Sun Green Plants Redback Vole Garter Snake Great Horned Owl Scavengers, Decomposers Soil [Illustration: A Pyramid of Numbers Necessarily, the number of plants in an ecosystem far exceeds the number of plant eaters, and the number of prey species must exceed the number of predators. During its lifetime, a golden eagle will consume a vast number of lesser animals. The combined mass of prey animals necessary to sustain an eagle greatly outweighs the eagle itself. Ecologists refer to this proportional relationship of mass between each link in the food chain as the _pyramid of numbers_. The diagram represents a numbers pyramid for the alpine zone. Because of its limiting environment, the alpine zone supports a lesser plant mass than the forest zone. As a result, the carrying capacity of the alpine is less than that of the forest. 1 Kilo _Tertiary_ (third-order) _consumers_ are the predators (Golden Eagle, Swainson’s Hawk, etc.) that feed upon other predators. Because of the 90% loss of energy at each level of the food chain, there will be very few hawks and eagles in comparison to the numbers of marmots. 10 Kilos _Secondary consumers_ are the predators (weasels, shrews, carnivorous insects and birds, etc.) that eat herbivores. The animals at this level of the pyramid are often—though not always—larger than the animals they feed upon. But they are much less numerous, because it takes many prey animals to sustain one predator. 100 Kilos _Primary consumers_ (plant eaters, or herbivores) convert plant tissue into animal flesh. In the process about 90% of the energy stored as plant food is lost, mostly as heat energy. In the alpine community the herbivores include pikas, marmots, ground squirrels, and ptarmigan, as well as herbivorous insects. 1,000 Kilos _Producers_ are the green plants at the base of the food pyramid, manufacturing food for the animals of the alpine community. The _biomass_ (total weight) of each level of the food chain is ten times (more or less) the weight of the stage above it: 1,000 kilos of green plants will produce only 100 kilos of primary consumers.] [Illustration: Great horned owls are the nocturnal equivalent of Cooper’s hawks and goshawks in the low-elevation forests of the park. Large and powerful, they are capable of taking prey as big as skunks. This young bird, disturbed on its day roost, clacked its bill and fluffed its feathers in a menacing manner.] [Illustration: The only sizable mature stand of ponderosa pine found within the park is along the North Fork truck trail. A scattering of old ponderosas growing at the lower end of Lake McDonald suggests that at one time ponderosa forests were more extensive in this region than at present.]