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Wednesday, June 13, 2018

Invasions I

If I didn’t know better, and I had to bet whether a flaccid grass could outcompete a blackberry capable of flinging its spine-studded canes 20 feet up into the crowns of trees, I’d have bet on the blackberry. I probably wouldn’t have thought about either invasive species, honestly, living as I do in the lush belt of coastal forest in western Oregon, whose understory used to be dominated by shiny Oregon grape, shaggy ninebark, and the sturdy upflung arms of the sword fern. But I turned around in the last five years and the ferns were gone. 

In fact, the grass wins, by exuding chemicals from its roots that cut off its competition far below the knees. If the enemy of my enemy is my friend, I should love the grass that overwhelms the blackberry. Instead, there is an army marching in on the forests of my home, one that might well bring down even the massive trees. We know that invasive species can utterly overwhelm native vegetation, change ecosystem dynamics, and thus alter entire landscapes. They can be plants, insects, fungi, viruses, or even birds or mammals or snakes. Think kudzu, gypsy months, white-nose syndrome or sudden oak death, the starling, the wild pig, or the python in the Everglades. It’s the sort of overwhelming problem that might make you think that somebody, somewhere, must surely be doing something about it.

By and large, we are not. In fact, we rarely track the spread of even the most egregious invasive species, as a quick visit to the various state databases revealed to me. A glance out my window revealed the gaps, as the mass of invasive ox-eye daisies offered up a white-mouthed hoot of derision at the scanty occurrence map on my computer. They aren’t even in my county, according to the Authorities. Yet here they are, drifting thickly across my pasture. Almost none of the invasive species on my small farm are documented to be here.

Worse, we know even less about the consequences, particularly in a world facing climate change as well as the rapidly spreading army of non-native species. My colleagues and I reviewed hundreds of scientific papers dealing with climate change and invasive species. Almost none of them were based on hard experimental data. Instead, they were mostly limited to computer projections of climate models, themselves subject to considerable revision as more data are obtained. In sum, we have no idea how climate change will interact with and affect the rapid spread of invasive plants, animals, insects, and disease. The little data that do exist suggest that native species and habitats will not be favored. How this extraordinary, reckless experiment in shifting biota and climate will play out is not a matter of academic interest only; everything from food and fiber, fire and rainfall, ecosystem services from nitrification to pollination, hang in the balance. 

Yet our efforts are at best perfunctory, dealing only with the most egregious invaders in a rear-guard action that can only fail. Boats carrying zebra mussels are frequently found just before they are lowered down the boat ramp. You can buy an incredible array of invasive species on the internet, and release them, undetected, when you tire of them. Entire neighborhoods of Oregon’s largest city are being subjected to mandatory chemical treatment for an infestation of Japanese beetles, whose spread was facilitated by a regrettable cut in funding for monitoring. It goes without saying that treating the infestation is costing orders of magnitude more than was saved. Each day, more cargo unloaded from ships and planes that have traveled from all parts of the globe may carry new invaders. At some point, we’ll have to ask ourselves just how addicted we are to this high-stakes game of biological substitution speeding in on the wings of cheap and easy transportation, globalization, and free trade, unfettered by any considerations of collateral damage.

I spent the winter cutting blackberry along the creek. I uncovered trees and light-starved stands of snowberry, freed the branches of ninebark and Indian plum. But there were no more ferns, and along the newly revealed stream banks, the forward scouts of false brome are infiltrating the cow parsnip. The enemy of my enemy is still my enemy. I can’t begin to know how all the shifting balance of species and processes will affect even this small bit of creek bank, let alone what the occupying armies will create out of the wreckage of the world we knew. But we need to start asking the questions, and seeking the answers as quickly as we can.

Wednesday, February 7, 2018

Groundhog Day on a Bicycle II

Early in my career, I worked in Prince William Sound, Alaska in the aftermath of the Exxon Valdez oil spill. The memory of the sight and smell of heavily oiled shorelines and slicks out on the water against the most gorgeous, wild backdrop imaginable kept me away from Exxon filling stations forever after. Given my tendency toward tiny, fuel-efficient cars, Exxon surely never felt the sting. But if by the simple act of avoiding one gas station sign even while I still pumped gasoline I would remember the terrible cost of oil, it was well worth the inconvenience to me.

And I hadn't even heard of global warming or climate change yet.

I've been a pretty dedicated bicycle commuter now for most of my adult life.  Although my dismay over the impacts of fossil fuels has certainly been part of the motivation, I don't believe in hair shirts. I rode my bicycle because I love to ride, I enjoy the exercise, and over the years the views of sunrises, wildlife, and unexpected encounters with friends both new and old along the way were an enormous added bonus. I also hate driving, which I really don't view as a bad thing as long as I am still able to do it safely and well when I must. There are always days when convenience beckoned, and even days that convenience won out, and I drove rather than rode. It still happens. But the trick to sustained change is making doing the right thing the easy alternative, and ensuring that the best parts of the alternative strategy are enhanced over whatever benefits might be obtained by the default you're trying to change.

I ride a Trek 520 touring bicycle outfitted with racks, fenders, lights, and a bell. Over the years I've put together quite a good assortment of high-quality rain gear and warm clothing to fend off western Oregon's winter weather. I've learned to maintain my bike and I keep it in excellent working order at all times, partly for safety, but largely because a smoothly operating bicycle is far more fun to ride than one that is not. It isn't always easy to get the bike out of the shed, but I've managed to  ride over 30,000 miles on my bicycle to and from work and on errands over the decades. It hasn't replaced or even equaled the miles I've driven, but it still has helped push back against rising atmospheric carbon dioxide.

I'm not getting any younger, however, and recently the cumulative wear was getting to me on top of swimming to manage the tendinitis in my forearms and walking to keep my dogs happily exercised. I needed a better solution. This was more frustrating that it should have been, because we've had decades to think of better solutions to transport given our current infrastructure, including smarter development patterns. Mostly, they have been wasted decades. I contemplated buying a small electric car, now that more of them are on the market, but that was so much more steel and mass and energy than I need 95% of the time.

The answer had actually presented itself on a bicycle trip my husband and I took several years ago, when a guy watched us pedal by on our loaded touring bicycles and hopped in his electric-assist trike, and ran us down to show it off. Aha....

The idea of owning one turned into a reality this January, when a used one popped up in our town. Even used, the ELF ("electric, light, and fun!") by Organic Transit isn't the cheapest solution to non-car travel, but there are other considerations, including accounting for the cost of a ruined planet. This one even had a small passenger seat. We jumped on it.

I had buyer's remorse for about five days. It took that long to get used to the fact that this vehicle is not a bicycle in the traditional sense, although legally it certainly is. I had to learn to integrate pedaling with using the electric motor assist (run by a battery that can either charge from the rooftop solar panel or plug in to a standard wall outlet for a couple of hours). One mechanical disc brake screamed incessantly and I had to learn how to service those, and troubleshoot them. There were various modifications needed to deal with the rain. The shell rattles and the electric motor hums and the roof holds in the racket. On the other hand, I don't get wet, I'm more visible to motorized traffic, and I can spontaneously stop in at the grocery store without strategizing about space and weight.  Even better, I don't arrive at my destination covered in filthy, soaked rain gear and feeling like I just rode 6.5 miles into a stiff headwind as well as driving rain.

My biggest enjoyment, however, has been just riding it around and seeing the reactions. I often catch people circling it and peering into it when I've parked it. People honk and give the thumbs-up. They cheer from bus stops and sidewalks. A young guy smoking a cigarette rode up on his poorly maintained bike and eyeballed the ELF at a stop sign. "It even has a solar panel?? That thing is way cool!" he pronounced, then disappeared into the rain.

We are more hungry for other options than we know.

Monday, January 15, 2018

Martin Luther King Day

It is Martin Luther King Day, and I just finished reading the “Letter from the Birmingham Jail,” written by Dr. King in response to the criticism he received from white clergymen over his decision to take nonviolent action to protest systemic racism. You can find the letter published on the Washington Post’s website here.

As I read the letter, it struck me that there are parallels between how we as a society are dealing with racism, and with the threat posed by climate change. In both cases, broad patterns of facts are disregarded in favor of intense fighting over specific situations. In both cases, accepting and confronting those broader patterns of facts require a fundamental reorganization of how our society works. In both cases, the status quo involves leaving power and economic structures intact, without disturbing the immediate comfort of those who benefit at the cost of those who do not. In both cases, the status quo means not only perpetuating harsh consequences of social and environmental injustice, but also a deferred but terrible price for those who currently benefit from the status quo.

Does it matter what Donald Trump said in any given instance? Certainly this administration has made no effort at all to address the terrible inequities facing American citizens of African descent, or other citizens whose genetic heritage is not predominantly western European. By extension, the question then becomes one of how much have the rest of us have resisted, and responded to these larger patterns of injustice. Perhaps it shouldn’t be just black football players who take the knee, metaphorically or otherwise.

Similarly, the “debate” over global warming centers on large arguments over small fragments of data. Does the “heat island” effect explain warming?(No, it does not). The last 20 years don’t show warming (that argument limited itself to data from only the atmosphere, and it isn’t accurate anyway). Arguing over whether tree ring data really fit this or that pattern is ludicrous in view of the extraordinary range of data that all point to the same conclusion. Given that, the fact that we haven’t yet quite figured out the role of low-elevation clouds caused by diesel particles seems rather insignificant. The larger patterns will speak for themselves, if we pay attention.

This presidential administration has shown itself to be openly defiant of facts, willfully ignoring data for belief, and has skillfully used the stories we create about ourselves to inflame denial, hatred and fear. Stories are indeed a powerful component of the human psyche. Yet, deliberately overlooking the stories told by broad patterns of facts in the service of protecting our own little stories is neither worthy of the ideals upon which this nation was founded, nor an effective strategy to protect ourselves from the violent changes that denial will bring in the end. We are far better off choosing the story framed by the ideals of Dr. King than the dark, dystopian story that has swept over our national discourse over the last two years.

It is fitting we have set aside a day to honor one of the greatest American citizens who ever lived. It is even more fitting when the conversation today centered on how we move forward to ensure that the facts, those stubborn things, are recognized, so that we can realistically assess how far we have yet to go on our journey toward true equality and justice, indeed our species’ long-term survival. We will all need to face the best version of truth that we have in order to begin the move toward solutions.

Wednesday, April 17, 2013

The Natural History of Skunk Stink

I never knew that fresh skunk spray smells exactly like burning rubber.

Instead, as my dog leaped into the back porch after his brief pre-dawn potty break in the yard, I thought it was just some new form of particularly odious flatulence.  This dog often has gas, and I had not yet had coffee.  However, as I bent down to wipe his feet and the odor increased sharply in its intensity, I realized that my dog wasn't directly responsible for the stench.  He seemed unconcerned, but he loves stinky odors, and the spray had missed his face.

There had been strong sulfurous fumes in the back yard for the previous week.  It was almost March, and the skunks were stirring, looking for food and for love after winter.  They are not shy about wandering around outside our house, although because they are normally strictly nocturnal we almost never see them. Skunks will spray predators that threaten them, but a female skunk will also spray persistent males bent on mating if she's really just not in the mood.  Skunks aim quite well, so I suspected that my dog had interrupted an unhappy love affair and been splattered by the consequences.

striped skunk
Striped skunk, Mephitis mephitis. Photo: NPS

Anal glands are used by many species of mammal as the creators of scent calling cards; when your dog sniffs around another dog's feces, she's most likely focused on the droplets of scent secretion that are released during defecation.  Possums also use anal gland secretion as a method of self-defense, but only skunks have the ability to take aim and fire.  Skunks' glands are quite large, over an inch or three centimeters long, and each of the pair is equipped with a nipple-like structure called a papilla that acts as a movable nozzle.  The glands contract with enough force to send the oily ooze flying ten feet or 3 meters distance. 

Skunks are born blind and helpless, but their glands contain musk by the end of their first week, and they are capable of spraying at the age of 17 days, more than two weeks before their eyes open for the first time.  Researchers found that young skunks were more likely than adults to spray than to run, hide, or charge.  I found no reliable reports of how long it takes for a skunk to refill its glands after a full discharge.  Presumably it takes some energy and time, because skunks give plenty of warning before firing, and don't seem willing to use all of their supply in a single encounter unless they must.

 Spotted skunk or civet cat.
 Striped skunks.  Image from

Elements of the chemical composition of the spray were described as early as 1862 by German chemists, and a fellow German named Dr. O. Low did his best to continue the inquiry during an expedition to Texas in 1872.  Low commented on the abundant opportunity to collect skunks and their musk during his travels, but his companions objected so vigorously to the ensuing odor that he was forced to abandon his efforts.  He was further stymied from studying his few skimpy samples by colleagues and students in the college at which he worked "when the whole college rose in revolt, shouting 'A skunk, a skunk is here!' I had to abandon the investigation." 

 A more thorough treatment of the chemical elements of skunk spray was published in 1896 by Thomas Aldrich of Johns Hopkins University, who managed to obtain the glands of a number of skunks collected in Maine. “I have been more fortunate than my predecessors in being surrounded by those who, for the cause of science, would endure even the odor of a skunk in close proximity,” Aldrich wrote. 

 Aldrich found that the fluid’s vapors were highly flammable and gave off sulfur dioxide when burned.  He also discovered that even humans can sense the presence of these compounds at concentrations of ten parts per billion. This is equivalent to tasting a pinch of salt distributed across one ton of potato chips.  

Striped skunk. 
Spotted skunk, Spirogale gracilis 
Image from

The composition of the musk is astonishing.  Over 150 compounds containing sulfur have been isolated.  Even more interestingly, each species of skunk has its own chemical signature. The striped skunk’s musk contains seven major volatile compounds, including three thiols, three thioacetate derivatives, and an alkaloid compound, 2-methylquinoline, which is also used in pharmaceuticals including anti-malarial drugs.

 The recurring skunky smell of a previously sprayed dog who seemed odor-free until the dry fur is dampened results from the reaction between water and one of the thioacetate derivatives remaining in the fur, creating one of the more volatile and smelly thiol compounds.  I found nothing in the literature regarding that first stench of burning rubber, but the odor had morphed into the sickening, familiar sulfur smell by breakfast time.  The highly volatile chemicals responsible for the first overwhelming impression must have already begun breaking down in the presence of water and oxygen in the air.

To get rid of the odor, the thiols need to be converted to other, less objectionable chemicals.  Exposure to oxygen will lead to their conversion to sulfonic acids.  Tomato juice or other acids do not accomplish this critical piece of chemistry, although a properly prepared solution of hydrogen peroxide will do the trick. Regarding the well-established folklore regarding tomato juice, the authors of the book Land Mammals of Oregon commented, "Don’t waste good tomato juice- add a little vodka and drink it; it won’t reduce the odor, but the odor won’t bother you so much!”

I didn't have any tomato juice or vodka on hand, only a bottle of doggy shampoo.  I went to work at once, and by dawn, the dog was still stinking with sulfur, but now had undertones of green tea and lavender.  At least he was clean.  Fortunately, olfactory fatigue had set in, and we stopped noticing the stench unless we left the house for a while.

 I'm not sure my dog has learned his lesson. I'll pay more attention to the atmosphere of early morning next year, making sure that no bad love is in the air before flinging open the door.  Or at least, I'll make coffee first.


Aldrich, Thomas B. 1896. A chemical study of the secretion of the anal glands of Mephitis mephitica (common skunk), with remarks on the physiological properties of this secretion.  Journal of Experimental Medicine 1:323-340.

Anderson, K. K., D. T. Bernstein, R. L. Caret, and L. J. Romanczyk, Jr. 1982. Chemical constituents of the defensive secretion of the striped skunk (Mephitis mephitis). Tetrahedron 38:1965-1970.

Medill, S.A., A. Renard, and S. Larivie. 2001. Onogeny of antipredator behavior in striped skunks, Mephitis mephitis. Ethology, Ecology & Evolution 23(1):41-48.

Verts, B. J., and L. N. Carraway. 1998. Land Mammals of Oregon. University of California Press, Berkeley, California.

Wood, W. F. 1989.  New components in defensive secretion of the striped skunk, Mephitis mephitis. Journal of Chemical Ecology 16:2057-2065.

Wood, W. F. 1999. The history of skunk defensive secretion research. Chemical educator 4:44-50.

Wood, W. F., B. G. Sollers, G. A. Dragoo, and J. W. Dragoo. 2002.   Volatile components in defensive spray of the hooded skunk, Mephitis macroura.  Journal of Chemical Ecology 28:1865-1870.

Wednesday, January 16, 2013

Possum Soup

The racket had gone on for quite some time, and it was getting hard to ignore.  I was up in my attic room, studying during the days of coursework for my master's degree in wildlife science.  The rattle of pots had gone from a brief shimmy of sound that you might think you really hadn't heard to a steady clatter.  I had a hypothesis.  A few days before, a rat had come in from the dairy barns, and chewed up a wooden spoon I'd used to make jam.  A repeat visit appeared to be underway.  I wasn't interested in facing down a rat in the cupboard, but the call to some kind of confrontation became unavoidable.  Reluctantly, I headed down the stairs.

I'm often told by people who want to become wildlife biologists that they are motivated by their love of animals and of being outside.  I try not to tell them that most biologist spend an obscene amount of time tied to a computer keyboard, because a few of us manage to escape that fate.  Who am I to accidentally discourage the next extraordinary naturalist-ecologist? For myself, however, some of my best wildlife encounters have occurred when I've been off-duty, although admittedly nearly always when I'm away from my desk.

That evening, I left my makeshift desk and climbed down the attic stairs.  Grabbing the broom as some means of self-defense, I flipped on the light switch and cautiously opened the cupboard door.  A sharp face decorated with glistening button eyes and spiky hair gazed back at me.  Not a rat.  A young possum sat in a saucepan, its tail arching up into a question mark, punctuating perfectly the look of bemused confusion on its face.

Much better than a rat, but if I left the possum there, I would get none of my work done, and I doubted that staying in the cupboard was what the possum had in mind for the evening's agenda.  The saucepan handle was angled toward me.  I cautiously extended a hand toward it, thinking the easiest solution was simply to carry the pan to the door and unceremoniously dump the possum into the bushes off the porch.

The possum froze for a moment, and hissed.  The hiss was almost exploratory, as if the possum had not yet had to do this before and wasn't quite sure of the etiquette of self-defense.  Despite its uncertainty, the impressive teeth were on full display.  I decided that this was not the time for experiential education, and withdrew my hand.

The possum then seemed to realize that it was in a compromising position.  It scrambled out of the saucepan and retreated to the back corner of the shelf, still facing me.  I thought about trying to prod it out with the broom, but playing broom hockey in the tight quarters of the kitchen with an upset possum wasn’t the resolution I was looking for.  Then as I squatted, staring into the dark recess of the cabinet and wondering what to do, I could have sworn the possum was shrinking.

After a moment or two, there was no doubt about it- there was much less possum left on the top shelf.  The shelf had been poorly cut, leaving a large gap in the corner chosen.  The possum's backside had started to descend through the gap, the back legs and tail hanging down into the lower shelf space, the front legs and paws now pinned to the side of its head as it sank still further.

I grabbed the largest kettle, and positioned it under the possum's dangling backside.  I coaxed the rest of the animal through by tapping gently on its head with the broom, and finally gravity brought the possum down into the kettle with an audible plop.  Moving quickly, before the possum could regain its composure, I slipped the lid onto the kettle and carried it outside, the possum scrabbling impotently against its enameled prison.  The possum's vague uncertainty about the whole misadventure prompted me to simply tip the kettle on its side rather than flinging the contents out into the blackberry thicket.  I stood and watched as the possum ambled out, blinked a few times, and then unhurriedly slipped off the edge of the deck and disappeared into the darkness.  Equilibrium was restored.

I wished the young possum well, and returned to my attic and the theoretical study of wildlife.  My housemate later admitted he'd left the door open all morning, and had even heard a faint scrabbling that must have been the possum settling into the cabinet to get out of the unwelcome early daylight. The noise then stopped, so he did not bother to investigate.  He laughed when I told him of our visitor, and I've never had such a good look at a live possum since.

I'd much rather encounter the natural world on its terms rather than my own, and watch what unfolds without the need to capture, tag, measure, or otherwise harass whatever it is I'm studying.  We can learn a lot from ecological research when we design it properly and all goes well.  It is an important kind of information.  But I'm convinced that we can learn just as much by being more attentive to the everyday interactions we have with the lives of all of those around us, no educational degrees required.