The Eggs of Birds 437 
whose nests average a dozen eggs in each set. Explana- 
tions are ready for this: the birds themselves are exposed 
to unusual peril, from weather as well as from active 
enemies, since they mostly emigrate to the extreme North 
and nest in the edges of marshes, where the sitting birds, 
Fie. 347.—Nest of Laughing Gull. 
eggs, and young are all subjected to freezings, floods, 
and countless marauders that depend largely upon them 
for food during the Arctic summer, so that a heavy annual 
recruiting must be made to repair losses. Few birds are 
liable to so many misfortunes and mishaps as the water- 
