SKYLARK 317 



Some eggs have a very green tinge; others show dark blotches on 

 every egg in the clutch. 



The shape also varies a good deal ; besides the usual ovate, almost 

 spherical eggs have occurred, as well as extremely elongated ones. 

 One hundred British eggs, measured by the writer, averaged 23.77 

 by 17.05 ; the four extremes measuring 26.6 by 17.3 and 22.8 by 18.4 ; 

 21.8 by 16.2 and 25.1 by 15.3 millimeters. 



To%mg. — The eggs are laid on consecutive days and incubation 

 begins on the completion of the set. All the evidence goes to show 

 that incubation is performed by the hen only. As to the period, I 

 have before me a number of field observations, and in every case the 

 results vary between 11 and 12 days. 



Yet incubator tests by W. Evans (1891) showed 13 to 14 days, and 

 one would have expected them to be slightly less, as the absences of 

 the hen to feed must result in frequent cooling of the eggs and con- 

 sequent prolongation of the period. Continental observers also 

 usually give 14 days, but whether from original observation or not 

 is not stated. The young usually hatch out on the same day and, as 

 soon as their down has dried, present a curious appearance. They 

 are covered with long, very pale straw-colored down, so that when 

 one glances down at the nest nothing is visible but a mass of hairy 

 down. The only sign of life is the breathing of the young birds. 

 When one or the other of the parents arrives at the nest (for both 

 sexes share in feeding the young) all is changed, for three or four 

 yellow mouths, widely opened, spring into sight. The cock and hen 

 do not fly directly to the nest but alight at some distance and work 

 their way toward it on foot, adding to the store of insects carried in 

 the bill on the way. Generally each bird has a favorite track by 

 which it approaches the nest. 



The young develop rapidly, and shortly before they leave the nest 

 they acquire the habit of running out to meet the parents. It is not 

 uncommon to find the nest deserted after 9 or 10 days, but at that 

 age the young are quite unable to fly and are skulking in the neigh- 

 boring herbage; the actual fledgling period is about three weeks. 

 Two broods are regularly reared and occasionally three. 



Plumages. — The juvenile plumage is not unlike that of the adult, 

 though less distinctly marked; and it is completely molted in 

 August-September. For full description of the plumages, see "The 

 Handbook of British Birds," by H. F. Witherby, F. C. R. Jourdain, 

 N. F. Ticehurst, and B. W. Tucker, vol. 1, 1938. 



Food. — This has been studied volumetrically by W. E. Collinge 

 (1924-27) on the basis of stomach contents of 69 adults and 36 

 nestlings. There is a slight preponderance of vegetable food, 54 

 percent, over animal matter, 46 percent. An analysis of the vegetable 



