THE EGGS OF BIRDS 



357 



ostrich-like bird of Australia, must be incubated for about 

 ten weeks. 



Much of the fascination of bird study lies in the 

 questions which continually come to mind. Why do 



Photograph by A. A. Allen. 



A SPOTTED SANDPIPER AT HER NEST 



The eggs of the sandpipers are large becayse the young are well- 

 developed when hatched, being able to run about as soon as dry. 



many of the sea birds lay only one egg and why must 

 the ducks and partridges lay nearly a score? Why are 

 some eggs pure white while others are most brilliantly 



Photograph by A. A. Allen. 



THE UNPROTECTED EGGS OF THE KILDEER 



The kildeer lays her eggs on the bare gravel. They are very incon- 

 spicuous, however, because of their protective coloration. 



colored and still others mottled with shades of brown 

 like the sun-flecked forest floor? 



The number of enemies which a bird has seems to 

 control to a large extent the number of eggs which it 



lays. The auks, murres, and gannets, by their habit of 

 retiring at the nesting season to isolated cliffs and islands, 

 are comparatively safe from harm and therefore lay 

 but a single egg. At the other extreme are the gallinules, 

 ducks, and partridges with their ten to twenty eggs. Not- 

 only have these birds many enemies among the predatory 

 animals, but, since they nest rather early in the spring 

 their eggs are frequently flooded out by storms. Fortu- 

 nate it is, if a clutch of eggs is successfully hatched, that 

 the brood is large for it is more than likely that several 

 of the young will be the victims of snapping turtles, 

 snakes, and hawks. 



This brings us to the coloration of eggs, which pre- 



Photograph by A. A. Allen. 



NEST AND EGGS OF THE RED-WINGED BLACKBIRD 



The eggs are pale blue, streaked and spotted with dark purple and 



black, chiefly about the larger end. The addition of color and markings 



is the last stage in the formation of an egg. They are added slowly 

 before the egg is laid. 



sents problems more difficult to explain. We have heard 

 a great deal about protective coloration in nature, and 

 when we consider the advantages which accrue to pro- 

 tectively colored eggs we may wonder why some eggs 

 have remained pure white through the ages, why others 

 are of the most conspicuous greenish blue, and why still 

 others stand out by their spotted or speckled patterns. 

 We should bear in mind that white eggs are for the most 



