Red Hens and Wooden Eggs

We had chickens once before, until a persistent weasel and an interstate move together conspired to eliminate that first flock.  Starting another flock has been on the projects list ever since, and this spring Dan managed to borrow all the equipment necessary for starting chicks.  This led to the building of a sturdy little coop so all would be ready for the moment the as-yet unpurchased chicks grew large enough to need it.  The coop led our neighbor to help us acquire six yearling New Hampshire Red hens that had reached the end of their lives as research subjects at the local university's poultry program.

Dan's not-quite-finished coop.  Photo: D. K. Rosenberg.

Why wait five months for your chicks to mature just in time to stop laying as winter sets in?  We thought these hens would likely be solidly at the peak of their egg production, and the idea of rescue appealed to us as well.  New Hampshire Reds are known to be hardy birds with a proclivity for brooding.  This is handy if you have a rooster and a desire to keep your flock growing with some new broods of chicks occasionally.  A few days later six refugee hens came home in an assortment of cat and dog transport crates to begin new lives on our little farm.

The university raises chickens according to industry standards.  This means each hen had spent her days in a small cage just big enough for her to turn around in, with a sloped wire floor.  When an egg is laid, it rolls down into a collection chute.  It is possible that these hens never get to inspect an egg up close.  They also don't get to give their wings a good stretch, scratch and peck on the ground, perch, or engage in a lot of other typical chicken behaviors.  We wondered how they would adapt to a barnyard.

We kept the hens confined to the coop for several days to adjust to their new life as real, live chickens rather than industrial egg production machines. Our coop is small but it was still much more space than they'd had for most of their lives, and included a window with a view of the sheep pasture, branches to perch on, nest boxes, and a layer of shavings to scratch in.  It must have been a staggering change.

A whole new world... Photo: D. K. Rosenberg

Instinct, that knowledge we hold without thought or learning, is a powerful force.  A hen kept her entire life in an indoor facility under artificial lighting in a small cage still knows what to do when she's presented with a patch of dirt and grass.  The first day we opened the door, the chickens learned to navigate the ladder to the ground, and soon all were pecking, scratching, clucking, and interacting as if they had never been anywhere else.  Except for one crucial detail: they did not recognize their own eggs.

A challenge in backyard chicken husbandry is to prevent your chickens from ever learning what good food eggs can be.  If the shell cracks and a hen takes an exploratory peck, she'll enthusiastically eat the whole thing, shell and all.  Once she sees an egg in this light, there seems to be no going back.  We quickly discovered that our six hens had no idea what to do with eggs, laying them carelessly around the coop and outside in the mud.  Very soon after that, despite our constant checks to remove the eggs as quickly as possible after they were laid, at least one chicken took an exploratory whack.  We haven't gotten an egg since.

I tried to break the habit or at least prevent all the hens from learning it by stocking the coop with some wooden eggs I acquired from a craft store selling Easter supplies.  Unfortunately, the reward of hitting a real egg seemed too great to discourage a hen who simply came up with a jarring thud when she explored the possibilities of one of the wooden ones.  Dan watched one hen attack a decoy egg so savagely that she pushed it halfway around the coop.  Motherhood was clearly not in her future, nor in any other hen's future if the infanticidal chicken remained part of the flock.

Wooden eggs.  Photo: D. K. Rosenberg

Of all the instincts that constrictive captivity had broken, it was the one most critical to the long-term survival of the species: thou shalt not eat thine own children.  The drive to reproduce is so strong that many animals risk their lives to mate or defend their young, or push themselves to the point of starvation to provide for them.  It is sobering to think that we have managed to subvert the basic wiring of being a chicken to the point it cannot recognize its egg as its own.

This isn't the worst we've done.  Meat chickens are bred to grow so quickly that their legs sometimes become unable to bear their weight.  The feeding of corn to beef cattle during the final stage before slaughter is a carefully managed balance between initial weight gain on this highly unsuitable diet, and weight loss once the acidity of the rumen caused by the corn begins to dissolve the rumen lining.  Concentrated Animal Feeding Operations, or CAFOs, are notorious for the conditions in which individual pigs and other animals are kept, not to mention the significant issues of air and water pollution from the staggering amount of waste you get when you keep tens of thousands of animals in a very small space.

What do we owe the livestock we rely on for meat, milk, and eggs?

The backyard food movement is certainly driven at least in part by peoples' desire to take more control over how their food is produced.  This is a good thing in a culture that has become increasingly alienated from the life forces that sustain our own, even if the motivation is only rarely the welfare of the soil, plants, and animals.  In an increasingly crowded world, however, not everyone will have the luxury of space, good soil, and clean water plentiful enough to raise food of any sort.  We're still going to need large, efficient farms at some scale.

All the same, awareness will at least keep us honest in our obligations to the animals that feed us, to keep them fed, sheltered, and provide them with the opportunity to express the most basic essence of what they are: living beings.  At what price to our own humanity do we want cheap bacon?

Five hens still scratch and peck underneath the new coop, ignoring the sheep who come by every evening to take a look at them.  They may yet complete the transition into a hardy little productive flock for us; we'll give them more time to settle in to their new world.  Whether they provide us with eggs or meat, we'll be grateful for the gifts of their lives, sustaining ours.

Photo: D. K. Rosenberg

The various contrivances of orchids

I joined the local orchid society this winter.  The months of soggy dark require unusual coping measures at times; the displays of blooming orchids on the "show and tell" table at the monthly meetings alone are worth the membership.  My own little collection isn't doing too badly.  My phalaenopsis and paphilopedilum are blooming, and the zygopetalum's buds are swelling steadily. 

Phalaenopsis, known as the moth orchid.  Photo: J. A. Gervais

Orchids make up the largest plant family on the planet, with about 24,000 species.  They live in a staggering array of environments, from the tropical rainforests most of us associate with them to tundra environments, in the deep shade and out in the open sun, perched in trees or on the ground.  They are united, however, in their extraordinary biology, making use of an incredible array of other organisms to help them through their life cycle.

The local orchid society has about thirty members, small enough that guests are immediately recognized as such and welcomed with enthusiastic delight.  How do you not join a group of people who love to talk about flowers?  The skill level ranges from experts who hone their skills cultivating the most challenging plants, to people like me who can kill just about any orchid effortlessly.  I suspect the experienced growers look on us neophytes as a great way to clean out the clutter of their greenhouses: giving an extra orchid to someone who at least admires it seems less heartless than throwing it straight on the compost heap.  I view it as a type of symbiosis, although the plants may not.

Orchids have developed trans-species  interrelationships to a remarkable degree on several fronts.  The seeds require the services of a mycorrhyzal fungus in order to germinate, relying on the fungus to make up for their lack of endocarp.  Many species are epiphytes, perching on the trunks and branches of larger plants.  The pseudobulbs of other orchids harbor ferocious ants that offer protection to their hosts.  Most noteworthy, some orchids have developed extraordinary coevolutionary relationships for pollination.

Anagraecum sesquipedale.  Charles Darwin hypothesized that this magnificent orchid is pollinated by a hawk moth.  The moth, Xanthopan morganii, wasn't discovered for another 41 years, and proof of pollination services had to wait 130 years after Darwin's insight.

Although many flowering plants have built relationships with animals for the purposes of both pollen delivery and seed dispersal, orchids have gone to extremes.  The pollen of the vast majority of plant species is released as a dust of individual grains, but in nearly all orchids pollen is wadded up into two to twelve waxy balls, called pollinia.  It's a high-risk strategy, because each flower on the plant (and many produce only a single flower) has exactly that many chances to fertilize another plant's flowers for seeds.  It's a twist on putting all of one's eggs in a very few baskets.

The pollinia are designed for long-distance transit.  Pollinia on hawk moths in the wild have remained stuck in place and ready for deposit for over three weeks.  Insects, birds, and moths that visit orchids may have multiple pollinia stuck to their heads, beaks, and proboscuses like yellow bunny ears.  Different species of orchids place their pollinia in slightly different positions on the pollinator, ensuring correct delivery when the animal visits the appropriate orchid species again. 

This trait can be quite useful for someone interested in propagating orchids, and in creating new hybrids.  It isn't hard to use a pencil or other pointed object to lift the pollinia free of the flower column; they will quickly bind tightly to the object and orient themselves for maximum contact with the receiving flower's stigma.  It is a system easily manipulated by people.  In fact, we're the only mammal that pollinates orchids.  Once fertilized, the flowers quickly wilt.  This, announced my high school biology teacher with a wicked grin, opens up interesting possibilities if you don't like the prom date to whom you are expected to offer an expensive orchid corsage.

The flowers are all about sex, as all flowers are, but for some orchids it's a double entendre.  The sneakiest orchids are those whose flower parts have evolved to resemble female insects, complete with a release of chemicals that mimic the insects' own pheromones.  The strategy is known as pseudocopulation, as the befuddled male insect attempts to copulate with the flowers, and gets tagged with a pollinium for his pains.  Presumably he either doesn't learn, forgets quickly enough, or becomes desperate enough to visit another orchid of the same species before he dies.  The odds are long, and because of that the flowers remain intact for many weeks.  This is, of course, one of the characteristics that makes them so irresistable to humans bent on romance. 

The aptly named bee orchid, Ophrys apifera.  It is pollinated by male bumblebees and is an example of pseudocopulation.  Photo by Nancy Cottner

Not all orchids try to forgo paying the pollinators for their services through deceit.  Many offer nectar, which varies in sugar concentration depending on the pollinator. Specialized avian pollinators such as sunbirds earn the highest reward; hawk-moth-pollinated flowers offer a somewhat lower sugar level, and the least concentrated nectar is payment to the least-specialized pollinators from the more generalist orchids.  Within the flower, the most concentrated nectar is the farthest in, encouraging a good push to obtain the reward, and maximum contact with the pollinia.  Other orchids offer scents or waxes and resins that are gathered by their pollinators.

My fellow orchid enthusiasts range from generalists who do not seem to have ever met an orchid they didn't like, to those who specialize on one small subgroup.  Some folks seem taken up entirely by the challenge of the cultivation of the most exacting varieties, whereas others of us are unapologetic fans of the lowest-maintenance plants that reliably produce bright, interesting blooms with the least amount of fuss.  We're all in it for the flowers. 

For all their trickery and bribes, less than one in five tropical orchids typically achieves fruit set in the wild.  Pollination is generally thought to be the limiting factor for reproduction in wild orchids, even with their absolute dependence on fungi for seed germination.  Wild orchids are perhaps most amazing in the fact they exist at all, let alone having successfully woven themselves into the ecological fabric of so many places.

The orchids on the monthly show and tell table are often so hybridized by human breeders that the names of the crosses don't always fit on the plants' tags.  These are organisms of the greenhouse and windowsill, depending on the passion, space, and financial allocations of the owners.  I asked one of my fellow club members how many plants he had.  "Seven hundred, I think," he answered.  "I have two greenhouses now.  We all started with a few orchids on a windowsill."  Orchids have been amazingly successful at bending yet another species to the task of continuing their existence. 

I swear my little collection isn't going to need more space than my windowsills.  Soon, after the peas have sent up tendrils and the lambs have all been born, I'll be out in the woods hunting for my favorite orchid: Calypso bulbosa, which grows in heavily shaded understory, and tricks bumblebees into pollinating it.  I don't have to do anything at all, except admire it and the extraordinary ecological relationships that sustain it.  I don't think, however, that either the club members or their orchid masters have given up on me.

Calypso bulbosa.  Photo: J. A. Gervais

Sources:

Boyden, T. C. 1982. The pollination biology of Calypso bulbosa var Americana (Orchidacea): initial deception of bumblebee visitors.  Oecologia 55(2):178-184.

Cozzolino, S., and A. Widmer.  2005.  Orchid diversity: an evolutionary consequence of deception? Trends in Ecology and Evolution 20(9):487-494.

Darwin, C.  1882.  The various contrivances by which orchids are fertilized by insects. 2nd Edition, Revised. London: John Murray.

Micheneau, C., S. D. Johnson and M. F. Fay.  2009.  Orchid pollination: from Darwin to the present day. Botanical Journal of the Linnean Society 161:1-19.

Tremblay, R. L., J. D. Ackerman, J. K. Zimmerman, and R. N. Calvo.  2005.  Variation in sexual reproduction in orchids and its evolutionary consequences: a spasmodic journey to diversification.  Botanical Journal of the Linnean Society 84: 1-54.

The Balance of Voles

The barn owls will be nesting very soon.  They've already started the process of dating, the males bringing Valentine's gifts of dead voles to their prospective mates and spending the daylight hours together tucked safely away in a dark corner somewhere.  If the female likes the gifts and the company, she'll soon begin laying her white eggs, counting on the male to provide all the food for her and then the entire family for weeks to come.  Hundreds of voles will be consumed in the process.

Some years ago, I provided some dark corners in the form of nest boxes to see if barn owls might help the local farmers with the ebb and flow of wild voles, which can cause thousands of dollars per farm in crop damage in a peak year.  I put out eighty boxes spread between two counties, in strings of three to five boxes per fence row.  The study finished several years ago, the funding gone, the results inconclusive, but the boxes are still standing.  To help out both the owls and the farmers who gave me access to their lands, I go out each December and maintain the boxes.

Barn owl nest box.  Photo: J. A. Gervais

Farming must be the most difficult form of legalized gambling, where those who farm have to work very hard, in often physically demanding and dangerous conditions, in hopes of producing a crop that can then be sold at a profit.  Almost nothing in this process seems to be in the farmer's control beyond the calculated decision of what to plant.  More so than any other livelihood directly linked to natural resources, farming is a long-term gamble, a balance of good weather and not too many pests, then favorable market conditions.

Barn owls rely on small rodents for their living.  The females will lay up to thirteen eggs, although the average clutch is closer to five eggs.  They hedge their bets by incubating during laying, so the eggs hatch over several days and the young owlets range in size.  The biggest owlets eat first.  In a pinch, they'll eat their younger siblings if the parents do not bring enough voles.  In the best of years, the adults will raise a second brood.

The farmers I work with like wildlife, and do what they can to accommodate the owls while they also pursue a precarious living.  Far more than most professions, farming reminds us that nature is ultimately in control, and we all rely on good weather, healthy soil, and clean water far more than most of us remember.  For a farmer, it is each year's bottom line, the balance between inputs and outputs tipping precariously on the edge of the appetites of voles.  Unfortunately, the appetites of owls are not great enough to swing the balance on the bad years, but they help.  Barn owls nesting in a barn make a mess but are usually tolerated.  Barn owls in a nest box are universally welcomed.

Cleaning out a nest box.  Photo: J. A. Gervais

The necessary maintenance of a barn owl box requires cleaning out the detritus of the past year, occasionally making repairs to the flap, or reinforcing the connection point between box and post.  Although natural cavities may fill with nesting material and prey remains over the years without much problem, the weight of all that material in a box that leaks a bit is much too great to be allowed to build up over time.  Armed with a gardening hand rake and a face shield, I open the flap, reach inside, and haul out all manner of rubbish into the dim December light.  It is a messy act of renewal.

My assistants are frequently showered with starling nests, great wads of sticks and straw that nearly fill the generous cavity.  It is usually raining, so the rain gear we wear serves a dual purpose.  Other unknown inhabitants bring bits of lichen and moss, or a few strands of grass.  Kestrels leave almost no traces of their nests, and a box used as a roost by barn owls may give no hint of its sometime occupants.  In a year with abundant voles, sometimes a vole carcass or two comes cascading out of the box, often with little else; we put those back, as they were put there by someone as a hedge against hard times.  Sometimes deer mice take up residence, bringing a light fluffy mass of shredded bark and leaves inside.  Others are empty except for a the abandoned comb of the paper wasp.  A barn owl nest, however, is an entirely different story.

Inside a barn owl nest box.  Last year's abandoned egg sits on the remains

 of hundreds of voles.  Photo: D. K. Rosenberg.

For those, I whack away with my hand rake at the thick, compacted mat of fur and bones and nameless dried goo, cemented in layers if the box is in the lee of some trees, a wet sodden mass if the rain can get inside.  Sometimes we find the remains of a young owl that did not survive the nestling period, or an unhatched egg now dessicated and filthy.  There is some satisfaction to getting all that mess out of the living quarters, leaving things ready for another year's accumulation.  Farmers, meanwhile, maintain tractors and other equipment, and soon they too will be getting down to the business of the year in the fields.

It is hard to leave a warm house on a cold, wet December morning before dawn to spend the day plodding along the fence lines in the rain carrying a ladder for miles.  There are compensations.  Sometimes we're given beautiful views of light and cloud, the song of a flock of swans, the calls of killdeer or snipe, and occasionally, the silent explosion of a white and fawn barn owl, as it exits the box just as I raise the flap.  There's time for the owl to get over the fright before the decision of where to lay must be made.  There is still time to plan out the new year, room for hoping for a good harvest and the right balance between voles and owls and people, all counting on the green grass in the fields.

Of Love and Dancing

The albatrosses began to return in late October.  One day I looked out from our cook tent and there were perhaps a half-dozen of the huge white birds standing serenely on the sand, looking both grave and comical with the stark, sharp beauty of sea-gray wings folded crisply across their backs.  They waddled uncertainly over the dunes to just the right spot, there, that's the nest, right there.  A few days later, there were hundreds, and a week later, thousands.  Their season on the tiny speck of sand in the middle of the Pacific had begun.

 Laysan albatrosse pair on Laysan Island.  Photo: J. A. Gervais, 1992

You can find Laysan Island on most world maps, although it is only about a mile and a half long, a mile wide, and cradles a large super salty lagoon.  Essentially it is nothing more than a large sand dune perched on a remnant volcano.  There isn't much else out in this part of the world, a thousand miles northwest of Honolulu, and Laysan is the second largest of the Northwestern Hawaiian Islands.  For a few years over a century ago, it was inhabited, briefly, by humans, who mined the guano, harvested the albatrosses' eggs, and killed the birds for their feathers.  It has belonged to the birds for many thousands of years.

Land is a rare commodity in the middle of the ocean, and all seabirds are tied to it for breeding.  The birds of Laysan do a time-share, where different species come in from the far reaches of their wanderings and breed at different seasons.  Winter belongs to the bonin petrels, the black-footed albatrosses, and Laysan albatrosses.

Blackfooted albatrosses dancing, Laysan Island.  Photo: J. A. Gervais, 1992.

The albatrosses were mostly quiet at first.  It must be very strange, to land on unyielding ground for the first time in nine months, and the newest arrivals seemed to suffer from the same "sea leg" syndrome that people do.  They wobbled around and studied the clumps of bunchgrass and their neighbors in silence.  But as the few birds swelled to thousands, the singing and dancing began in earnest.

Albatrosses dance.  These are spectacular dances, involving wild bows and snapping beaks, with some individuals becoming so excited they gape and scream, whipping their heads back and forth.  They whinny and moo and clap that huge beak.  Sometimes they throw themselves up on tiptoe and point skyward, with a soulful moan at the apex.  The black-footed albatrosses have a different dance than the Laysan albatrosses, but both dances are exotic, energetic, and incredibly noisy.  Living on a colony numbering tens of thousands of pairs is like being in the middle of a demented barnyard.

Laysan albatross skypointing.  Photo: J. A. Gervais, 1992.

We quickly learned that young albatrosses were so anxious to get going with their adult lives that they would throw themselves into a frenzied performance if we just waved two fingers back and forth in front of them, mimicking the first moves of the dance.  When we failed to deliver the correct response partway into the performance, they would retreat hastily, looking flustered.

I tried coaxing a few of the pairs who settled into spots right around my tent into a cross-species tango.  These birds' mates had already arrived, and after a few passionate rounds of dancing it seemed that old ties were renewed well enough to get down to the business of breeding.  Waving fingers in front of these birds elicited a sidelong look.  The albatross would draw in its chin, that huge, hooked beak held down along its neck, and waddle emphatically away.  Sometimes interspecies communication is shatteringly clear.

Every now and then, a Laysan albatross and a black-footed albatross mate, and raise a chick.  The chick, however, is doomed to be completely unlucky in love, because its dance is stuck halfway between the species.  Nobody seems to want a partner who can't do all the right moves.  The vast majority of birds belong to one species or the other, however.  Nearly all find a partner and stay together for many years, renewing the relationship each autumn with the ritual of the dance.

Blackfooted albatross dance on Laysan Island.  Photo: J. A. Gervais, 1992.

I worked on Laysan for a magical four months, picking away at invasive grass that provided shelter for none of the birds, but crowded out the native bunchgrass that nearly all of them need.  Although the work was far from special, sneaking by sea turtles and monk seals, admiring the antics of boobies and albatrosses, and watching tropicbirds and frigatebirds engage in aerial warfare made even plodding over sand dunes carrying backpack sprayers full of herbicide the best job I ever had.

I left Laysan Island on a November morning nearly twenty years ago, and I still dream sometimes of the intense color of the sea, the enormity of the sky, and the noise of all those birds.  It was an early love, one you don't forget, even if you go on to fall in love with many other places.

Do we need the wild?

A friend threw out a question she was pondering, which in turn had been posed to her by another friend.  "Do we need the wild?" 

At first pass, I thought the real question is why we ask this question, because my immediate answer was absolutely yes.  We can only ask this question if we see ourselves as somehow separate from "wild", however we define it.  At its worst, the question betrays the extraordinary level of artificial separation a small percentage of humanity has been able to create, on borrowed time and stolen resources, from the natural systems that sustain us.  We can maintain it only briefly and at increasing environmental, social, and economic cost.  When viewed from this angle, the real question is how long can we keep up the charade.

Petroglyph, Olympic National Park, WA.  Photo: J.A. Gervais



However, the question becomes far more interesting and far more complex on further reflection.  The Wild is the world beyond the comfortable circle of light thrown around the campfire ring, the impenetrable and sometimes terrifying world that harbors gods, demons, and other spirits that are beyond our control and often deaf to our supplication.  We are a part of this Wild, certainly, but more as stepchildren watching deep rituals beyond our capacity to master or to understand.  This Wild is one we fear and venerate, the one we approach with intermediaries and sacrifices held out as flimsy shields to protect ourselves even as we seek it.

This Wild has largely been forgotten in a human world whose cultures are increasingly dominated by materialism and gratifying any immediate whims, where the idea of something larger, something out beyond our self-imposed fence of goods and gratification, has been exiled like some sort of childhood legend for which we have no further need.  Most of the time, until some catastrophe slips out of the darkness and across the circle of self-imposed limit, laying bare the belief that we are all we need.  War, natural disasters, sickness, and loss of those we love to things that have no purpose are windows back into the dark and dangerous world we cannot control.

Stone circle, Island of Arran, Scotland.  Photo: J.A. Gervais

What draws us outside of ourselves, calls us to any higher purpose or holds us to any greater standards that might require us to act directly against our own immediate interests?  What guides us to see ourselves as taking our place within the larger mystery, which holds both the inanimate earth and all of the life forces within it?

This is the realm of the spiritual.  Arguably, we need to acknowledge our ties to this dimension of our world just as much as we need to acknowledge our dependence on fertile soil, fresh air, clean water, and the other inhabitants of land and ocean.  We may find echos of the spiritual Wild in a church, or a temple, or out in the woods; what resonates within each of us is a function of our culture, our upbringing, our experiences, and is deeply personal.

Do we need the wild?  Do we need souls and the spiritual, the belief in something greater and more durable than ourselves?  The two questions are really one and the same.

Olympic mountains, WA.  Photo: J.A. Gervais

Road Kill

There are two more dead deer lying along the road that ends just a few miles from town.  One is a doe, probably pregnant, the other a young buck just out of rut.  Someone has stopped and sawn off the antlers of the buck but both carcasses remain in the ditch, apparently inaccessible to scavengers.  They are hardly visible from a car, and possible to overlook even from a bicycle, as the cold weather has prevented the usual tell-tale smell.

We think of roads as opportunities for our own rapid movement and convenience, if we think about them at all, not the ribbons of death that wind through the home ranges or migration routes of many animals.  Stand at a rest stop along a busy interstate and see how many seconds pass in which there are breaks in traffic from one side of the highway across all lanes to the other side.  Not surprisingly, research has shown that roads can be major obstacles to animal movement.

How much roads cut off movement depends on not only the traffic load but the animals themselves.  Some animals such as urban gray squirrels seem almost oblivious to the traffic despite the risk and frequent near-misses.  There are video clips of urban wildlife using crossroads and even apparently waiting for lights to change before they cross.  They include deer, gray squirrels, coyotes, and Japanese crows.  The crows, of course, can easily fly over the traffic, but it seems that some of them have figured out that if they drop nuts into the crosswalks, cars will run over them, and the cracked nuts can be retrieved when the light changes.  These animals have adapted to live in the new world we've created for them.

But the vast majority haven't adapted.  Desert bighorn sheep populations are already showing reduced genetic diversity in just four decades after interstate highways threaded among them, raising the risks of extinction for the now-isolated populations.  Cougars avoided two-lane paved roads although dirt roads did not deter them.  Both wolves and elk in the Canadian Rockies avoided roads and trails in national parks as their traffic increased, but elk were less repelled and actually used the areas near moderately busy trails as predator-free zones because the wolves appeared more sensitive to the disturbance.  There are gradients in responses, and consequences.

At the other end of the spectrum, freshwater turtles don't seem to recognize the danger.  Turtles moving between two wetlands in Florida were willing to attempt to clamber over a barrier made of plastic netting to cross the busy highway separating the wetlands; nearly all those that succeeded were killed.  Populations of turtles near roads have a sex ratio skewed towards males relative to populations away from roads. More dead  female turtles are found on roads than males because the females are driven to leave the safety of water to find nesting sites.

The biggest issue may not be just the body counts, as staggering as they may be (upwards of 350 million wildlife deaths per year in the United States).  The worst thing about road kill may be what it reveals about our own fundamental thoughtlessness.  We are the one species that seems able to contemplate killing in an abstract way, evaluating the moral and ethical consequences of taking another's life.  The vast majority of us would not describe ourselves as careless killers, and would claim to avoid causing senseless death when possible.  Then we get into our cars.

The speed limit on the road with the dead deer is fifty miles an hour.  Every branch of this winding road ends a few miles farther into the hills, serving an exurban bedroom-community development.  People claim to like living in the country because they enjoy nature, but nature had better not get in the way of easy access to town.  Of course, very few wildlife-vehicle collisions occur on purpose; after all, people are often also victims of severe injuries or death when large animals like moose are involved.  But nearly all animals that are hit die.

When animals die of natural causes besides predation, they tend to die in places where scavengers can get to them, so that the occasion of death is also an occasion for the continuation of other life.  One of the elements of roadkill is its wastefulness, because the traffic may prevent scavengers from at least cleaning up after our carelessness.  Worse, other animals may be attracted to the bounty then also die in traffic.  This is only one aspect of the particularly repugnant facets of road kill.  Another facet is its anonymity, with neither killer or victim aware of the other.  It is the ultimate in thoughtless take.

The vast majority of victims are not ever seen before being hit, especially if they are low to the ground and cryptic, like snakes, lizards, or salamanders.  It is easy to ignore the carnage if you never see it, easy to believe that you don't contribute to it, easy not to think about it at all.  What if we did think about it?  What if seeing a dead animal, even a snake or a slug, required a moment of reflection and grief?  We would have to slow down enough to see the corpses.  If we slowed down, there would be far fewer of them.  That would be one benefit.  The process of acknowledging the losses might have a far greater benefit, that of helping us recognize our own place in the scheme of life, the first critical step to salvaging our planetary home.

Tale of Two Skinks

There are two edges to the sword of change that is slicing through so much of the biological skin of our planet.  The first is the staggering loss of biological diversity, adding up one of the great waves of extinction in Earth's history.  Along the trailing edge, ecosystems and the species that evolved in them are under increasing pressure from species new to the system.  We pay a lot of attention to the problem of extinction, but much less to invasion, even though it can and does contribute to the former.  It is perhaps a bit easier to rally to save a charismatic species such as a panda rather than organize to fight the diffuse threat posed by signal crayfish or purple loosestrife or kudzu.  However, scientists have started asking why some species become so destructively overabundant even though close relatives may be on an endangered list. 

Behavior alone won't dictate success.  Species that establish in new places also tend to be introduced over and over,  increasing the odds that eventually, a few individuals will survive the initial colonization event.  This in turn may be dictated by who lives where the most common transport routes start.  However, individual behavior seems to play a larger role than we expected.

Kudzu consuming a barn in North Carolina. Photo: NASA

If you want to successfully colonize a distant planet, you might consider taking a close look at how this works right here at home.  First, you've got to get yourself on some kind of transport vehicle, whether in the gut of another animal or the hold of a trading vessel or cargo plane headed elsewhere.  Realize you're probably not a welcome passenger, so you've got to be discreet.  You have to survive the journey, which means somehow finding or maintaining conditions in which you can live, with enough water, warmth and energy to avoid death.  Once you arrive, you need to sneak out of the way lest you be caught in the act and exterminated.  Very few stowaways make it this far, but the journey isn't over yet.  You need to find appropriate food, water, and shelter in these new, unknown surroundings.  Eventually, you need to reproduce successfully, which means you need to find, recognize, and successfully interact with a mate.  Next, your children must also raise children.  The resulting little community must avoid being found and eradicated, and finally, new colonists must leave and establish more communities before the invasion can be considered a success.

The odds, in short, are heavily stacked against you.  However, even if animals don't get help (in the form of deliberate introductions by people, such as starlings in North America, cane toads in Hawaii and Australia, or possums in New Zealand), some species still manage to pull it off.  We've just started to think about how animal behavior influences the risk of successful invasion.

Delicate skink. Photo: Peter Robinson, Museum Victoria, Australia

The delicate skink, Lampropholis delicata, and its cousin the garden skink (Lampropholis guichenoti), illustrate the point.  The delicate skink is native to eastern Australia, but has managed to colonize New Zealand, Hawaii, and Lord Howe Island.  The closely related garden skink, however, has stayed home even though it is quite similiar to its more adventurous cousin in many ways.  The two skinks are similar in size, have similar diets, and similar life histories.  Both species live together in urban areas in Australia, close to transport hubs such as major shipping ports and airports.  Both are common, and occur at high densities, suggesting no lack of individuals available for export.  What, then, is different?

Although both skinks like to explore new environments, the delicate skink was far more willing to move through a tube when it couldn't see the exit, enter a small black box in the test cage, and walk up a graveled ramp to reach a heat lamp suspended above the cage floor.  A greater willingness to explore, then hide, may explain a good part of why delicate skinks are called plague skinks while garden skinks have been at worst temporary tourists who never established outside their native range.  The opportunity to become a problem appears to be the same, but the behavior of the animals influences who takes advantage of that opportunity.

Garden skink.  Photo: Peter Robinson, Museum Victoria, Australia.

Not all delicate skinks successfully found the elevated basking site; animals, after all, are individuals.  Other research found that individual mosquitofish vary in their tendency to strike out for new horizons.  Interestingly, fish that chose to disperse also seemed less tolerant of other mosquito fish, and these personality traits were consistent in individuals over the study.  There may need to be a range of personalities and behavioral tendencies to support a successful invasion from start to establishment. 

We don't often think of the individuality of wild animals, or how much that might matter to the survival of a species.  If we were better at recognizing the individuality of non-domesticated animals, how might that change our view of them?



Sources
Chapple, D.G., S. M Simmonds, and B.B.M. Wong. 2012. Can behavioral and personality traits influence the success of unintentional species introductions? Trends in Ecology and Evolution 27:57-64.


Chapple, D.G., S. M. Simmonds, and B.B.M. Wong. 2011. Know when to run, know when to hide: can behavioral differences explain the divergent invasion success of two sympatric lizards? Ecology and Evolution 1:278-289.


Colautti, R.I., I.A. Grigorovich, and H.J. MacIsaac. 2006. Propagule pressure: a null model for biological invasions. Biological Invasions 8:1023-1037.


Cote, J., S. Fogarty, K. Weinersmith, T. Brodin, and A. Sih. 2010. Personality traits and dispersal tendency in the invasive mosquitofish (Gambusia affinis). Proceedings of the Royal Society B 277: 1571-1579.