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The Sociable Nest
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Written by Candice Swarts
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Thursday, 27 November 2008 |
Life Cycle of a BirdPart 3: Taking Flight
Sooner or later, young birds start to develop feathers. Precocial chicks hatch with down feathers already present but Altricial chicks often hatch naked. All birds depend on feathers for flight, for temperature stability, courtship purposes, keeping dry, etc. 
Whistling Swans can have up to 25 000 feathers but replace them once a year to remain airworthy. The Ruby Hummingbird has the least feathers with only 940 feathers in total. The longest feathers in the world belong to an ornamental chicken bread in Japan in 1972, this specimen had tail feathers 10,59m long. The longest feathers of a wild bird belong to the Crested Argus Pheasant which commonly reaches lengths of 173cm.
(Photo of a Young Tancho by Bret Saalwaechter)
Ornithology Jargon: Fledging (Altricial or semi-altricial): The number of days it takes for the young bird to acquire its full set of feathers and muscles need to fly, after which it leaves the nest. Thus the time needed to get fully feathered and time spent in the nest are essentially the same.
Fledging (Precocial and semi-precocial): This indicates not the number of days that pass before the young leave the nest but the time from hatching until they can fly.
Structure of a Feather:
Feathers are made up of keratin, the same protein found in our fingernails. The feather consists of a hollow shaft and a rachis with barbs on either side. The base of the shaft is bare (this forms the quill), it is the most important part as it keeps the feather anchored in the skin. The barbs lock together with struts called babules (microscopic hooks). Owls lack babules on their flight feathers, this makes the edges softer making their flight silent.
Types of Feathers: Down feather: (Left) The shaft and rachis are short and the barbs are loose, making the feather small and fluffy. This creates a layer of insulation next to the bird's skin.
Contour feather: (Middle) These feathers have a longer shaft and the barb typically has a downy base. The barbs are stiffer and they are locked together by babules. Their rachis extends to the feather's tip. The feathers are naturally waterproof although water birds go one step further by adding a coating of oil from their preening glands. A streamlined shape is created by these feathers as they are mostly arranged like roof tiles.
Flight feather: (Right) The shaft and rachis are the largest, length and width wise. The feather is highly asymmetrical which helps to generate lift. These are generally found on the wings.
The number of feathers a bird has depends very much on its size and where and how it lives, in general a third of a birds feathers are on its head.
Coulour: The colours in the feather of birds are formed in two different ways, either from pigments (melanins, carotenoids, and porphyrines) or from light refraction caused by the structure of the feather. In some cases, feather colours are the result of a combination of pigment and structural colors. The greens of some parrots are the result of yellow pigments overlaying the blue-reflecting characteristic of the feathers.
Fledgings: On Altricial nestlings, the feathers start growing in defined areas called feather tracts. These feather tracts are seperated by bare skin. 
Once all the feathers have fully developed as well as the muscles needed, the young leave the nest.
(Photo of a Pied Wagtail fledgling by Fimb)
This period differs for different species of birds. The longest fledging period of flying birds belongs to the Wandering Albatross at 278 days.
The fledging behaviour of the guillemot is quite spectacular: the adult will lead the chick through the colony and look for large drops like cliffs. It will then fly down the cliff and call to its young from the bottom. The chick will then launch itself off the cliff, attempting to fly as far as possible. They will crash land on the ground below before continuing its run towards the ocean.
Moulting: In most adult birds, their plumage is replaced once a year. 
This is by no means not the most attractive stage of a bird's life. Penguin chicks moult from down to their adult plumage (stiff feathers). Many adults replace their plumage in a Prenuptial moult, the stage where adults adopt their bright courtship colours. The second moult takes place after the breeding season and the male's plumage becomes dull.
Most birds shed their feathers in symmetrical pairs so they can still remain airbourne. However, many waterbirds moult all their primary feathers at once so they are unable to fly.
(Photo of a pair of Molting Gentoos and single Molting Gentoo by Gilad Rom )
» 4 Comments
1Comment
at Thursday, 27 November 2008 14:12
I am so glad the bird in me is a Penguin and not a Wandering Albatross!!
I need to google a couple of terms now. BBL. :-)
2Comment
at Thursday, 27 November 2008 18:07
eish Gwen, a moulting penguin is a sorry sight though hehe ;-)
I collect feathers, and no not just becaue I'm into birds, but because even the seemingly dullest looking bird, if you take a close look at their feathers they are just beautiful, the patterns and designs are absolutely incredible!
3Comment
at Thursday, 27 November 2008 21:14
Brilliantly written!!!! Thank you Candy-floss!!
4Comment
at Friday, 28 November 2008 11:26
I also collect feathers, Jay :) I've got a collection of Gunieafowls, Hadedas, a Blue Crane tail feather etc. The photos of the feathers above are part of my collection. They are mostly Budgie feathers but there is a Cockatail feather as well.
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