Perhaps the mysterious and ever-novel realm we dub “nature” holds no more magical aspect than that of mimicry. Select species have evolved various aspects that imitate looks, sounds, or behaviors found in their environments. We often call the most common form of mimicry “camouflage.” When an animal matches some aspect of its physical environment, such as a soil color, rock texture or a plant background we tend not to think of it as overt mimicry. We generally reserve that distinction for animal species that imitate other animals. This is understandable, as looking like one’s background is common. Still, we find many fascinating local examples of such “static or environmental mimicry.”
Witness a western screech owl stretched upwards near the trunk of a tree. It appears like one more broken branch top. Accentuating the ruse are the so-called ear tufts of the owl, which are, in reality, mere points of feathers that look like a jagged branch end.
Too many species to recount here mirror their environments in an effort to eat and yet not be eaten. Snakes that look like rocks, lizards that match a bark background, poor wills – birds that when perched on the ground look like a pile of dung. The list goes on…
The richest place to troll for local mimics is in the invertebrate world. Hardly a day goes by when I fail to encounter a Sky Island invertebrate mimic. Monarch butterflies and their close cousins, queens, are both toxic and are quite similar in appearance, rendering them Mullerian mimics – “two or more well-defended species, often foul-tasting and that share common predators, have come to mimic each other’s honest warning signals, to their mutual benefit.” If a predator tries to eat one species it will likely avoid consuming the other species as well in the future. Birds, lizards, and other would-be predators swiftly become neurally imprinted with the toxicity of such species.
Velvet ants are, despite their name, wingless wasps, the females of which pack a potent sting. They serve as a template for many an invertebrate mimic hoping to come across as a painful meal. Some spiders, including the animated jumping spiders, which have their own venomous bite, have evolved to look and act like a velvet ant. Their combination of a black and red dorsal pattern and jerky movements apparently is enough to fool most predators. Even one fly species gets in on the act, sporting the same color combo, as well as the hesitant movements of the real deal. All are cases of Batesian mimicry – “ a form of mimicry where a harmless species has evolved to imitate the warning signals of a harmful species directed at a predator of them both.” The bottom line? Live to eat and mate another day.
Among my favorite local fakes is the zone-tailed hawk. This large buteo plies our skies looking like a slightly downsized turkey vulture, which poses little or no threat to healthy prey. Thus, the black and gray plumage of the zone-tailed hawk and its vulture-like flight lull prey into thinking “the coast is clear,” sometimes resulting in a fatal error in judgement. A classic case of aggressive mimicry “where a predator or parasite mimics a harmless species, avoiding detection and improving its foraging success.”
A strange case of auditory mimicry comes from our local burrowing owls. The chicks of this species are small and quite vulnerable to predation in their ground dens. When alarmed, however, they do an unnerving imitation of a western diamondback rattle! Case likely closed; look elsewhere for a meal!
Why do birds mimic each other’s songs/calls, as well as environmental sounds? Greater roadrunners occasionally do a call that is very similar to that of a Cooper’s hawk – an emphatic “kek-kek-kek-kek.” As the hawks are a key local predator of roadrunners, are these strange cuckoos aping their sounds in an attempt to dissuade dangerous aerial predators from setting up shop in the roadrunner’s backyard? Similarly, Stellar’s jays in our mountains do convincing imitations of both hawk and owl vocalizations.
We end with mimicking, well, “the end” itself. Several Sky Island denizens have evolved to mimic or feign death. Famously, our Virginia opossum when pressed by a would-be predator sometimes flops on the ground, ceases movement, allows its tongue to loll out of its mouth, and may emit a foul small from its anal scent glands. As many predators have evolved to hunt active prey, the lack of signals required to incite an attack may well save this marsupial’s life. Western hog-nosed snakes and Ring-necked snakes employ a death stupor as well.
It seems that simply “being yourself” is not enough for some species. Next time you go for a stroll outside look for these dupes, as nature’s astounding “con men” abound!
Vincent Pinto & his wife, Claudia Campos run RAVENS-WAY WILD JOURNEYS LLC, their Nature Adventure and Conservation organization – devoted to protecting and promoting the unique biodiversity of Sky Islands region. RWWJ offers a wide variety of private, custom-made courses including Birding and Biodiversity Tours. Visit: www. ravensnatureschool.com