164 THE ZOOLOGIST. 



FECUNDITY IN EACH AVINE SPECIES, VARYING 

 ACCORDING TO ACCIDENTS OF LOCALITY. 



By Basil Davies. 



In a former article I attempted to describe how the peculiari- 

 ties of any species might cause its reproduction to differ from 

 that of another : it is now my purpose to describe, if in a some- 

 what partial and incomplete manner, how the members of a single 

 species may differ inter se as regards this function, because of the 

 more or less favourable circumstances under which they may 

 happen to breed. The possibility, and, later, the certainty of 

 these differences and their origin, was early brought under my 

 notice, seeing that for several years I alternately resided in the 

 bleak and smoky outskirts of a northern manufacturing town, 

 and on the edge of some of the richest land in the fertile western 

 counties. I have also to thank Mr. W. Storrs Fox for supplying 

 a little evidence upon my present subject in his kindly criticism 

 of last month. 



My ornithological books early informed me that a Hedge- 

 Sparrow laid from four to six eggs, yet near my northern home 

 I never found a clutch to exceed two; and so scant was the 

 insect-life of the neighbourhood that a year would occasionally 

 pass without my finding a single nest of the species. I personally 

 have notes of many completed clutches of two, and a friend's 

 voluminous diary can only furnish three clutches exceeding that 

 number during a continuous residence of several years in the 

 same district. In Gloucestershire, however, five was the usual 

 number, and a nest of six occasioned no remark. In Lancashire 

 the lingering winter, combined with a foul and smoke-polluted 

 atmosphere, rendered insect-life nowhere abundant. In most 

 English localities you may rely on retaining a pair of " resident " 

 birds to breed with you during the summer, if you mark them 

 frequenting your fields and hedgerows in the latter end of March ; 

 but at R the birds would weary of waiting for the tardy 



