76 BRITISH BIRDS. [vol. xv. 



the incubation, and tor the greater part of the nestUng periods. 

 I personally saw the cock bring a twig to a nest while the 

 hen was away, during incubation. Dr. Lewis saw a cock 

 bring twigs during the nestling period. In 1919 T. Colly er 

 helped me to photograph a nest. Unfortunately, the bird 

 only had two eggs. One of these was infertile, and the chick 

 from the other died when very young. The hen sat on the 

 other egg for two or three days more before deserting it, and 

 even after that brought fresh material to the nest. 



Two nests have been visited daily, or oftener when 

 necessary/, to try to make more certain of the incubation 

 period. The results seem likely to make the confusion on 

 this point greater than ever. 



No. I. Nest in an apple tree in a large orchard 1919. 

 Laid. Chipped. Hatched. 



Tills bird was immature and absurdly timid. It required 

 the greatest caution to get a glimpse of her on the nest unless 

 it was pelting with rain. All the observations had to be made 

 at a distance and from the ground. Judging from the eggs, 

 I estimated that she began to sit after No. 3 was laid, as they 

 were always warmish after then. This would give a period 

 of 35 days for the first three, t^2> for No. 4, and 31 for No. 5, 

 which sounds too great a variation to be correct. On the 

 other hand, the first four eggs took each three days full to 

 hatch after chipping, whereas two is more normal and the 

 chipping period for No. 5 is short. A shower in the night 

 June 21/22 may have contributed towards that, as the 

 moisture would certainly make the birth of the chick easier. 



The other nest is one at which we are still busy, and which 

 is giving a certain amount of new and interesting information. 

 Several boys are helping me to keep as large a watch on it 

 as possible, but particularly J. Nott. This bird first of all 

 prepared, and lined, and even brooded in, an old nest used 

 last year and some years previous to that. This, to my 

 disgust, she left, and I thought she had been shot, until 

 May 14th, when, after finding signs of a Hawk in the wood, 

 I found that the 1915 nest had been built up, and contained 

 one egg and that the platform of the hut we used then was 

 nearly safe and could easily be made absolutely sound, and 



