Why raw bamboo shoots are a no no

I was sitting on a wet, slimy boardwalk watching tiny leeches inch their way up my mud-caked boots.
Huge trees loomed all around, their foliage heavy and dripping from a recent downpour. Dark clouds still pressed low, making the forest as gloomy as I was feeling.

The conversation didn’t help.

My companions were debating how long a species could remain unseen before it should be declared extinct.

There was good reason for both the topic and our despondency.

You see we were awaiting the impossible.


How did we get into this predicament? Well we’d clambered up this steep, slippery hillside, in the rainforest of Ranomafana National Park, in the hopes of glimpsing one of the world’s rarest primates. Critically endangered, the greater bamboo lemur (Prolemur simus) once frolicked across the entire island of Madagascar but today it clings on in just twelve isolated forest fragments. Fewer than 200 of the critters draw breath.



Ranomafana National Park is a 39,200 ha (96,900 acre) tuft of rainforest growing on the bald pate of eastern Madagascar. It was protected after a new species of lemur (the golden bamboo lemur) was discovered here in 1985.


We’d been shepherded up to this isolated spot by our park guide and his posse of ‘wildlife spotters’.
You see gawking at lemurs is big business in Madagascar and Ranomafana (home to 13 species) runs a tight ship.
When you rock up at the park you're allocated an (unexpectedly knowledgeable) guide, who specialises in visiting just one specific lemur group (of each of the common species). The guide's bevy of spotters race off into the forest to locate the beasts, while you saunter along the forest trails marvelling at minutia (bugs, frogs, chameleons, weird geckos, weirder tourists). Then a cell phone trills. ‘They’re found!’ With agitated hast the guide musters any stragglers and chivvies you off to do your gawking.



A minutia. The tree frog, Boophis viridis, or so I was told.

It could be a Martian for all I know.



Another rainforest skulker: a pitta-like ground roller (Atelornis pittoides). Ground rollers raise their families underground and are endemic to Madagascar.



Now I can’t deny that this system is efficient and lemur-friendly (any one lemur group is subjected to gawking for a limited time only). But it’s also surreal.

Lemur home ranges are small, so bands of gawkers are constantly drifting by, like ships in the night, and the forest echoes with excited cell phone conversations. And woe betide anyone who inadvertently stumbles across the wrong group of lemurs. You’re expected to avert your eyes shamefully and hurry on by.



The eastern grey bamboo lemur (Hapalemur griseus) is one of three species of bamboo lemur (also known as gentle lemurs) that call Ranomafana home.



So it was our guide who’d parked us beside a towering stand of giant bamboo while he and his posse sought our quarry. But before he left, he shared a few facts.

He told us that this group of greater bamboo lemurs was the ONLY ONE surviving in Ranomafana National Park.

‘You mean, it’s the only one tourists visit?,’ we suggested hopefully.

‘No, no. There is just one.’ 

We stared at him non-plussed.

He explained that the lemurs’ nearest neighbours lived 200 km (124 miles) away in a forest fragment on the slopes of the Andringitra massif.

Oh.

We asked how many lemurs were in the group.

‘There used to be eight, but when we last found them, there were only two left.’

‘When was that?’, a brave soul asked.

'Six weeks ago.'

Ahh.

We were still standing gob-smacked, mouths opening and closing like goldfish, when he and his team trooped off into the trees. Our dismay hadn't yet coalesced into cogent thought, so we didn't manage to holler,

‘Hey, why are we squandering our precious time in this park pursuing phantoms?!’

So we waited.

Miserably.

Now don’t get me wrong. Bamboo lemurs are worth investing time to see. They’re intriguing critters. With atypical accuracy, their common name really does reflect their tastes: they dine almost exclusively on bamboo, and giant bamboo (Cathariostachys madagascariensis) usually makes up 80-90% of their munchies.

The problem is, giant bamboo contains cyanide.

To thwart plant-nibblers big and small, many bamboo species stuff their tasty young shoots with taxiphyllin, a cyanogenic glycoside. When digested, taxiphyllin breaks down into deadly hydrogen cyanide. The bamboo’s branch shoots (which thrust up out of the ground like whopping asparagus spears) are the most heavily fortified; in giant bamboo they tote 15-40 mg of cyanide per 100g of shoot.
The lethal dose for humans is 0.5 to 3.5 mg per kilo of body weight.
Fortunately, cooking destroys the cyanide.
Unfortunately, lemurs don’t cook.

Lucky to be alive? If so, this eastern grey bamboo lemur is intending to waft the message to the world. It's smearing its tail with its own personal 'eau de lemur' from the scent glands on the inside of its wrists. 

No one knows how bamboo lemurs cope. They're the only primates to specialise on bamboo. Golden bamboo lemurs, who prefer to dine on the branch shoots, routinely guzzle 12 times the dose of cyanide needed to snuff out your average mammal. Researchers have found that the urine of all three of Ranamofana's bamboo lemur species is tainted with hydrogen cyanide (but their droppings aren't) showing that they really do digest and absorb the poison.

  


A golden bamboo lemur (Hapalemur aureus). Feeling a touch of indigestion?

    

Eastern grey bamboo lemurs sensibly favour bamboo leaves which are relatively low in cyanide. Tipping the scales at less than a kilogram (< 2.2 lbs), they're the smallest lemur to romp about by day.

For those of you fond of Asian cuisine, who might doubt the toxicity of the humble bamboo shoot, beware! Eight people keeled over in a well containing pickled bamboo shoots, blacking out instantly due to the hydrogen cyanide gas given off by the pickles. Two of the victims never recovered, their hearts having failed them entirely. Frustratingly, the research paper fails to address the most obvious question: what were eight people and a load of pickled vegetables doing down a well anyway? Although suspiciously mute about the veggies, the authors do allude to a ‘botched rescue attempt’.

But I digress distressingly.
Back to the rainforest.

We’d been sitting about despondently for around twenty minutes, and conversation had lapsed into a silent contemplation on the nature of loss (or the loss of Nature). We weren’t really listening to the surround-sound screech of frogs, cicadas and other unseen stridulators; in fact most of us were staring off – unseeing - into the eerie, primeval gloom. One of our group, glancing up at the huge bamboo thicket looming above us, said chirpily (in a transparent attempt to lighten the mood), ‘I keep expecting to see fairies or something suddenly pop out.’

And within a matter of minutes they did.

It started as a rustling overhead, and then a clump of bamboo canes swayed wildly as something dark clambered down among them. We snatched up our binoculars and jostled one another for the best view of the moving fronds.
OK, there was some fur...
Oh, and look a tail.
Yes, yes, they’re lemurs for sure... But what sort...?
Oh my God!

The impossible had happened.

Above our heads, the last two greater bamboo lemurs in Ranomafana National Park were nibbling bamboo!

About the size of small house cats and clothed in dark brown fur, they sinuously wound between the bamboo canes. One peered down at us, his bald nose and prominent grey ear tufts giving him a nutty professor look. As we watched, he began gnawing at the woody stem of a bamboo cane. Once he'd made a small hole, he clasped an edge of the wood in his teeth and pulled down a strip to reveal the soft pith inside. This he munched with enthusiasm. Greater bamboo lemurs are alone in using this part of bamboo plants.


Greater bamboo lemurs (Prolemur simus) specialise more exclusively on bamboo than any other lemur. This reliance makes them very vulnerable because bamboo is also coveted by humans. Used as scaffolding, it's often removed from forest remnants, even in protected areas.



Greater bamboo lemurs normally hang out in groups of 7-11 individuals. These two survivors are father and adolescent daughter.

About ten minutes after the lemurs had disappeared further up the mountainside our posse of lemur spotters trudged back. Sweaty and bedraggled, they shook their heads glumly, only to be greeted by an uproar of excited exclamations. As they peered at the images on our cameras, their eyes widened and smiles broke out all round; there was much back-slapping and laughter. I must admit that I was greatly heartened by their obvious delight and relief over the continued existence of their greater bamboo lemurs.

As we slipped and slithered back down the muddy track, we talked of our amazing good fortune in seeing these rarities. But somehow our elation and sense of privilege just wasn’t strong enough to lift the heavy, underlying despair. These creatures were almost certainly doomed.

I found myself wishing that I could give the good luck back; somehow pass the blessing over to the lemurs like a vial of golden Felix Felicis (Liquid Luck).
They were going to need every drop they could get.

Praying for a future?