lated for birds. All seed-eating parrots need grit, which is used in the gizzard to grind up food. This is best sprinkled on the ground for birds which use the aviary floor, or sprinkled on the feed­ing shelf for others. Many parrots will ignore grit if it is placed in a small container, yet pick it up from the floor.