Egg Production:
Avian Female Reproductive Question


I share my life with a nine-year-old Moluccan cockatoo hen named Calypso. I live in dread that the day will come when she becomes egg-bound. I have heard so many horror stories about egg-bound hens that I am afraid Cal will have a problem laying an egg and I won't recognize the condition in time. Can you explain the signs of an egg-bound hen and what I should do if the situation ever arises? I even asked my vet about "spaying" her so I won't have to worry about egg-binding anymore! Thanks for your information.


Most people are afraid of things they don't understand, so let's learn a bit about the hen's reproductive activities. That way, armed with correct information, you won't have so much to be worried about.

A hen doesn't just lay an egg out of the blue. There are often clear signs that a hen is becoming reproductively active, so once you learn what to look for, you can be prepared for any situation.

The good news is that it is uncommon for a single pet Moluccan cockatoo to lay eggs. Of course, there are always exceptions, but for the most part, a pet Moluccan hen won't lay eggs. I have known a few pet Umbrella cockatoos, very attached to their owners, that laid eggs. One actually deposited an egg in her owner's hand! Another, while snuggling with the owner and watching TV, laid an egg into the owner's cleavage! But I have not known any Moluccans that have done that.

There are many and varied cues that induce a hen into beginning an egg-laying cycle. Some hens become reproductively active with increasing daylight. Some hens will become active in the presence of a con-specific male (meaning he's of the same species), but others become active when a suitable nesting site is provided. Some birds begin breeding with the onset of abundant food, which is often tied in to the weather patterns (for example, during the rainy season). In Florida, where I live, cockatoos tend to breed year round, so many of the cues that initiate reproductive activity don't seem to apply. But it is safe to say that without a nest box, and perhaps a male, most Moluccan hens aren't likely to lay eggs.

So, what if Cal goes into reproductive mode? What should you expect? Most hens will have predictable changes that you can observe. Many hens that are getting ready to lay eggs will begin chewing everything in sight. In the wild, she and her mate would be chewing up a hollow in a tree to prepare a suitable nesting site. So, something in a hen's brain tells her that she should start shredding. Perches, toys, window and door molding, newspaper, magazines and just about anything not nailed down, will be chewed up.

Often, a hen that is getting ready to lay eggs will begin holding her droppings for longer periods of time and then pass huge bombers. Normally, a hen won't pass droppings in her nest, whether it be a tree hollow or a nest box. Even in the absence of a box, a hen may begin holding her droppings. When she does pass a dropping, it may be very different in consistency. These droppings may have a stronger than normal odor, and they may be "sloppy." By this I mean that the three portions of the dropping, the urine, urates and feces, are poorly defined, and the feces may have the appearance of diarrhea. Since eggs contain a lot of water, a hen that is beginning to produce eggs will start drinking more water than usual. The increase in water consumption is usually quite profound. If you pay close attention to Calypso's water consumption, you will know if she is drinking more water than usual.

A hen getting ready to lay eggs may become much more protective about her cage. She may resist coming out of her cage, and she may be much more aggressive if you put your hand in her cage.

There are hormonal changes that occur when a hen begins a reproductive cycle. To facilitate the passage of an egg through the cloaca, hormones are produced that cause the muscles of the pelvic floor to relax. They also are responsible for the cloacal muscles loosening. The ligaments holding the pelvic bones also relax. All of these changes make it possible for an egg to pass through the pelvis and cloaca. People often ask me about sexing birds by palpating (feeling) the pelvic bones. Generally, a male's bones are more sharply pointed and closer together than those of a hen, which are usually more rounded. However, when a hen is NOT reproductively cycling, her pelvic bones will also be very close together, since we now know that hormones cause the bones to separate somewhat. A hen not breeding will often have pelvic bones that are as close as a male's, and after breeding season has ended, the bones usually return to the pre-breeding position. So, for the most part, it is not possible to determine, with any degree of accuracy, the sex of most parrot species by the pelvic bones, unless the hen is reproductively active at the time.

Egg-binding, a condition where the egg fails to pass through the oviduct at a normal rate, can lead to serious problems. Dystocia, a more serious condition, occurs when there is a mechanical obstruction of oviposition (egg-laying) or disruption of cloacal function, because of the egg's presence at the end of the oviduct. There are many causes of egg-binding: problems related to the oviduct (the muscular organ that the egg moves through), including infections, tears and muscle problems, excessive egg laying, systemic disease, nutritional deficiencies or excesses, obesity, lack of adequate exercise and muscle tone, genetic predisposition and other conditions. Egg-binding is much more common in cage-bound birds, those that are overweight and those birds on a poor diet.

Signs of egg-binding vary. Commonly, a bird will become depressed, stop eating and will sit all fluffed up. She may be straining occasionally. Droppings may be absent, since the egg is preventing them from passing out through the cloaca. Occasionally, a hen will develop lameness of one or both legs (if one leg is involved, it is usually the left). The abdomen may appear swollen, especially around the vent area. Some hens will sound as if they have respiratory problems because of the noises they make when straining. An egg-bound hen will be obviously uncomfortable, and she may pick at her vent.

So there you have it. Since Cal is your best friend, I'm sure you would notice some of the many changes in her, both physically and behavior-wise, before she ever reached the stage of egg-binding. Of course, most healthy birds should have no trouble laying an egg for the first time, so it is a remote possibility that your Cal would ever have these types of reproductive problems anyway. "Spaying" a pet cockatoo that has never had a reproductive problem is certainly not recommended, nor necessary. Just be aware of any changes in her behavior, appetite, water consumption or droppings that would alert you to any potential problems. Forewarned is forearmed.

Copyright 2006 Margaret A. Wissman, D.V.M., D.A.B.V.P.
All Rights Reserved

Printer Friendly Page