Field Report to the Academy of Natural History on Evolutionary Behaviour
of Sciurus carolinensis

Why the squirrel crossed the road.

Posted: 1/28/04

We are in the middle of the peak months for squirrel road fatalities again. The body count is high. Small carcasses dot the asphalt. Ravens use these little grey road bumps much like social clubs, catching up on avian gossip and exchanging jokes while snacking on crêpe d’ asphalte. “Hey, know why the chicken crossed the road?….to show the squirrel it could actually be done!

A wet summer here in the east has caused the trees to convert most of their sun-produced sugars into growth as opposed to a hefty crop of nuts and berries.
This dictates that the common gray squirrel, Sciurus carolinensis, must travel further distances to gather acorns for the upcoming winter. There are those squirrels lucky enough to live in a territory uncrossed by pavement. Their evolution is left unchecked by human interference. Others are confined to territories where squirrel-v-tread tragedies are played out on an hourly basis. Their evolution is an ongoing process dictated by speed signs, tire width, number of axles and their own reaction times.

I have documentation that proves squirrels living in high traffic areas can be classified into three categories:

The Bold Crossers - Those who run across the road, totally indifferent to any threat.

The Shy No-Crossers - Those who, prior to setting foot on the asphalt, change their minds in the face of an oncoming automotive threat and flee in a direction away from the road. They are on the opposite end of the spectrum from the Bold Crossers.

The Indecisive Mid-Roaders - Those who change their minds while on any part of the street and reverse their direction (this group also includes those squirrels who zig-zag across lanes or run parallel with traffic while the decision-making part of their little brain randomly fires left-right, stop-go signals to their little legs).

To further our understanding, I began to tally these three groups to see if an underlying commonality could be deduced. For a period of roughly two weeks I classified 187 squirrel encounters as I made routine trips through town:

The Crossers/Group 1 - 129 squirrels or 68.9% of the sampleThe No Crossers/Group 2 - 49 squirrels or 26.2% of the sampleThe Mid-Roaders/Group 3 - 9 squirrels or 4.8% of the sample. **

** I personally ran over two of these. The first was a halfback (got halfway across and decided to go back) the other was a zig-zagger (far less common).

If you are a statistician or are familiar with standard deviations the percentages should be very familiar.
The population of Group 1 closely corresponds in number to the One-Sigma standard deviation grouping of 68.6% of a total population of 100%. Group 2 corresponds likewise with the Two-Sigma grouping of 26.8% and Group 3 corresponds with the Three-Sigma grouping of 4.6%.
From these numbers and my own personal observation it can be surmised that the Three-Sigma group is slowly and un-naturally being eliminated from the population.
In addition, the One-Sigma group is suffering a higher attrition rate than the Two-Sigma as the Two-Sigs, being asphalt shy, will not be found in any road fatality group (off-road fatalities are beyond the scope of this report). I would venture to guess that the vast number of squirrel fatalities were from the Three-Sigma group with a few from the One-Sigma group.
Trapping, tagging and observation is required to verify this hypothesis. I presently have a number of research grant applications submitted.

Tread-related fatalities are inducing genetic drift in the general squirrel population that counters 100 million years of natural selection based. Is not the unpredictability of a squirrel’s retreat its sole defense against predators? Is not the inability of a squirrel to decide which way to flee the single characteristic that saves it from death by jaws or talons?
It seems that the evolutionary roadmap is being redrawn to eliminate that group of individuals from which ancient squirrels obtained their best genetic material.
This has artificially induced an instance of Punctuated Equilibrium- that evolution occurs in huge and sudden jumps.

In past generations, being a Three-Sig squirrel placed you in the top echelons of the breeding population. You were a stud. You were a ‘playa’ in the squirrel hood. I can only guess how the Three-Sig label might translate to social interaction of squirrels in this generation.
Would it be a badge of honor or of disrepute? The Three-Sigma grouping of any population includes actually two groups: those on the very upper end of the bell curve AND those on the very lower end.
The fastest and the slowest, the heaviest and the lightest, the happiest and the saddest.
Putting it in terms of I.Q., the Three-Sigma sample of a population includes the 2.4% of the population that is in the genius range on the high end of the bell curve and also the 2.4% of the population that is in the comatose/brain-dead range on the low end.
This leads to an observation that directly applies to most any animal population:
Whether you are a genius squirrel or a squirrel who does not know which end of the nut to crack first, your average life expectancy will be the same bleakly low number.
Brains don’t count diddly.
Your longevity is inversely proportional to the distance your behavior lands you from the statistical mean.
In present times, inability to make a decision will increase the likelihood of getting flattened, of going from vertebrate to invertebrate in the squeal of a tire.
In the midst of traffic the genius squirrel in the Three-Sigma group - the Mr. Spock of the squirrel world - is logically deducing the safest course of action, all variables considered in the calculation, the instant it is run over. The stupid one, the Dumb and the Dumber, is just screaming wildly.
Yet, they both run identical patterns directly to their little chalk outlines on the pavement.

Squirrel age group must be a determining variable of social labeling. In all populations the youngsters equate danger with a positive labeling while the adults equate it with negative. I can imagine the juveniles hanging out on the power line one day.
One juvenile points to his erratic uncle on the pavement below and proudly proclaims: “MY Uncle Chip is a THREE-SIGMA”. All the other juvies go “Oooooooo” as Chip disappears under a car.
Or, when saying their prayers at night: “Bless Barky, bless Wire Runner, bless Grey Jumper….and please let me grow up to be a Three-Siggie so I’ll be cool and everyone will like me.”

Whereas the parents are saying in their nightly prayers: “…please watch over Little Grey Paws.
Make him a Two-Sigma.
Don’t kill him in some senseless nut-gathering accident.” I strongly suspect that there is remedial schooling for young squirrels identified through testing as being outside the Two-Sigma grouping.
Squirrel parents send their One and Three Siggies off to military convents for re-programming.
If the training is not successful, are the Three-Sigmas stigmatized as “…not the kind of material suitable for raising pups?” Are they pushed into lower social classes? I have observed and documented groups of squirrels spending their days eating fermented acorns and playing Black Wire Roulette at the local transformer.
“Come on Scruffer…one more nibble on the black wire…show us all you can do it……Bite! Bite! Bite! Bite! Bite!”

Do squirrel bookies handicap bets on street crossing based on a Sigma Rating of the runners?
Do the Three-Siggies earn higher odds? Can a shy Two-Sigma squirrel be intimidated into throwing a bet? “Gee…..he bolted….and didn’t make it across.
The racing sheet says he was a Two-Sig non-crosser but you know these numbers can be wrong sometimes.”
Is there a wall of honor in some hollowed-out tree in some ancient forest where the engraved names of all past Three-Siggies hang on little wooden plaques?
The St. Andrews of tree dwellers?

I came across an anomalous squirrel the other day that defied any label I was familiar with.
The I-240 Loop around town is one of those brainchild highway projects that is the product of an over-funded State Transportation Department. An eight-lane highway befitting Los Angeles complete with a wide landscaped median that skirts a town of only 70,000. A line item in a bloated budget of years past.
Since the drive time across town is roughly 13 minutes any way you go, building 240 was equivalent to putting tits on a Winnebago.

So, here I was driving down I-240 and about 20 car lengths ahead I spot a squirrel sitting directly atop the white-striped line in the middle of the four southbound lanes.
As I bore down on it at 70-miles per hour, I could see that it was standing on its haunches staring directly into oncoming traffic. It’s tail was whipping back and forth with every passing car, but It was not moving an inch.

There is a term used by those who pursue dangerous past-times for the sake of self-gratification.
This term applies when one achieves a milestone of bravery or endurance in an anonymous manner.
The term is ‘Silent Glory’.
Prior to Sir Edmund Hillary and George Mallory, there was George Ingle Finch. He took to the top of Everest just to “…have a good walk…it keeps me out of the bars and the Missus happy” and made it to 27,000 feet (1,128 feet short of the top). He wasn’t into the climb for the fame and fortune but for the personal goal and didn’t care if anyone knew about it. After Finch was Edward Norton and Theodore Somervell, two Englishmen who repeated the feat but without supplemental oxygen. “Oxee-gen? Wha’s thot???” They were purists.
Perhaps this squirrel standing in the middle of four lanes of oncoming interstate traffic was the George Ingle Finch of squirreldom. The one squirrel out of the entire worldwide population who stares down four lanes of oncoming traffic FOR THE SHEAR JOY OF DOING IT. Unannounced personal gratification. He keeps the accomplishment to himself.
Forever un-rewarded by his fellow squirrels. Basking in solitude in the warm glow of Silent Glory atop his own personal Everest.
I tipped my hat as I sped by this little warrior.

Sir, I will keep your secret.

You cannot apply a ‘Four-Sigma’ label to a squirrel like this because Four-Sigma does not exist.
It’s like saying “One-hundred thirty-two and a half percent”. I can only suggest that this squirrel was a penultimate example of Punctuated Equilibrium- an evolutionary discontinuity.
A genetic anomaly where a road crossing decision matrix was not included in it’s genetic soup.
It represents the beginning of a branch in the evolutionary tree where one’s remaining on the painted centerline is based solely on hedonistic gratification. As his genes spread through the general population, shall we be seeing his offspring duplicating this feat? Will there be little grey ones sanding casually in formation to face the morning rush hour? Will they be mowed down like dominoes, only to be replaced by their fearless progeny?
It is entirely possible.
Genetic anomalies of no consequence or sensibility have become common in some isolated populations of Sciurus carolinensis. Case in point:

In Transylvania County in Western North Carolina (yeah, it is actually called Transylvania just like the Dracula movies), there exists a small population of squirrels isolated by mountains on all sides that have defied laws of natural selection.
Their genetic mutation makes the fur of these squirrels white (Don’t believe me? Do the web search). They are not albino squirrels, but common gray squirrels that grow white fur.
Now explain to me how this white fur provides an advantage in predator avoidance or reproduction, the two primary determinants of an evolutionary step. Evidently, human success at destroying birds of prey that would use this defect to their advantage has played a major part.
A white squirrel wandering across a front yard on a summer’s day might as well have a ‘Very Tasty and Slow’ sign taped to its back for all hawks and owls to see. White fir is definitely classified as a three-sigma event. It is off to one side of the bell curve as much as pink fir with orange polka dots would be.
I hiked around Transylvania County for a few years trying to find one of these illusive white squirrels, but to no avail. I heard about them from friends while sipping scotch at cocktail parties and read newspaper articles describing huge populations flourishing in the hollows and ravines of the mountains. Trees turned white with the critters, branches bending under the weight.
I never saw one in the flesh.

Then one day I was lucky enough to spot one after picking my child up from a friend’s house.
This white squirrel ran unfazed across all five lanes of a state highway. One-Sigma (behavior) Three-Sigma (coloring).
Think about it for a second.
What is the statistical probability of seeing a One-Sigma WHITE squirrel on a road in action after not having spotted ANY white squirrels while hiking their territory for the previous 5 years?
The odds have got to be about zero in minus two. Yet, there it was for a few fleeting moments. It took a few seconds for me to realize I had actually seen a squirrel because my first impression was that I had seen a very fast ferret.
It was highly unusual, but I have to point out that there is one occurrence that is statistically less probable….observing a THREE-SIG THREE-SIG (Three-Sig squared???) run a five-lane gauntlet AND LIVE. This could quite possibly be The Holy Grail of amateur zoology for those of us who are keen observers of squirrel behavior. A Three-Sig Three-Sig is an event I may not observe in my lifetime, but I do keep up hope in the possibility that fate will fall in my favor.

I shall continue to make accurate scientific observations related to the genetics and behaviour of Sciurus carolinensis and submit regular field reports to the Board of The Academy for publication and open debate.

Yours Humbly,

L.G.A. Manofsky Esq.


Copyright © 2002 SLM. All rights reserved.