03/25/2014 05:40 pm ET Updated May 25, 2014

Extinction at the Hand of Man

As someone who lives in the Bay Area, it's almost always on trips away from home when I find myself bumping into people who deny (a) that there's climate change ("what do you mean global warming, this is the coldest winter I remember"), (b) that climate change is a function of us (i.e., people) screwing up the environment, and (c) that climate change has accelerated the rate of extinction at an alarming if not apocalyptic rate. I was away from home just a few days ago and confronted once again by the sad phenomenon of people who confuse fact with theory (their argument was "Just because you believe the planet's getting warmer doesn't make it so"). As the result, I found myself thinking about pigeons.

Not just everyday pigeons which, I freely admit, I find to be as beautiful as they are plentiful. But rather the pigeons who are as good an icon as any for the role humans play in extinction. This is, of course, the passenger pigeon.

The passenger pigeon is not a victim of climate change. The species, now extinct, is however still a victim of those same two human traits responsible for climate change: human shortsightedness and head-in-the-sand denial.

Let the numbers tell the story.

In his book A Feathered River Across the Sky, Joel Greenberg writes that the population of passenger pigeons once "may have exceeded that of every other bird on earth", noting that as recently as the 1880s it was the most populace vertebrate in North America. Two decades earlier, in 1860, a naturalist estimated one flock to have been made up of 3,717,120,000 pigeons. That is 3 billion with a b.

You think the "common" grey pigeon is common? There are 260 million of them filling our skies and city streets. That means about 15 passenger pigeons for every common pigeon.

Today, there are 1,532 dead, stuffed passenger pigeons left on Earth. That's it. There are zero live passenger pigeons left.

The last one, Martha, died September 1, 1914, a sad and lonely animal, sitting without moving, alone on a perch, a caged wild animal confined in a zoo.

Passenger pigeons went from a population of 4 billion to zero in a matter of decades. They were hunted out of existence for their meat, their feathers, and just for the sheer joy of shooting lead into the sky to produce a corpse.

Such a rapid extinction was impossible not to notice and, interestingly, the fact of their extinction was equally impossible for people at that time to accept. Science magazine imaginatively reported that the birds had migrated to the Arizona desert, while others theorized relocation to Chile, Puget Sound, and Australia.

Nope. The fact was that an animal whose nesting grounds were so massive that one colony covered an expanse of land almost 40 times the size of Manhattan had, in a matter of a few years, but hunted to extinction.

One of the several sad things about denying the facts is that they catch up with you anyway.