Thursday, September 25, 2014

The amazing invertebrates of Ferncliff Camp

Every year the Arkansas Audubon Society rents classrooms at Ferncliff Camp and Conference Center for a weekend to teach nature courses (tree identification, native plant gardening, mammals, and so on). For the past several years Cheryl and I have taught classes in butterflies and in insect ecology. This past weekend we did butterflies.

The camp consists of 1200 acres nicely situated in mountains 10 miles west of Little Rock. There are meadows, woods, two big lakes, a stream running through it. It would be perfect, except someone there has this thing about tidiness (always antithetical to nature). Everything is mowed. The fields are mowed right down to the edge of the lakes. In dry years they can get their mowers into the ditches alongside the road, and the weedy flowers there are mowed. Butterflies look for flowers, but flowers are nonexistent.  There is an underpass to come off the highway and get down to the camp, and in the concrete structures above it there are places that so far their mowers have not reached, and that is often our single hope for a few wild flowers and a few butterflies. Because in those little unmowed patches, the wildflowers are quite good and teeming with butterflies and other insects.

So, as always, our hearts sank a bit as we drove in. What are we possibly going to be able to find for our classes? But again this time, as always, the insects turned out to be fantastic. We see bigger, more exotic creatures here than anywhere we know in the state. Of course part of reason is an intensive weekend of searching (somewhat desperate on our parts), but aided by the many sharp eyes of our eager classes.

We had come a day early to look the place over, and as we walked towards our classroom we came to a tree that had several large wounds in it bleeding sap, and there were butterflies attracted to the sap. That would be terrific to have this insect draw right outside the door. And the first thing we saw as we approached it was unbelievable, a beetle at least two inches long and in bright red and green and gold colors.  We looked at it almost stunned, and didn't get our cameras out until it started scampering up the trunk so that it was too far above us for a really good shot. But we did get this, anyway.

Our books told us its name was Plinthocoelium suaveolens. We had never seen it or even heard of it before. They are attracted to sap, so this was the place to find them, but we were lucky to see it anyway. When we told Brian "Bugs" Baldwin about it, he said it was very late in the year for it.

We had only been on site for half an hour, and already had a big new exotic insect. Now, what we had noticed in past years is that the place was outstanding for caterpillars. Partly it was because we came late in the year when caterpillars are at their peak, but partly it was the tremendous variety of trees, which is part of the reason the tree identification class here is so popular. (The main reason is because Eric Sundell is the teacher.)

Anyway we're very fond of caterpillars (we always have jars full of ones we are raising) and Cheryl with her sharp eyes is always watching for them. This day she was looking down at some bushes near that sap-leaking tree and began seeing caterpillars, probably half a dozen. They were quite pretty.

They were tussock caterpillars of some kind (there are dozens of kinds) and I was trying to remember which. "The orange brushes in the front make it Hickory Tussock Moth caterpillars? No, that's not quite right. Some tree name." Then I remembered: Sycamore Tussocks. We looked up and there was a sycamore tree right by us. These had all fallen out of the tree and would never get back. They were doomed to starve. We looked for a place where some sycamore leaves came within our reach, and very carefully held the caterpillars up to the leaves till they caught hold and climbed up for another chance at life.

But there must have been thousands and thousands of them up in the sycamore trees we could now see were all about us, because only a small fraction falls off, and when we looked around, they were swarming everywhere on the ground. Here they are sheltering under the window frames of the buildings. Multiply this by all the window frames of all the buildings around.

We pretty quickly gave up on trying to save all the thousands of fallen caterpillars. To tell the truth we were rather pleased that if all else failed, at least we would have this phenomenon to show our students. In fact, when our class was with us the next day and we were examining these caterpillars, we found that there was a second caterpillar in amongst them, another kind of Tussock Moth caterpillar, the White-marked Tussock.

That gave me a chance to talk to our class about mimicry in insects, one of my favorite topics. In my Caterpillars of Eastern North America (Wagner, 2005) book some twenty species of caterpillar are listed under the name Tussock (named for the tight bunches of bristles on their backs). These caterpillars come from different families, and only a few of them are "true" tussocks, and the rest are mimics. The White-marked is a true tussock. If you look at the picture above you will see there are two little red bumps on its back near the tail end. These are the "defensive glands," which contain a severe skin irritant.  (Indeed, in one species, the Browntail Moth, the irritant has caused allergic reactions that have even led to death.)  I had read that while grooming, they rubbed their hairs over these glands, to coat them with the irritant. While the class was studying one, we jostled the leaves it was on so much it became annoyed enough to begin crawling off, and that's when it stopped and went through motions that looked like it might have been rubbing its brushes over the little red cups. Birds know about the cups, and leave these caterpillars alone.

The moral of the story is that all these other Tussock Moth caterpillars were mimicking the true tussocks so that birds would leave them alone too. Judging by the ineptitude of the Sycamore Tussocks wandering all over the landscape, they needed all the help they could get.

In addition to neat caterpillars, Ferncliff also has wonderful spiders, the biggest of their kinds. One of the pleasures of teaching a class for these alert, intelligent, nature-loving people is that when we discovered an enormous spider on the wall of our classroom instead of shrieks and a stampede for the door, they were thrilled, and cameras were flashing at it from every direction, including mine.

This is an exceptionally large Tiger Wolf spider (tiger for the orange stripes on the legs). They live in burrows during the day and come out hunting at night, but as winter approaches, a number of spiders begin to move into more sheltered places, from hollow logs to warm classrooms.

And when we led them up a trail that followed a wooded path along a streamside, we found an even bigger spider. This was Dolomedes vittatus, one of the fishing spiders known for catching tadpoles and small fish and diving under water to escape their enemies. This large female spider had woven a little tent out of leaves and had cached its young spiderlings inside, and was now standing guard over them and would faithfully remain until it starved to death or froze this winter. Those babies certainly looked well guarded (just the spider's body was over an inch long). They should have a good start when they all go off in their separate directions in the spring.

And another spider of great interest to me, a male Geolycosa. I said in an earlier post that with spiders in the genus Geolycosa, the Burrowing Wolf Spiders, the females spend their whole life in or immediately around their burrows, but that the males, when they become sexually mature, leave their burrows and head out looking for females. I had never seen one of these males on the move, but here in rather deep woods where I hadn't expected it, we suddenly saw one.  It came by and was gone in a moment, but we got good pictures.  Here is Cheryl's very fine portrait.

There was at least one noteworthy vertebrate for the weekend. Some of the group were farther up the path with Cheryl when they saw a half-grown copperhead on the path, which quickly crawled off the path into the leaf litter which its pattern was designed to blend into.

The snake is centered in this photo, and the flash brings it up, so this probably won't work for you. But when I came up, the people who had stayed behind to point it out to me kept saying "It's right there," pointing their fingers as close to it as they dared, and saying it was under this stick and over that leaf, but I absolutely could not see it. And then, click! suddenly I could see it, and it was as if a light turned on, and it was perfectly clear and obvious, and each person who came up after me went through the same embarrassing experience of not being able to see it for the longest time, then suddenly there it was.

The camouflage pattern, matching the tangle of dead leaves, was perfect, but still, there was some other, psychological, thing blocking us from disentangling the snake out of it, which is why, once we broke out of it, it was then easy to see.

I guess I should at least have one butterfly picture, since that is what we were meant to be directing our class towards. There was fog fruit growing along the lake edge (a low growing plant that managed to keep underneath the mowing blades). That's the caterpillar food for the Phaon Crescent, a handsome little butterfly, and there was a small population of adults hanging around the plant, which our students could get acquainted with and practice using their close-focusing binoculars on. Otherwise, there weren't many species of butterfly about, and those that were about were the very commonest species, Cloudless Sulphurs, Eastern Tailed Blues, Pearl Crescents, Red-spotted Purples and other species like that. If Cheryl and I were there alone and looking for butterflies, it would have been disappointing, and we worried that we wouldn't have enough to show our students. But we were wrong. For a class of mainly beginners it was just right, a small amount of information for them to practice learning field marks on, without being totally overwhelmed. And because we kept veering off to look at spiders or snakes or phantom crane flies I think we might have helped them discover the intense pleasure not just of finding butterflies, but of seeing every living thing.

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