Author Archives: David George Haskell

Nested sets

Sandy Gilliam brought by this nest of a colony of bald-faced hornets (Dolichovespula maculata). The nest was attached to the wall of his barn.

bald faced hornet nest

Bald-faced hornets are well-known for the vigorous defense of their nests, a strategy that often follows the Bush Doctrine of pre-emptive strike. Unlike honeybees, the female wasps can sting repeatedly without harm to themselves.

But this nest had no angry occupants. It was abandoned last year when the winter set in. This is part of the normal life cycle of the species: a solitary female starts a nest in the spring, builds a large colony through the summer, then the whole colony dies except for young queens who overwinter alone.

A glance at the nest’s entrance (located at the bottom tip of nest) shows that this is a special nest. Straw and feathers protrude. We can peek into the opening and see a tunnel of dry stems.

bald faced hornet nest inside from bottom

The nest was built against a wall, so it has no backing. Now that the nest is down we can easily see inside: another nest! House sparrows had climbed into the old insect nest, added some bedding of their own, then set up shop to breed.

bald faced hornet nest inside

This was a stroke of avian genius. No chipmunk or squirrel would be stupid enough to try to raid this nest. (In the tropics, some birds take this further, protecting themselves from raiding monkeys by nesting next to active wasp nests.) The nest also comes with its own insulation system. The hornets build multiple layers of cellulose around the core of their nest, allowing them to stay warm through the night and thereby start work earlier than most insects (see The Thermal Warriors by Bernd Heinrich for more on the the various ways that insects manipulate their thermal environments). The incubating mother bird no doubt benefited from the extra warmth.

bald faced hornet nest wall

The nest retained its old comb, revealing the hornets’ kinship with bees. Here are the hexagonal arrays again, but this time built from chewed wood, not wax.

bald faced hornet nest comb

bald faced hornet nest comb close

Entomological enthusiasts should note that although we call these insects “hornets,” they are more accurately called “wasps” or “yellowjacket wasps.” True hornets belong to the genus Vespa and have bulkier heads and abdomens than the more slender “yellowjacket” species (Dolichovespula and Vespula).

I’ll close with my thanks to Sandy for bringing this remarkable nest-in-a-nest to my attention.

Wrestling with privet on Bluebell Island

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Sharp blades and muscles: These are the lab tools used lately by my class. We’ve been mapping and eradicating privet from Bluebell Island, a local hotspot for wildflowers. Privet is a non-native invader and it overshadows and kills native plants.

Setting up the mapping transect.

The View from Lazy Point used as a field clipboard. The class combines field work with discussions of readings, so hardback books find multiple uses. I hope Carl Safina would approve of the students’ improvised use of his fabulous book.

This project started in 2001 when my Ecology class measured and mapped every privet stem on the east side of the island where the flower populations are concentrated. I repeated the project in 2007 with my Seminar in Ecology and Biodiversity, then this year with the Advanced Ecology and Biodiversity class.

We uproot the privet plants. Easy to do when they are small…

…not so easy when they are big. Katie pulled this one by hand. All that work on the swim team has paid off. No need to pull out the saw.

We’re building an interesting dataset. There are not too many places where we have long-term data on the details of how invasive plants respond to attempts at control. Along with this scientific goal, we’re hoping to leave the island in much better shape for wildflowers.

What have we found? At first glance, the project seems to be failing spectacularly. There are many, many more privet plants within the project area now than there were in 2001.

Total number of privet stems increased over time.

But this graph does not capture the whole story. The vast majority of the stems in 2012 are tiny little sprouts, reaching to knee-height. In 2001, the stems reached over our heads and were casting dense shade.

The number of large plants has decreased over time.

The number of large plants (>15 or 30 mm in diameter) has decreased over time.

The average (mean) size of stems decreased over time. The graph also shows that the variability in stem diameter (standard error of the mean) also decreased over time.

So we’ve lost big plants and gained lots of little seedlings. It seems that the removal of large privet plants allows light to reach the ground which encourages both wildflowers and new privet plants. Long term success will depend on continued visits to the island to stop new privet sprouts from getting too big. The rest of the island, outside the study area, serves as an interesting contrast. It is overrun with large privet plants and the wildflower populations are dying out. Eradication of privet over the whole island would be a more major undertaking than could be accomplished by one class, even with many days’ work. Fire and goats might help.

Tyler Johnson prepared this map of the location of every privet stem (2007 data) in Dr. Chris Van De Ven’s GIS class. We’ll be expanding the mapping analysis in coming months to include all three sampling periods, examining whether the spatial distribution of privet has shifted over time.

Bluebell Island is owned by the South Cumberland Regional Land Trust and was bought with contributions from naturalists in Sewanee and beyond. It hosts dense populations of bluebells, trout lilies (including white trout lily), and even the rare dwarf trillium. I’m grateful to the SCRLT board for their continued support for this work, a project that started when I served on the board but has now extended for more years than I at first imagined.

Privet is not the only threat to the island’s famous wildflower display. Gill-over-the-ground is another non-native plant species that has made inroads on the island, as has exotic honeysuckle. In addition, poachers have dug significant numbers of plants over the years. About ten years ago they hit the island so hard that many parts looked as if they had been rototilled. The bluebells gradually regrew. This year, the trespassers hit again, digging large patches. I’m pretty sure that one of these patches encompasses the only known plant of the dwarf trillium in this part of Tennessee, so this rare species may now be extirpated from the island. The poachers are targeting bluebells, but the tiny trillium plant got taken as collateral damage. I may be wrong – we’ll know in the spring – but the digging crosses the exact spot where the plant lives. So if you’re tempted by the pretty bluebells for sale at the nursery, I’d advise you to skip them unless the seller can prove to you that they were nursery-propagated.

Despite the pressures, Bluebell Island is still a marvelous place. In addition to the flowers, old trees provide great habitat for woodpeckers, owls, and wood ducks. Beavers and mink swim the river. Migrant birds ply the riverbanks in the spring. Butterflies are abundant in summer. The river itself is different on every visit. It runs clear and calm in winter dry spells; swells silty and trashy in the floods; then courses bluegreen in the warm algal summer months. Suwannee is a river, but Sewanee is not; so I enjoy my visits off “the mountain” to see some real flow.

Beavers came around after us and snacked on the discarded privet stems.

I’m grateful to the many cohorts of Sewanee students who have yanked, sawed, tweaked, measured, mapped, and analyzed these thousands of privet stems.

Sewanee's Bio 315 class in "gaze at the sun as if something inspiring and important was happening" pose after pulling 4275 privet stems. The largest vanquished stem is held as a trophy. We omitted the blooding ceremony.

Sewanee’s Bio 315 class in “gaze at the sun as if something inspiring and important were happening” pose after pulling 4275 privet stems. The largest vanquished stem is held as a trophy. We omitted the blooding ceremony.

Bee comb

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This week I took advantage of what may be the last warm, sunny days of the season to tidy up the bee hives for winter. I removed unneeded boxes of frames from the tops of the hives and shuffled frames within the boxes to keep as much honey in the hive as possible. Thus prepared, winter hives are less likely to blow over in storms and, more important, all the honey is gathered into one place within the hive. In cold winters, bees huddle in a ball around their honey stores, slowly eating the honey as fuel to keep them warm (the center of the hive is as warm as human body temperature). If honey is thinly dispersed, the balmy bee ball cannot form.

I had forgotten just how beautiful the wax combs of honeybees are. The near-perfect six-sided geometry, repeated hundreds of times is a fabulous piece of natural architecture.

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The wax is secreted from chinks in the abdominal exoskeleton of worker bees. The bees then mold the wax into the six-sided pattern using chewed wax particles. This task falls to middle-aged (2-3 week old bees) worker bees. Younger workers look after the brood; older workers leave the hive and forage.

This weekend marks the 153rd anniversary of the publication of On The Origin of Species. It is therefore fitting to include here Mr. Darwin’s thoughts on the wonders of beeswax.

He must be a dull man who can examine the exquisite structure of a comb, so beautifully adapted to its end, without enthusiastic admiration. We hear from mathematicians that bees have practically solved a recondite problem, and have made their cells of the proper shape to hold the greatest possible amount of honey, with the least possible consumption of precious wax in their construction. It has been remarked that a skilful workman, with fitting tools and measures, would find it very difficult to make cells of wax of the true form, though this is perfectly effected by a crowd of bees working in a dark hive. Grant whatever instincts you please, and it seems at first quite inconceivable how they can make all the necessary angles and planes, or even perceive when they are correctly made. But the difficulty is not nearly so great as it at first appears: all this beautiful work can be shown, I think, to follow from a few very simple instincts. (First edition, Chapter VII, page 224).

He elaborated these thoughts with a series of calculations and experiments, summarized in a recent essay at the Darwin Correspondence Project. As you might expect, Darwin concluded that natural mechanisms could explain the structure of bee comb and that sophisticated combs could have evolved from simple beginnings.

This naturalistic view contrasts with the opinions of Darwin’s contemporaries. After reading Darwin’s passage, I pulled down Langstroth’s Hive and the Honey-bee, an important review of bee biology and bee-keeping published in 1859 (the 4th edition, 1878, is the one that I have on hand; post-Darwinian for sure, although Darwin is not mentioned). Langstroth writes of comb:

To an intelligent and candid mind, the smallest piece of honey-comb is a perfect demonstration that there is a “GREAT FIRST CAUSE.”

These enraptured references to the Divine are peppered throughout his work.

Langstroth was a priest, but depression kept him from many of the usual priestly duties. Instead, he studied insects, especially honey bees. Although his theology seems unsophisticated to modern ears, his entomology was not. His careful studies of bee behavior transformed bee-keeping. In particular, these studies led to him a new design of bee hive, a design that is still the preferred hive for most bee-keepers, especially in North America. Unless you’re eating honey from wild nests, you can almost guarantee that the honey in your kitchen came from a Langstroth hive. I use a modified design: Langstroth in the upper portion (from which come the photos in this post) and open in the lower part (no photos — I never open this part, leaving it for the bees to do as they will).

Winter birds

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This afternoon, I heard the querulous call of my first yellow-bellied sapsucker of the season. This migratory woodpecker breeds in mixed coniferous woodlands in the northern forests, then winters in the southern U. S. and in Mexico. Unlike their woodpecker cousins, sapsuckers prefer to feed on live trees. They take a delicate approach to drilling, making horizontal lines of holes from which they drink sap and eat sap-tippling insects. With the sapsucker’s arrival, Sewanee’s woodpecker count is up to seven species. The others are: pileated, hairy, downy, red-bellied, red-headed, and northern flicker. (The endangered red-cockaded woopecker used to breed in Savage Gulf, just north of here, but has been extirpated from Tennessee for more than thirty years.)

So far, this has been a good year for sightings of winter birds. Pine siskins have been quite abundant and I saw a pair of red-breasted nuthatches in early October. In some winters both these species are rare or absent. All this good birding for southerners results from hard times for the birds up north. When pine and hardwood seed crops are poor in Canada and the Northeast, birds are driven south by hunger.

According to Ron Pittaway of the Ontario Field Ornithologists, this will be a bad year for northern seed crops. His “bird forecast” focuses on Ontario, but what happens up north will be reflected in bird life across the country.

Humans add an interesting overlay to this natural year-to-year variation in food supply. As I note in The Forest Unseen, our love of birds results in the transport of millions of tons of sunflower seeds from the former prairies into bird feeders all over the country. This makes life easier for many birds, causing some of them to expand their winter ranges northward. Bird-hunting hawks therefore also linger in the northern woods. Our bribes have shifted the calculus of migration.

We know surprisingly little about how feeders affect the day-to-day behavior and ecology of birds. New technology, deployed (appropriately enough) at Sapsucker Woods where the Cornell Lab of Ornithology is located, is starting to shed some light into these questions. Least we humans feel left out, the same technology is being used to study our own “day-to-day behavior and ecology” and, like the birds, as long as the sunflower seeds keep coming, we’re happy to play along.

Stream bows

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I came across some unexpected sights on my morning walk in Shakerag Hollow. Water was snaking its way through the tangle of rocks and leaf piles that form the boundaries of the little streams on the mountain slope. As the water flowed, the barriers in its way created little falls which emptied into eddies in pools below. All this tumbling motion stirred up air bubbles that turned in slow circles on surface of the pools.

I watched this gentle gyration for some time before my eye caught what was happening below. The bubbles acted as lenses, refracting the sunlight that was coming in at a low angle through the trees. The streambed was covered in underwater stars, each one gliding behind a bubble.

As the light angled through the bubbles, its constituent wavelengths were teased out. Seen close, the stars were edged with prismatic color. Rain can bow the light, even when the rain is old and earth-bound (or, if we look forward, so young that it has not yet risen to the sky). Bubbles were not the only objects drifting on the water’s surface. Leaves and the shells of hickory nuts floated past.

One such hickory shell had some passengers, a dying caddisfly and a cluster of minute eggs encased within a blob of jelly.

I’m guessing that the eggs were deposited by an aquatic snail. (I’d be happy to be corrected or further enlightened about this guess — I have found no adult snails in this stream which makes me suspect that I’m mistaken. Addendum: these are caddisfly eggs. Thank you David Johnson and Dave McLain for clarifing.) The caddisfly probably flew here from downstream to lay eggs in the water. The adults of many stream insects have an instinct to move upstream when they are ready to breed, counteracting the inevitable downstream flow of aquatic larvae and nymphs.

I took particular pleasure in seeing these two rafters. This is the stream that a few months ago was choked with silt from erosion on the golf course construction site. I took the eggs and the recolonizing caddisfly as signs that, although the stream is still severely impacted by sediment, some aquatic animals have persisted here and others are returning. Soon, I hope, young caddisflies and snails will join the bubbles and stars swimming and crawling in the stream’s waters.

Trash whale

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As Homo plasticus shambles its clumsy way through the world, pieces of junk slough off its body. Much of this exfoliated detritus finds its way to water. The sea is now comprised of water, plastic, and life, in that order.

A collaboration among scientists, artists, and engineers at Olympic College in Bremerton, Washington, holds these facts before us in a striking way. A three-month-old gray whale hangs in the gallery, its body made from plastic bags woven into the surface of a welded armature. The baby whale swims through a room strewn with one month’s worth of rubbish collected from the shoreline along a small sampling area in Puget Sound. Toys, tags, wrappers, cups, pieces of Styrofoam, bits of houses, syringes, bottles: the downstream remnants of our appetite for indestructible plastic stuff.

The whale reminds us that many parts of our oceans contain as many bits of floating plastic as plankton. Seabird guts are choked with these fragments. Dissections of the stomachs of beached gray whales show that they also ingest large quantities of plastic. Because they feed, in part, by scooping at the sea floor, their guts get populated not just by the floating plastic, but by heavy sunken objects. And here we find a surprise: golf balls, sitting like modern Jonahs in the guts of whales. Immediately I was transported out of the gallery, away from the coast and across the continent: back to the Tennessee woods, gazing at plastic globes in a mountain forest in Sewanee.

There is no escape, it seems, from the products of our re-creation.

[Special thanks to Susan Digby, geography professor at Olympic College, one of the whale’s creators, for opening the gallery after hours to give me and my friend Peter Wimberger a tour. You can read more about the project on the gallery’s website.]

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Forest on Whidbey Island, Washington

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An empire of moss and broadsword ferns. Douglas fir trees bend the sea wind. Reams of gold leaf — bigleaf maple — drop through thickets of hemlock and cedar.

Kinglets hammer the forest’s ceiling with sharp brads of sound. Then they drop, working the ferns. Ten of them, right here: hazed wings and stone-bright eyes. Sulfur headstripes; bright, they slice open the heavy green drapes.

Wads of old leaf caught in maple tree crotches, rotted mats lodged inside sprays of alder twigs. Seedlings take root there, above our heads. The soil’s upper boundary is fogged. In walking, we worm through soil passages, burrows of air.

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Savanna

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The photos above are from the savanna restoration site along the Mackinaw River at Merwin Preserve near Bloomington, Illinois. The site is managed by the ParkLands Foundation. The savanna portion of this natural area is maintained by periodic burning which thins the understory but keeps in place the mature trees. Illinois was, until settlement by Old World colonists, over ninety percent prairie and prairie-savanna. Now, about one tenth of a percent of the original habitat remains, and maybe one tenth of that is in “good shape.” So small islands of remnant habitat, such as the one we visited, serve both as reminders of the past and as critically important habitat for today’s native biodiversity.

All around, the land has been ploughed, revealing the famously productive soil that underlies the region. The soil is the color of dark chocolate. Just gazing at the soil made me hungry: here is land that can feed. The soil’s richness was built by the plants and animals of the prairie. But that very richness expelled these creators from most of the landscape. Now the former prairies grow corn and soy, in fields whose size is measured in thousands of acres. That food sustains many people and, lately, our cars. Nearly half of this year’s corn crop will be poured into gas tanks. So as we drive over this land to see its native species, we’re powered by the work of those species’ ancestors.

Even in its plowed state, central Illinois has an open beauty, a beauty that was magnified many times in the savanna itself. The wind loves that openness, so the sound of air against grass (whether prairie grass or corn) and trees (in savannas or in farm windbreaks) forms the acoustic frame for an experience of the land. And, like the soil, the wind now also powers our technology. Copses of wind turbines stand at the edge of town, hopeful new savannas, twisting electricity from the sky.

I am very grateful to Given Harper at Illinois Wesleyan University for arranging my visit. Thanks also to the students, staff and faculty for greeting me with such warmth.

Taking some contemptuous cross-fire. Disappointed.

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Wow. The NY Times piece about my book has inflamed some sensitive nerves out there. Jerry Coyne, a distinguished evolutionary biologist at the University of Chicago, has taken issue with part of the article, a so-called “drive-by diss” of Richard Dawkins (the Dawkins Foundation site has reposted Coyne’s attack). Further, Coyne argues that this diss was a craven attempt to gain readers. He writes:

What galls me is the increasing desire of people to gain credibility by a drive-by snipe at Dawkins’s materialism and atheism. There’s no need for that here, and no need to mention the man. Haskell is going for readership, pure and simple, and wants to get it by criticizing a well known atheist.

This saddens me and, to be honest, seems uncalled for. Coyne says that he has not read the book, so I would expect maybe just a touch more humility in his questioning of my ideas and perhaps the civility not to impute my motives. He also sticks his neck out and offers a critique of my writing (“breathless lubrications”) without having set eyes on the book. I’m disappointed that an honest and non-aggressive expression of a difference of opinion about a difficult philosophical question — the nature of the universe — should be greeted with such a vigorous and contemptuous slap-down.

For the record: Dawkins’ work is one the reasons I got into biology in the first place. But, yes, I personally stop short of the kind of full-blooded philosophical certainty that Dawkins has used in his writing. All this is evident in my writing and in the many interviews I’ve given lately. But none of this data was used, nor did Coyne stop to ask what I meant.

Drive-by diss, indeed.

[Correction: the first draft had an errant “a” added in the last paragraph which I have now removed.

Additions: For those who do not want to wade through the entire comments section, I have cut-and-pasted Jerry Coyne’s follow-up and my further comments below.

Coyne: I’m curious, though. Did you make that statement about Dawkins or not? Jerry Coyne

Haskell:

Hi Jerry,

Thanks for connecting here. I sure did say that I *suspect* that the universe (multiverse?) may consist of more than atoms re-arranging themselves. (If inherent value and “rights” exist, as you say in your post, then you’ve perhaps agreed — neither of those are made of atoms and both are pretty hard to pin down.) I also said that I do not buy the full Dawkins position on atheism. To suggest that this was an attempt to get readers is absurd — I had a multi-hour conversation with Jim Gorman about the book and biology, so of course we talked about the big questions in evolution and the world of ideas. Dawkins has outlined MANY of those big ideas and so I don’t think it is unreasonable for me to say that I disagree with him on some of them. Surely we’re allowed to have disagreements without getting slammed for being desperate book-sellers, bad writers, etc, etc. Especially when those disagreements are about things with such a history of being quite difficult.

I’d be happy to send a copy of the book. It is, in part, a book-long celebration of what it means to look at the world through evolutionary lens. You might like it. :)

Again, thanks for connecting here. I admire your work and have done for many years.

Haskell: Oh, I just saw the post on your website. Simple answer: no I did not DISS anyone. To diss is, as I understand it, to disrespect someone, treat them rudely.

Haskell (after several days of comments by others):

Thank you to everyone who has contributed comments here.

A few brief thoughts from my end of things:

1. Comment about atoms. Ethical claims (about species extinction, human rights, etc) are not, to my knowledge, fully derivable from the laws of physics, chemistry, or biology. Yet I “deeply suspect” some ethical claims reflect more than the passing whims of nervous systems and might, therefore, have some kind of objective nature. What that nature is, I do not know, but it seems unlikely to be made out of atoms. I’m the first to admit that the suspicions that I harbor might just be feelings in an evolved brain and nothing more. But perhaps not.

2. For those who want a single number on the Dawkins probability dial, I’ll have to disappoint you. The answer to the question depends on what you mean by “God”. If the god that you’re imagining presupposes a fundamental ontological division between humans and other creatures, then the needle surges up, red-lining the dial. But if by “god” you mean the idea that ethical statements might reflect some kind of objective reality in the universe, the needle does not know what to do, but is inclined to remain low, listening.

3. Dawkins’ long-standing and vigorously argued positions on religion are well known and in many ways they define the way in which the field of biology is seen by non-biologists, especially in the area of biology’s relationship with religion. As my book’s Preface makes abundantly clear, I used an idea taken directly from religious traditions – the potential insights offered by contemplative practice, a practice that has an important role in my life – and applied it to observation of the ecology of a forest. Mine is a markedly different attitude toward the biology-religion relationship than has been advocated by Dawkins. So I mentioned him briefly in a multi-hour interview, indicating that I did not agree with some of his positions and statements. For those who don’t want to read the book, but want to assess my approach, the reviews of the book (http://theforestunseen.com/reviews/) do a good job of outlining my basic stance towards the use of contemplative practice in the context of scientific observation and reflection.]

Itch, magnified

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My Advanced Ecology and Biodiversity class continues its investigation of our local tick populations. A few weeks ago, we collected ticks in the field and preserved some of them in alcohol. We’ve now looked through these collections using microscopes. We collected only “seed ticks,” little animals that are barely visible to the naked eye, so this close examination lets us identify the life stage and species of each individual.

For anyone who has been attacked by a swarm of seed ticks, the view down the microscope is at first a little horrifying. These agents of suffering loom up at us, unlocking a shiver of fear. Several of us unconsciously reached down to scratch our legs as we looked through the eyepieces.

After a few minutes and, paradoxically, at higher magnification, the little creatures take on a certain rotund charm. The fact that they are pickled helps a lot. We can tell larvae (the first life stage after the egg) from nymphs (the stage that comes after a larva feeds and molts) by counting legs: six for larvae and eight for nymphs. If only all biological identification were so easy.

The majority of the ticks in our collection were larvae. These two are lone star ticks, identified by the shape of the mouthparts and the number of crenelations on the rear of their body (this feature is hard to make out, especially in home-spun photos like these — taken by holding a camera up to the microscope lens…):

We also found a few dog tick larvae. Note the different shape of the mouthparts:

Nymphs were much less abundant, although we did find a few. The following is a the nymph of a lone star tick (the hindmost pair of legs is tucked in, but you can see them if you look closely).

Undoubtedly, the mouthparts are the most fascinating part of the animal. The two outer parts are the palps, used to feel around for a choice spot to drill. The inner portion is made from two knives and a barbed feeding tube. The knives, called chelicerae, open the skin. Then the tube, the hypostome, is inserted and cemented. The cement both holds the animal in place and serves as a gasket to stop leaking. The animal then spits a mixture of chemicals into the host to loosen up the blood. The ticks are fracking us for protein. Without the permission of the landowner.

Of course, when ticks feed, they may also transmit diseases such as Lyme, Rocky Mountain Spotted Fever, and Ehrlichiosis. In the case of Rocky Mountain Spotted Fever, the larvae may hatch already carrying the disease, having received it through the egg from their mother. But the other diseases are not transmitted through eggs. Instead, larvae become infected when they feed on mice and other vertebrate hosts. Larvae only feed once before turning into nymphs. So a bite from a larval tick is generally less dangerous to a human than a bite from a nymph or adult. The latter have fed on other vertebrates and are more likely to carry disease. Good to know, but little comfort when your legs are aflame with the itches of a hundred bites.

My students are currently extracting DNA from the animals to confirm our identifications and to test for diseases. I’ll keep you posted. In the meantime, remember to tick check. These diseases are a reminder that parasitism and disease are ubiquitous components of the ecology of our world.

Scratch, scratch.