SIZE AND SITTING-TIME 159 



Fowl belong to long-period families ; among the 

 short-period birds we have in domestication, the 

 Pigeon takes seventeen and the Collared Dove 

 fifteen days, and the Canary a fortnight, both 

 Pigeons and Passerines having short incubation 

 periods. 



Owing to this family limitation of periods, we get 

 some very curious contrasts ; such big birds as the 

 Crowned Pigeon (Goura coronata) and the Raven 

 only taking three weeks, while the tiny Painted 

 Quail (Excalfactoria sinensis), no bigger than a 

 Sparrow, and the Teal, not larger than a Pigeon, 

 take as long, and the Storm-Petrel even five weeks, 

 in spite of its small size. 



It will be seen that however small the bird, the 

 reduction of its incubation-period does not keep 

 pace with the size ; nor does the increase in the 

 case of large species. Some of the smallest Finches 

 only sit for eleven days, and even the Humming-birds 

 are only credited with a day less ; the longest incuba- 

 tion period is that of the Emu, in which the devoted 

 male sits for nine weeks, longer than the Ostrich, 

 with its six or seven, but this bird belongs to a 

 distinct family, all the clans of flightless giants being 

 very well differentiated anatomically, and evidently 

 representing independent degenerations from flying 

 ancestors, though of an early type. 



In a few cases the smaller bird in the same family 

 may take a longer time than a larger ; thus Part- 

 ridges and Gold Pheasants take longer to hatch than 

 Fowl chicks. The case of the common Pheasant, 



