Written by Peter Pearsall/Photos by Peter Pearsall
The natural world is full of deception. Choose almost any realm in nature and one will find organisms putting precious time and energy into appearing as something they are not—and often benefitting from the ruse.
Like parasitism, mimicry is a widespread and often successful lifestyle. Visually oriented organisms mimic the colors, shapes, and patterns of more dangerous or foul-tasting species; others may mimic odors, sounds, or behaviors.
One form of mimicry, known as Batesian mimicry, involves harmless species taking on the warning signals of harmful species, to ward off shared predators. At Malheur Refuge in spring and summer, one needn’t look far to find wildflowers buzzing with pollinators, including both true bees their Batesian mimics, the “wanna-bee” hoverflies (Family Syrphidae). Like bees, these flies feed on nectar and are preyed upon by birds, spiders, and other invertebrates; unlike many true bees, hoverflies lack stingers and rely on their similitude to stinger-packing true bees to keep them safe.
Another form of mimicry is Müllerian mimicry, in which two species—both already “well-defended” by spines, teeth, toxicity, or some other stratagem—converge on a similar appearance or behavior, to the benefit of both species. The effect is that predators need just one encounter with the look-alikes—either species will do—to avoid crossing paths with them in the future.
An example of Müllerian mimicry that can be observed at Malheur Refuge occurs between the monarch (Danaus plexippus) and viceroy (Limenitis archippus) butterflies. Both species are foul-tasting—monarchs contain cardenolides obtained from their plant hosts, the milkweeds; cardenolides are often toxic to vertebrates, causing heart failure if ingested in sufficient quantities. Similarly, viceroys use willows as hosts and contain bitter-tasting salicylic acid—a precursor to the primary ingredient in aspirin—which also deters predation.