Biography of the Vizcacha. 301
tually destroyed. Often when the young foxes are large enough to follow their mother, the whole family takes leave of the vizcachera where such cruel havoc has been made to settle in another, there to continue their depredations. But the fox has ever a relentless foe in man, and meets with no end of bitter persecutions; it is consequently much more abundant in desert or thinly settled districts than in such as are populous, so that in these the check the vizcachas receive from the foxes is not appreciable.
The abundance of cattle on the pampas has made it unnecessary to use the vizcacha as an article of food. His skin is of no value; therefore man, the destroyer of his enemies, has hitherto been the greatest benefactor of his species. Thus they have been permitted to multiply and spread themselves to an amazing extent, so that the half-domestic cattle on the pampas are not nearly so familiar with man, or so fearless of his presence as are the vizcachas. It is not that they do him no injury, but because they do it indirectly, that they have so long enjoyed immunity from persecution. It is amusing to see the sheep-farmer, the greatest sufferer from the vizcachas, regarding them with such indifference as to permit them to swarm on his "run," and burrow within a stone's throw of his dwelling with impunity, and yet going a distance from home to persecute with unreasonable animosity a fox, skunk, or opossum on account of the small annual loss it inflicts on the poultry-yard. That the vizcacha has comparatively no adverse conditions to war with wherever man is settled is evident when we consider
3O2 The Naturalist in La Plata.
its very slow rate of increase, and yet see them in such incalculable numbers. The female has but one litter in the year of two young, sometimes of three. She becomes pregnant late in April, and brings forth in September; the period of gestation is, I think, rather less than five months.
The vizcacha is about two years growing. A full-sized male measures to the root of the tail twenty-two inches, and weighs from fourteen to fifteen pounds; the female is nineteen inches in length, and her greatest weight nine pounds. Probably it is a long-lived, and certainly it is a very hardy animal. Where it has any green substance to eat it never drinks water; but after a long summer drought, when for months it has subsisted on bits of dried thistle-stalks and old withered grass, if a shower falls it will come out of its burrows even at noonday and drink eagerly from the pools. It has been erroneously stated that vizcachas subsist on roots. Their food is grass and seeds; but they may also sometimes eat roots, as the ground is occasionally seen scratched up about the burrows. In March, when the stalks of the perennial cardoon or Castile thistle (Cynara cardunculus) are dry, the vizcachas fell them by gnawing about their roots, and afterwards tear to pieces the great dry flower-heads to get the seeds imbedded deeply in them, of which they seem very fond. Large patches of thistle are often found served thus, the ground about them literally white with the silvery bristles they have scattered. This cutting down tall plants to get the seeds at the top seems very like an act of pure intelligence; but the fact is,
Biography of the Vizcacha. 303
the vizcachas cut down every tall plant they can. I have seen whole acres of maize destroyed by them, yet the plants cut down were left untouched. If posts be put into the ground within range of their nightly rambles they will gnaw till they have felled them, unless of a wood hard enough to resist their chisel-like incisors.