NATCHEZ NATURALIST
NEWSLETTER:
from the woods near Natchez, Mississippi, USA

March 21, 2004

SNAPPING TURTLE DAYS
Twice this week I've run into Snapping Turtles, CHELYDRA SERPENTINA. The first time, I was sitting next to the forest pond when something came moving through the woods rustling dry leaves as clumsily as a human. It was a snapper, who proceeded to enter the water and keep going in a straight line to the pond's other side, as if the pond had been but a station on his journey due south. The next day I found one two-thirds submerged in a muddy pool at the bottom of an intermittent little stream through the lowlands along Sandy Creek. He just sat there looking up at me. You can see almost exactly the way he looked at www.biology.wustl.edu/tyson/faunareptsnap.html

That picture clearly shows the snapper's main features: A relatively small shell, but a massive head, thick neck and legs. As the snapper at the forest pond swam just below the water, its head and neck looked so oversized for its shell that I thought of a football player wearing a tutu.

The only other turtle that might be confused with a snapper is the Alligator Snapping Turtle. The easiest- to-see difference between them is that on the Alligator Snapper's top shell, its carapace, each "scale," or "scute," rises in a low pyramid, so that the shell looks very bumpy. The Snapping Turtle's carapace has one or two very low "teeth," but nothing like the Alligator's. Another difference is that Snapping Turtles are likely to be found in the kinds of places I've found them this week, but Alligator Snapping Turtles are mostly found in deepwater rivers, lakes, oxbows and sloughs.

As a kid in Kentucky I referred to snappers as "Loggerheads," and that was a good name for them. However, fieldguide writers like to reserve the name "loggerhead" for a certain kind of sea turtle, so they settle on "Snapping Turtle" for our species. If you've ever held a stick in front of a snapper, you know that that's an appropriate name, too.

There's a whole Web site dedicated to Snapping Turtles at www.chelydra.org

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BLACK OAKS FLOWERING
This week the Black Oaks, QUERCUS VELUTINA, have been pea-green with flowers and young leaves emerging from buds along elongating stems. They as well as other trees have been producing so much pollen that this Sunday morning as a front moves in from the north, breezes send puffs of bright yellow pollen curling over the barn's eaves.

If you see an oak blossoming, you can have some fun locating its male and female flowers. Its dangling, yellowish, 2.5-inch-long (6 cm), wormlike things are catkins composed of dozens of pollen-producing male flowers. Once the male flowers release all their pollen, the catkins will fall to the ground. In cities, sometimes these fallen catkins make a real mess on sidewalks.

Be sure to look for female flowers -- the oak's future acorns. They look like miniscule buds nestled in the angle between the expanding leaves' petioles, and the stem. I've scanned an image showing exactly this, with a much-enlarged inset showing the future acorns, and you can see that image on my new Oak Flowers Page at www.backyardnataure.net/fl_bloak.htm

Dozens of oak species exist, and they can all be divided into two great groups, depending on how long it takes for the female flowers to develop into acorns. Acorns in the White Oak Group mature the year they appear, and the acorns' kernels are often sweetish and edible. Chestnut Oaks belong to this group. Acorns in the Red and Black Oak Group need two years in which to mature, and often their kernels are very bitter.

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CEDAR-APPLE RUST GALLS
Since last fall I've been keeping an eye on several brown, knobby items about the size of golfballs growing like tumors on the stems of the Eastern Redcedar next to my compost bin. This Monday I saw what I'd been waiting for. From each bump on the golfball things, slender, sharp-pointed, orange- colored "horns" had emerged, and from these horns yellow, pollenlike powder was falling. The knobby balls were Cedar-Apple Rust Galls, caused by the fungus known as Cedar Apple Rust, GYMNOSPORANGIUM JUNIPERI-VIRGINIANAE. Naturally I scanned a gall for my Rust Fungus Page, and you can see that image, which turned out quite well, as the second picture from the top at www.backyardnature.net/f/rusts.htm

Rust fungi are fascinating. Many species have life cycles so complex that they seem made-up and impossible to accomplish. Cedar-Apple Rust's life cycle is about average in complexity.

The yellow, pollenlike powder emerging from the galls' orangish horns consists of masses of fungal spores. The spores are carried by the wind to an apple tree where when a spore germinates it forms a kind of sore or blister on the apple tree's leaf. At first the sore is yellow but later it turns brown and the leaf curls. When the sore matures in late summer or fall it produces a new kind of spore, and that spore is then launched into the wind, and germinates when it lands on a redcedar tree or other kind of juniper (redcedars are junipers). Then this second kind of spore infects the redcedar's stem and a gall of the type I've watched since last fall develops. Next spring, horns emerge from the gall, spores dribble from them, and the cycle starts all over.

Of course hardly any of the vast number of spores released by our redcedars this week will find an apple tree. I've read that sometimes hawthorns get infected, and we have hawthorns here but no apple trees, so maybe that's how the fungus survives here. Notice that right now the spores are being released exactly as leaves are emerging from apple-tree buds -- the leaves' most vulnerable moment.

This disease usually isn't deadly to either redcedars or apple trees. Typically it only slows growth, causes leaves to fall early, reduces fruit size and the like.

The USDA's page on this disease can be viewed at www.forestpests.org/southern/Diseases/cdrapll.htm

The fungus's lifecycle is actually much more complex than I have outlined it here. If you can handle words like "meiosis" and "dikaryotic," you might enjoy reading a good description of the details at http://botit.botany.wisc.edu/toms_fungi/may99.html

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ANNUAL BLUEGRASS FLOWERING
In lawns, along roads, around the barn, and even here and there in the forest, especially on exposed bayou banks, nowadays you see flowering tufts of Annual Bluegrass, POA ANNUA. This is a small grass usually standing no more than two or three inches high (5- 7cm). You notice it now because its flower clusters are pale and silvery against the grass's emerald green. The top two pictures on my "Grass Flower Page" at www.backyardnature.net/fl_grass.htm   show an entire Annual Bluegrass plant, plus a very nice close-up of its flowers.

The plant shown on my Grass Flower page is a "wild type" Annual Bluegrass. Many strains of Annual Bluegrass are known, however, and some are perennials spreading by stolons, completely unlike our "wild type," which just lives for a year and has fibrous roots. Those stoloniferous perennials get a lot of attention because they can be mowed and made into neat lawns, and they make ideal putting surfaces in golf courses. Here I resist the urge to launch into a tirade about the chemical pollution and waste of water and land occasioned by golf courses...

One reason it makes sense that Annual Bluegrass is flowering now is that bluegrasses are "cool-season species" using C3 photosynthesis.

Well, in the Plant Kingdom there are two broad categories of plants, the cool-season and warm-season ones, named C3 or C4, respectively. The difference between C3 and C4 plants relates to the chemical pathway they employ during photosynthesis. Both C3 and C4 use light energy to manufacture sugar from water and carbon dioxide, but C3 photosynthesis is most efficient in cool, moist weather, while C4 is best when it's hot and dry. Most higher plants use the C3 pathway.

It makes sense that Annual Bluegrass is a cool-season C3 plant because it evolved in Europe where it's much cooler and moister than here. It also makes sense that it is flowering during our cool, moist spring instead of later when it's really hot. When the heat turns on, C3 grasses tend to die back while C4 grasses thrive.

One thing this means is that in town where lawns are mostly composed of cool-season C3 grasses such as bluegrass, an unconscionable amount of water will be needed to "keep the lawn green" when summer comes. If C4 grasses were used instead, the lawn would need much less watering. However, C4 grasses tend to be shaggier than C3 bluegrasses. Bermuda Grass is a hot-season C4 grass introduced from Africa but most people find it too unkempt for a lawn. The wonderful bluestems I've told you about earlier also are C4 grasses.

If you'd like to study this C3/C4 matter and can deal with concepts like the Calvin Cycle, ATP, and carboxylation, you can download a technical paper about it provided in PDF format at www.ehleringer.net/Biology_5460/Lectures/A_quick_review_of_C4.pdf  

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THIS WEEK'S MIGRATING BIRDS
Here's this week's list, compiled on Friday, March 19th, on a warmish, overcast morning:

New arrivals this week include the Blue-gray Gnatcatcher and Louisiana Waterthrush. The gnatcatcher was silent but the waterthrushes were calling very loudly. Waterthrushes have an especially resounding and ringing call you can hear a long way off, especially in the kind of swampy woods where I usually find them, bobbing their tails as they work along meandering streams. You can hear this wonderful song, visualizing it in a somber, dense, lowland forest, at www.mbr-pwrc.usgs.gov/id/framlst/Song/h6760so.wav

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SEDGE WRENS
The stars in the above list are the Sedge Wrens, which used to be known as Short-billed Marsh Wrens. They are CISTOTHORUS PLATENSIS and they are stars just because they're so uncommon. In Connecticut Sedge Wrens are on the state's Endangered and Threatened Species List, the cause being "the loss of wetland habitats through human development and degradation." The ones I spotted Friday were in a marshy part of the weedy Loblolly Field, an environment nicely corresponding to my fieldguide's habitat description of "wet meadows, margins of marshes and sphagnum bogs." You can see a Sedge Wren at www.rbnc.org/images/birdband/sewr.jpg

You can view the Sedge Wren's winter distribution map (CBC) and summer-distribution map (BBS) at www.mbr-pwrc.usgs.gov/id/framlst/i7240id.html

In our area the only wren species most people know is the abundant, very familiar Carolina Wren. However, in Mississippi we have six wren species -- the Carolina, Bewick's, House, Marsh, Winter and Sedge Wrens. Among these, our Sedge Wren can be distinguished by its having NO white eyebrow, a tail that's NOT uncommonly short, but it DOES have conspicuous, fine streaking atop its head and back.

I really feel lucky to be near habitat agreeable to Sedge Wrens. What three or four years ago was exhausted farmland, now after being left alone for awhile, has become important habitat. If this ecological healing is allowed to continue, as time passes and trees invade, new habitats will develop, each more complex and species-rich than the last. These Sedge Wrens are just the beginning.

But, of course, the trend is in the other direction. This week someone bush-hogged in and around parts of the Loblolly Field. As a consequence, the Savannah Sparrows I told you about a while back, and which I've enjoyed seeing each time I walked past their foraging grounds, have completely lost their habitat, and disappeared. What was a weedy field with good cover for nervous sparrows, next to a blackberry thicket into which the sparrows could escape when danger lurked, now is uniformly lawn-like. Thirty seconds of a fellow on a tractor converted a sparrow-tribe's winter homeland into suburbanish lawn.

This week Hillary on the Mississippi Gulf Coast sent me a link to an article about "The Sixth Mass Extinction" of species populating Planet Earth. The "Sixth Mass Extinction" is taking place right now. At the end of the article, all six extinctions are listed and described. The wave of human-caused extinctions we're experiencing right now is the first to take place since the one that 65 million years ago killed off the dinosaurs and caused nearly half of the main groups of marine animals to go extinct. Most likely that last extinction was caused by a large asteroid colliding with Earth.

You can read the article at Hillary's link at  http://news.independent.co.uk/uk/environment/story.jsp?story=502762

*****

LONELY BLACK OAK
Back to that Black Oak flowering next to the barn.

Each morning this week at breakfast I've sat next to my campfire gazing up into the flowering and leafing- out branches of that fine tree. Thing is, though through the binoculars I could see plenty of insects darting back and forth among the flowers, the birds that should have been eating the insects have been practically absent.

What vivid memories I recall from the 1960s in Kentucky, learning my birds from the old Peterson fieldguide. Surely no time in my life has been happier than those days of recognizing for the first time that I shared the landscape with such glorious beings as Summer Tanagers, Yellow-breasted Chats, Cerulean Warlbers...

Back then, during spring migration, if you found any oak with catkins busy with insects, inevitably that oak also would be swarming with warblers, vireos and maybe a flycatcher or two. You could just sit beneath such a tree and tick off the species, one after the other, and sometimes some real bird-species surprises would appear.

At least, that's my memory. But sometimes memories fail, or even synthesize themselves over years of wishful thinking. Maybe I'm just remembering a few special trees, thinking that all trees were like the ones I recall. If any other old-timer out there has memories like mine, I wish you'd drop me a line.

We've all heard that many migrating bird species are losing ground. This week my Black Oak's loneliness sent me to the Internet to see how bad the situation is. There I found the Audubon Society's "fact sheet" dealing with the very matter, at www.audubonpopulation.org/newpop2/pages/facts/poproost.htm

On that page I learned that in most US states, most migrant bird species are in decline. Mississippi actually is one of the least impacted states. Only 54% of our species are in decline. In Tennessee, 74% are failing, while in Vermont it's 85%.

I am hardly surprised. During the 1970s I served as naturalist on archeology tours in the Petén Region of northern Guatemala, and I was always tickled to see there so many of the migratory species that up here I know as summer residents. The Audubon page says that at my time in the Petén, in 1977, 77% of the original forest cover still existed. By 1980, however, that number had fallen to 42% and by 1989 just 29% of the original forest cover remained. It's estimated that as little as 10% will survive in 2025. In southern Mexico's Selva Lacandona I have followed troops of Howler Monkeys for days and days, never seeing another human or even a trail. Now most of that forest has been converted to cattle ranches supporting US tastes for hamburgers. Of course, the US use of pesticides and the tendency to "clean up" hedgerows, weedy field and the like has been just as hard, or harder, on migrants than destruction of vast ecosystems in Latin America.

What does it mean that young people born today will never experience the gloriously alive and vibrantly healthy world that I have known and lost, and lose more of each day? When people no longer can feel what wild nature is like, how deadly will be the staleness and unrealized potential-for-joy conveyed into the human spirit?

All this week the big Black Oak next to the barn has been asking me this, in its loneliness, again and again.