Viceroys aren’t faking it

I finally finished Doug Tallamy‘s book “Bringing Nature Home” today. I’d highly recommend it. You might also like this talk from him and his site homegrownnationalpark.org.

One aside in the book that caught my attention:

One of my favorite butterflies, the viceroy (Limenitis archippus), is most commonly found near willow hosts… The adults are the spitting image of a small monarch butterfly. For decades, the viceroy’s mimicry of the monarch was the textbook example of Batesian mimicry: a tasty insect copying the looks of a distasteful insect to gain protection from predators. David Ritland and Lincoln Brower (1991) have tested this hypothesis by letting redwing blackbirds taste viceroy abdomens. To Ritland and Brower’s surprise, they found that, like its monarch model, the viceroy was unpalatable to birds. Viceroys are not Batesian mimics of monarchs at all, but rather Müllerian mimics. That is, monarchs and the viceroy share the same color pattern to make it easier for predators to recognize bad taste when they see it.

p. 156, “Bringing Nature Home (Updated and Expanded)”

Here’s the 1991 article that he’s referring to: “The viceroy butterfly is not a batesian mimic”. From its abstract:

Our experiment refutes this interpretation by revealing that viceroys are as unpalatable as monarchs, and significantly more unpalatable than queens from representative Florida populations. This implies that viceroys are müllerian co-mimics of the danaines and prompts a comprehensive reassessment of this widely cited exemplar of mimicry.

Ritland, D., Brower, L. The viceroy butterfly is not a batesian mimic. Nature 350, 497–498 (1991). https://doi.org/10.1038/350497a0

I’m delighted with the surprise of learning I had the wrong idea in mind but also annoyed since I was taught the wrong idea about the viceroy’s mimicry well after 1991, and I’m pretty sure I’ve seen it repeated even within the past few years. Were you miseducated the same way as me?

I’ve added a willow to our garden largely because I’m curious what insects it might attract, but it sounds like we won’t be seeing viceroys since they seem to only be found east of the Sierra Nevada.