Vol. xli.] 44 



much more certain in their working than the attempted 

 protection oE insectivorous birds, who would not devote their 

 whole energies to the particular species which it is necessary 

 to destroy, and which, even if they did, would be unable to 

 eat more than a certain number each day. 



From these instances we can draw two general deductions, 

 viz. : — ■ 



(1) That if we wish to destroy any particular pest, 



artificial menus are best, and 



(2) our efforts should be directed to the breeding-places. 

 Artificial means are best, because we probably destroy 



only the one species, and also because we keep the means o£ 

 repression witliin onr own control. If we attempt to destroy 

 one species by protecting its enemies, we at once upset the 

 balance of Nature. The fly- and mosquito-feeding birds, if 

 we could get them here in sufficient numbers to destroy the 

 mosquitos in autumn, would have to turn to another food in 

 winter when the mosquitos are much fewer, and we could 

 have no guarantee that they would only feed on noxious 

 insects, and thus we get Nature locally in a state of unstable 

 equilibrium, and the matter may easily get beyond our 

 control, whereas by using artificial means we can make it 

 much more effective and we never lose control. 



The destruction of breeding-places is the most effective 

 of all methods, because thereby you can destroy a far 

 greater percentage. Suppose, for instance, it was desirable 

 to destroy Moorhens — a skulking water-bird that wanders 

 into the crops for its food, — to try and shoot it down would 

 be impossible owing to its skulking habits, an increase of 

 natural enemies, such as Hawks, would fail for the stime 

 reason. Poisoned grain would destroy other species, but by 

 draining the ponds, destroying the water-vegetation, or even 

 by stocking the ponds with predatory fish, the birds would 

 be bound to die out or to seek other quarters. 



We must remember that, save in exceptional cases, most 

 species are increasing or decreasing very slowly, because to 

 do so they are largely dependent on the increase or decrease 



