THE INCUBATION PERIOD. 49 



the head was thrown back with a slight jerk, followed by a second jerk as the egg dropped. 

 The whole operation lasted about 30 seconds. The dove then continued standing and 

 closed her eyes as if in sleep for a few moments. After a lapse of a few minutes she lowered 

 herself over the egg and went on sleeping. 



At precisely 4 h 50 m p. m., the female of a pair of ring-doves laid her first egg. I first 

 noticed the bird sitting upright in the usual position. In the course of half a minute the 

 egg was dropped, and just as it came the head was thrown back and turned momentarily 

 to one side, with an evident strain. After the egg was dropped the bird remained standing 

 over it, barely touching it above with her feathers, for nearly an hour (4 h 50 m to 5 h 45 m ) ; 

 then she settled down and covered it so that it could no longer be seen. This is the same 

 as I have before described in another female, and I am now sure that it is the usual thing. 

 The bird appeared to go to sleep soon after dropping the egg, and remained quiet most 

 of the time, though closing the eyes only occasionally. The small end of the egg always 

 comes first. I have seen this in several cases. 



I saw the second egg laid at 8 h 50 m a. m. The female moved about a good deal, prepar- 

 ing her nest and getting ready for oviposition. At length she took the usual position and 

 dropped the egg in not over 15 seconds. As the egg dropped she toppled forward as 

 if she had lost her balance. The head was thrown back and twitched once or twice as 

 the egg passed. 



The egg-laying of the crested pigeon was observed. The bird sat upright in the nest 

 and spent 2 to 5 minutes in laying the egg. She made plain efforts, one following the other 

 at little intervals, to relieve herself of the egg. I have seen the same bird lay another 

 egg, and she behaved in the same way. After laying she stood up for about 10 minutes 

 only, then sat down on the egg and went to sleep. 



I saw the first and second eggs laid in the case of a pair of blond ring-doves. A crested 

 pigeon laid her second egg at the same time the female blond ring laid her first egg, and I 

 gave my attention mostly to the former. The laying of the second egg by the blond ring 

 was carefully watched. In this latter case the female took the usual position and spent 

 about half a minute in laying. She made several efforts, and the final one caused her to 

 throw her head back and then turn it to one side as if in pain. She stood over the eggs 

 during 8 minutes and then sat down upon them. In case of the first egg she stood 15 

 minutes before sitting down. The crested pigeon stood for 10 minutes over the second 

 egg before sitting. 



The female of a pair of ring-doves laid her first egg at 6 h 05 m p. m. The time taken, 

 from the moment when she began to stand upright, was 50 seconds. The bird showed 

 plainly that she made efforts at short intervals, and the final effort was marked by the 

 usual behavior. She stood over the egg 9 minutes, then left the nest to eat; she returned 

 after 3 minutes, looked at the egg, appeared to hesitate about sitting, and after standing 

 8 minutes came off and went outside. The male went in and sat a moment, but soon 

 left. The female returned a little later and stood beside the egg. She finally took the 

 perch and remained away from the egg all night. The following morning I found the 

 egg warm, showing that one of the birds had been on the nest. But they were sometimes 

 both off at one time and were irregular in sitting. 



Another female crested pigeon in laying an egg took the nest a few minutes before 

 5 p. m. She then gave the call-note, which answers for a "coo," several times. She again 

 gave this same note several times while fixing herself upright for laying and while in the 

 upright position, and only ceased a moment before she was ready to drop the egg, which 

 she did at 5 h 18 m p. m. 



The female of a pair of mourning-doves laid a first egg at 6 h 07 m p. m. In laying she 

 sat about as nearly upright as the ring-dove does, and at the moment of dropping the egg 

 she gave her head a turn to one side with her beak raised, not vertically, but at an angle 



