For those of you seeing avian patients, this time of year can provide some interesting challenges. With our patients typically eating healthy diets and undergoing preventative health care, we are seeing hens becoming reproductively active at a young age.

Some of the older literature suggests that most larger psittacines won't breed until they are 6-7 years of age. However, with optimum health, you can expect that many conures, Amazons, Eclectus, macaws, cockatoos, pionus, Poicephalus and cockatiels will breed by their 2nd or 3rd year. South American and Central American birds (considered New World birds) usually breed with increasing daylight hours. Most African birds breed with decreasing daylight hours, and most breeders set up their birds on Labor Day and consider Memorial Day the official end of their breeding season, although some pairs will breed year round. Eclectus and cockatoos tend to breed year round as well. Cockatiels usually breed with increasing daylight, but some may cycle year round. Cockatiels are indeterminate layers and will often continue to lay eggs to complete their clutch, if the eggs are taken away as they are laid. However, budgerigars (parakeets or budgies) are determinate layers and often lay just 4, 6 or rarely 8 eggs to complete the clutch.

Amazons, in particular, have an intense hormonal surge in the springtime, and often exhibit extreme behavioral changes at that time. Both males and females may become very possessive of their cages, and if allowed out of the cage, they often seek a dark closet, empty cardboard box, the dark areas of the home (cupboards, under the bed, empty paper bags). They may engage in "redecorating", chewing on wood moldings, chair legs, etc. They may attack any people that they consider to be threatening to their perceived human mate. Female Eclectus often seek out a dark area to "nest" in.

Since many birds are sexually dimorphic, this is important information to ascertain with your avian patients. Cockatiels are dimorphic, with hens having yellow dots on the wings and yellow bars on the tail feathers, and males (of the normal grey color) having a bright yellow face with bright orange cheek patches. Male budgies have a bright blue cere when sexually mature (4 months of age), unless they are a very pale color mutation, and hens develop a tan or brown cere that may hypertrophy with sexual maturity. Spectacled Amazons are dimorphic, with cocks having five or more bright red covert wing feathers, and the hens lacking the red feathers. Male Eclectus are primarily green and hens are red, purple and orange. Most of the Poicephalus are dimorphic, and a good avian atlas will provide the differences. Male African grey parrots have solid red secondary tail feathers, and those are tipped in silver in hens (after the first molt). Most adult cockatoos can be sexed by the eye color. Hens have red or brown irises, and cocks have such a dark brown iris that it appears black (shine a strong light into the eye for this).

Most Amazons, macaws, pionus, Timneh greys, conures and lories are monomorphic. A few species of lory are dimorphic; a good avian atlas can be invaluable when working with birds. While you might think that you can determine sex by behavior, this can fool you. Male macaws have been seen sitting on a toy bell or ball, and trying to incubate it. Males may try to mount other males, and hens may try to mount hens. Masturbatory behavior may be exhibited in both male and female birds.

Both sexes may begin holding droppings for longer periods of time during breeding season, and this is because in the wild, they will not usually soil their nesting site (often in a tree hollow). So, when they do pass a dropping, it may be quite large, often more odorous than usual, and often the three components are admixed (urine, urates and feces), with a more diarrheic appearance to the feces.

Often, a bird may be presented with the clinical signs of behavior changes: more aggressive in the cage, territorial and biting family members. Often, it is reported that the bird is PU/PD, which also occurs as a result of hormonal activity in the hen. She will begin drinking much more water than usual, as the water is necessary for egg production. She may begin plucking chest feathers in an attempt to make a "brood patch", an area of chest skin that becomes thickened in some hens, and allows better contact with the eggs for incubation.

On physical examination, the hen may evidence a recent weight gain, as the developing follicles and enlargement of the oviduct are responsible for increased weight. The pelvic floor muscles often become loose, to allow the passage of an egg, and this is under hormonal control. The cloaca may also become looser, again from hormonal influence.