Episode 061: Mourning Cloak Butterflies

You can download and/or listen to the audio of this episode here!

Transcript 3/9/19:

Some days I struggle to get out of bed. “I want to sleep forever!” I think to myself. Then I think harder about those that hibernate, those that experience torpor, and those that experience diapause. I pull myself from bed, put on the kettle for tea, and embrace the wild world around me. Welcome to The Nature of Phenology where we share the cycles and seasons of the outdoors. I’m your host, Hazel Stark.

There are many times of year in Maine when it feels impossible to predict the weather and early March seems to be one of those times. I tend to take note of the weather in early March because it happens to be when my birthday falls and the weather on an outdoorswoman’s birthday is always noteworthy. On my first birthday, I am told my mom made three different birthday cakes due to a series of blizzards that meant that my birthday party kept having to be rescheduled. On my tenth birthday, I had a sleepover that involved a treasure hunt over matted brown grass on the first day and on the second day my friends’ parents rushed to pick up their kids, wading through three feet of snow to get to them. On my 27th birthday, I awoke to a 75 degree sunny day in southern New Hampshire so took to the woods to climb a mountain in a t-shirt (an article of clothing I rarely have had the opportunity to wear on my birthday). What did I see on that particular warm and sunny early March day but another creature that seems to revel in getting outside whenever physically possible: a mourning cloak butterfly fluttering amongst the leafless trees.

When their wings are folded closed, mourning cloak butterflies are perfectly camouflaged against tree bark. The undersides of their wings are mottled with shades of brown, gray, and cream, giving the impression of a flake of bark. But when they open their wings, they display a velvety deep red-brown pair of wings with a cream border beyond a row of bright blue spots. That dark velvety look of this Lepidoptera member is what gives the butterfly its name of “mourning” cloak as they have been said to resemble the cloaks that mourners once wore. While their coloration is captivating on its own, what I find even more captivating is watching the first butterfly of spring flutter among remaining patches of snow before deciduous leaves or flowers have emerged.

Surprisingly, mourning cloak butterflies actually overwinter here as adults hidden in sheltered cracks in wood or rocks or behind flaking bark. While some butterflies migrate to warmer places during winter, like the famous monarch butterfly, others overwinter as eggs or as pupa. Mourning cloaks, our longest lived butterfly, go into what’s called “winter diapause,” almost like an insect hibernation, where they rely on fat they put on during the fall and some sugary antifreeze agents in their blood that help safely lower their freezing point. It’s rough going as a delicate butterfly surviving for months in a sheltered spot at sub-freezing temperatures and their struggle is often evident in the tattered look of their wings this time of year. So why go through all the trouble of staying put for the winter?

The advantages of being one of the first butterflies to emerge in the spring outweigh the challenges for the mourning cloak. While there isn’t reliable flower nectar available yet, they can instead feast upon tree sap oozing from winter-damaged trees or rotting fruit leftover from the fall. They can also find necessary minerals by visiting puddles and piles of scat as they melt out of snow banks. By mating early enough for their larvae to be able to rely on the young leaves of willow, birch, and poplar, they give their offspring a little extra time to prepare for winter once they metamorphose into adults mid-summer. And, while the early bird may get the worm, the earlier butterfly can avoid the bird altogether as many of this butterfly’s predators haven’t yet migrated back to the area.

So as I spend some of today reflecting on my past 30 years of life, I will also save some figurative cake for the mourning cloak butterflies beginning to emerge from their winter slumbers as they enter the final phase of their 8-10 month lifecycle.

You can download this episode and find a link to the transcript, references, contact information, photos, and information about how to subscribe to this show as a podcast by visiting archives.weru.org. Have a nature question that you want us to answer in our show? Simply reach out to us! Theme music was by a pileated woodpecker, made available by the US Fish and Wildlife Service. Thanks for listening and please join us next week for another dive into The Nature of Phenology.


Holland, M. (n.d.). Mourning Cloak. Retrieved February 15, 2019, from https://naturallycuriouswithmaryholland.wordpress.com/category/mourning-cloak/

Holland, M. (2016). Naturally curious day by day: A photographic field guide and daily visit to the forests, fields, and wetlands of Eastern North America. Lanham, MD: Stackpole Books.

  Wondering where Episodes 001-033 are? Find out here.

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