The time spent in building a nest varies from two days to 

 two weeks according to the nature and location of the nest and 

 the urgency of the female to deposit her eggs. Woodpeckers 

 and Kingfishers and Bank Swallows need the longest time 

 because of the difficulty of their task, while Robins and Hens 

 make quick work of nest-building. After the nest is finished, 

 an egg is laid every day or every other day until the clutch is 

 complete. Immediately, the incubation by one or both birds 

 begins ; and it continues night and day until the eggs have been 

 hatched. The period of incubation varies from ten days to 

 four weeks according to the size of the bird ; but for most of 

 the small birds it is fourteen days. 



The number of eggs laid ranges from two to twenty vary- 

 ing with the species. Many birds raise two and some three 

 broods in a season. The earliest nesting is begun in February 

 by the Hawks and the Owls and the latest by the Goldfinches 

 and the Cedar Birds in July and August. 



19 



