Why do birds have to sit on their eggs?« Back to Questions List


Birds sit on their eggs to make sure the young ones develop properly inside the eggs due to the warmth provided by their mother. The young one cannot develop well when the temperature is less than about 80°F (27°C). Parent birds normally keep the eggs warm with their body heat. This process of providing warmth to the eggs is called incubation.

 

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Feathers actually block the body heat transfer to the eggs. So, the parent bird drops off some of its belly feathers (molt) at incubation time. Thus a ‘brood patch’ as it is called develops on the female birds. The brood patch causes the warm skin on the belly touch the eggs. In addition to it, a dense network of blood vessels brings additional heat to the skin.
 


The birds also turn their eggs several times a day during incubation. They do this with the help of their bills or by twisting their bodies. Turning of eggs ensures eggs are evenly warmed and also prevent the young one from sinking to one side. Different species of birds incubate for a different period of time. The time period may range from just 11 days (about 2 weeks) to 65 days (about 2 months). Ostriches, swans, eagles have a longer incubation time (35-45 days) compared to pigeons and hens (20-25 days). Some parents continue to brood even after hatching till the young ones maintain steady body temperature.

 

There is one group of birds that rear its young one in a much different way. These are pheasant like birds called megapodes (meaning ‘large-footed’) found near in Australia. Megapodes include scrub fowl, mallee fowl and brush turkeys. These birds bury their eggs in a mound (big piles of earth and leaves) and nature does the job of incubation. Heat from sun and fermenting vegetation helps in development of eggs. When the young ones hatch, they dig their way out and then fend for themselves. Intelligent and Clever Animals and Birds

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