Hard to tell from this angle whether these Kentuckians are decided or un. (Darrin Phegley)

They once covered the landscape, darkening the skies with their wings, tinting entire states purple as they flocked together.

But their ranks are thinning.

First the Mohican, the passenger pigeon and the buffalo. Then the AOL subscriber. Now, the undecided voter.

In 2008, the majestic undecided voter looked resurgent. Their numbers increased. They seemed healthy. Some of them mated and started families. Poll-watchers everywhere breathed a sigh of relief.

But the trouble with undecideds is that any time their numbers increase, the poachers return. They are so much more attractive and glamorous than voters with established preferences. Those can be taken for granted and mobilized with the flick of a finger when the time is ripe. But the undecideds! Cruella de Vil never pursued her quarry with such single-minded ardor. Campaigns were willing to litter the roads with glittering policy positions and celebrity endorsements to attract a single undecided voter. They, after all, were the ones who ultimately settled who would win in tight races.

And what could they do against such an onslaught? After the election, as belts tightened and unemployment climbed, their numbers fell. This, experts long trained in the observation of the undecideds said, was only natural. A seasonal pattern, like the thinning of the herds of deer with the approach of winter.

But now, with their numbers once more taking a sharp descent, observers fear the worst. They are at 3 percent — according to a Wall Street Journal/NBC poll — or at most, 5 — a horrible drop since 2008, when they comprised 12 percent of the voting populace.

Perhaps this should come as no surprise. We are more polarized than we have been in a while.

There are all of six or seven undecideds still remaining in the wild. The rest reside in small preserves in swing states, where you can visit them and gently extend incentives to them through the bars of the enclosure. Some of them are even moderates.

But their habitats are in danger. Kansas is turning redder and redder as we sit here, growing too hot for undecideds to thrive. Virginia, once the home of many an undecided voter capable of swinging either way, has seen a decimation of its former population. The GOP director there told Politico that there may be a scant 2 percent left.

Americans everywhere are victims of a creeping certainty. Polarization does not happen overnight, like bubonic plague. It comes on you by degrees. One morning you awaken with the sudden conviction that you are right about something. And then it spreads.

You switch to a television station that concurs. You buy an opinionated T-shirt. You begin to lecture your grandchildren. You ignore facts from people with whom you disagree and start sending them lengthy articles from unverified sources confirming your darkest suspicions.

Then you get a bumper sticker, and it is all over.

Something must be done.

The undecided is a beautiful, traditional American species, like the bald eagle or the newspaper subscriber, and they deserve our support. They hold together our ecosystem of national discourse, keeping us civil and occasionally even focused on the issues. Eliminate them from the equation, divide the world into people who agree with you and need to be louder and people who are wrong and need to be silenced, and Mother Oak weeps and everything begins to crumble.

That’s why your pledge matters so much. Fight the polarization! Protect the vacillators! If not for ourselves, then for our grandchildren, so they too can witness an election not decided entirely by which team can muster the largest showing of people who already know what they think about everything.

We are not there yet. By the next cycle, things may bounce back. This may be only a seasonal dip.

But just in case, please, give what you can. There is still time to save the few who are left, even though they are increasingly reclusive, skulking away from television sets and pollsters and hissing.

As the campaigns move away from hunting them, seeking unmotivated voters within their own ranks, the population may recover. So please, keep an open mind and give what you can, that these thick purple herds may once more carpet the landscape.