"Even more confusion of terminology could be avoided by realizing that making ever more precise or restrictive definitions does not generate greater precision in the understanding of any animal. Animals are dynamic. Each animal’s choices fit in somewhere in a long continuum of almost anything that can be measured or imagined. Different terms may apply in any one animal in varying degree, depending on circumstances, but ultimately the species, and often the individual, fashion their own solutions to fit the situation or the occasion. We gain understanding not so much by lumping and defining, but by differentiating the specifics form the generalized features. The latter have a tendency to become enshrined as rules or laws that are ultimately statistically derived descriptive artifacts. But animals don’t follow rules or easily allow us to pigeonhole them into convenient intellectual boxes. A “rule” is nothing more than a consistency of response that we have deduced animals exhibit because it serves their interests. Rules are the sum of decisions made by individuals. They are a result. The chaos, and the art, of nature remains."
— Bernd Heinrich (Winter World: The Ingenuity of Animal Survival)