Page:The Zoologist, 4th series, vol 3 (1899).djvu/190

164

a former article I attempted to describe how the peculiarities of any species might cause its reproduction to differ from that of another: it is now my purpose to describe, if in a somewhat 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