INCUBATION BEHAVIOE. 61 



INFLUENCE OF TEMPERATURE. 



A pair of blond and white ring-doves hatched a pair of eggs on January 19 and 20 

 in the aviary behind the house. The egg-shells were not removed from the nest on 

 January 23, when I found the birds and removed the shells myself. I have never known 

 doves to neglect this point during summer, nor in winter if they are kept in a warm room. 

 Evidently the bitter cold weather of the week of hatching must have been the condition 

 that prevented action. In the previous set the sitting was very irregular, owing to the 

 cold, and the male neglected his duty altogether on the colder days. That a low temper- 

 ature suspends breeding in Ectopistes and retards the process of breeding in all species is 

 well known. The secretion of pigeon's "milk" is also checked by cold. (R 17.) 



HIDING ON THE NEST. 



A male mourning-dove from California is now sitting in the first pen on the west side 

 of the house. The eggs were laid by a white ring-dove, 1 and 3 days ago. This is the 

 "tamest" of all my mourning-doves. He always flies straight to me and alights on my 

 hand or head or shoulders quite fearlessly. If I clasp him in my hand to carry him from 

 one place to another, he makes no struggle beyond trying to keep his equilibrium. To- 

 day I was astonished as I walked past his pen to see him exhibit the "instinct of hiding." 

 He sat on the eggs (this is the first time that he has taken part in sitting) facing the front 

 side of the pen. As I approached he drew down his head, closed his feathers, raised the 

 wing next to me, and as I passed by to the other side the other wing was raised. I passed 

 back and forth several times in order to see him perform. He kept up the hiding, and 

 raised first one wing then the other as I went from side to side. The wing is raised without 

 being opened at all. The shoulder is thrown up a little above the level of the head, so 

 as to alter the figure and thus lessen the chances of discovery. The habit of lowering 

 the head as far as possible is common in the crested pigeon and the common dove. 



I brought in a young white-faced pigeon of 18 days to put a ring on its leg, and while 

 I prepared the ring I left the bird in a cage near by. It soon took the characteristic "hiding 

 attitude," resting on its breast with tail up, and held its head low and still. There it sat 

 without moving, except for a slight breathing movement, for nearly 10 minutes, and 

 would probably have sat there for an hour had I remained and left it to act its way. 



(R17, Sh8/13.) 



VOICE. 



NEST-CALL. 



The nest-call is given frequently by both birds throughout the incubation period. 

 It is almost invariably given upon taking the nest; it is sometimes given as a signal 

 for relief, and frequently no purpose is apparent. These statements are evident 

 from the following excerpts taken from the record of the bronze-wing pigeons: 



The male gave the usual nest-call as he took his place over the egg. The female gave 

 two to three calls as she placed herself over the egg. She gave the call three times while 

 she was taking her place on the nest. The female is thinking of returning to the nest, 

 and the male has called once for her. The male gave two calls a moment or two after 

 resuming nest duty. The female went to the perch beside the nest and called twice, at 

 which the male came off. The male had just settled on the eggs when he gave several calls. 

 The male took his place and gave one nest-call. The male gave a call before leaving the 

 nest, and I think this call was for the female to relieve him; he seems hungry. The female 

 gives the nest-cell, or a call very similar to it, just before she takes her position to drop 

 the second egg. Hence this is not a call for hay, but perhaps a call that means, "I am in the 

 nest, don't disturb me." Other species also do this; at least some others do. 



