My favorite question in the game of Trivial Pursuit has always been "Do Beavers Eat Fish?" It's logical to assume they might, since they live in water. But animals don't always eat what we think they should, and animal feeding behaviors are far more complicated than implied by the simplified image of the food web.
Some animals are herbivores at certain life stages and carnivores at others. Tadpoles eat mainly algae, plant material, and detritus (dead and decaying matter); after metamorphosing into frogs, they eat mostly insects. Since both larval and adult stages live in the same pond, a single species occupies two different niches within the ecosystem during its different life stages.
Many animals are omnivores—eating whatever food is available to them, whether plant or animal. Coyotes are a great example. Since they belong to the order Carnivora and have the shearing teeth of a predator, we might assume they're strictly meat eaters. Yet coyotes are typical opportunists. Their diet includes rodents, birds, carrion, plants—whatever they can find. Examination of coyote scat bears this out; it typically contains not only fur and rodent bones but seeds, grass, dried berries and other plant material.
Bears are another omnivore classified as carnivore. They eat berries, nuts, roots, fish, mammals, birds, and invertebrates. At certain times of year, vegetation accounts for as much as 90% of a black bear's diet. Much of the "meat" in the remaining 10% of its diet comes from insects.
Pheasants, prairie-chickens, and many other birds we think of as grain and seed eaters are dependent on animal foods during certain times of their life cycles. Grasshoppers are essential to the growth of the chicks of many grassland grouse species. Without the protein from the insects, the young can't get the nutrients they need for growth. Similarly, during their migration through the San Luis Valley, sandhill cranes are highly visible while feeding on waste grain in fields. Cranes must supplement this vegetarian diet with grubs, insects, worms, fish, frogs, shellfish, and other animal protein to have the strength to endure an arduous migration and to successfully breed and produce young.
(** The answer to this question can be found in another article in this publication!)
Next: Report: Greater Prairie Chickens
(The information contained in these issues of Colorado's Wildlife Company was accurate at the time of original publication. Situations and circumstances described, staff positions, contact information, and dates of some events may have changed in the interim. Present knowledge and understanding of biological and behavioral facts and information may also be different than presented here.)