Method of Bird Study and Photography 13 



broods in the same season. The semi-domesticated and gre- 

 garious House Sparrow, which often builds lodges or large bag- 

 shaped nests for winter use, is credited with from four to six 

 broods, according to circumstances. The domestic Pigeon, 

 which spends seventeen days in incubation and two weeks in 

 tending its squabs, will sometimes rear upwards of ten broods, 

 while the domesticated fowl in the hands of skillful breeders has 

 been known to produce over 200 eggs (in one case 251 eggs) in 

 a single year. 



While the number of eggs to the litter is approximately 

 determinate, the actual number which even some wild birds 

 are capable of producing is surprisingly great, and cases of 

 apparent discontinuous laying have been observed. Thus the 

 Flicker ordinarily lays from four to nine eggs, but by removing 

 one egg at a time and leaving one as a "nest egg," this bird was 

 in one case stimulated to the production of seventy-one eggs in 

 seventy-three days. In most cases the instinct "runs down" 

 before this stage is reached if the physical powers are not 

 actually exhausted, and the process is interrupted by fear or 

 some other disturbing factor. A new nest may be built for 

 each litter, when the old is not repaired and made to do service 

 a second time, but, as often happens, no constructive work is 

 undertaken, the eggs being laid in a natural cavity or in the 

 converted nest of some other bird. 



In dealing with birds in general, and more particularly with 

 the wilder and more timid individuals, the net balance of their 

 conduct appears to be the result of a series of conflicting in- 

 stincts, although the disturbing factors may be few in number. 

 Chief among these is fear, which must be constantly reckoned 

 with in the analysis of animal behavior. Again, an important 

 place must be assigned to habit, or associative memory, and 

 possibly to emotions whose character is doubtful. Yet, when- 

 ever we attempt to measure animal behavior by rule and have 

 to deal with intelligence, we must expect to meet with individual 

 exceptions at every turn. 



When a pair are robbed during the breeding season, or in any 

 way disturbed in mind or property, three courses are open to 



