Predators, conventional wisdom holds, seek out and strike down the very young, the old, and the sick and injured, leaving the strongest animals to pass on their genes to future generations. But at least one species of predator, some biologists have recently found, is at odds with the image of carnivores as cullers of the unfit. Tengmalm’s owls in the forests of Scandinavia stalk not the weakest prey but the fattest.
Biologist Vesa Koivunen and his colleagues at the University of Turku in Finland examined 21 of the owls’ nests spread out over 500 square miles of forest and pasture. Because the owls store their kills during the breeding season to ensure an ample supply of food for their young, the biologists were able to examine caches of intact prey, invariably rodents such as voles and shrews. They recorded the size, weight, sex, maturity, and general condition of each and ...
