Ostrich eggs are the largest of all eggs, the yolk is the largest single cell that exists today on our planet, though they are actually the smallest eggs relative to the size of the bird.

Laying season generally begins in the middle of March and ends in the middle of August, during which time the female will lay 1 egg every two days.The female ostrich will typically lay 10 eggs, but some productive females will lay more.

The nest may contain 15 to 60 eggs, which are on average 15 cm (6 in) long, 13 cm (5 in) wide and weigh 1.4 kg (3 lb). The eggs are incubated by the females by day and the males by night. This uses the colouration of the two sexes to escape detection of the nest, as the drab female blends in with the sand, while the black male is almost undetectable at night. The incubation period is 35 - 45 days.

Modern ostrich farms use incubators to hatch eggs.

For comparison, the smallest bird egg is the humming bee, which would fit 4700 eggs into one ostrich egg.

One Ostrich Egg Is

1 ostrich egg is equivalent to about 2 dozen chicken eggs.1 ostrich egg contains about 2,000 calories and is packed with protein.1 ostrich egg would take you about 40 minutes to hard boil.

The Story of Robin Eggs

Early Birds Catch Worms, Then Lay Eggs Most birds lay their eggs at sunrise, but NOT robins! They lay their eggs at mid-morning. That's several hours later than most birds lay eggs. For robins, this makes good sense. Robins eat a lot of earthworms during the breeding season, and they use those early dark hours to hunt for worms because worms are most available before the sun gets too high. Robins lay their eggs mid-morning after feasting on worms. A robin can then fly over to her nest and lay her eggs easily, but most other birds seem to need a long period of quiet before they can lay eggs. Those other species can get a big breakfast even if they eat late because they don't want worms anyway!

An Egg a Day is Work If you think laying an egg is easy, think again! Robins lay only one egg per day for good reasons. Female birds have one working ovary, unlike mammals, which have two. Ovaries are the organs where eggs are produced. A bird's ovary looks like a tiny bunch of different-sized grapes. These "grapes" are the ova, or actually the yolks. The one ovum about to be released looks huge. One or two are about half this size, a few more are a bit smaller, and the rest of the ova are tiny. About once a day, the largest yolk is ovulated. That means it pops off the ovary and starts traveling down a tube to the outside of the robin's body. This tube is called the oviduct.

Egg FormationIf a female robin has mated with a male, the yolk will become fertilized. If the robin hasn't mated, the yolk still goes down the oviduct and will be laid like a normal robin egg, but it won't develop into a robin. As the yolk travels through the oviduct, the tube's walls slowly secrete (drip out) watery proteins called albumen to surround the yolk. Near the end of the trip down the tube, the oviduct secretes calcium compounds. The calcium compounds will become the eggshell, but the egg will remain a bit soft until it is laid. You can imagine why the formation of an egg is a tremendous drain on a mother robin's body!

Stopping At Four Robins usually lay four eggs and then stop. Like most birds, they lay one egg a day until their clutch is complete. If you remove one egg each day, some kinds of birds will keep laying for a long time, as if they can stop laying only when the clutch of eggs feels right underneath them. Robins

normally lay four eggs.

On The Nest Until they've laid a full clutch, robins allow all the eggs to stay cool so the babies don't start to develop. That's pretty smart! It means all the babies hatch close to the same time. Mother robins may start incubating their eggs during the evening after the second egg is laid, or after all the eggs are laid. They sit on the eggs for 12 to 14 days. The female usually does all the incubating. Even in good weather, she rarely leaves her eggs for more than 5 to 10 minutes at a time.

IncubationIt's mom's job to maintain the proper incubation temperature, keeping the eggs warm during cold weather and shaded during really hot weather. She also must turn or rotate the eggs several times daily. She hops on the rim of the nest and gently rolls the eggs with her bill. Turning the eggs helps keep them all at the same temperature and prevents the babies from sticking to the insides of the eggshells. Males only occasionally sit on the eggs, but they hang out in the territory throughout the daylight hours and respond immediately if the female gives a call of alarm. A male may even bring food to feed his mate, but usually she leaves the nest to feed herself.

Some birds, like hawks and owls, lay their eggs when weather is still very cold, and start to incubate as soon as the first egg is laid. The egg they laid on the first day hatches out a day before the egg they laid on the second day, which hatches a day before the third day's egg. Therefore, the oldest baby may be a lot bigger than the smallest baby. If hunting is very bad and the babies are very hungry, the biggest may sometimes eat the smallest. The oldest baby leaves the nest before the later babies, too.

Sharing Her Body Heat The eggs must be kept warm to develop. A robin's body is 104 degrees F. or even warmer. Feathers insulate by keeping the bird's body heat inside, and the outer feathers can still feel cool to the touch. That's why female robins need a special way to keep their eggs warm. They have an incubation patch, or brood patch, which is a place on their bellies where their feathers fall out. A mother robin shares her body warmth by parting her outer feathers and then pressing her hot bare tummy against her eggs or her young nestlings. Outer feathers cover the bare area so the brood patch is hidden. (It's a little like keeping the oven door closed so the heat stays inside.) Scientists who hold a female robin for banding will often blow on the tummy feathers to see if a brood patch is hiding underneath.

Many birds apparently sense the egg temperature with receptors in the brood patches. This helps the birds determine how much time to spend on eggs, and they can change their incubation behavior accordingly. For example, they may sit more or less tightly on the eggs, or leave the eggs exposed while going to feed or drink.

The End of the Egg: Hatching OutFighting its way out of the egg isn't easy for a chick. First it breaks a hole in the shell with its egg tooth, a hard hook on its beak. Then it must struggle with all its might, between periods of rest, to get out. No wonder hatching may take a whole day. The eggs usually hatch a day apart in the order they were laid. Naked, reddish, wet, and blind, the babies require A LOT of food. Now it becomes a full time job for both parents to protect the nest, find food, and feed the clamoring babies during the 9-16 days they spend in the nest

Owls

Owls lay between one and thirteen eggs, depending on the species and also on the particular season; for most, however, three or four is the more common number. The eggs are rounded and white; there is little need for cryptic markings given the concealed nature of most nest sites, and the vigour with which they are defended. Incubation of the eggs usually begins when the first one is laid, and lasts, in most species, for around thirty days. During incubation, the eggs are rarely left alone. Female owls, like many other birds, develop a sparsely feathered area on their bellies called a brood patch. The almost bare skin has a higher density of blood vessels than other parts of the skin, providing a direct source of warmth when in contact with the eggs.

Owl chicks hatch with the aid of an Egg Tooth - a unique protrusion on the beak, common to all birds, which drops off a week or two after hatching. Because eggs are laid over a period of several days, the hatching is also staggered. This means that there is always a gradation in the size of the chicks in the nest, the larger and more active individuals invariably getting more food from the parents than their smaller, weaker siblings. As a result, it is rare for all the chicks that hatch from a clutch to survive, except of course when food is plentiful. In most seasons the youngest chicks starve, or are sometimes even killed by their brothers or sisters. This seemingly brutal approach to the rearing of young has in fact positive survival advantages for the family as a whole: it ensures that, whatever the food availability, some offspring will always survive and produce further offspring. If all the young were fed equally there would be a chance that all might starve in years of poor food supply.

The food is delivered as many as 10 times a day to the nest by the male. Larger prey items are ripped apart and fed to the chicks piece by piece. Smaller prey can be swallowed whole by the chicks as they get older. Young owls begin producing pellets as soon as they begin eating whole prey, or prey parts with fur, bones and other indigestible parts.

Upon hatching, owl chicks are blind and have a thin coat of natal down. In 1-2 weeks, a heavier second coat of down appears, called the mesoptile. As early as 3-4 weeks, some species' chicks may leave the nest and clamber about. In tree nesting species, these chicks are called Branchers. The next stage of development will be fledging, or learning to fly. In Great Horned Owls, this is 9-10 weeks after hatching, Barn Owls take 7-8 weeks and Screech Owls 4-5 weeks. Fledglings are usually cared for by the parents for a short time before leaving to fend for themselves. This time can vary from a few weeks to a few months, depending on the owl species.

Most owls reach sexual maturity and are ready to reproduce about a year after they hatch. Some larger species, however, may not begin breeding until their second or third year.

Chicken Eggs!

Have you ever wondered how a hen can lay an egg every day? Why some eggs are brown and some eggs are white? How many days an egg takes to hatch?

 

Here are the answers to those questions and many more.

 

Hens and eggs

Female chickens are called pullets for their first year or until they begin to lay eggs. For most breeds, around 20 weeks is a typical age for the first egg.

Some breeds lay eggs daily, some every other day, some once or twice a week. Some individual hens never lay eggs, due to narrow pelvises or other

anomalies. Normal laying routines can be interrupted by molting, winter daylight

shortage, temperature extremes, illness, poor nutrition, stress, or lack of fresh water. Hens usually return to normal laying habits when the disruption-causing factor ends or is corrected.

Most hens are productive layers for two years before declining in production, but some continue to lay eggs for several years.

Hens will lay eggs whether or not they’ve ever seen a rooster. Roosters are necessary only for fertilization of eggs.

 

 

Egg development and laying process

A female chick is born with thousands of tiny ova, which are undeveloped yolks. Once she reaches maturity, an ovum will be released into a canal called the oviduct and begin its journey of development.

At any given time a productive hen will have eggs of several stages within her reproductive system. The eggs most recently discharged from the ovary are just tiny yolks, and the eggs farther down the oviduct are progressively larger and more developed.

From the time an ovum leaves the ovary, it takes approximately 25 hours for the egg to reach the vent for laying. During that time period, the yolk will grow larger while being surrounded by albumen (egg white), wrapped in a membrane, and encased in a shell. Pigment is deposited on the shell as the last step of the egg production process.

If sperm is present, the yolk will be fertilized before the albumen is deposited. As a chick embryo develops in a fertilized egg, the yolk provides nourishment

and the albumen cushions the embryo. Although a hen has only one exterior opening (the cloaca or vent) for egg

laying and elimination, eggs are not contaminated during the laying process. Two separate channels, the oviduct and the large intestine, open into the cloaca. As the egg nears the end of the oviduct, the intestinal opening is temporarily blocked off. The egg passes through the cloaca without contact with waste matter.

The typical interval between eggs laid is about 25 hours, so a hen that lays an egg every day will lay a bit later each day.

Hens don’t usually lay eggs in the dark, so once a hen’s laying cycle reaches dusk time, she will usually not lay till the following morning.

Eggshell production drains calcium from the hen’s body. The comb, wattles, legs, and ear lobes will fade as the calcium leaches out. Calcium must be replenished through either feed containing calcium, supplements such as oyster shell, or high amounts of calcium in the soil of birds with outdoor access.

 

 

Egg variations

Young pullets often lay malformed eggs before getting established in a normal laying routine. Older hens may occasionally lay abnormal eggs due to age, stress, or illness.

Pullet eggs--the first ones produced by each pullet--are smaller than the eggs that the same hen will produce as an older hen.

“Fart egg” and “oops egg” are terms for tiny eggs that quickly pass through the oviduct without reaching full size.

Shell-less eggs are released before they have time to develop a shell. They may have membrane holding them together or just be loose yolk and white.

Double eggs or “egg in an egg” are created when an egg with a shell is encased by the next egg in the oviduct and a shell is produced over the outer egg as well.

Double yolkers may have a normal amount of egg white with two or more yolks. In the shell, the egg may be unusually large.

Yolkless eggs, also called no-yolkers, dwarf eggs or wind eggs, consist of egg white alone.

Occasionally an egg will come out with a wrinkly, misshapen, rough, bumpy, or unusually colored shell.

Egg size is dependent on breed, age, and weight of the hen. Larger chicken breeds tend to lay larger eggs; banty breeds lay small eggs. Older hens tend to lay larger eggs than younger hens.

The shell color is a breed characteristic. Most chicken breeds lay light-to-medium brown eggs. A few breeds lay white, dark brown, green, blue, or cream colored eggs.

Shell color is only “skin deep”-- the eggs inside are the same as eggs of other colors.

The shell color intensity of eggs laid by one hen can vary from time to time, with an occasional darker or lighter eggshell.

While most eggs have a slight sheen to the shell, some breeds or individual hens tend to lay eggs with a chalkier texture.

 

Chicken-and-egg behavior

Most hens will lay eggs in the same nest box as flockmates, so it’s not necessary to have a nest box for each hen.

Some hens like to lay their eggs in private and others will join their sisters in the nest box. Often two or three hens will crowd into one box while another nest box remains empty.

Sometimes a hen will sit on previously laid eggs and add her egg to the clutch. Another might prefer to sit in another area and deposit one egg by itself.

Often a hen will sing “the egg song” before or after she lays an egg. Some will sing during the process of laying. It is a cheerful song that seems to be a proud announcement.

Chickens learn by example, so a fake or real egg left in a designated nest box may encourage hens to lay there instead of on the floor or outdoors.

Unconfined hens may lay eggs anywhere outdoors if they don’t want to return to the nest box. Sometimes a free-ranging hen will go missing and reappear weeks later with a parade of chicks.

Chickens like to eat eggs, even their own. An egg that gets accidentally broken will likely be eaten by one of the chickens. If you occasionally find pieces of shell or egg yolk in the nest box, it’s usually nothing to be concerned about.

Some chickens become habitual egg-eaters that break eggs open and eat them. An egg-eater should be culled from the flock if you wish to have eggs for the kitchen. Not only will that chicken continue to eat eggs, but others will learn from watching and you may end up with several egg-eaters.

Holes in eggs and cracked eggs do not necessarily mean there is an egg-eater in the flock. A hen can accidentally crack an egg in the nest when she sits down or adjusts the nest to lay her own egg. Sometimes curiosity or boredom leads a chicken to peck at an egg without the intention of eating it.

Chickens can be fed their own or other eggs either raw or cooked. Eggs provide protein and the calcium in the shell is beneficial for laying hens. A potato masher can be used to break boiled eggs into pieces of egg and shell.

Empty eggshells from the kitchen can be fed back to chickens as a calcium supplement without concern for developing egg-eaters. However, to be safe, crushing the shells or running through a blender is a good idea.