Rabbits make life hell for penguins, seabirds

The World Wildlife Fund warns that a population explosion of rabbits is threatening a remote Australian island’s seabird populations. That’s right, rabbits. We Americans think of them as cute, harmless long-eared friends that occasionally lay chocolate eggs or hybridize with antelopes. But in That Other Hemisphere, they are threatening a 4-million-strong seabird colony using little more than those sinister buck teeth.

Seal hunters introduced rabbits to Macquarie Island around 1880 (presumably because they were tired of eating seal). By 1960, scientists were calling rabbit grazing “catastrophic” in the Journal of Ecology and warning that if left unchecked, the rabbits could chew their way to major landslides. That’s because the dominant grasses had roots strong enough to collect several feet of peaty soil and hold it in place on steep slopes. Once those roots died, the scientists warned, the soil would slip.

Rabbit numbers had reached about 10,000 by the 1980s, and there was nowhere to go but up. Macquarie reached the 100,000-rabbits mark in recent years. And now, the World Wildlife Fund and Reuters report, the land has started to slip – 20 slides in the last month. Right down onto the nests of thousands of breeding albatrosses, petrels, and royal penguins, not to mention about 100,000 momma and baby seals.

The Australians are suitably concerned — one researcher has called for a $10 million rabbit-riddance campaign (large vacuum cleaner, perhaps?). But it’s interesting that even in the 1960 article, the authors noted that once the grass dies and slips begin, they will be hard to stop.

It’s a familiar arc – a population starts small on an idyllic patch of ground, uses God-given gifts (in this case, excellent nibbling skills) to get ahead, slowly goes from thriving to burgeoning, and eats up all its surroundings. At which point the island falls in on itself, chucking the rabbits into the cold Southern Ocean along with most of the other species that live alongside it. Sound like anyone you know?

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Has the climate change point finally tipped?

There’s been mounting evidence, since last year’s alphabet-depleting hurricane season, that the public are finally starting to get climate change. And that includes not just feeling sheepish or helpless about it, but even being interested in learning more about it.

Al Gore’s personal best in communication is still in some theaters around the country. Better yet, its success has inspired Regal Cinemas to run another climate change documentary in wide release.

And now, the icing on the cake (is that a bad choice of words?). Nature runs a paper refining the details of ocean circulation 50,000 years ago and it’s promptly covered by the South Asian Women’s Forum. Right between the stories on record-breaking fingernails and why blondes have more fun. I’m impressed.

They don’t shy away from the details, either. When was the last time you read a news item that contained jargon even half this thick: foraminifera, Dansgaard-Oeschger events, intertropical convergence zone, subtropical gyre?

You can’t explain it as covering the authors, either: neither researcher named in the piece is a woman, let alone a South Asian one. It must be that someone high up in the South Asian Women’s Forum corporate suites believes that their readers are interested in climate change. Hurrah!

The research itself sounds interesting, too, since it seems to counter the prevailing notion that adding fresh water to the North Atlantic can weaken its currents, causing less heat to escape into the atmosphere and making Europe colder. (This is what made Dennis Quaid snowshoe across New York in “The Day After Tomorrow” – remember?)

Today’s Nature paper says the opposite – sort of: that the North Atlantic was saltier during cool periods and fresher during warm periods. But in a neat bit of thinking, authors Matthew Schmidt, Howard Spero, and the only-slightly-South-Asian-sounding Maryline Vautravers suggest this saltiness built up during the cool periods and primed the climate to snap back out of its cold phase (how this works). They chalk up the saltiness to reduced rainfall in the North Atlantic due to changes in the aforementioned intertropical convergence zone. Dang these climatologists have big brains.

The whole story is quite satisfying to me, because the hardest part about buying abrupt climate change has not been accepting such a far-fetched scenario, but realizing it must possess a logical twin: some equally but oppositely complicated explanation about how things are set straight again. A twin that someday, someone is bound to introduce me to, and I will then have to try to both comprehend it and keep drool from collecting at the slack corners of my jaw.

I’m kind of relieved that this one is so simply derived from plain-as-day differences in the amounts of rare elements sequestered in the shells of millenniae-old microscopic plankton.

But then again, what do I know. We should get comments from some actual expert like Mea Cook. It’s a pity the South Asian Women’s Forum didn’t.

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Schrodinger’s woodpecker

The world at large has been enveloped in another fracas over the being or not-being of the ivory-billed woodpecker.

The story to date: (OSHA notice: this summary forgoes the religiously overtoned nicknames of the bird out of sheer nausea at their overuse.)

The ivory-billed woodpecker (is/was) a big black-and-white woodpecker with a gleaming pale hatchet for a beak and a voice like Mike Tyson. It lived in the cavernous swamps of the Southeast where it dug into rotting trees to eat beetle grubs – big, squishy things about the size and consistency of a ClifBar goo shot. Up through the 1940s, nasally “kent” calls, double-raps, and the sound of the great stripe-necked beast beating up on crows echoed among the tupelos and the titi. But hardwood prices and unfettered logging caught up, and for the last half of the twentieth century there were no ivory-bill sightings that didn’t start with “No shit, I seen this big sumbitch up off the shed goin on like Woody Woodpecker.”

But in 1999 we got the first of the Ivory-billed Visitations. An LSU grad student saw one while he was turkey hunting. His story was sanctioned by LSU’s own Van Remsen, curator of their museum and veteran of many a weird-bird story from his collecting days in Latin America. Birders descended on Louisiana like waxwings on mountain ash berries, and no one saw anything beyond white wing-edges and big holes in trees.

In 2004 came the second Visitation, with a similar story: a civilian report anointed by an actual ornithologist. This time, they were smart and sat on the story until they got conclusive proof — because how hard can it be to photograph a large, nonmigratory woodpecker known for prominently clinging to trees? Now perhaps the one thing we can be sure of is the absolute absence of ivory-bills from that particular patch of woods.

And now, the third Visitation, from North Florida. This time the story is even the samer: ornithologists in kayaks, a big woodpecker flying the wrong direction, a secret, six-month stake-out, audio recordings and brief sightings. Only this time it’s Geoff Hill, of Auburn University, and Dan Mennill, of University of Windsor, an ex-postdoc of the Cornell Lab of Ornithology.

Hill is an established behavioral ecologist who studies, among other things, house finches and the meaning of plumage color. On the face of it, he doesn’t have a lot to prove by shouting “me too!” while the Cornell reports get older and colder. Especially with a storehouse of critics and skeptics out there in the blogosphere with their knives out.

The skeptics, Tom Nelson perhaps the most vocal and (initially) well reasoned among them, have a good point: We’ve looked enough; why haven’t we turned one up yet? Why has the evidence gotten worse and more scarce, instead of better and better?

Excuses about the impenetrability of the swamp don’t hold up. We’re talking about birders here: single-minded twitchers with sharp eyes and space-age glassware who tramp across the Aleutians and have no trouble turning up exceedingly rare, dull-brown birds from Siberia as they hide behind large pieces of sleet.

And yet, the paradox is that that’s precisely the argument in favor of the ivory-bill’s existence. We are talking about a large bird with several very prominent field marks and a long history of ridicule being heaped on misidentifications.

The trouble with these debates, like any conspiracy theory or alien abduction story, is that the debaters quickly settle into the camps of believers and doubters, and the argument goes from contentious to snide. Rebuttals veer toward flat denial, and people start taking the whole thing personally.

I’m a skeptic myself. But the whole phenomenon – particularly Hill’s claim – is fascinating, if you step aside from the assumption that somebody has to be lying.

I can’t understand why no one’s gotten a picture of an ivory-bill yet. I myself spent three years blithely videotaping black-backed woodpecker nests at ranges close enough to identify the insects the baby woodpeckers ate. Woodpeckers just aren’t your classic wary, lost-in-the-foliage birds. Cornell’s conjecture that the only ivory-bills to survive the late twentieth century were the quiet, skittish ones — essentially, that ivory bills have recently evolved to be unseeable — is intriguing but self-serving.

Still, we’re talking about real people with real expertise and real consciences. So what do these recent, credible sightings actually mean? Are southern bottomland forests recovering the way the northeastern forests did after the decline of farming? Have ivory-bills developed some kind of mega-dispersal instinct so that you can never find them in the same place two seasons in a row? Were all those yokels talking to park rangers about Woody Woodpecker really right? Or is there some budding subspecies of pileated woodpecker with diabolically aberrant white wing patches?

Which brings me to the last reversal of the paradox: Birders weren’t any worse in the 70s and 80s than they are now. And people did follow up ivory-bill sightings then, too. So if we’re envisioning small populations persisting all over the South, why are we only just now getting shaky sight reports backed up by shaky sight reports? The woodpecker seems to exist only as long as you’re not looking for it.

Or is it really an environmentalist plot to shield perfectly good strip-mall and airport sites from the development that God intended for them? Perhaps the best answer is that the ivory-billed woodpecker both exists and does not exist, at least until such time as we cut down absolutely all of the trees and demonstrate, once and for all, that it is gone.

Thanks for reading; I’ll return to a mercifully short format next post.

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