Bird Eggs

Jan 10 09:02 2011 Jill Clow Print This Article

Facts about bird eggs.

Sizes

  1. Bird eggs vary hugely in size,Guest Posting like the birds themselves.
  2. The largest egg produced in the bird kingdom is that of the ostrich egg – weighing up to 1.2kg.
  3. The smallest egg produced in the bird kingdom is that of the hummingbird – weighing half a gram.
  4. So ostrich eggs are 2000 times the size of hummingbird eggs!
  5. The elephant birds of Madagascar, now extinct, laid eggs about 14 inches long with a capacity of about 2 gallons – much bigger than ostrich eggs.
  6. The first and last set of eggs produced by chickens tend to be smaller than the others.
Quantity
  1. The name for one or more eggs produced by a bird in a nest at one time is the clutch.
  2. Some of the penguins, albatrosses and other sea birds that nest in inaccessible places lay only one egg in a clutch.
  3. Wild ducks and game birds such as quail and pheasants, which have numerous enemies, lay 15 or more in a clutch.
  4. Most songbirds lay from 3 to 5, although hole-nesters like chickadees may lay 8 or more; tropical species seem to lay fewer eggs than their northern relatives.
  5. Hawks and owls lay more eggs when their prey is plentiful.
  6. Clutch size may also differ within the same species due to many factors including habitat, health, nutrition, predation pressures, and time of year[.
  7. Long lived species tend to have smaller clutch sizes than short lived species.
  8. The evolution of optimal clutch size is also driven by other factors such as parent-offspring conflict – when the parents and children have to compete for resources.
Shape
  1. The fancy math words to describe an egg shape are oblate spheroid.
  2. The word spheroid means that the egg is like a sphere, but isn‘t exactly a sphere. That‘s because an egg isn‘t perfectly round.
  3. This shape results from the egg being forced through the oviduct. Muscles contract the oviduct behind the egg, pushing it forward.
  4. Cliff-nesting birds often have highly conical eggs. They are less likely to roll off, tending instead to roll around in a tight circle; this trait is likely to have arisen due to evolution via natural selection.
  5. Many hole-nesting birds have nearly spherical eggs.
Anatomy
  1. Inside an egg you have three main areas: the air cell, egg white and the yolk.
  2. The air cell tends to be at the larger end of the egg.
  3. The air cell is caused by the contraction of the egg contents as it cools after laying.
  4. The air cell tends to get bigger and bigger as the egg ages and the embryo develops.
  5. The egg white is called the albumin.
  6. The albumin has two main layers – the inner (thin albumen) and the outer (thick albumen).
  7. The albumin‘s primary natural purpose is to protect the yolk and provide additional nutrition for the growth of the embryo.
  8. The albumin is 90% water.
  9. The albumin is rich in proteins and also of high nutritional value but doesn‘t contain much fat.
  10. The egg yolk contains the growing embryo and its main food source – the yolk.
  11. The yolk is an energy-rich supply of food for the embryo.
  12. The yolk is suspended in the middle of the egg by strands known as chalazae.
  13. Egg yolk is yellow because it contains a lot of carotenoids.
  14. Carotenoids are organic pigments that protect vulnerable tissues against damage caused by free radicals.
  15. Free radicals atoms, molecules, or ions with unpaired electrons on an otherwise open shell configuration – these unpaired electrons are more unstable and highly reactive to other elements, causing chemical reactions.
  16. Inside the egg yolk the embryo is surrounded by three membranes: the amnion, the chorion and the allantois.
  17. The amnion surrounds the embryo and provides fluid in which is floats and grows.
  18. The allantois is next to the amnion and helps the embryo breathe and excrete wastes.
  19. The chorion serves as a membrane around the egg yolk.
Shells
  1. The outside of an egg is known as the shell.
  2. Egg shells are porous – having thousands of pores hat allow gas to come in and out of the egg itself.
  3. Egg shells get their colors from pigments added when the egg passes through the oviduct.
  4. The original color of bird eggs is white but egg colors have evolved through natural selection to suit their surroundings – mainly to camouflage them when it is necessary.
  5. Egg shells are generally white in cavity-nesters as they don‘t need to be camouflaged.
  6. Egg shells are colored and patterned in open nesters as they need to be camouflaged.
  7. Sun radiation is also a factor in the determination of bird egg colors.
  8. Birds that nest in huge colonies tend to have very varied eggs – extremely variable in color and size. This would tend to suggest that this helps the parents find their eggs.
  9. Some of the pigments used in speckled eggs have now been proven to strengthen the egg shell.
  10. Passerine birds (perching or song birds) tend to have more variety in their egg shell speckling than other kinds of birds.
  11. Research shows that birds nesting in areas of the woods where the soil is known to be low in calcium produce eggs that are more heavily speckled.
  12. South American game birds, have solid metallic colors and a finish like that of a new automobile.

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Jill Clow
Jill Clow

Jill Clow is a bird fanatic and sells bird art on her website www.birdprintart.com.

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