February 2, 2013

Allen Afield: Wild cards aplenty in process of natural selection

By Ken Allen

Recently an Internet post describing a "snow tale" reminded me of similar winter incidents that I have noticed in life, "written" in this wonderful tracking medium.

Snow reveals myriad stories, even to casual observers. The 'Net anecdote mentioned evidence of a woodland event that a poster observed during a hike -- scattered grouse feathers and blood smudges on white.

However, the writer made my eyes roll upward when he used "survival of the fittest" and continued that the grouse lacked the intelligence to evade predators. To this man, a dullard prey specimen provided protein, while more acute grouse sneaked off to raise furtive offspring.

True enough to a point, but often observers miss the obvious: Intelligence offers no guarantee that prey will escape predation.

Dim-witted animals may survive predators and reproduce, particularly when predator populations periodically plummet or luck intervenes for prey.

The most efficient, omnivorous predator may die from starvation, particularly when natural causes such as adverse weather events or disease lead to a prey or forage-plant shortage.

Two other details about the nature passage on the 'Net bothered me:

First, the author didn't mention what had killed the grouse. Heavier predators like foxes, fishers or good-sized birds leave tracks on snow, easy enough to identify. Also, no tracks may indicate a smaller bird of prey or fatal crash, say with a limb.

Second, and more egregious to me, the writer's understanding of "survival of the fittest" hadn't progressed much beyond third-grade science.

People attribute "survival of the fittest" to Charles Darwin, but Darwin used "natural selection," as seen in this quote: "As natural selection acts by competition, it adapts the inhabitants of each country only in relation to the degree of perfection of its associates." Herbert Spencer, a 19th-century contemporary of Darwin, popularized the less accurate survival-of-the-fittest catch-all to describe nature's scheme.

Darwin claimed that competing species thrive in nature. As predators hone skills at catching prey, the latter also improves its talents at evading capture. The result of natural selection ensures predator and prey coexist with both sides winning and losing, but flourishing.

In northern Maine, market demands influence woodcutters to destroy mature conifers, robbing deer of dense canopies that protect against winter cold and keep snow shallow beneath the "evergreen-thatched roof." Declining winter habitat threatens to extirpate the species in regions.

Also, as declining winter cover pushes deer into fewer deer yards, coyotes can target them so well that deer populations in parts of northern and eastern Maine won't recover in our lifetime.

At the Sportsman's Congress 15 years ago, Gerry Lavigne, a deer biologist, claimed that deer could survive coyotes much better with proper winter shelter. After all, Maine whitetails once survived timber wolves just fine.

To change the subject without research aids, casual observers lack data to formulate conclusions. A quick anecdote:

In the 1980s, my setter and I were hunting in New Sharon and came across a story in snow. A grouse had walked into an abandoned orchard to feed, common behavior with this species.

Obviously a coyote had heard the grouse, determined the bird's exact approach trail and hid in ambush behind a grass clump, where the predator had patiently waited and captured its meal.

At first, I surmised that coyotes commonly used this tactic, but since then I have walked in many abandoned orchards with snow cover and have never seen evidence of this hunting technique again. Apparently, natural selection hasn't led to coyotes in the lower Sandy River valley to perfect this skill, but a layman such as myself lacks data to form a definitive conclusion.

My one abandoned-orchard grouse proved nothing about this species' long-term behavior, and neither did the pile of feathers at the beginning of this column show a definitive rule about the predator-prey equation -- other than an unnamed predator or random accident had killed a grouse.

After meticulous, specific, random observation, Darwin formed conclusions about general principles in the natural world and became a household word. Casual observers without ample data often lack enough specifics to form an earthshaking observation. Another point: A mature thinker like Darwin found more joy on the assiduous road to judgments than he did after arriving at his destination. The key words are "mature thinker."

Ken Allen, of Belgrade Lakes, a writer, editor and photographer, may be reached at:

KAllyn800@yahoo.com

 

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