Parrot reproductive system — a single left ovary and the egg's assembly line
Overview of parrot reproductive anatomy — internal testes that swell in the breeding season, a functional left ovary and oviduct only, the oviduct regions that assemble an egg in stages, and a cloacal exit shared with other tracts.
General educational reference only — not clinical or veterinary advice. Anatomy varies between individual animals; consult a licensed veterinarian for any health concern.
Internal gonads, and only the left ovary
A male parrot's testes are internal, lying against the front ends of the kidneys; they enlarge many times over in the breeding season and shrink back afterward. In the female, only the left ovary and left oviduct develop fully — the right side regresses during development, a reduction usually explained as weight saving in a flying animal. Parrots have no phallus: sperm is transferred by briefly pressing the cloacas together.
The oviduct: an egg assembled in stages
An egg is built around the yolk, which is ovulated from the ovary and caught by the infundibulum, the oviduct's funnel-shaped first region and the site of fertilization. The magnum then wraps the yolk in albumen, the isthmus adds the two shell membranes, and the shell gland or uterus deposits the calcified shell over many hours — in parrots an unpigmented white one. The finished egg passes through the vagina, whose muscular wall expels it, into the cloaca.
Laying and the cloaca
The oviduct opens into the urodeum, the middle chamber of the cloaca, so eggs leave through the same vent as digestive and urinary waste. Because the assembly line runs whether or not mating has occurred, a female kept without a male can still form and lay eggs; such eggs are simply infertile. Clutch size, egg size, and the interval between eggs vary widely across parrot species.
