Abstract
B efore I become directly involved in my topic, I would like to briefly comment on my introduction to the field of aviculture.
Parrot Fever
My first birds were a pair of Budgies which my mother quite innocently gave me for my fifth birthday. It wasn't too long after this event that I began to develop subtle signs of parrot fever. These symptoms, however, didn't reach their full manifestation until I was the ripe old age of seven - and this pair of birds raised five chicks!
Since that time, I have been a helpless victim of a rare and little known form of parrot fever for which there is apparently no known cure. The parrot fever I refer to, of course, is not psittacosis or omithosis in its classical sense, but rather the type of parrot fever with which I'm sure many of you are/familiar--one which is characterized by a
consuming interest in the members of the parrot family, accompanied by a strong compulsion to keep a number of these birds around you at all times. This need is never fully satisfied and the afflicted individual always suffers from a desire to have just one more. I am, in fact, addicted to parrots.
Macaws and Cockatoos
I am going to direct my comments to two groups of parrots which hold my particular interest: the cockatoos and macaws. These remarks are based on my personal experience and observations and are not intended to infer in any way that this is the only way it should be done. There are many ways to "skin a cat," and my objective is to help make the skinning process a little easier for some of you.
One basic premise which we should all consider in the aviculture of any species is that it is natural for wellcared-for, properly housed, healthy birds to attempt to breed providing all their behavioral needs are met. If they do not, in all probability, it is because we are doing something wrong.
A second premise is that while it is next to impossible to achieve breeding success with an incompatible or otherwise bad pair of birds, it is relatively easy to inadvertently stop a good pair of birds from breeding.
A third premise relates to Murphy's Law, which states that if something can go wrong, it will. From my experiences, I feel safe in saying that if you were not a pessimist when you started working with birds, you certainly will become one at some point during your avicultural career.
Breeding Macaws Macaws are Easier
In general, I have found macaws far easier to breed in captivity than cockatoos, as they seem to have no critical
requirements regarding aviary size, type of nesting structure, or specialized dietary needs. A review of the literature quickly reveals that macaws have been bred successfully under every conceivable type of circumstance: in aviaries; at full liberty or as pinioned specimens; housed as pairs or in colonies, and even indoors in relatively small cages.
The pair of Hyacinths at the Houston Zoo raised their first clutch of two chicks to full independence while housed indoors in a temporary wire cage which measured six feet by six feet by eight feet tall with a wooden next box attached from the outside at floor level.
Any Nest Site May Do
The larger macaws in particular seem willing to accept practically any type of nest site so long as it is relatively dark and defensible. It seems to make little difference what the nest looks like, or where it is located, either elevated or on the ground. I have seen them nesting in barrels, garbage cans, wooden crates and even dog houses. A pair of pinioned Military Macaws owned by a friend and kept at liberty in her back yard, regularly nested in a dark comer of a store room under a table. And yes, they did rear their young.
Hybridization
The urge to reproduce is so great in most macaws that hybridization readily occurs when a mate of the same species is not available. The primary prerequisite seems to be having a male and female housed together. Unfortunately, these birds are not dimorphic, which up to now has proven a major obstacle to breeding them in captivity. In the past, our efforts to determine their sexes have been little more than educated guesses. Checking the width of the pelvic bone on a macaw generally only tells you that the macaw has pelvic bones. Unless, of course, you happen to be checking a female about to start laying.
Homosexual Pairs
To further confound the problem, macaws are absolutely notorious for forming homosexual pairs. In fact, if
you have two adults which attempt to copulate frequently and never produce eggs or consistently produce large clutches of infertile eggs, in all probability, you do not have a true pair. I would caution you that while the average clutch consists of only two or three eggs, some females may lay large clutches of five to seven eggs. Large clutches, therefore, do not necessarily mean you have two females. One of . our female Blue and Golds never lays less than five eggs in a clutch. This presents a problem, since her egg-laying sequence is every third day. The oldest chick is two weeks old and quite large by the time the fifth egg is due to hatch, and in order to save the last chicks, it is necessary to pull them for hand-rearing. Otherwise, they would in all likelihood be mashed in the nest by their older and larger siblings. Also, rearing five chicks for 10 to 12 weeks is a considerable strain on a pair of birds.
Modern Sexing Techniques
Now that modern techniques are available to help solve the dilemma of accurately sexing birds which are not dimorphic, and by this I mean laparoscopy, fecal steroid analysis, or chromosome techniques, not the needle and thread method, I predict a sharp increase in the number of macaws successfully bred each year.
Breeding Cockatoos Most Cockatoos Readily Sexed
Fortunately, sexing most cockatoos is not as great a problem as sexing macaws. Adult specimens ina number of species show distinct differences in eye color: dark brown or blackish in males and light brown to red in females. In some species, especially the various sub-species of Cacatua galerita, males are significantly larger than females. In addition to their larger size, many male cockatoos also have pelvic bones so close together as to seem almost fused. The black cockatoos, with the exception of the Palms, are easily sexed as adults by the dimorphic coloration of their plumage. For species which lack any apparent dimorphism, such as the Moluccans, Bare-eyeds, and Slender-bills, the use of modern sexing techniques is also quite useful.
In all cockatoo species, juveniles may prove difficult to sex. The transitional development of adult eye color in females usually begins to occur during the first year and generally reaches its final stage of development in two to three-year old specimens. Young female cockatoos kept on diets low in vitamin A and kept indoors without prolonged exposure to direct sunlight during this period of time often fail to develop the intensity of eye color characteristic of adult females (of their species). This may, in part, account for a number of the so-called brown-eyed females which are occasionally seen.