Friday, July 4, 2008

A Very Rare Butterfly

I had the good fortune to go along on an excursion into a Michigan fen the other day, to help tally numbers of one of North America's scarcest butterflies. Thanks to Mike Penskar and Daria Hyde of the Michigan Natural Features Inventory for allowing me to come along.

Your blogger in a habitat that not all would find overly alluring. I'm smack in the middle of a boggy tamarack fen, loaded with Poison Sumac, Toxicodendron vernix, and nasty deer flies. Of course, for a lot people I know, they'd love the place. The soil is waterlogged and can be very much the quagmire, and dense tussocks created by clump-forming sedges further hinder one's ability to navigate. A misstep can easily put you to your waist in muck, if not deeper. That happened to several people this day. Twice I went in nearly to the top of my hip waders, and the only way to get them out was to remove my foot and pull - hard! - with both hands. Slowly and with a giant sucking sound I could eventually extract them from the mire. Nonetheless, this fen was absolutely fascinating from the perspective of a biologist - loaded with all kinds of interesting and rare flora and fauna.

A view of the habitat within this fen, located somewhere in Michigan. The specific location must remain anonymous, partly because it is private property, partly because of the extremely rare insect that lives here. The above shot depicts an open tamarack savanna. The overstory is sparse, and created by our only deciduous conifer, Tamarack, Larix laricina. The understory is primarily sedges of many species, but their rank is dominated by Tussock Sedge, Carex stricta. This species does just what its name implies - creates foot tall mound-like humps as a byproduct of its growth. Great habitat for many things, but it makes for challenging walking.

Here's a plant that anyone who explores bog and fens will want to learn: Poison Sumac, Toxicodendron vernix. It is a treelet, growing to perhaps 20 feet when fully mature. Although capable of causing a blistering dermatitis, Poison Sumac is quite showy with its handsome pinnate leaves, leaflets held on bright pinkish-red petioles, and later, bright china-white berries. Make a wonderful native plant for landscaping if it weren't for the obvious ill side effects. Probably not too many nurseries would be interested in stocking this one.

We had a good crew of people in on this action. The idea was to locate and record as many of the rare butterflies as possible, and assisting in that effort was one of the sharpest crews of biologists I've been around for some time. Above is Daria Hyde on the right, who spearheads this survey, and Troy Shively, who came along with me from Ohio. Several folks from the Indiana Nature Preserves Commission were also along.

You know the butterflying is going to be good when you start seeing these. This beautiful caterpillar grows up into a winged creature that is among the most stunning butterflies in North America - but not the primary subject of this expedition. This caterpillar is chowing down on its host plant, Turtlehead, Chelone glabra.

Here's the final stage of that caterpillar - the Baltimore Checkerspot, Euphydryas phaeton, named after Lord Baltimore's exquisite taste in colors, which also provided the moniker for the outrageously colored Baltimore Oriole. This fen was filled with them. We saw dozens; in places it was the most common butterfly.

The underside of the Baltimore Checkerspot's wings are the most striking part of the insect, in my opinion. This one was very fresh, and was still in the process of hardening up after emerging from its chrysalis. Needless to say, I returned home with scads of gorgeous checkerspot images; they are irresistable subjects for the lens.

In addition to a dozen or so butterfly species, we saw scores of moths. There were a lot of showy ones in the genus Haploa, and this interesting one, which looks a bit like a firefly. It is a Virginia Ctenucha moth, Ctenucha virginica. They are day-fliers and would be easy to dismiss as a non-moth at first blush. Notice its long, feathery antenna - a dead give away as to its real taxonomic affinity.

Dragonflies were also a major diversion in this fen. Even though the day was not ideal for seeing them - or butterflies for that matter - as it was cool and overcast, we saw lots. There were plenty of bluets, dancers, some clubtails, tons of spreadwings, and several magnificently massive Swamp Darners, Epiaeschna heros. The above is a striking female Green Darner, Anax junius, that I was able to sneak up on quite closely. That might be overstating my abilities. They have up to 30,000 individual facets per eye, and she no doubt saw me WAY before I saw her. The cool conditions probably slowed her down, allowing for an eventual approach to within inches.

Of course, the botany wasn't to be ignored in such a floristically diverse site, and we made note of many interesting and highly specialized plants. And it certainly is not everyday that one can add a "life" hybrid birch to their list, but we all did today. Lee Casebere, one of our team, spotted an odd-looking birch growing in the depths of the fen - sort of half tree, half shrub. We moved in, and were ecstatic to discover that it was Betula x purpusii, a cross between Swamp Birch, Betula pumila, and Yellow Birch, B. allegheniensis. The former was quite common throughout the fen, and small numbers of the latter were on wooded slopes adjacent to the fen. It was quite a striking plant, in some respects better looking than either parent, which is sometimes the case with hybrids. I don't know of any Ohio records for this hybrid, but will certainly be better prepared to find it after seeing the real McCoy in the wild.

Finally, after much buildup :-), here we are: one of the rarest of the rare. This is a Mitchell's Satyr, Neonympha mitchellii, one of the scarcest butterflies in the country. This was the main focus of our expedition, and we weren't disappointed. The Michigan Natural Features Inventory keeps careful tabs on the satyrs, and we found over 130 butterflies on this trip. Micthell's Satyr is listed as Federally Endangered, and it is only found in Indiana and Michigan. The latter state has the best populations, and the most colonies - about 13 currently known.

Doesn't look like much from afar, and these satyrs flow with a peculiar slow bouncy flight, staying low in the sedges. They often perch hanging upside down in the vegetation.

Seen well, the Mitchell's Satyr is a stunning exhibit in hues of brown. Fresh specimens display bright orange-rust terminal bands along their wings, and vivid ocelli, or eyespots. Overall, they range from a tan-brown to an almost vibrantly rich chocolate brown. It was very exciting to see this fabled butterfly in the flesh, and help count them. We carefully recorded each individual's location with GPS units, and the populations are monitored by the Michigan folks each year.

I was particularly interested to get a firsthand immersion into their habitat. This mega-rarity was once known from Ohio, in a fen in the northeastern part of the state, where it was last recorded in 1950. The fen still exists, albeit not as much of it as back then, but the satyr flies there no more. A factor that likely played a role in the decline if not outright extirpation of this butterfly, and other rare ones, is irresponsible collecting. Over the top lepidopterists, both amateur and professional, have been known to make repeated visits, year after year, to known colonies of rare butterflies and collect many specimens. That's one reason locations like this have to be guarded secrets. For an interesting read about this subject, have a look at Butterflies through Binoculars, by Jeffrey Glassberg, where he talks of the extirpation of Mitchell's Satyr in New Jersey due to overcollecting.

I look forward to looking at some spots in Ohio for this butterfly, now that I have a "search image". There are some places, probably never before checked for Mitchell's Satyr, that look pretty good based on what I saw in the state up north.

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1 comment:

Jason Folt said...

Looks like a great spot, so where are the Sistrurus catenatus??