Nov 1, 2010

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.

Oct 16, 2010

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.

Sep 11, 2010

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.

Sep 7, 2010


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.

Aug 28, 2010

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.

Aug 11, 2010

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.

Aug 10, 2010

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.

Jul 27, 2010

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.

Jun 15, 2010

Rockhouse flowers

The Cumberland Plateau is home to many unusual plants. A seafloor when the Appalachian mountains were younger and taller, the plateau's geology is distinct, but its forests are similar to Appalachian forests. Where the plateau's geological youth is most apparent -- at the eroding rim of the gorge and in the dynamic river channel -- the unique conditions posed an evolutionary opportunity.

Plants that took advantage of that opportunity diverged from their Appalachian ancestors. Numerous species are known only from the Cumberlands. Some of these are found on the river shoals, others in the rockhouses along the rim, like the pictured catchfly. A close relative of fire pink, roundleaf catchfly (Silene rotundifolia) grows only on rock faces in the Cumberlands.

A rockhouse is a cliff that has eroded beyond vertical, creating an overhang and a sheltered space below. These sheltered areas may be large enough for a camp. Some like Hazard Cave in Pickett State Park are large enough for a village. The floor of a rockhouse is sandy, offering a dry, soft place to sleep, and the sloping rock face carries smoke from a fire up and away. Native Americans used rockhouses for shelter, but they considered the Cumberlands dangerous and cursed, so these camps were temporary stopovers during hunting or trading excursions and never as elaborate as cliff dwellings in southwestern states.

To protect endemic plants and animals, camping in rockhouses is now forbidden. One of the most vulnerable endemics is the Cumberland sandwort (Minuartia cumberlandensis), a lacy plant that lines the edges of rockhouse floors, living off what little moisture flows down the rock or blows in during rains. Roundleaf catchfly grows higher up in nooks etched into the sandstone, so it can not be trampled, but heat and smoke from a fire could harm it. Mountain spleenwort (Asplenium montanum), a fern, likes the same sort of nooks as roundleaf catchfly.

In the drip zone along the mouth of a rockhouse you can find lady fern, sedges and rockhouse featherbells (Stenanthium diffusum), a rare lily only recently recognized as a species. University of Tennessee botanist Gene Wofford realized the plant he kept finding in the Cumberland plateau was different than eastern featherbells (Stenanthium gramineum). He published his findings and a new endemic was born to science.

These plants grow happily in a rockhouse's unusual habitat, but how they get there in the first place is a bit of a puzzle. Sandstone in a rockhouse often appears crusted, with a harder layer above eroding more slowly than the rock below. These crusts are curved and irregular, not stratified like typical rock layers.

On my most recent visit to the Cumberlands, a botanist explained how those crusts form. It is a present-day phenomenon, not a trace of an ancient process. Just as tree roots stabilize a riverbank, mosses and lichens protect sandstone from erosion. In particular they slow the impact of winds. On a still day it is hard to imagine what a wind could do when it hits a rockhouse, but if you get caught in one during a storm or just put your imagination to work, you can see the sand at the base of the rock wall kicking up or rain and debris blowing in to knock grains from exposed sandstone.

Those same winds can cast a small seed onto a ledge evolution made its ideal home. Those same winds are what carves a rockhouse from a cliff in the first place. Where winds in the gorge tend to collect and swirl is where rockhouses form, so what looks like shelter from a storm can actually concentrate its power. No wonder native Americans preferred to live elsewhere.

Jun 3, 2010

upriver from Nashville

The same storms that flooded Nashville filled the banks of Big South Fork, the major eastern tributary of the Cumberland River. Most of the rocks in this photograph were submerged during the flood, and their surfaces were scoured of soil. Riverbank plant communities took a hit, but these plants are adapted to floods and should rebound before rains that improbable strike again.

Yesterday along Big South Fork, recently deposited debris marked high waters 20 feet above current flow. Tree trunks were submerged at the edge of the gorge's forest, but not much evidence of uprootings or other damage was apparent. Among the rocks along the bank, alders, viburnums, birches, sycamores and other woody plants remained firmly rooted and full of leaves. Royal ferns were abundant; what was missing were last year's fronds.

When this river flooded last month, plants along its banks would have been flush with tender new growth. Shrubs and saplings may have lost leaves, and smaller herbaceous plants may have lost all their above-ground growth. Trees above flood stage had maturing, waxy leaves while those in the river had newer leaves.

Judging from what the riverbank looks like a month later, I would guess the early May flood stripped leaf litter, fresh growth and topsoil, but was not strong enough to cause major damage. Rainfall totals east and north of Nashville were not as epic. An epic Big South Fork storm would tumble most rocks in the photograph a bit further downriver and completely reset riverbank ecosystems.

One plant that may have suffered setbacks in the flood is the Cumberland rosemary, one of several endangered or threatened species found only in the Cumberland and Emory river systems. Yesterday I had the privilege of accompanying professional botanists on a search for rare and endemic plants, and we checked two known populations of rosemary. One population was but a dozen plants in a small span of a large boulder field. The second was not found; we may have misunderstood our map. My guess is the rosemary and other smaller plants got a setback that will limit this year's seed set, but they will recover within a year or three.

May 12, 2010

cranefly siesta

Craneflies fly at night and seek shade during the day. Many begin life in streams and ponds as long, fat, white worms, and their physiology is geared toward cool and damp.

This orange species sought perch inside a cluster of Virginia creeper leaves, refuge from the sun all afternoon until evening light crept in.

In damp Southern Appalachia, craneflies are among the most speciose insects, coming in a variety of sizes and patterns. Few are as colorful as the one in the photo, but some have black markings on their wings or abdomen that add a bit of flair. Most are weak fliers, slow and drifting, with their long legs serving as bumpers and feelers.

Sometimes called mosquito hawks or mistaken for mosquitoes, crane flies have tiny, weak mouthparts used primarily to slurp water. Their long abdomen is a storehouse of fats eaten during wormhood, so they have little or no need to eat in adult form and are harmless to man and mosquito alike.

May 7, 2010

yard week

Despite a vigorous spring for the native flora and fauna, bird migration has been slow this year. Not just me but many Southern Appalachian birders report late arrivals and low numbers of warblers and the rest of the lot that winters in the tropics. This week things picked up.

An indigo bunting set up a territory in the front yard, joining the thrasher and field sparrow already raising families in the unmowed scrub. A Cape May warbler and blackpoll sang during a brief feeding stopover, and male grackles displayed amid tuliptree flowers.

I saw something I had never seen before, a traveling flock of kingbirds, and I added gray-cheeked thrush to my life list, though I've seen them in fall several times. Finally I got not only a good look but a chance to hear it sing, go inside to listen to minimus and bicknelli, then hear it sing some more. Check.

I am close enough to a river that I get flyovers by swallows, waterfowl and other riparian birds, so when I spotted a kingbird flying above the trees I was pleased, but not surprised to add eastern kingbird to my yard list. Later I saw first one, then three, then six, ten kingbirds hopping around the treetops. Not only have I never seen a kingbird in my yard, I have never seen them in a flock.

A cedar waxwing flock busied itself gobbling pollen from tuliptrees, while tent caterpillars gobbled the first flush of leaves from black cherries. These caterpillars will not eat the flowers, already fertilized, so the tree will grow new leaves and produce a full crop of fruit by August. It is an agreement between insect and tree which also worked out well for the female tanager gorging herself on caterpillars in the small cherry near my front porch.

It has at least five tents in it, and the caterpillars will eat it bare. Once they have eaten all the leaves, the caterpillars will pupate into a good-sized moth that looks like this. A brood of scarlet tanagers and a flight of brown fuzzies will grow from the cherry tree's sacrifice.

It is tempting to ignore chickadees this time of year in favor of passersby and gladyrbacks, but I watched one long enough to notice it was only visiting the dead tips of oak twigs where wind had ripped leaves or limbs out. It was finding caterpillars, a different species, taking refuge from the afternoon sun. About every third twig the bird checked it swallowed a worm.

A chickadee I saw later in a hickory hopped from one just-opening leaf cluster to another, having similar luck with yet another species of baby moth.

Apr 30, 2010

bald-faced hornets

Yesterday I saw my first and second bald-faced hornets of the year but did not get a photo. They were queens looking for a good place to construct a nest. That might seem like something to discourage, possibly even grounds for extermination, but this is our only native hornet, so I tend to cheer for them.

Years of encounters with stinging insects have lead me to be comfortable around them. They will sting ruthlessly if you get near their nest, but outside that danger zone of a couple square yards, they will not sting unless provoked. Unfortunately, many people's reaction is just that: swat, flail and freak out. If human stupidity were met with painful stings more often, the world would be a better place. Perhaps it's a bit misanthropic, but I'm on the side of wasps and hornets and against stupidity.

This is the time of year when being diligent and observant pays off. Inspect your porches and outbuildings for nests now. Early morning is a good time for inspection since wasps fly poorly when they are cold. If you can find nascent nests before the founding queen has hatched her first brood of workers, extermination can be achieved with minimal risk to you or the insect. Once that first brood hatches, there is almost always a sentinel on guard. When it's just the founding queen, she'll be away from the nest often, and when she is, knock it down. When she returns and finds her work destroyed, she will most likely take up her mission elsewhere rather than rebuilding in a cursed location.

Why might you want wasps and hornets around? They are nature's janitors. They spend most of their time hunting for dead insects and animals, which they feed to their larvae. Despite their aggressiveness toward intruders, they are not predators, just opportunists. Adult wasps and hornets feed mostly on nectar, saving richer meals for their brood, so they work a little pollination duty into their routine.

If you are going to get stung by these social insects, it will likely be from wandering too close to a nest you did not know existed. Nests up in a tree or near the peak of your roof are not a danger. If feel safest when I know where the nests are, so I go on inspection runs now when it is easy to respond. Sometimes I choose to let the nest be, knowing I can avoid it. One year bald-faced hornets nested under the awning of a window that is painted shut. It was perfect. I could safely watch them from inside. One day I came home to find the nest in ruins. The summer tanagers, known locally as "bee birds," had found the hornets and made a meal of them.

You might want to keep them around as tanager food.

Apr 19, 2010

bird strikes

Five people died in Oklahoma in March 2008 when their Cessna hit a white pelican during takeoff. Last November, a western grebe shattered the windshield of a small plane and crashed just over the pilot's head into the back wall of the cockpit. According to an FAA report published in September, planes have struck 30 species of duck since 1990.

About 7,000 bird strikes are reported each year, up from around 2,500 in the early 90s. The bird always dies, but damage to the plane ranges from trivial to expensive to tragic. A gadwall sucked into a descending jet's engine in 2008 left a $900,000 repair bill, though the plane landed safely.

Reporting of wildlife strikes is voluntary. Sometimes feathers and remains are sent to museums for identification, but many reports just say "unknown bird." The vast majority of the 168 reported strikes at the airport near me are "unknown bird or bat."

Birds are more likely to be hit on approach than takeoff, and one reason may be that birds are harder to see against a background of land than against sky. Many bird strikes occur on or near the ground as startled birds flush into harm's way. You know Capt. Sullenberger for his heroic water landing in New York City last year, but he also flew the plane into a flock of geese. Pilots get warnings about statistical risks, but not about actual flocks.

Bird strikes are heaviest from July through October, when birds are migrating southward, and drop off significantly in winter. There are more juvenile birds during those months as well. Bird strikes caused $308 million in damage in the U.S. over the past two decades. Terrestrial animals, primarily white-tailed deer, get hit too, often as the plane lands. This caused $38 million damage over two decades. Bats did $3 million worth of damage.

The good news from the study is that populations of many large, native birds are on the rise. Planes are more likely to strike geese, turkeys, eagles, vultures, cranes, cormorants and pelicans because those birds are all increasing in number.

Gulls are hit most often, followed by doves and pigeons, then hawks. Most damage from bird strikes happens when heavier birds are hit, and birds smaller than a dove rarely cause problems. Birds that prefer flat, open habitats -- killdeer, horned larks, kestrels -- show up on the victims list far out of proportion to their abundance, and you can also deduce from those lists that many airports are adjacent to wetlands and shoreline.

Not much is known about small-bird strikes. Impacts with warblers and other small migrants would not leave much evidence of the calamity nor much opportunity for pilots to identify their victims. Many migratory birds fly at night, when pilots have no chance of avoiding or seeing birds.

Fortunately, the aviation industry teamed up with biologists to develop the Avian Hazard Advisory System, which incorporates not just historical data about wildlife strikes, but also basic biological data and weather radar. Birds migrate when weather systems give them a tailwind, and they cross the Gulf of Mexico in large flocks that show up on radar, so this tie-in to weather data adds fine resolution to the risk assessments. With the frequency of air travel and the populations of birds both on the rise, good risk analysis is critical.

Airport managers are also learning ways to better exclude wildlife from danger zones, and one sad conclusion from studying strikes is that airports are poor neighbors for wildlife refuges and nature parks.

Apr 12, 2010

a plea for reality

Knox County's School Board faces a challenge, and they need strength. A parent has complained about a passage in an honors biology text that describes the seven-day creation story as a myth. The passage covers the battle over teaching evolution that has transpired for decades throughout the United States, sometimes flaring up in Tennessee, Kansas or Texas. It is Tennessee's turn again.

Creation of the Earth in seven days is obviously mythical, but that does not mean it is false. It means it is poetic. We know the cooling of the crust took almost a billion years. We know plants have been around for two to four billion years, depending whether you count algae as plants. "Day" clearly means something different to God than it does to Earth dwellers, but if you admit the timing is mythical, you are left with a creation story that meshes surprisingly well with science. The few varieties of life named in Genesis appear in the fossil record in the order they appear in the Bible. Allow for poetry and you have reconciliation.

Unfortunately, men like Ken Zimmerman will spare no absurdity in choosing war over peace, so he has taken his own side's "teach the controversy" stance to the mat, declaring it inadequate. Creationists slipped into "intelligent design" costume in recent years to demand schools "teach the controversy." This is what the Farragut text does. Zimmerman wants the controversy tippy-toed around so his delicate feelings do not get bruised. "Myth" is more than he can bear, though Jesus bore death on a wooden cross for him.

I spoke with some friends who teach biology, thinking I could rally them to attend the next school board meeting, but I discovered that for them this issue is ongoing, part of their routine even when it is not in the news. They need the rest of us to attend the board meeting, not just to give the board courage and guidance, but so science teachers can know the community supports their efforts. Their job is to teach students about the natural world, not to navigate the minefield of fragile fundamentalist emotions.

At its next meeting, the Knox County School Board gets to choose whether to be politically correct or scientifically literate. Those who understand that creation did not happen in seven human days might want to keep May 5th open. Fundamentalists will be out in force for folly. Advocates for reality should show up too.

Apr 7, 2010

every orchard starts as a seed

A lot has been said about the faith of mustard seeds, but not enough about the faith of spiders.

Spiders choose a spot then wait. They find a gap to bridge with silk then set a strand aloft on a breeze to find purchase. They hang a spiral trap from a scaffold and sit in self-spun thrones, centers of a silken universe, waiting, and dinner does buzz in.

This tiny, creekside spider gets a steady diet of caddisflies and midges, rewards for spider faith.

Mar 29, 2010

sloppy science journalism

This science news in USA Today pissed me off. I am a dogged champion of the idea that insect wings evolved as an aquatic structure. When I read about "two" competing theories of wing evolution I know someone will come up short.

One theory, as Dan Vergano wrote, is "wings are brand new features" that evolved from an insect's shell. The other is that they are modifications of legs. In truth, there are other theories and many possible ways wings may have evolved.

Deciphering evolutionary history from available evidence is science with a dose of art. Pretending only two ideas exist about how wings evolved cuts out the art; vastness of the data set limits understanding of the science. The result is a worn nub of a narrative that misses the best tale: wings were swimming organs long before they became aerial appendages.

Once I read the abstract of the article, I saw my beloved aquatic theory. The omission was in the reporting, not the science. The authors studied mayflies because their tracheal gills are a likely precursors to wings. They concluded that wings grow when regulatory genes triggering leg growth and gill growth are both expressed, affirming the theory that abdominal gills begat thoracic wings as mayflies radiated into fresh waters almost a half billion years ago.

The authors also studied bristletails, a wingless insect that is an ancestor of mayflies. If you could go back a half billion years and watch for a few hundred million, you'd see tiny silverfishy things slithering into fresher water and drier habitats, breathing through gills, then flapping gills, then flapping thoracic gills built for power, which became wings.

This is a dragonfly, an early offshoot of the mayfly lineage. Mayflies spawned all insect lineages.

Mar 14, 2010

How cold was this winter?

Finally elms have flowered. Last year I took a photograph of elm flowers emitting pollen on February 21. They bloomed three weeks later this year.

Elms are wind pollinated. So are maples, oaks and other trees. Wind-pollinated trees typically flower before they leaf out. Insect-pollinated trees do the opposite, and their flowers are large, even ornate. Wind-pollinated flowers are tiny. The plants up their odds of fertilization by saturating the air with pollen, sparing the cost of growing larger flowers. Before insects evolved, flowering plants relied on wind to spread pollen. The most primitive plants require water for pollen transport.

Because elms need not synchronize their flowering with the emergence of some bee or beetle or butterfly, they have more flexibility in their timing. If winter is colder and pollen production takes longer, they just postpone flowering.

I have seen elms flower as early as February 11 after a mild winter. The day their flowers open is probably as good a measure of winter's severity as a statistician could manage. The winter of 2010 was 21 elm-days harsher than winter 2009.

Mar 10, 2010

fishermen catch the crazy

The ranting hysterics of the tribal right showed up in an unexpected place today, a supposed news article on the ESPN Outdoors website. Robert Montgomery has been writing about a proposed federal rule on fisheries management since October, but today's installment got picked up by a right-wing PR firm called Special Guests, which email-blasted the article with the subject "FEDS SET TO BAN ALL U.S. FISHING! Says ESPN." The press release said, "The Obama administration is reportedly putting the final touches on an Executive Order to ban all fishing in the United States."

The ESPN article does not go that far, but it does insinuate dire outcomes. It is the fifteenth installment in Montgomery's series, but this one got more attention than most thanks to the PR blast. Soon it was generating complaints to editors, and executive editor Steve Bowman issued this statement: "Though our series has included numerous news stories on the topic, this was not one of them -- it was an opinion piece, and should have been clearly labeled as commentary."

Calling it "commentary" is supposed to make us feel better, but what it means is claims in the article can not be substantiated and are likely wrong. Looking over the previous 14 articles, it becomes clear that Montgomery has been writing in the same style all along, starting with the first installment, "Why anglers aren't environmentalists," which begins with the first-person declaration "I'm for a stronger Clean Water Act." Montgomery has been writing commentary throughout his series.

Beyond that, his claims make no sense. The task force recommended that nine regional groups form and adopt fisheries plans appropriate for their region, so decisions like the ones Montgomery and his oft-quoted sources say are being made are at least another year down the road, will be different for each region and will be made through collaborative, public processes yet to begin. Sadly, it has become routine for right-wing groups to hit the most shrill note available and screech it incessantly.

Obama is no more on the verge of banning fishing than he is Kenyan-born or a socialist, but when you can't or won't do the heavy lifting of being honest and informed, insufferable bullshit is an option. Montgomery's shtick is familiar: guilt by association, absence as evidence, and lots and lots of quotes from industry. He tries to create a wedge between anglers and environmentalists, but both groups want clean water and healthy fish. He also warns anglers that they are being lumped in with commercial fishermen, his evidence an alleged absence of language distinguishing the two. The document talks about "commercial fishing" and "recreational fishing" repeatedly, so Montgomery uses the phrase "recreational angling" and draws worrisome conclusions from the fact that this phrase appears nowhere in the document.

That's the quality of propaganda the right is churning out these days: shrill and vacant. Believing outrageous lies is the secret handshake of the Republican Party. Are you a member?

Mar 1, 2010

Sand dune mushroom

Mushrooms are abundant in the moist forests of the Southern Appalachians, but I did not expect to find a colony growing in the dunes of Tybee Island, Georgia in February. Here they are. Dozens of these small, gilled mushrooms were sprouting from the sand at the toe of the dunes.

An Internet search failed to turn up clues to its identity, but a few minutes with my Peterson field guide uncovered Laccaria trullisata, Sandy Tallowgill. The description is not an exact match, but close enough. According to the McKnights, no other mushroom grows on sand dunes, and this species fruits in summer and fall. It is found as far north as the Great Lakes, and there it surely is dormant in winter. Southern populations apparently emerge on a different schedule, possibly preferring the cooler, shorter winter days.

Feb 9, 2010

blackberry gall

A gall is an aberrant growth on a plant. Typically these are caused by an insect, and the growth acts as a rearing chamber for its larvae. How does the insect get the plant to grow it a nursery?

The insect, usually a tiny wasp or fly, injects the plant with a poison of sorts. This photograph hints at the underlying chemistry. The injected compound is likely a mimic of the plant's own growth hormones. In this case, it looks like the signal to grow a fruit was given to a blackberry stem. The fruiting hormone, when expressed in the proper tissue, triggers the production of a cluster of juicy orbs that will ripen into the black bear's favorite fruit. When expressed in the wrong tissue, the resulting growth is more tumorous than tasty.

Many galls appear to be fruits growing where fruits shouldn't grow, but sometimes they look more like an aberrant flower. The common oak gall, a hollow globe, may be what happens when you ask a leaf to grow an acorn. For an insect, a gall is a safe home. For a naturalist, they are lessons in gene expression and developmental chemistry.

Feb 7, 2010

brake in the storm

While assessing the risks and pace of climate change remains a difficult task, our core understanding of the physics and chemistry of the atmosphere grows ever more complete. Last month a new study was published that helps explain why surface air temperatures have not increased as rapidly over the past decade as have ocean temperatures. According to NOAA researcher Susan Solomon and colleagues, the stratosphere has dried by about 10 percent since 2000, resulting in a 25 percent decline in surface temperature relative to what would have been without the drying effect. The Economist published a good review of the paper.

This research is largely observational. The authors are not sure why less water vapor passed through the tropopause into the stratosphere, and this will surely become an object of study. Climate scientists suspect that increased thunderstorm activity in the tropics caused the drying, with more water vapor exiting the troposphere as rain rather than rising into the stratosphere. Why there were more thunderstorms is not known, but increased variability in weather is one of the basic predictions of global warming.

Atmospheric heat can either dissipate into the oceans and land or it can get converted to entropy. Storms are weather patterns that become organized, thus they represent energy becoming organized into entropy. The most persistent and destructive effect of global warming is thermal expansion of the oceans. Most of the heat that has accumulated in the past century has wound up in the oceans, not the atmosphere, and sea level rise threatens people and economies more than storms. More frequent and powerful storms are a bad thing, but this new study shows there may be a silver lining in those storm clouds. They consume energy and act as a buffer against warming.

Feb 4, 2010

Too far south

by David Hollie, Ringgold, Ga.

An ivory gull was spotted last week in Georgia at West Point Dam, north of Columbus on the Alabama border. This species of gull rarely leaves the Arctic circle, even in winter, though there are many records of vagrant individuals along the East Coast and around the Great Lakes. This was the first record of the bird in Georgia and one of the most southerly sightings ever. Twitchers drove from several surrounding states to see the gull.

Sadly, the bird was injured, apparently by a bald eagle, suffered a broken wing. Rangers captured it to provide veterinary care, but the bird died before it could be treated. It was taken by the U.S. Fish and Wildlife Service for study.

Photograph by David Hollie

Feb 2, 2010

why red?

To my eyes, male cardinals stand out like they want to be seen. Several resident birds have red markings, including several woodpeckers. None are as brilliant as a cardinal, but a pileated crest glares like a tanager from the woods. Red-headed woodpeckers, more common at lower elevations, also have bold red on their head. Red-bellied woodpeckers sport a full red cap, and flickers wear a long red teardrop that wraps around their head. Downy and hairy woodpeckers have a bright red square on the back of their head, males only.

This prevalence of red makes me wonder whether predatory birds have good color vision. Blindness to red is the most common form of color blindness in humans, and red may be more difficult to see than other colors. Color vision requires pigments, proteins that fold into shapes that reflect or transmit certain wavelengths of light, and red pigments could be less common or more fragile than proteins that enable perception of green, blue or other colors.

You don't spot birds by looking for colors; you see their movement, track them and find them where you think they perched. Cardinals, males especially, are much easier to spot than most birds, but they can still hide if they hide still. Their preferred habitat is tangles of brush and hedges.

Accipiters like sharp-shinned and Cooper's hawks eat birds almost exclusively, and both will kill a cardinal given the chance. Dense branches are impenetrable protection against stooping hawks and owls. Accipiters prey on cryptic birds at least as much as birds with red markings, and they surely hunt by detecting movement, not color. We know hawks have powerful eyesight, so adding red to their visual repertoire offers marginal advantage.

Maybe smaller birds use red for gender and species markings because primary predators lack pigments sensitive to red.

Jan 13, 2010

frozen accidents


A tuliptree seed cone fell onto a freezing pond during recent snowy winds, and it wound up trapped in ice.

There are several species of magnolia native to the Southern Appalachians. Fraser magnolia is most abundant in the Smokies, and umbrella and cucumber magnolias can be found. In the Cumberlands, bigleaf magnolia joins the mix. Most magnolias planted around homes and buildings are exotic, even Southern magnolia, whose wild range does not reach the Tennessee Valley.

The most familiar magnolia is the the tuliptree, but since it is often called tulip poplar, you may not realize it is closely related to magnolias. Poplars are distant relatives, and tuliptree shares many similarities with magnolias: upright, simple, large flowers; large leaf buds; straight, tall growth form; whorled leaf growth. Tuliptrees only grow in Appalachian and in Chinese forests, one species in each region and the only two members of their genus of the magnolia family.


Seed morphology is where tuliptrees differ from other magnolias. Magnolias grow upright, oblong cones with bright seeds inside. Tulip seeds are wings with a fertile foot.

Early flowering plants had blossoms and seeds similar to magnolias. Oaks, maples and most extant tree groups show up only in more recent fossil strata. As the Appalachians transitioned from coniferous forests to hardwood forests, magnolia-like ancestors and other ancient lineages gave rise to modern trees. The tuliptree is a magnolia specialized for wind dispersal of seeds.

Poplars branch from the tree's evolutionary tree far from magnolias, over near willows and aspens, none of which grow in any abundance in eastern forests. Liriodendron tulipifera is a hint into the deep history of Appalachia. I prefer to call it tuliptree.

tuliptree tuliptree

Inside those flower petals grows a small, green cone that gets longer through summer, eventually dries and spills dozens of winged seeds onto the wind, a modern version of an ancient flowering plant perpetuating.

Jan 8, 2010

strange find

Earlier this week I visited a frozen farm pond and discovered a puzzle. The owner of the pond had scattered feed corn onto the ice, and all around it in the thin layer of snow were footprints. The corn was uneaten. The footprints were shapeless since no impression was left in the ice, so only size and gait could be detected.

Raccoon and possum are the leading candidates, but both would surely be happy to eat corn. The gait ruled out a hopping creature like a rabbit or squirrel, and the prints and stride were too small for a fox or coyote.

There was one more clue, a box turtle on the ice about five feet from the shore. It seemed to have crawled out there and simply stopped. I retrieved it and discovered that it was partially eaten. Its shell had been damaged some time in the past but had healed over and continued growing, but the wound left a gap where its right shoulder would be if turtles had shoulders. The head and right leg were gone, but the rest of the turtle remained. It weighed as much as a live turtle would. Something managed to get its mouth into gap in the shell and bite off the leg and head.

Pondering the clues, this is what I believe happened: the wounded turtle was feeding on the corn, the noise drew the attention of a feral cat, which was desperate enough with hunger to persist with the difficult meal.

Update: I returned the next day to find fox tracks across the pond and around the dead turtle. It was likely a fox that dug up and ate what it could of a hibernating box turtle.

Jan 5, 2010

all the leaves are brown

When mountains go into deep freeze things survive in warm pockets of decay under the frozen crust. Mushrooms keep feeding, as do molds, worms and voles. Tiny, wingless insects barely large enough to be seen wriggle under rotting logs, collembola, one of the oldest insects.

Modern insects have wings; collembola do not. They diverged from insects somewhere around silverfish, before mayfly. All those squirmy, ancient things lived in muck. When life existed in the seas and land was barren, there was muck, and it was squirmy, burrowing things that first crawled from swamps into the freezing hills. Colonization of land by plants and animals took hundreds of millions of years, and something like collembola, tiny, prolific guts, crawled through every minute of it.

Even when a crust freezes on soil, a microecosystem percolates away where heat from rotting leaves stands against the thirsty cold. As a pond freezes only on its surface, a muck world lingers in pockets and layers under frozen forest soil. Summer has its garish leaves and crickets, but winter is not death. It is a retreat to a weak, small world.

Primitive things mastered weak worlds long before there were rich, complex worlds, and they remain masters to this day. Their abundance is the rich world's sustenance. Their weak percolation brews a nutritious stew for spring's roots and another year's garish feast.