Eggs & incubation periods of birds

 

Incubation is a process by which birds hatch their eggs, and to the development of the embryo within the egg.

Incubation period is very critical and maintaining constant temperature required for its development over a specific period is a vital factor of incubation. In most species, body heat from the brooding parent provides the constant temperature. Several groupsinstead use heat generated from rotting vegetable material, effectively creating a giant compost heap while some make partial use of heat from the sun.

The act of sitting on eggs to incubate them is called brooding.The action or behavioral tendency to sit on a clutch of eggs is also called broody, and most egg-laying breeds of poultry have had this behavior selectively bred out of them to increase production.

The incubation period, the time from the start of uninterrupted incubation to the emergence of the young varies from 11 days (some small passerines and the Black-billed and Yellow-billed Cuckoos) to 85 days (the Wandering Albatross and the Brown Kiwi).

In these latter, the incubation is interrupted; the longest uninterrupted period is 64 to 67 days in the Emperor Penguin. In general smaller birds tend to hatch faster but there are exceptions, and cavity nesting birds tend to have longer incubation periods.

Details of egg and incubation period of some birds are given below

Ostrich

The ostrich lays the biggest egg in the world. On average they are 15 centimetres (5.9 in) long, 13 centimetres (5.1 in) wide, and weigh 1.4 kilograms (3.1 lb), over 20 times the weight of a chicken egg.

The females will lay their fertilized eggs in a single communal nest, a simple pit, 30 to 60 centimetres (12–24 in) deep and 3 metres (9.8 ft) wide, scraped in the ground by the male. The eggs are incubated by the females by day and by the males by night.

The incubation period is 35 to 45 days. Typically, the male defends the hatchlings and teaches them to feed, although males and females cooperate in rearing chicks.

 

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Eagle

Eagles build their nests typically it is around 5 feet , called eyries, in tall trees or on high cliffs. The female lays a speckled off-white or buff colored egg about the size of a goose's. The second egg is laid a few days later, followed by a possible third. On average they are 7cm (2 7/8 inches) by 5 cm (2 1/4 inches) weight 126 grams (4.5oz)

The 35 -36 days of incubation duties are shared by both male and female, but it is the female who spends most of her time on the nest. The eggs hatch in the order they were laid. Eaglets break through the shell by using their egg tooth, a pointed bump on the top of the beak. It can take from twelve to forty-eight hours to hatch after making the first break in the shell.

The older, larger chick frequently kills its younger sibling once it has hatched. The dominant chick tends to be the female, as they are bigger than the male. The parents take no action to stop the killing.

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Swan

The swan's nest is on the ground near water and about a metre across. Unlike many other ducks and geese the male helps with the nest construction. Average egg size (for the mute swan) is 113×74 mm, weighing 340 g, in a clutch size of 4 to 7.

The incubation period is around 34–45 days for swan.

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Below are the incubation periods of few birds
     
Rhea 36-40  
Flamingo 30-32  
Owl
28-32  
Turkey 28- 30  
Duck 26–28  
Goose 25–28  
Pheasant 23-28  
Partridge 23-25  
Quail 21–23
 
Chicken 20–22  
Kingfisher
19-21  
Parrot 17–31  
Woodpecker 12-16  
Finch 11–14  
Pigeon 10–18