Manchester Memoirs, Vol. Ixvi. (1921) 17 



, fails to destroy, though he may* succeed in keeping them in 

 check by materially reducing numbers. But when he pits 

 his science and cunning against the less developed intelli- 

 gence of the larger forms, he can entirely wipe a species out, 

 and often does this in his greed to secure wealth in advance 

 of his human competitors. Thus the rat, sparrow, house fly 

 and louse defy his efforts, and until his whole moral outlook 

 changes, for sanitation is a moral question, his cleverest 

 devices will fail to utterly check their ravages. Even then it 

 is doubtful if he will ever destroy the fly and mosquito though 

 he may render their attacks innocuous. The rat, indeed, 

 persistently following man, has often undone his best work. 

 Its arrival on Lord Howe Island has resulted in the ruin of 

 that successful Australian bird-reserve. 



With larger and less numerous animals the fight is more 

 one-sided, for they are not numerous because he is numerous. 

 How effectually he can destroy is shown by the extinction of 

 the vast hordes of passenger pigeons, the Esquimox curlew, 

 the great auk, and many of the Australian parrots. But we 

 need not go beyond the limits of our own land for examples. 

 It has often been argued that drainage of marshes or cultiva- 

 tion of land explain the extinction as breeding species of the 

 bittern, ruff, black-tailed godwit, great bustard, Savi's warbler 

 and crane. Yet the bittern, after long- absence, is nesting 

 once more in the marshes where it derives protection, private 

 protection be it remembered, and the ruff too has returned ; 

 there are many suitable places still remaining where these 

 birds might nest if allowed. What has happened with another 

 marsh species, the black-headed gull ? Driven from place to 

 place by the drainage of one after another of its haunts, it has 

 still found sites to colonise and wherein to increase. True 

 there may be factors which explain the increase of one species 

 and the decrease of another which have no connection with 

 the influence, at any rate direct, of Man; we can for instance 

 explain the increase and spread of the great crested grebe, at 

 one time nearly swept away by the demand for its soft breast 

 plumage — protection gave it the start it needed. But it is 

 hard to imagine that the same factor operated in the case of 

 the turtle dove. A change of habit and of breeding range 

 may have influenced the godwit and black tern. It is, how- 

 ever, certain that immediately these and other species were 

 seen to be rare their commercial value rose and they were 

 hunted out of the country by the collector. When Seebohm 

 pointed out that the St. Kilda wren differed from the main- 

 land form it was an evil day for the little islander; one 



