Caiques are monomorphic, i.e., males and females look the same. With the possible exception of a report that caiques have a sex-linked trait in which some males have a white toenail, one has to resort to an alternate means of determining a bird’s sex. There are a number of these—some highly reliable and others pure bunk. I have included a table in this section listing a number of the methods used to determine the sex of monomorphic birds as well as my opinion of their reliability for caiques.

Before about 1980, identifying the sex of a caique was a major challenge. The only reliable indication was when a bird laid an egg. This made setting up breeding pairs a matter of chance. Even the observation of copulation of one bird with another was not a sure sign since same sex birds often mount each other and render this observation useless (Ireland, 1988)  So the people who bred caiques had to resort to a number of other poor indicators. Some thought they could tell a bird's sex by examining the closeness of a set of bones called the pubic symphysis near the bird's vent. This method works well for some bird species, but not for caiques. I even ran across a person who claimed that he could determine the sex by following the direction of motion of a steel sewing needle suspended by a thread over the bird's head. This person offered to demonstrate the method on Sammy, one of my pets whose sex I did not know. He predicted that Sammy was a male—sometime later Sammy laid an egg.  Some breeders claim they can distinguish sex by observing subtle visual and audio differences. Fran Gonzales, speaking at the 1995 American Federation of Aviculture convention, claimed that males have a more squared head shape, darker eye ring, and lower pitched voice than females. I have been unable to see these distinguishing traits in my birds. Thankfully, however, we no longer need to depend on these unreliable methods.

There has been a succession of increasingly better veterinary approaches for determining a parrot's sex. An early one was hormone analysis (Erb, 1981). While it was non-invasive, only requiring a specimen of the bird's blood or feces, it proved unreliable and it quickly lost favor. A bit later in the 1980’s, the first two reliable methods came into common use. These were laparoscopy (also known as otoscopy or "surgical sexing") and karyotyping. In the laparscopy method, the veterinarian makes a tiny hole in the abdomen, inserts a laparoscope, and views the bird's sex organs. Because of the need to enter the body cavity, there is a small risk to your bird. This method works for most parrots, but my experience indicates, it is not always as accurate some veterinarians think, particularly if the birds are very young or out of season (Prus, 1987). When I was securing male breeder birds, I purchased five birds in succession that had previously been surgically sexed as males. In every instance, my veterinarian found them to be females. A prominent veterinarian, who wrote many articles for bird magazines and even a book on avian medicine, sexed one of these birds. Even my trusted vet, indicated that one of my females was immature, but she laid her first egg three months later. Another bird, which he indicated was a mature female, never laid an egg in the four years I owned her. Dr. George Smith, a veterinarian, whom I regard as one of the world’s leading authorities on caiques, also feels surgical sexing of caiques, particularly young birds, is unreliable. This method, however, is still reasonably reliable and is offered by some veterinarians because it is the quickest method for determining a bird’s sex.

The second method, karyotyping, is also a good method, but few laboratories perform this assay anymore. This method is based on the difference in size of the chromosomes that determine the bird’s sex. In birds, the sex is determined by a set of chromosomes called the ZW pair. If a bird receives two Z chromosomes from each of its parents it is male, but if it receives a Z and a W it is female. The W chromosome is smaller than the Z chromosome and this size difference can be seen when the cell is dividing. (It should be noted that this is different from the XY chromosome inheritance pattern of mammals in which the smaller X chromosome is associated with the male.) A major disadvantage of kayrotyping method is that it requires living blood cells. The blood is usually obtained by pulling several blood feathers. The blood cells in the feathers are then treated with a mitogen to induce cellular division during which the individual chromosomes are visible with a microscope. If the smaller W chromosome is seen, the bird is a female. The accuracy of this method depends on the person doing the assay, and it fared poorly in a head to head comparison with surgical sexing (Prus, 1987). All these early clinical methods, except for the surgical method, have nearly disappeared because a new, highly reliable, relatively non-invasive method has been commercially developed—“DNA sexing”.

Actually, there are multiple “DNA sexing” methods. All are reliable and based on unique sequences of DNA within the W chromosome that are only inherited from the female. Halverson (1990) gave one of the earliest descriptions of a DNA based assay—the restriction fragment length polymorphism (RLFP) method. In this method, enzymes called restriction enzymes cleave the DNA at specific sites defined by the nucleotide sequence. Haalverson discovered a single DNA probe capable of annealing to the DNA of both the Z and W chromosomes; however, the length of fragment resulting from the digestion with the enzyme from the two different chromosomes was of different length. Thus, when the digested DNA fragments are resolved according to size by agarose gel electrophoresis one may determine the sex of the bird. If a fragment of only one size is seen, the bird is a male since males only have the Z chromaosome. If two different sized fragments were seen, the bird is a female—one fragment from the Z chromosome and a second fragment of different size from the W chromosome.  There are alternative methods that detect other genes only found in the DNA of the female determining W chromosome.  Whatever method, for the commercial assay, you only need a small drop of blood containing cells for the extraction of DNA. You can collect the blood by clipping a nail or pulling a feather. A big advantage is that it does not require live blood cells. In fact, the cells in the blood are immediately killed by mixing with the alcohol in the tubes provided with the test kits supplied by the testing laboratory.  Avian veterinarians and some pet shops offer this service, but you can submit the blood directly and save money. There are a number of sites on the World Wide Web that offer this service. A disadvantage of this method of sexing is it requires up to two weeks to get the result.

Behavior is another way of telling sex. At one time Dr. Smith thought you could tell a male from a female by whether it makes a "piping with wing-lifting" when stimulated by the presence of another pair of caiques. He has since changed his mind about this. Nonetheless, I feel behavior may still be used to distinguish sex. When a flock sets up a pecking order, the top or alpha bird is usually a male. Further, males tend to be more open and aggressive, while females generally sit tight or flee. This difference would explain the success of Bernard Roer’s method of sexing monomorphic birds (Hawley, 1997). One of his rules of parrot aviculture was “The first bird you catch is the male, the second one you catch is the female.” If you have a pair of tame caiques, you will find that the male usually is the first to leave the cage when it is opened. If you have a pair of breeding birds, and you bring another bird near them, the male will usually place himself between the stranger and his mate.

This behavior may explain a popular misconception among aviculturists that breeding parrots, including caiques, produce more male progeny than female progeny. Indeed, there is a scientific basis for birds being able to control the sex of their offspring and there are reports of this for non-parrot species (Sheldon, 1999; Nager, 1999). However, this has not been my experience with caiques, and a published report on sex ratios among parrot species confirms that they hatch in about equal numbers (Clipsham, 1997). The origin of this fallacy probably lies in the availability of wild caught birds and more males seemed to be available than females. This may reflect Roer’s rule as applied to the catching of wild birds, i.e., proportionately fewer females were caught. Yet, despite this new knowledge, breeders still often charge more for females than males because of their erroneous belief that they are less numerous.

As far as selecting one sex as a pet over the other, it’s a matter of what kind of traits you want in your bird. Males are thought to have a greater propensity to talk, but females will talk. I have had only two birds that talk well. One is a female, the other a male. A more important consideration, I believe, is the bird’s behavior. Generally, males are more fearless than females. They will jump off their perch and track you down when you leave the room for too long while females usually remain put. Males like to explore their surroundings more than females. Males also tend to be more destructive and are more likely to chew on your furnishings than females, although females go into high gear chewing just before they go to nest. Males tend to remain chummier when they get older; older females, while they still like to be held, usually demand less attention. Of course, these comments are general and individual birds may not fit these behavioral profiles.

Lastly, while still on the topic of sexuality, I want to discuss love and the single parrot—well almost single. Some parrots will rub their posteriors over your hand while making distinctly different sound. They are masturbating. This reality of life will not go away despite the forced firing of the former Surgeon General Dr. Jocylyn Elders during the early Clinton administration over her comments recommending masturbation. Bestiality is perhaps a better term, since they usually want to masturbate with their favorite human. Both sexes indulge in this. Females tend to do it only when they are in season, and infertile eggs are sometimes laid. Males will do it almost anytime. Not all birds engage in this behavior, but if they do, it does not mean they are maladjusted. Sexuality is pervasive, even for birds. They are just following their natural instincts. Many dog owners are used to this behavior in their pets. Fortunately, birds usually only get it on with persons they know, not complete strangers like dogs.

Home page