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.