they're here

Toothworts sprouted today. Most have a good bit of growing left before they flower, but that will not take long while the days are as warm and bright as today. Soon our woods will be sprinkled with a pinkish white that is the starter's pistol on the wildflower bloom, cutleaf toothwort.

Sure, bloodroot and hepatica can emerge earlier, but their appearance does not foretell spring like Dentaria laciniata. Bloodroot and hepatica are hard to find, whereas toothwort is all over the place. It is the uncurling of their stalks that defines the start of spring, and it was today.

unexpected nature

Ten Mile Creek runs through the heart of West Knoxville's sprawl, accompanied in segments by a paved greenway. Today I hiked there, and I found it clogged with privet and bush honeysuckle to the point that little else grows. The canopy is native trees, but much of the understory is invaders. Native vines have been crowded out and replaced by honeysuckle and bittersweet.

Recent construction has respected the creek more than a few older developments with flat grades and rubble piled to the lip of the creekbed. Such earth moving restricts the floodplain, raising floodwaters. Sprawl's parking lots, rooftops and roadways allow less rain to soak into the ground. Instead, it finds its way quickly to creeks, which overtop their banks more often.

Scouring along Ten Mile is a culprit in the absence of biodiversity. Much of the seed bank that might have restored native plants after construction was washed away in sprawl-exacerbated floods. The sprawlyburbs are flood-prone by design. That is why it is comforting amid all that ecological damage to see life persevere.

Ten Mile Creek Greenway curls between a fence and an artificial cliff at the edge of the Sam's Club/Walmart complex. The cliff is constructed of wire-baled rocks, but the trees below were not cut, so large tulips, sycamores, hackberries and others butt up against the fake cliff. Below that fence and through the woods, a wetland remains, and I saw ducks in the water.

I stopped to look through binoculars and found two pair of mallards feasting on aquatic plants. I heard a rustling from the leaves on the other side of the fence, looked down and discovered a hermit thrush flipping leaves and hopping toward a rusted shopping cart of uncertain age. Around the next bend I stopped to scan the wetlands from another vantage point and noticed a lump on a limb overhead. It was a sleeping raccoon curled into a cradle of tree limbs.

Nearby I saw a Cooper's hawk fly up from the creek to a low perch. It was probably cleaning itself after devouring a small bird. A few native alders linger in the sea of privet.

fooling a heron

After a delicious lunch at Sweet P's BBQ on the Stock Creek embayment, I wandered over to the water to see what was around. A song sparrow lurked in the weeds, but mostly I saw great blue herons, about a dozen. Most had staked out a hunting spot, and the few that had not were squabbling over turf with swoops and squawks.

Then the gulls moved in, at least a hundred ring bills. They glided over the water and soon began diving en masse into the water with vigorous plunges. A nearby heron had the same thought I did: they are after fish. The heron excitedly ambled out into the water, right into the center of the flock of gulls, but there were no fish. After a few indignant moments amid plunging gulls, the heron returned to its spot.

I snapped a bunch of photos at the fastest shutter speed the overcast day would allow, and upon inspection I could see the gulls were hitting the water feet first. Gulls have webbed feet, not talons, and when they pluck fish from the water, they grab them with their bill. My guess is the gulls were taking a bath. I'm not sure what the heron thought.

sky behind a sycamore

No native tree is as easy to recognize as the sycamore. Its bark peels in unique ways, leaving smooth white branches and trunks that can not be mistaken. Sycamore trunks and branches curl and twist. In moonlight sycamores glow; in sunlight they offer odd shapes and shades of of green and brown.

An animal you would never suspect of using camouflage: huge, mint green luna moths, wings edged in thick purple with tails and eyespots, vanish against sycamore bark. Sycamores are most abundant along streams and rivers, happy with wet roots, thirsty, and the flush of spring turns their white bark green. Moths the size of your hand can be next to invisible perched on a sycamore.

Sycamore wood burns poorly and is difficult to cut and mill. With little productive value but an ability to stabilize streambanks, sycamores are often left alone when land is logged or cleared for pasture or development. Even where most trees are gone, majestic old sycamores might remain, doing no one any good except luna moths, stream dwellers and whatever depends on stream and river water being clean.

lichen this

It was one of those beautiful days when everything is wet. Between wind, rain and fog, moisture creeped in every crevice from all directions. Water being that which merits the most gratitude, I see wet days as beauty, though they break limbs and topple trees. Mist feeds things like mistletoe and lichen. Water is a rare delicacy they savor, and when they get a drink on a new year's first day, it is cause for celebration.

Against wet bark, lichen glows brighter than normal. Flat, winter light and exaggerated contrast bring pale lichens to prominence, but it may not just be wet bark at work. Lichen may actually glow brighter in wet, winter weather.

Lichen is a symbiotic pairing of algae and fungus, the original pioneers of dry land. Long before there were trees, flowers or fields of grass, algae and mold grew on a stark landscape of rock, sand, dirt, but nothing that could be fairly called "soil." Soil is an end result of biodiversity, not its ancestor. Algae, moss, molds and mycelia don't need soil; soil is the graveyard of their proliferation and evolution.

Lichen likely predates most or all terrestrial plant and animal life, and a warm, wet winter afternoon may remind it of the stark, ancestral Earth where algae and mold first partnered. It may glow mint-green and grateful against gray bark.

one decade left

Science now estimates that we have 10 years left to stabilize carbon emissions before we doom the future to serious problems.

Anyone who has taken chemistry is familiar with the principle behind the threat: the volume of a liquid increases with temperature. When the liquid in question is our ocean, each degree rise in temperature adds about 10 centimeters, not enough to drown coastal cities, but enough to speed up beach erosion and expand flood risk zones.

The tides change sea level by as much as 10 meters, and storms can do the same, so the rise from thermal expansion will not be catastrophic but gradual. It will make coastal storms more lethal and destructive.

Compounding the problem is the fact that the sea erodes glaciers and sea ice like it does beaches, and glaciers and sea ice are themselves melting. Sea level rise from the loss of ice also happens on a centimeter scale, but a little faster than thermal expansion, with the added risk of collapses.

If carbon emissions continue to rise, thermal expansion and ice melt will raise sea level enough to flood coastal land. Researchers estimate that the point at which climate change transitions from making weather harsher to being a destructive force of its own is around a two degree Celsius rise in temperature. At that point, the ocean will be a meter higher and big pieces of Louisiana, Florida and Texas will go underwater, plus a lot more land worldwide. So far industrial consumption of fossil fuels has caused a rise of 0.6 degrees.

To preclude catastrophic coastal floods and the loss of cities and towns, global carbon emissions must peak within the next decade and start to decline. Inaction on carbon emissions is becoming a violent, destructive policy.

hunting sandhill cranes

The Tennessee Wildlife Resources Agency is considering a proposal to allow hunting of sandhill cranes and is accepting public comments through January.

This is a good sign in many ways. Nearly extirpated during our country's industrial expansion, these birds have rebounded to healthy population sizes, thanks mainly to the arrest of wetlands destruction. Another crane, the whooping crane, remains on the brink of extinction, but decades of extraordinary effort have restored an eastern migratory population that produced its first wild-born birds in the past couple of years. These critically endangered birds flock with sandhills during migration and on wintering grounds, and this is the prime reason for concern about this proposed hunt.

TWRA has taken steps to reduce the possibility of a whooping crane being accidentally shot, but they should do more. Hunting will not be allowed on Hiwassee Refuge, where the majority of both species congregate during Tennessee stop-overs, and permits will include identification guides to help hunters learn the differences among sandhills, whooping cranes and snow geese. Crane season coincides with the late duck season, primarily the month of December, when whooping cranes will have mostly moved on to their ultimate winter range in Florida.

This is all good, but the fact of the matter is that whooping cranes are closely monitored, and TWRA could suspend hunts while whoopers are present. In materials describing this proposed hunt, TWRA says, "This population of whooping cranes is an experimental flock. TWRA does not propose to stop hunting sandhill cranes if/when whooping cranes migrate through." Dismissing the whooping crane flock as "experimental" is a profound insult to the hundreds of people who have dedicated themselves to rearing and training the flock, a decades-long effort that culminated in teaching the cranes their route by guiding them behind an ultralight plane.

Whooping cranes from the larger Central Flyway population have been shot accidentally, but by goose hunters, not sandhill crane hunters. A few years ago in West Tennessee, the first wild swan seen in Tennessee since Audubon's time was shot by a goose hunter. It takes minimal competence to distinguish a goose from a crane, but goose hunters have not demonstrated even that baseline skill. Perhaps TWRA should aim its educational efforts more toward that larger population of hunters.

Tennessee farmers have been granted depredation permits for sandhill cranes in recent years, but damage to agricultural crops is a minimal problem, if not entirely exaggerated, since cranes arrive after harvests and leave before planting time. Perhaps there are winter crops I am unaware of. Even so, cranes eat insects and mice and may very well earn their share of grains. Damage to crops is a greater problem in the northern states where cranes are present during growing season. Hunting here can benefit northern agricultural interests, but it provides little value to Tennessee farmers.

Sandhill crane meat is reportedly prized for taste and color, and populations can support the proposed take of up to 2199 birds per year. In principle I have no objection to allowing this hunt, but I believe TWRA should do all it can to prevent the accidental death of an endangered whooping crane.

early adopters

If you are trying to learn tree identification, certain times of year are better than others. Right now is the time to learn black gum, sourwood, sumac and tuliptree. These trees get a head start on fall, turning colors while the rest of the trees remain green.

Tulips are turning yellow, the others red. Sumac tends toward fiery tones like you might see in a sunset. It also has compound leaves, and if it has produced fruit, the red, conical berry clusters are distinctive. Sourwood takes on regal tones that approach purple.

Black gum has the purest reds. Gums start losing leaves as soon as its fruit ripens, possibly as a signal to birds to come eat. Migrating thrushes are especially fond of black gum fruits. Leaves begin to turn red in August, but it takes weeks for all the leaves to turn, so there are always a few bright red ones on any tree at any point during fall migration.

Right now, all these trees are recognizable at a glance, so it's a good time for roadside dendrology. As you drive around, you can get a sense for how abundant these species are, where they grow and what is distinct about their growth form. As other trees start to turn, new colors will appear and the roster of trees you have learned to identify will get a bit longer.

milkweeds

Butterfly weed is a native of meadows and clearings. It's rich orange color is among the most spectacular on the Southern Appalachian palette. Because it produces several flower clusters per stalk and they bloom progressively, its hue accentuates our meadows for weeks on end. The plant may even flower twice in good years.

Pollinated flowers turn into okra-like seed pods that break open and release round seeds attached to long, feathery filaments that lift them off on wind gusts. All milkweeds do this, as do many of their relatives. There are 14 species of milkweed known from Tennessee, plus five more in sibling genera. Nationwide, we are home to about a hundred species of milkweed.

Dogbane, another meadow plant, is a close relative, as are persimmons and blueberries. Flowers on that segment of the evolutionary tree tend to be tubular, fleshy and clustered. Seeds are more variable.

Many native pollinators visit butterfly weed flowers, including bees, wasps, beetles, flies and their namesake. Orange butterflies such as monarchs and fritillaries love butterfly weed, whereas tiger swallowtails prefer the pale pink common milkweed often growing nearby.

origin of bird flight

A Nova episode currently in reruns on PBS features bird fossils discovered in China that have shed new light on the origin of flight in birds. Wind tunnel tests on a life-like model suggest a traditional assumption about hip articulation in fossil birds is wrong.

Instead of attaching in a running posture capable of holding the animal's weight, the hind legs attach at a different angle. Researchers call it "splayed" posture, and it is found in crocodiles and other branches of reptile phylogeny. Splayed articulation allows the legs to extend backwards toward the tail, useful for actions like walking on four legs, diving, leaping and gliding.

Running on splayed legs means less power and speed, so the new fossils make the hypothesis that birds evolved flight by being able to run at flight speed and leap into a glide less likely. Part of that hypothesis is the idea that the large middle claw on the hind legs was a "killing claw" thrust at victims using the same power and articulation needed for running. Splay posture suggests other functional possibilities, and the claw may instead have aided in climbing, perching and propelling the protobird from a branch.

Instead of jumping from the ground into flight, the first birds dove into glides from a perch.

There is one more assumption that must be questioned, that protobirds dove into the air. More likely, they dove into water, a more buoyant fluid that creates lift at lower speeds and weaker wing strokes. The fossil record of birds is consistent with a marine origin, with diving birds like loons resembling fossil ancestors more than other modern lineages.

Swimming is easier than flying, and wings likely evolved as swimming appendages before developing the power for airborne flight.

stone free to ride the breeze

This is the shed skin of a stonefly. Aquatic all its life, the insect crawled from Hazel Creek in July, cracked open its thorax, wriggled out, pumped its wings and took flight on misty night air. The white fibers on its head are like an umbilical cord, a remnant connection to the stonefly's former body.

I found the skin on a rock the next morning. It could not have been there long since the rock had been submerged by the prior day's afternoon rain. As the water receded, the stonefly crawled atop and began its brief aerial adulthood.

It will attempt to mate and contribute to the batch of eggs laid in the creek, timed to hatch as autumn leaves drop into the water, bringing nutrients on which the creek's ecosystem depends. Many types of insects and worms live on the rotting organic material that perpetually washes into a mountain stream, and these are prey for crayfish, darters and salamanders, in turn eaten by trout, raccoons and owls.

More than 100 species of stonefly occur in Southern Appalachain waters, with some likely undiscovered, some lost to science at the turn of the last century due to intensive logging, chestnut blight and slaughter of the passenger pigeon. There are more than 1,000 species of stonefly worldwide. Nine families occur in our region. The age of their oldest fossils (about 250 mya) combined with the geological history of the Appalachians makes it quite likely stoneflies evolved in these here hills.

The first winged insects were mayflies, which soon gave rise to damselflies and dragonflies. It was not long after that another mayfly lineage morphed into the first stonefly. All this took place in the Southern Appalachians some 300 million years ago as the shallow, inland sea west of the mountains receded, leaving behind the Cumberland Plateau and finally the Mississippi basin and the grand river herself.

The pictured skin is about an inch long, not counting the tails, and this is about as big as stoneflies get. They resemble roaches, and the similarity is not coincidence. It is likely the roach branch on the tree of life arose from the stonefly limb. In fact, the common ancestor of roaches, crickets and the whole Orthoptera assemblage may have been a stonefly.

Stoneflies spend most of their lives crawling slowly through the stones and muck of a streambed, grazing on crud, shedding occasionally to grow, then one day crawling from the water to sprout wings. Their flight is weak and slow, and they have little ability to manuever. If they run into something, they cling. Their search for a mate is clumsy and fraught with peril, but they have been succeeding for hundreds of millions of years, long enough to diversify into many genera and spawn a major assemblage of terrestrial insects.

to glorify evolution

Evolution is a scientific theory; it explains much of what we observe in the living world. Atomic theory explains observations in chemistry. Gravity explains observations of the cosmos and movements of earth-bound objects. Theories are grand ideas which illuminate and elucidate what we see around us: life, the universe, all that.

Many refuse to see the beauty and truth of evolution, and a common ingredient among adherents of intelligent design, baraminology or other supernatural explanations is a poor appreciation of the diversity of life. This lack of appreciation is understandable. The modern world frees us from worrying which plants are edible, what kind of wood burns best or which insects are truly a threat, so it is easy to become oblivious to the huge variety of plants, trees, insects and life around us.

No naturalist doubts for a moment that life is a grand tableau of evolutionary lineages changing and diversifying. Doubt comes from not realizing how grand the tableau. We can all tell a pine tree from an oak, but if your curiosity stops there, can you be expected to understand the evolution of flowering plants?

Fortunately, it is not necessary to know every pine tree or moth in order to appreciate life's diversity. Knowing the basic parameters -- about a dozen pines occur naturally in our region a thousand or more moths -- is adequate, or at least a good start. An understanding of biodiversity fosters stewardship and wisdom.

Just as gravity explains Earth's trajectory around the Sun, evolution explains the diversity of life. To appreciate evolution, you must first appreciate what needs to be explained, and that is biodiversity. Plants, fungi, microorganisms, mammals, spiders, birds, insects; evolution explains them all.


Intelligent design and other flavors of creationism explain nothing. They push diversity into the unknowable and render planetary history and the tableau of life an incoherent mess. That is unacceptable. Evolution has no competing theories because nothing else comes close to explaining as much about life as evolutionary theory does.

I have decided a running theme of this blog should be the diversity around us. Southern Appalachian forests are a good classroom for learning what evolution explains. Our mountain's age corresponds to the earliest emergence of terrestrial life, plant and animal, so local natural history encompasses events like the origin of flowering plants, insect flight, mammals, birds and the rise and fall of dinosaurs. Much can be learned from the patterns of diversity around us.

another year of unsustainable emissions

The cowardly era of United States history enters its third decade. This week the U.S. Senate opted not to pursue long-overdue climate controls in favor of an easy cop out: tightening offshore drilling limits.

Never mind that funding for regulators, a purge of corrupt Bush appointees and hires and the market demise of BP is all that is needed to prevent future Deepwater Horizon disasters, the Senate's decision not to control carbon emissions is perverse regardless of its excuses. Top its cowardice off with the death of Stephen Schneider and a federal court's reversal of North Carolina's win over TVA and you have the worst week in air pollution history since the discovery of Appalachian oil.

Schneider was a truth teller who not only understood the science of carbon gases, but also why people have trouble understanding global warming. He stressed the clear and present danger of rising gas concentrations. He died July 18 on a plane to London. Rather than honor his memory, the U.S. Senate chose to spit on science and continue free abuse of the atmosphere as an emissions dump. The cowardly era remains entrenched despite Obama's plain mandate for change.

The U.S. Fourth District overturned a federal indictment against TVA because it claimed nuisance laws, rather than decade-old Clean Air Act deadlines constituted the force of North Carolina's argument. The court said "the injunction would encourage courts to use vague public nuisance standards to scuttle the nation's carefully created" clean-air laws, so TVA need not obey those carefully created laws. Such logic is the hallmark of corporate ownership of government.

Our Senate is desperate for funds to cover its gross bailout of investment firms. Taxes on carbon emissions, lucrative even at rates imperceptible to consumers, could help offset the damage inflicted when Congress repealed Glass-Steagall in 1999 and set the stage for the current economic collapse, but the Senate lacks courage to pass even a trivial tax on a dangerous practice.

Sustainable emissions are the easiest to accomplish and first necessary goal in a transition to a sustainable economy, but the U.S. Senate and the corporations that own it have no interest in a sustainable future for the United States or the planet. Sustainable futures do not maximize profits nor garner huge executive bonuses.

A truly democratic government would tax elite earnings and pollution; our Senate will not.