Why Did My Bird Lay an Egg? Finding
an egg on the bottom of a bird's cage is a surprising and sometimes an alarming event for any bird owner. The surprise
is even greater if the bird does not have a mate and the bird's name is John! Breeders and pet shops usually try to determine gender before selling birds based on visual clues, behavior traits or bone structure
typical of male or
female cockatiels. These methods are not always accurate. Your bird , who was
as being a male, now lays an egg, providing proof as accurate as any DNA lab test,
that he is really a female. Now for the even bigger question, why did John, (who
has now been renamed Joan,) start laying eggs without a mate?
There are several
reasons why eggs are laid without a mate, including the fact that female
cockatiels are notorious egg layers. Egg laying in captivity is based on
the breeding behaviors and needs of cockatiels living and breeding in the wild.
For wild cockatiels, egg laying and breeding are seasonal activities that only
occur during the Spring and Summer months. Several changes in nature occur
during these months that stimulate breeding hormones, resulting in breeding
activities such as mating, nesting and egg laying. The primary influence on
breeding behavior is an increase in daylight hours. Other changes include a
warmer climate that is more favorable for breeding, and the availability of more rain
for bathing and more food to eat.
A variety of plants, grains, berries and insects can be found during the Spring
and Summer months. (During the Winter months, a bird's diet is limited to mostly
seeds.) Wild cockatiels nest and lay eggs inside of hollow
trees, as shown in the picture to the left . Cockatiels usually mate and
stay with the same partner for life.
Unlike wild cockatiel, our pet birds have a Spring/Summer like environment that provides ideal
breeding conditions all year long. When something in the environment stimulates a pet
bird's breeding hormones, she/he will display breeding related behavior.
Females will start laying eggs and males
will display seasonal aggression.
Any of the factors listed below can
stimulate breeding hormones, resulting in a
reproduction cycle for either a female or a male bird living in captivity.
Laying Process: This is a very brief description of a female cockatiel's reproductive system. Adult, female parrots have only 1 ovary and 1
oviduct located on the left side of their body,
under the "elbow" of the wing. Although females are born with 2
ovaries and 2 oviducts, the other ones gradually recede as a bird approaches
breeding age. When
females are sexually mature and something in the environment stimulates
breeding hormones, hens will ovulate and start producing eggs. The yolk of the
egg develops first in the follicle of the ovary. The egg then passes on into the
oviduct, a long, muscular tube that has 5 sections, each one performing a
specific function. All of the other stages of development take
place in the oviduct, where other components
of the egg are added, including albumin and membranes. If a male is present and a successful mating has taken place,
eggs will be fertilized
in the oviduct as well. Females can store sperm in their bodies for up to 15 days,
making it possible for 1 entire clutch of eggs to be fertilized from 1
- Exposure to increased daylight hours are caused by long hours of
artificial indoor lighting.
- Warm, indoor, environmental conditions are favorable for breeding all year long.
- The bird has bonded with a mirror, human or toy and perceives the object of her/his
affection to be a mate.
- An abundance of a variety of foods, including soft foods which are
needed to feed chicks are always available.
- Water is plentiful and pet birds have the opportunities to bath
frequently indoors all year long.
- The bird has been hanging out in dark cozy corners, a nestbox or birdie tents which
are similar to a hollow tree.
- The bird has paper, straw wood and other natural fiber toys inside of
the cage to shred for nesting material.
- Petting a bird on the back, stomach or under the wings (where ovary and
testicles are located) stimulate breeding hormones.
After fertilization, the egg then moves into the 5th and last part of
the oviduct, the uterus or shell gland. This is where the egg will spend the most time,
hours. While in the uterus, a watery solution will be added to the egg,
increasing the weight of the albumen. The
actual shell itself, which is composed of about 95% calcium carbonate crystals,
will also be formed around the bare egg in the uterus. The egg then passes
into the cloaca and vent until it is laid by the hen. The process of egg laying, from
ovary, (fertilization if male present), to development of shell to egg laying
takes about 2-3 days. If your single female cockatiel lays 1 egg, more
will be on the way. You can expect your female to lay 1 egg about every 48 hours
(2 days). until a clutch of 2-8 eggs is laid. Cockatiels and other parrots
are "indeterminate" egg layers. This means parrots do not lay a
specific number of eggs. If an egg is lost, broken or removed, they will replace it by laying an another egg.
Signs of Egg Laying
Females getting ready to lay eggs will feel heavier, weigh more and their lower
abdomen near the vent may feel firmer and look larger. When producing an egg, females will also start drinking much more water
because eggs are made up of so much water. Chewing activity will also increase, as
females start to shred more paper, perches, wood, toys etc. in preparation of a
nest. Females may also become very protective of their cage, backing up
into a corner, chirping softly. Prior to and during the egg laying process,
the female will have very large, loose and odorous droppings. This is also
Droppings are retained in the cloaca and they are eliminated by the
female in the morning. A total absence of droppings indicate egg binding.
to do When Eggs are Laid:
Do NOT remove eggs from the cage. You can place the eggs on top of a
cloth on the bottom of the cage, or inside of a little basket, box or other container that has been lined with white paper towels. This will make
your bird more comfortable and it will prevent the eggs from rolling around. If
an egg breaks or your bird starts pecking at them, remove the eggs and replace
them with white
marbles or wooden dummy eggs. Clean the area thoroughly to prevent bacteria from growing.
Allow your single cockatiel to nest (sit) on the eggs for 21-30 days. Cockatiels
and other parrots are "indeterminate" egg layers. This means
that the species does not lay a set number of eggs. If 1 egg is lost,
broken or removed, a cockatiel will just replace it by laying another egg.
If you remove the eggs, your bird will go right into another breeding cycle and
start laying more eggs. This will lead to chronic egg laying. The average size
clutch for a cockatiel is 2-8 eggs. Sometimes
cockatiels wait until a few eggs are laid before nesting on them. So
don't throw out eggs if your bird is initially ignoring them.
What Stops Egg Laying?: The hormone prolactin is needed to stop the
egg laying cycle in a female cockatiel. When the first egg is laid, her level of
prolactin is low. The level will increase with each additional egg laid and the
amount of time she nests on the eggs. (Source: Facts on Hormones: Exotic
Bird Report, Psittacine Research, Univ. of Calif. Vol 2, Number 3.)The
University of California also reported that clutch size is influenced by hormones and
that clutch size can be controlled to a certain extent. If one egg is removed
from the female' s nest, 1 additional egg will be laid, increasing the clutch
size. If 1 additional egg is placed in the nest each time the female lays
an egg, clutch size is reduced by 1 egg. (Source: Facts on Hormones: Exotic Bird Report, Psittacine Research, Univ. of Calif. Vol 2, Number 3.)
Nesting Phase Care: Nesting on eggs is both physically and
psychologically stressful for your bird and any type of stress impairs the
immune system. Sometimes females that are nesting on eggs are reluctant to move
out of the nest to eat food, drink water and exercise. Keep an extra set of food
and water dishes close to your bird. Females that are laying eggs will also lose
calcium. Provide plenty of extra calcium in her diet from fresh, dark green
vegetables such as kale, cilantro, parsley, beet greens, turnip greens, endive,
chard, mustard greens, watercress, broccoli leaves and stalks. Also offer
her bright orange foods, like baked yams, sweet potatoes and carrots, that
are rich in Vitamin A to boost her immune system. Offer her other
calcium and vitamin A rich foods as listed on this page Healthy
Table Foods and this page Table
Foods. If your bird is not eating pellets, make sure she has access to full spectrum
UVA/UVB lighting, 15 minutes each day from a Zoo Med or another brand of full spectrum light bulb. Birds
that are not eating pellets need this type of lighting in order to metabolize
calcium. It's normal for your bird to be more
aggressive with your during while nesting. She'd doing her job and protecting
her nest. When the eggs are eventually removed after 21 days, the aggressive
Chronic Egg Laying (Chronic Reproductive Syndrome) and Health Problems. Cockatiels living in the
wild only produce 1 or 2 clutches of eggs each year. More than 2 clutches
would be considered unnatural. Chronic egg laying in pet cockatiels is described as laying more than 2 clutches of eggs per
The stress and physical demands of excessive egg laying include some of the following health problems.
- Calcium deficiencies
- Seizures, low calcium
- Brittle Bones, low calcium
- Weight loss.
- Poor health in general.
- Poor feather condition.
- Feather loss or dermatitis around vent.
- General muscle weakness.
- Reproductive Diseases.
- Abnormally formed eggs.
- Poor muscle tone of oviduct or uterus.
- Prolapsed cloaca or uterus.
- Egg impactions in oviduct.
- Egg Binding.
- Other reproductive ruptures, infections and disorders.
- Sudden death.
Preventing Egg Laying: Avian veterinarians usually consider it safe for
an adult, healthy, well nourished cockatiel to lay 2 clutches of eggs a year.
Females that lay more than 2 clutches of eggs a year are considered chronic egg
layers, having a condition which avian vets refer to as Chronic Reproductive
Syndrome. In most cases, chronic egg layers will seem
healthy for years but eventually they will suffer from malnutrition and other
serious health problems because of the progressive stress
and physical demands associated with egg laying. Stress impairs the immune
system, making it easier for birds to get sick. Egg laying in excess of 2
clutches a year should be discouraged because it also compromises a female's general
health and causes reproductive disorders. Once a female
starts laying eggs, all future egg laying is influenced and controlled by
hormones. By interrupting, changing and removing the environmental stimuli that
cause a hormonal egg laying cycle, future egg laying can be prevented.
Environmental changes should create undesirable breeding conditions, just the
opposite of what optimum conditions are for breeding.
Modifying your Bird's Environment: (also for male, seasonal,
hormonal aggression) Remove birdie beds and sleep tents from the cage.
Remove cage mirrors that your bird seems overly attached to and toys that she/he
may be using for masturbating. Remove toys made out of paper, wood and other
natural fibers that she is chewing and shredding. Re-arranging the cage so it feels less secure and reducing the
number of daylight hours your bird is exposed are often very effective in
preventing or stopping chronic egg laying. Birds will not set
up nest and start producing eggs if the site they have chosen feels insecure. Re-arrange, switch and move perches, feeding dishes and toys or
replacing them with new items that are a different size, color, texture or
shape. Other changes that can make the cage feel less suitable for nesting
include moving the cage to another area side of the room or moving cage into a completely different
room. Putting your bird into an entirely different looking cage in a
different room is even better. The more drastic the change, the more effect it
will have on preventing egg laying. Since exposure to daylight has a
strong influence on breeding hormones, reduce the amount of daylight hours that
your bird is exposed to so the environment resembles Winter, non-breeding
months. Reduce daylight exposure to 10 hours a day and keep the cage covered for 14 hours each
night in a very dark, quiet room, for 2 weeks. If this doesn't help, reduce your
bird's exposure to daylight to 8 hours a day Cover the cage so your bird is in darkness for 16 hours for 2 weeks. Avoid
giving your bird baths, water misting or soft foods during the 2 week period. After
2 weeks resume normal bathing and feeding routines. Note:
Re-arranging, moving the cage and reducing light should all be done at
the same time. Reducing light alone may encourage egg
laying by making the cage seem like a nestbox. (The same suggestions work for
males that are going through seasonal aggression.)
Dark, Cozy Corners and Petting Effect both Females and Males: The
presence of an acceptable nesting spot and nesting material always encourages
breeding behavior. Both female and male birds will seek out dark corners.
Females will lay eggs and males will become very territorial and aggressive,
often attacking and biting you to protect the spot they have found. The space
in-between the bottle and microwave, in the photo to the right is a good example
of the type of area that encourages egg laying and breeding behavior. If you
notice your bird investigating dark, enclosed areas like cabinets, open bureau
drawers, the top of closets, the inside of shoes, socks etc. don't allow it.
Close, block or cover the "entrance" because your bird is probably looking
for a place to lay eggs. Cockatiels do not need an actual nest to lay eggs
in. They just need a cozy, little out of the way corner, like the one the bird
in this picture has found. It's not uncommon at all for cockatiels to lay eggs
under chairs, under beds or other out of the way places in the home where they
are allowed to spend time. Sleeping tents, huts and birdie beds that are sold in
stores also provide a place for egg laying so avoid using them with
cockatiels as well. Last but not least, Avoid petting your bird on the back,
stomach or under the wings because that's where a female's ovary and a male's
testicles are located. When you show your bird affection in these areas,
you're stimulating her ovary or his testicles.
Hormones & Surgery: If your
bird continues to lay more than 2 clutches of eggs per year despite all of
the measures presented, take her to an avian veterinarian. Lupron, a prescription hormone therapy is available
that may help your bird. Another method suggested, (when all other methods fail
and when the hen is still in good health), is to allow the female to raise 1 clutch of
chicks. This may end chronic egg laying. As a last resort, an avian vet
may recommend that a chronic egg layer have a hysterectomy to prevent egg
laying. An avian hysterectomy is the removal of just the 1 oviduct, not the
ovary. Most of the egg's development takes place in the oviduct and the ovary is
located near a very large artery which would make the procedure too risky.
Click Here to read about Egg Binding. It may save your bird's life.
Note: Replace toys that are used to chew on and shred after egg laying or
male aggression has stopped. Your bird needs these types of chew toys to prevent
boredom and feather plucking