The Invaders

By Thomas Urquhart
Photo: © Isselee | Dreamstime.com

Maine’s first EURASIAN COLLARED-DOVE spent the 28th at 51 Carroll Street in Falmouth. The bird was seen visiting the feeders here then spent the day roosting in trees around the yard.
— Audubon Rare Bird Alert May 21-28, 2013

Quick, Thomas! Rare bird alert!”

I had been at my desk polishing some prose when I first became aware of the clamor of voices off. More precisely, they were at our front door and had now been joined by my wife, Amy. It was she who called out.
Naturally, I dropped everything.

“It’s a really rare bird . . .right around the corner . . .it’s a . . .” Amy stalled and looked expectantly at our neighbor.
“A Eurasian collared-dove!” declared our neighbor proudly.

“I’ll get my gun!” I said.

Minutes later, though, we were driving slowly through a subdivision not far from our home in suburban Falmouth, looking for “a house with a bird feeder and a big tree,” according to our neighbor’s directions. And armed with binoculars, not guns. A couple of winters earlier we had scoured the same neighborhood for a yellow-throated warbler that had been sighted at someone’s bird table there. We were crushed to return “empty-handed” — and ecstatic to find the bird in our own yard the next day. It must have established a neighborhood circuit, because over the following weeks I could set my watch by its appearance at our feeder. Then came a February blizzard, and it appeared no more.

“Really, Thomas,” Amy reproached me as I scrutinized the passing yards. “You might have shown a little more enthusiasm. It’s the first Eurasian collared-dove ever seen in Maine.”

On the face of it, you would think a “first” (the dove) would trump a vagrant (the warbler) that, however rare, does pop up in Maine from time to time. So why was my excitement tainted by thoughts of avicide? When it comes to Streptopelia decaocto, I carry a long-standing grudge.

As a birdwatcher, I came of age in the English countryside during the 1950s without Eurasian collared-doves. When the poet Tennyson wrote of “the moan of doves in immemorial elms,” he meant the ringdove, or wood pigeon, and he might have been describing our village street. The memory of those comforting, deep-throated coos, punctuated every now and then by the clatter of wings as one rocketed into the air, is part of my childhood’s soundscape. Going off to college, I turned my back, as it were, on this pastoral idyll, only to find, when I returned a few years later, a nasal version in place of that noble sound. The village had been taken over by collared-doves. (The elms were gone, too, but I won’t blame the birds for that.)

Never mind that their call supposedly sounds like the Greek for “eighteen” (decaocto), which gives the species its scientific name. Even the bird-friendly RSPB (Royal Society for the Protection of Birds) calls it “monotonous”; “irritatingly” so, adds the judicious BBC. As if to upset the rural order still further, the collared-dove’s benighted cooing can be taken by the uninitiated for a cuckoo’s call; country weeklies, once confident in the letters of vicars and retired colonels upon hearing the first cuckoo each spring, had now to winnow out slews of earlier, mistaken reports.

How did all this happen? Early in the twentieth century, the Eurasian collared-dove — till then content with the warm grasslands and agricultural regions of Turkey and points east — began a resolute march — or flight — into the west. Seven hundred years earlier, the Mongols took a century to swarm over much of the same terrain, but the wild riders from the open steppe were stopped at the Balkans by Europe’s rugged geography. Not so the collared-dove. It colonized the whole of Western Europe in thirty years. According to the International Union for the Conservation of Nature’s Invasive Species Specialist Group, these birds typically become “viable breeders within two years of invasion.”

The first breeding pair in the United Kingdom was actually reported in 1956. There are now nearly 300,000 of them, according to the RSPB. And though the wood pigeon keeps a healthy numerical superiority, the much-loved turtle dove, a summer visitor whose numbers are declining, likely suffers from competition with its prolific collared cousin.

Could this be the shape of things to come in Maine? I wondered as the car crept along the suburban road like we were casing the joint. We soon spotted the bird, and its dispirited appearance made such a future seem unlikely. It looked like a cream-colored duster wedged into the fork of a tree branch; Monty Python’s dead parrot came irresistibly to mind. Only its eyes moved, feebly closing and then just as feebly opening again. Below, a chipmunk skittered after the seed being dropped from the feeder by a pair of house finches — themselves accomplished colonizers.

After several minutes waiting in vain for a little action from our bird, I began to feel self-conscious just sitting there. I could imagine looking out my own kitchen window and finding myself under observation by a plainclothes team weighed down with binoculars; and not liking it. Getting out of the car — in this case unnecessary — would have been worse. When a rare bird descends on the neighborhood, private property rights tend to evaporate before birders’ eyes as they prowl around backyards to get as close to their quarry as they can.

Which raises a tantalizing question, akin to the age-old puzzler about trees falling in forests. If a rare bird lands where no one can see — and report it — has its presence happened? Some accomplished birders swear that such an occurrence would be a rarity in itself; there is always someone there, they claim, to spot it sooner rather than later. I can just about get my mind around this trust in ornithological vigilance in a place like England, which is small, densely populated, and counts an unusually high number of intense birdwatchers per capita, the famous “twitchers,” obsessives ready to drop everything in order to sprint to the spot when and wherever a rare bird has been sighted.

But in Maine? Surely some straggling seabird could find a sliver of our 3,500-mile coastline sheltered from a telescope; or some passerine blown off course could alight deep in our millions of unpopulated forest acres. Inherently, I like to think that a healthy number get through under our radar.

There is another, more pregnant, question: when is a wandering rarity a “one-off,” and when is it the outrider for an advancing invasion? If Europe’s experience is any indication, the Eurasian collared-dove is likely the latter. And my romantic suspicion of our powers of observation could easily imply that the biologically crucial second collared-dove is already or will soon be here, looking for a mate and nesting site.

My musings all began to sound like a sci-fi program I used to watch, The Invaders. “For him, it began one lost night on a lonely country road. . .” a voice intoned as each episode opened. “Now one man knows that the Invaders are here. . . Somehow he must convince a disbelieving world that the nightmare has already begun.” As soon as we got home, I would do a little research.

I had already guessed that Maine’s first collared-dove was not exhausted because of a trans-Atlantic flight. I remembered watching a colony of the birds in St. Marys, Georgia, in the early nineties, while waiting for the ferry to Cumberland Island; and thinking it no more than a local curiosity.

Eurasian collared-doves made it to the New World about forty years ago, although not under their own steam. The consensus is that the “American” scion escaped from a breeder in the Bahamas in 1974. From there, the birds quickly colonized Florida, then expanded northwest in a swathe that soon reached the Pacific and up into western Canada.

Cornell’s Lab of Ornithology asserts that no avian species “has colonized North America at the speed with which the Eurasian collared-dove. . . has marched across the continent.” The range map shows only a triangle consisting of the Northeast and upper Midwest are still collared-dove free. Sporadic sightings across it indicate that the line is less than impermeable and is inexorably receding. Last year, the Audubon Christmas Count found them in thirty-two states.

Whenever a population of a single species explodes, one must be concerned about its impact on others. Just as, in Europe, Eurasian collared-doves may have had a negative effect on turtle dove populations, they may well compete with mourning doves here. Perhaps more seriously, they are known to carry West Nile virus. Again, their rapid expansion from regions with “abundant ornithophilic mosquitoes” (as IUCN puts it) could bring unanticipated health issues in their wake.

Remember the bit about being “viable breeders within two years of invasion”? Counting down from May 2013, Eurasian collared-doves will soon be a common sight in Portland. As it always has, human endeavor — on farms, in suburbs, in cities — will guarantee their food supplies. They’ll be able to raise four broods between March and October; in warmer climates they breed year-round. They lay two eggs per brood. You do the math. And watch how today’s Twitcher’s dream very soon becomes tomorrow’s trash bird.

Thomas Urquhart is a former executive director of Maine Audubon Society.  He is the author of For the Beauty of the Earth: Birding, Opera and Other Journeys.