Life Cycle of a BirdPart 1: The Beginning"Which came first, the chicken or the egg?" a quote repeated over the generations and a topic much debated over. Personally, I have not made up my mind yet. I will start the series of the 'Life Cycle of a Bird' with eggs.
Oology: the branch of ornithology that deals with the anatomy and physiology of eggs as well as the size, shape, colour and other characteristics.
The Egg Chart:
Wikipedia Public Domain Image
Key for 'The Egg Chart': 1. Honey buzzard
2. Falcon
3. Eurasian Sparrow-hawk
4. Blackbird
5. Thrush
6. Rook
7. Corn Bunting
8. Hawfinch
9. Sparrow
10. Chaffinch
11. Pipit
12. Reed Bunting
13. Cuckoo
14. Hummingbird
15. Crossbill
16. Wren
17. Nuthatch
18. Nightingale
19. Kinglet
20. Accentor
21. Rock Bunting
22. Reed Warbler
23. Sedge Warbler
24. Warbler
25. Tit | 26. Tree Warbler
27. Waxwing
28. Oriole
29. Jacana
30. Grouse
31. Lagopus
32. Pheasant
33. Partridge
34. Quail
35. Avocet
36. Spotted Redshank
37. Dotterel
38. Plover
39. Lapwing
40. Green Sandpiper
41. Tern
42. Common Tern
43. Tern
44. Seagull
45. Guillemot
46. Great Auk
47. Puffin
48. Puffin
49. Grebe
50. Loon
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No species of birds give birth to live young but instead lay an egg. A bird's eggs is a single giant cell protected by watertight membrane and a porous shell. Eggs are laid by the Female which is then incubated.
Egg size:
 The egg size has no connection to the size of the bird but rather to the size of yolk. The bigger the yolk, the bigger the egg.
Largest egg: Ostrich measuring 17.8 by 14cm
Smallest egg: Bee Hummingbird at 7mm in length weighing up to 1,5kg (Refer to egg 14 on 'Egg Chart')
Largest egg laid by a passerine (perching bird): Australian lyrebirds weighing in at 57g
Largest egg laid relative to body weight: Little Spotted Kiwi at 26%
Smallest egg laid relative to body weight: Ostrich egg at 1.5%
(Hummingbird's eggs by Jessie Terwilliger) Shape:
The majority of avian eggs match the shape of chicken eggs, but there are some exceptions. Fast-flying, streamlined birds such as swifts and swallows lay long, elliptical eggs. The Guillemot and Great Auk's egg has a sharp point to stop the egg from rolling off cliffs (Refer to egg 45 and 46 on 'Egg Chart').
Roundest egg: Laid by Owls and Tinamous.
Colour:
Eggs come in various colours. Shells have basic colours and the markings are added just before they are laid. All parrot species have white eggs with no markings. Tinamous lay very shiny, emerald green eggs. Bluebirds and robins produce blue eggs.
(Robin's eggs by Dawn V Storm)
 
Emus have greenish-black eggs. Rheas lay creamy beige eggs. Chickadee eggs have a red tint to them and falcon eggs appear brownish-orange. Researches believe the colouring of the shell is used for camouflaging the eggs.
(Killdeer's egg by Daniel Johnson)
Clutch size:
Seabirds are known to produce a single egg while gamebirds (quails, partridges, grouse, turkies etc.) lay the largest cluthches. They can lay over 20 eggs each time they breed.
Largest clutch laid: 28 by a Bobwhite Quail
Smallest clutch size: 1 egg laid every 2 years by Albatrosses
Incubation period:
During incubation, the embryo starts to take shape. This is done by the original cells dividing repeatedly, creating the tissues and organs of the developing chick. This time period differs widely between species of birds as well as the method of incubation. In some bird species, both parents incubate the eggs. The Maleo has a very unique method for incubation. Each egg is laid in a separate hole, up to 1m deep, and is left to be incubated by the heat from the sun or volcanic activity. This incubation period lasts for 60-80 days. The Malleefowl lays its eggs in a giant heap of leaves, sticks and bark (0.6m high). As this heap decomposes, it gives off heat to incubate the eggs which takes about 11 weeks.
Shortest incubation period: 11 days by small passerines
Longest incubation period by a passerine: 50 days for Australian lyrebird
Turning of the egg:
This is another debated issue. Researches have said for a long time that it is essential for the incubation process. If eggs are not turned then the embryos inside the eggs will settle and the eggs will not hatch. However, Sasol-Birds: The Inside Story, say quote, "eggs suffer no ill effects from not being turned".
(Black Swan by Jen64)
Longest interval between eggs laid: Maleo at 1012 day intervals
Highest price paid for an egg: 1,000 British pounds for an egg of extinct Aepyornis maximus.
» 3 Comments
1Comment
at Thursday, 13 November 2008 12:53
very interesting indeed, Candy! especially re the eggs not needing to be turned, as well as the Maleo burying its eggs!
2Comment
at Thursday, 13 November 2008 15:52
Great series, Candy.
So much iinteresting info. Those poor Albatrosses: 1 egg every 2 years.
I love the egg chart, look at those pretty eggs. And I learnt a new word .. Oology hehehe
3Comment
at Friday, 14 November 2008 10:57
Loved this very informative - well done
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