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Bird- Lore 



present-day birds from their reptile-like ancestors in glorifying them with 

 feathers and giving them a blood of uniform temperature, has likewise brought 

 about this change in the coloration of birds' eggs, for those of all reptiles are 

 white or parchment-like. 



It is interesting to consider the development of the bird from the reptile 

 in studying the varied colors and shapes of eggs as they occur today. Un- 

 doubtedly the greatest single change that took place was the change from the 

 so-called cold-blooded or variable temperature condition of the reptile to that 

 of the warm-blooded or constant temperature condition of the birds. This 



A FLORIDA GALLINULE RETURNING TO ITS NEST ANT) PROTECTIVELY COLORED EGGS 



change entailed a great many others and modified nearly every activity of the 

 bird. Particularly did it modify their nesting habits and the nature of their 

 eggs, for the cold-blooded reptile was accustomed to depositing its eggs in the 

 sand, in decaying vegetation, or in holes in trees, leaving them for the heat of 

 the sun to hatch. It mattered little how much the temperature varied so long 

 as they finally received sufficient heat. But after the change to a warm- 

 blooded condition had occurred, it was necessary to maintain the eggs at a 

 ronstanl temperature, and, as the heat of the sun could not be depended upon 

 for this, it became necessary to supply the heat from the bird's own body and 

 the habit of incubating them arose. It was then (with rare exceptions) no 

 longer possible to bury them and, of necessity, they were laid on the surface 

 of the ground or in cavities where the old birds could be with them. At this 



