There is not much more that is unappealing to a bird gastronomically as it’s own faeces or that of others. Similarly, in wooded areas populated by birds the incidence of guano staining on leaves and other vegetation is quite high. Consequently, evolution has yet again taken extreme steps to provide shelter for the vulnerable in the form of bird dropping mimicry.
Many species of arthropods use faecal mimicry as a camouflage, including moths of the Drepanidae family. Typically camouflage incorporates the glossy fecal component, the white mottled urate component and the clear or coloured urine component of guano in the wing pattern and shape, body and surface-hugging stance of the moths. And it works; not only on potential predators. The number of times I have overlooked such examples with a cursory glance, but detected the ruse on deeper investigation is beyond counting. What is more, individuals seem to be able to place themselves amongst concentrations of real guano stains beneath a bird roost to deepen the deception.
In the top image, Macrocilix maia, simple bird dropping mimicry has been taken a step further with (arguably) a pair of flies or similar insects standing either side of the coloured component as if themselves feeding on the faecal waste.
Even Drepanid caterpillars exhibit bird dropping mimicry…..
Found this beautiful Dogwood Thyatirid (Euthyatira pudens) at the porch light last night. Then proceeded to spend about an hour looking for the id of what I presumed to be a Noctuid moth (Noctuidae, the “Owlet” family). Turns out it’s actually a “False Owlet” in the Drepanidae. And this specimen is still sitting in the same spot this afternoon, mocking me :-).