Over the past four Nature Smart columns we have followed the progression of birds building nests, how mother birds lay eggs, the intricacies of incubation and so much more. So it only makes sense that this time we finalize this series by examining baby birds.
Nearing the end of incubation period, while still in the egg, the chick develops an egg tooth which is a short pointed structure on the tip of the upper beak pointing upwards. This “tooth” is used to break its way out of the shell. Or more accurately put, scrap its way out of the shell. The chick within the egg is generally in the fetal position with its head towards the belly. With specialized muscles the chick straightens out enough to rub the egg tooth against the inner wall of the shell. Also, at this point the egg has been weakened by the absorption of calcium by the developing chick.
The constant rubbing of the egg tooth against the inner shell produces a small hole in the shell which is called pipping or the egg is pipped. Then the chick scrapes another hole in the egg, usually on the blunt end of the egg. Once enough holes are created the chick pushes out of the shell. This process take a lot of strength and once the chick has emerged from the shell it often lays very still for a long time while it gathers up its strength.
The time between pipping and hatching can vary greatly from species to species. Most small birds take up to 6 hours to complete the process while some very large birds make take up to 5 days. Once the chick has hatched the egg tooth is absorbed back into the beak or the tooth falls off.
Baby birds are classified in one of two ways when they are hatched. The first is called altricial. These baby birds are what you think of when you envision a young bird. They are born with their eyes closed, have very few if any feathers, are unable to move around very well, have no ability to regulate their own body temperature and are completely dependent upon their parents for everything from warmth to food. An example of this kind of bird would be most songbirds such as robins, blue jays and cardinals.
Altricial birds look like they have huge jelly bellies with a tiny head and two bulging eyes that are sealed shut. About the only thing these tiny helpless birds can do is hold their heads straight up and open their mouths (gape). This may seem very simple but it is also very important. The inside lining of the baby birds mouth is often a bright red or orange and acts to stimulate the parents to feed the babies.
These birds have no feathers to conserve warmth and in addition they have no ability to regulate their body temperature. The parents need to brood (see the last column) to keep them warm. Baby birds grow so fast you can almost see it before your very eyes. Over the next 5 or 6 days most birds will develop feathers, their eyes will open and they will be able to maintain their body temperature on their own. They can move around the nest freely and they start to flap their wings. In another week to ten days the young will be ready to leave the nest.
The second type of new born bird is called precocial. These birds have their eyes fully open and functional, are able to walk, run, or swim depending upon the species, feed themselves, fully feathered and have no problems regulating their body heat. An example of a precocial bird is ducks, geese and most shorebirds.
So there you have it. Everything you ever wanted to know about bird nests, eggs, incubation and so much more. Until next time…