KESTREL 103 



been a case of this land. A more definite instance is that recorded 

 by M. A. Mathew (1882), in which three kestrels, a male and two 

 females, were seen at a nest containing six eggs, of two quite distinct 

 types, four of one and two of the other. E. C. Stuart Baker also 

 informed me that he saw 11 eggs taken from one nest in Finland, 

 six of which were evidently the product of one hen and five of another. 



When the first set of eggs has been taken, the female will lay again 

 at least twice in the season, possibly oftener. The eggs are not laid 

 on consecutive days, but at intervals of about 48 hours. Incubation 

 generally begins as soon as the first egg is laid, and the eggs hatch out 

 on alternate days, but apparently there are exceptions to this rule, as 

 some sets show no differences in state of incubation. The period is 

 estimated at about 28 days (A. G. Leigh), 27 to 28 days (W. Evans), 

 and 29 to 32 (W. A. Shaw); both sexes take part in brooding, but the 

 female takes the greater share. The male supplies the hen with food 

 at the nest and takes her place when she leaves it. In the case of a 

 pair that bred in captivity, the male relieved the female in turn, but 

 some caution must be used in dealing with data of this kind, as the 

 conditions are not natural. 



The eggs are almost oval in shape and are very variable in color. 

 The commonest type is that in which the ground is almost concealed 

 by red-brown blotches and spots, varying in depth of color from light 

 tawny-yellow to almost black. In some cases a great deal of the white 

 ground is visible, and when the markings are rich bright red, or are 

 concentrated in large blotches, they form very striking and effective 

 contrasts. It is not rare to find single eggs in a set, white or nearly so, 

 with only faint markings, but on one occasion I found a clutch of four 

 infertile eggs without a trace of markings except a few nest stains. 

 Bluish-gray or violet shell marks are also to be seen on some eggs, and 

 in some cases the red-brown is replaced by dark chocolate. The 

 average size of 100 British eggs, measured by the writer, is 39.73 by 

 31.77 millimeters; the eggs showing the four extremes measure 43.7 

 by 33.5, 41.6 by 34.2, and 35.4 by 29.7 millimeters. 



Young. — Only one brood is reared during the season. When the 

 young are hatched, the male at first brings food which is given to the 

 young by the female, who broods them ; later both parents bring food 

 to the nest, but according to Ludwig Schuster (1928), this does not 

 take place till the young are two or three weeks old. Heinroth also 

 noted, when rearing the young, that at the age of about three weeks 

 they were capable of feeding themselves. Schuster also notes that 

 feeding took place fairly regularly about once an hour from daybreak 

 till late in the evening, and remarks that the hunting ground was not 

 in the immediate neighborhood of the nest. The mean of a consider- 

 able number of observations on the fledging period shows that all 

 estimates, with one or two exceptions, fall between 27 and 34 days, 



