THE BROODING INSTINCT IN THE DOMESTIC FOWL 283 



A change in the order of events in the cyclical processes of 

 reproduction is well known for other birds. While normally 

 broodiness follows a period of laying, it does not always do so, 

 even in other birds than the domestic fowl. Replying to an 

 inquiry regarding this point in pigeons, the late Professor C. O. 

 Whitman wrote me on October 22, 1909, as follows: ; You ask 

 whether in pigeons broodiness ever occurs without the laying 

 of eggs. I have had such cases in different species many times. 

 For example, a pair of Pouters, hatched last year, have repeatedly 

 built a nest this summer without laying any eggs and yet have 

 incubated the empty nest in quite regular order, the male and 

 female alternating in sitting." 



Similar disturbances of the normal sequence of events in the 

 reproductive cycle of mammals are not unknown. I might cite 

 here by way of illustration a case of appearance of heat in a 

 mare shortly before parturition (Bell, [1] ). He says: 



' The thorough-bred mare, Lady Gower, foaled on April 12. 

 The foal was a very small one, and only lived for a short time. Dur- 

 ing the period of utero-gestation there was nothing to call for remark 

 until March 5th, five weeks before the mare was delivered of 

 the foal. On this date the symptoms of oestrum were most 

 marked, and she was put to the horse, no suspicion being then 

 entertained that she was in foal. What is still more remarkable, 

 however, is the fact of the recurrence of oestrum on April 7 and 

 April 11, on both of which dates the mare was served, parturition 

 taking place the day after the last service." 



THE BROODING INSTINCT MANIFESTED WITH A VERY SLIGHT 



DEGREE OF INTENSITY 



It is not infrequently found to be the case, especially with 

 birds which are good layers, that well denned brooding behavior 

 may appear, only to disappear very quickly under the confine- 

 ment treatment. Such cases indicate that either the original 

 intensity of the instinctive behavior was slight or else it was 

 very quickly aborted. 



Records of this kind are shown in Figs. 12 and 13. 



Fig. 12 gives the record of bird No. 401 from November to 

 July 1. It will be seen that this bird was a fairly good winter 

 layer. She showed no signs of broodiness until May 6, when she 

 very clearly gave the manifestations of broodiness, and was, 



