442 



The Bird 



contend. Toucans are able to get along with a pair of 

 eggs; while a hornbill, by sealing its mate up in its little 

 arboreal cavern during nidification, is so adequately 

 protected that one to three eggs in each family suffice 

 to keep the race going, since practically every }'oung 



Fig. 351. — Burrowing Owl at nesting hole. 



bird is brought to niaturit}-. Of the host of smaller and 

 weaker birds nesting in cavities, two to five eggs are the 

 usual quota. This brings us to the tribes of little singing 

 birds with which we started, whose average is about 

 five; but a few interesting excej)tions may be noted. 

 Our whippoorwills and night-hawks, for instance, lay 

 only two eggs. These are placed on the ground in the 



