It is all very well to suppose that by eating fourteen flies a Sparrow disposes of their subsequent progeny to the tune of 280,000,000; but we know what these calculations, which look so prodigious on paper, are worth. Under ordinary conditions, how many of the two hundred million flies would reach maturity ? perhaps very few, or none at all.
It is a shame to see how the pretty House-Martins are decreasing in this country at the hands of the Sparrows, which dispossess them of their nests. There is hardly a country-place where this has not gone on at some time or other, although it has never happened to Mr. Morris (cf. 'Sparrow-Shooter,' p. 7). Some have argued that this does not matter, because the Sparrows do not kill them, but only evict them ; but wherever they go it is all the same, they are so much bullied that very few of them succeed in rearing young.
It may be that in some exceptional seasons (when a great plague of insect-life shall again occur), as in 1574, when it is said cockchaffers gathered in such numbers on the banks of the Severn as to prevent the working of the water-mills, and in 1868 when they formed a black cloud in Galway, which darkened the sky for a league, destroying vegetation so completely as to change summer into winter ('Wild Birds' Protection Report,' p. 170), Sparrows will do good. Bearing this in mind no one should advocate their extirpation; but Mr. Morris and his friends claim much more than this for them. They claim that in an ordinary year, when insects are not more than usually numerous, Sparrows do more good than harm: it is exceedingly difficult to prove a negative; but I do not believe that any one who has not made a series of dissections realizes how much corn they eat.
From On the Misdeeds of the House-Sparrow (Passer domesticus) by J H Gurney
0 comments:
Post a Comment