h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

In the past I have kept both rabbits and guinea pigs nad have found them both to be very hardy, easy to keep and prolific breaders. The one thing that has always baffled me is, why are rabbits so successful in the wild wile guinea pigs are not ? many other animals introduced into this country have escaped and cause devistation in the wild examples are coypu and mink, why not guinea pigs. By my analysis they should be more successful than rabbits when you consider their breading patterns. A rabbits gestation period is 30 days, at birth rabbits are blind, very underdeveloped and completely dependant on their mother who must retun to them to fead them, they remain in this state for at least another 30 days. Guinea pigs however have a gestation period of 60 days and are born fully able to run about and follow their mother. You would expect this stratagy to be more successful in the wild but it is obviously not. In all other respects guinea pigs are much the same as rabbits i.e. they live in large packs with similar patterns of domination and behavior, they eat the same things i.e. anything vegitable, they can stand extreams of temperature. So why are there no plagues of guinea pigs ? any thoughts ?