96 MASS. EXPERIMENT STATION BULLETIN 199. 



Variation in Amount of Broodiness. 



A bird once broody may exhibit the character in various degrees which 

 can be classified under two heads, — first, variation in the number of 

 times a bird becomes broody in a period of given duration, usually the 

 laying j^ear; and second, variation in length and intensity of the indi- 

 vidual broody periods. The latter is the less important of the two, for 

 the length of time required by the vast majority of birds to "recover" 

 from the attack is of comparatively small importance. To be sure, some 

 birds take double the time that others require in "recovering," but it is 

 an extreme case when more than a week is required, if no extraneous 

 factors are present. Further, on forming a correlation table between 

 number of days confined and subsequent egg production, it became evident 

 that the coefficient of correlation (though not calculated) was so small 

 that no relationship of importance existed between the subject and rela- 

 tive. The large factor in variability in broodmess is found in the varia- 

 tion in the number of times the broody cj'^cle is repeated, as is sIioaati later 

 on. 



Four sample egg records are showTi here to illustrate individual varia- 

 tions in amount of broodiness. A numeral in a square indicates the hour 

 at which an egg was collected; B. L., broody and placed in brood}'- coop; 

 A, released from broody coop; N, associated with a numeral, means that 

 the bird visited the nest, but did not lay. 



