186 THE BOOK OF THE OPEN AIR 



i. FINCHES, PIPITS, BUNTINGS, and caterpillar, and the ova of these insects. 

 LARGER WARBLERS (such as the night- This diet denotes search and pursuit 

 ingale and blackcap warbler). Through- on the part of its caterers, and in view 

 out the counties of England five is of the quantity required, two parent 

 the usual average number of eggs for birds would certainly be quite unequal 

 all of these birds to lay in a clutch, to the task of catering for a larger 

 The migratory species certainly con- brood than five ; nor could a hen of 

 fine themselves to a single brood, pro- this size well produce more than five 

 vided they are not interfered with ; but eggs : if she did, she would take so 

 if they lose the first clutch, they quite long to do it, that the nestlings would 

 as regularly proceed with a second and show a large range of growth, and by 

 even a third, till they have added dissensions in the nest, those latest 

 their quota of recruits to their species, hatched would never survive. Four 

 Nearly all the finches annually rear a is the usual clutch in districts where 

 second clutch, even if the first has insect food is not abundant, and six 

 been brought to maturity, and should is exceptionally rare even where food 

 either first or second clutch be taken, is most abundant, simply because the 

 they will go on to a third. This birds could not collect more of it. On 

 is rather difficult to verify, but very the other hand, five is the minimum 

 careful observations quite justify number a blackcap must produce if 

 confident statement about it. Thus her species is to be maintained ; her 

 it would appear the migratory species breeding season is curtailed by migra- 

 of this arbitrarily designated class tion at both ends. She arrives ex- 

 start the breeding season with the hausted by the arduous journey, and 

 fixed intention of rearing five nestlings, often finds herself too soon for the 

 and the resident species are equally English spring, and has to face the 

 ardent in pursuing a family of ten. expiring frosts of winter with a frame 

 Nor is it difficult to understand the that has not been hardened by pre- 

 laws at the back of these varying vious exposure ; then when June is 

 desires, at least in a rough outline, over, her young must be well-grown 

 These small birds, migratory and resi- and hardened to face their first ocean 

 dent alike, feed their young chiefly passage. Thus a smaller clutch would 

 on various forms of insect life flies, not suffice the needs of the case, and 

 grubs, aphides, the smaller sorts of a larger one is impossible. On the 



