Plan your Link Trail hike!

Sunday, April 12, 2009

A quick followup

For more images see the Picasaweb album for this hike.

On the previous day I forgot to get size references for the bloodroot and the moss, so I took Grace on a quick hike in from Quarry Road. I got my size reference, but the tape measure was very awkward. There must be a better way, and after this hike I spent lots of time pondering what that might be. I need something that will hold itself in place next to the subject - perhaps something I can stick in the ground? I don't want to go poking large holes in the ground, so something narrow such as a hatpin might be just the thing. I haven't found a hatpin yet, so I've stuck two of my mother's old white teardrop corsage pins into my camera case. As I was typing this it occurred to me that I should take a small file and score millimeter markings into the shafts. This should give me an excellent size reference for flowers or insects on the ground, or even insects on trees or wooden structures.

Saturday, April 11, 2009

My first hike with Morgan and Ben

For many more pictures from this hike, see the Picasaweb album.

We had an hour to spare before getting Morgan and her boyfriend Ben back to Ben's house, and Morgan asked if we could take a hike to the quarry. The dilapidated structures along that section of trail fascinate her, and she enjoys photographing them. I was particularly quick to say yes because I'd just gotten a new camera: a Canon EOS Rebel XSi with a Tamron 90mm macro lens. I was eager to get the new rig onto the trail and find some small subjects.

We hiked in from Quarry Road, and almost immediately I got a pleasant surprise: a wee bloodroot poking up through the leaf litter blanketing the south side of the trail. Apparently I haven't seen them this early in the year before, because I never knew that the leaf wrapped itself around the blossom stalk like a slender woman wrapping her cloak around herself for warmth. But what surprised me more was the fact of its location: I've never seen a bloodroot growing in such a dry and sunny spot. This was my first hike with Ben, so I took the opportunity to tell the story of how native Americans used the red sap of the roots to dye their clothes, and how it's illegal to pick the plant because it's endangered.

The patch of moss shown here is about 3" wide.

The patch of moss shown here is about 3/8" wide.

Minutes later my eyes landed on the melange of greens and browns in a small patch of moss. Then I saw the tiny stalks sprouting up through the mat, and I was hooked. I got myself into macro mode: kneeling, crouching, bracing my elbow on whatever was available, and exhaling smoothly in calculated intervals, I started snapping away.

Three days before, when I got the camera, I didn't know a thing about SLR photography. During those three days I gave myself a crash course. Between my friend Karen's uncle Joe and various internet resources, I gained a theoretical understanding of apertures, shutter speeds and ISO settings. That's sort of like saying "I gained a theoretical understanding of juggling." It takes a long time and a lot of work to go from understanding it to being able to do it well. This was the first step on that path.

The little heads on the moss sprouts are between 1/8" and 1/4" long.

The depth of field of this new macro lens is stunningly shallow, so I kept refocusing on different clusters of the little capsule heads nodding on their slender stalks. I also experimented with different F-stops*. I wanted to get a sense of my aperture limits for handheld shooting, so I didn't use the tripod yet. I didn't bother going above F8 because I figured I'd get nothing but blurs if I narrowed the aperture too much.

It wasn't long after I tore myself away from that first subject that I was captivated by a trio of them. A pair of bloodroot stood in front of one of the many remnants of the old railroad: a rusty spike jutting from a tie that was slowly being overcome by moss. This time I set up the tripod and used the two-second timer so that I wouldn't be touching the camera when the shutter went off. I wanted to see what my effective aperture limits are for tripod-mounted field shots.

I started with the two bloodroot, moving all the way up from F/2.8 to F/32 while focusing on the nearest one, then moving the focus to the farther one and going back down to F/2.8. I see that the shot I chose to show both flowers in the same frame was taken at F/16. I'll have to review my original shots to be sure, but this may confirm the claim I read that this lens starts to produce softer images once the F-number goes higher than 16.

I moved on to the railroad spike, again trying different F-stops. These two shots show the dramatic difference in mood between F/14 and F/2.8. I particularly like the F/2.8 shot because I find that having everything blurred but the spike, the tree trunk, and the narrow strip of tie, gives it a feeling that's intimate, even lonely.

I finally tore myself away from the flowers and the spike when Morgan and Ben came back, Morgan excitedly telling me to come look at what they'd found. It was the same stone structure Mary and her fellow hikers wondered at two weeks ago. I put a mental star next to my mental note to research it. I should have taken a picture of it! Oh well... next time.

While the youngsters hung out by the quarry I went ahead to where the trail reenters the trees. This is where, during the summer, we found lots of snails and a few tiny frogs. I didn't find any frogs or occupied snail shells, but I was very pleased with the closeup shot of a shell that turned out to be empty.

Right after I left the shell I saw rabbit remains of a fresher sort than the coyote droppings Grace and I saw a few weeks ago. It seems likely that coyotes were responsible for this too.

On the way back I got some shots of one of the coltsfoot that are sprouting near the quarry, and some of the first bloodroot I saw. Then I snapped away at the lovebirds. There was smooching. It's good to know that a hike with dad doesn't kill the romance.

*To see the camera settings I used, click the "more info" link to the right of any photo in the Picasaweb album.

Friday, April 10, 2009

The humble origins of yet another obsession

This is the first in a series of entries about my fascination with a spider found on the Link Trail. If you're not interested in population genetics, give this one a miss.

Up until July I'd never heard of Enoplognatha ovata. Now I'm not only reading research articles on the little suckers, but getting ready to contact some of the folks who wrote those research articles so that I can better understand the population genetics involved. Oh well, anything for a weird life.

Back in July I saw a lot of spiders on the section of trail south of Freber (aka Hodge) Road. At the time I thought that most of them were the same species. After taking a look at the macro shots, I saw the differences in coloration and laughed at my silliness. But after I spent some more time looking at the shots and trying to identify them in BugGuide, I was startled to find that I was right the first time: they were the same species!

Since the female E. ovata shelters her egg sac in a rolled-up leaf, her species only lives near foliage that it can curl up just so. Those kinds of leaves grow on the blackberry bushes along the Link Trail - and in the hedgerows of Nidderdale, a town on the far side of England in Yorkshire. As it turns out, researchers as far off as Nidderdale and as nearby as the Syracuse University research station in Lafayette, New York have been puzzling over E. ovata for decades. And the reason they're so interested is the same reason I thought I was seeing different species.

E. ovata has a striking color polymorphism, which is a pretty way of saying that a spider can have one of several distinct color patterns that are determined by the color genes it got from its parents. Most of the spider's body is a creamy white, yellow, or greenish color. The Lineata morph has no additional color. Redimita individuals have a pair red stripes running down their backs, and in the Ovata morph there's no gap between the stripes: the entire back of the abdomen, i.e. the dorsal opisthosoma (god, I love saying "dorsal opisthosoma") is red. The individual in the lower right corner of the composite image above is Redimita. The other two are Lineata. I didn't see any Ovata, and I'm not likely to: none of the researchers found any in this part of New York State.

Now here's the hook: Although the gene for Ovata is dominant over that for Redimita, and both of the red morphs are dominant over Lineata, percentages of the three morphs in natural populations are the inverse of what one might expect. Most surveys show somewhere around 70% Lineata, 25% Redimita, and 5% Ovata. And these proportions are remarkably stable within almost every local community sampled. This piqued my curiosity. It did the same to a lot of researchers. In the posts to follow I'll be telling you about their findings.