Posts Tagged ‘Bocas del Toro’

Ecologist at large

June 23rd, 2009

When I was at university, involved in the cutting-edge discipline of sponge classification, I regarded ecology as “soft” science, suited to those who lacked the intellectual molars to chew more demanding meat. Ecologists, I liked to think, were the ones Mark Twain had in mind when he wrote, “There is something fascinating about science. One gets such wholesale returns of conjecture out of such a trifling investment of fact.”

Candy Feller and team exploring a new river.

KENNEDY WARNE
Candy Feller and team exploring a new river.


Now I think differently. Ecology is about getting the big picture. And today, with the extinction rate in overdrive and ecosystems in crisis, how sorely humankind needs that perspective. Candy Feller’s CV calls her an insect ecologist, but this really means she’s interested in everything that has to do with an insect’s world of interactions, which is a wide world indeed. Tracking those interactions may entail analysing the sugar content of flower nectar or making aerial surveys of mangrove deforestation as much as it involves slicing open twigs to see what’s living inside.

Candy is part of an ecological subdiscipline called biocomplexity, the study of the mechanisms—physical, chemical, biological—that determine ecosystem structure and function. She came to mangrove ecology in an unusual way. She was a scientific illustrator, and was assigned to draw the underwater component of a mangrove ecosystem. Actually to draw under water, using waterproof materials and a scuba tank.

Pelliciera reflections.

KENNEDY WARNE
Pelliciera reflections.


She found she liked mangroves. They reminded her of the rhododendron forests of her youth—the feeling of being enclosed and embraced by nature. These days Candy lives in Maryland, but at heart she’s a Carolina gal. I asked her what her favourite southern comfort food was. “Squirrel,” she said, without missing a beat. When she was little she and her brothers used to go out and shoot squirrels for breakfast. It was pretty much a no-brainer to find out she liked bluegrass music as much as I do. We swapped stories—I’d backed Emmylou Harris on a New Zealand TV show; she’d met Gid Tanner of the legendary Skillet Lickers. Then she opened up the iTunes playlist on her laptop and we spent an hour getting high and lonesome on four-part harmony.
Candy and Anne Chamberlain team up to trap tree crabs lurking in liverworts.

KENNEDY WARNE
Candy and Anne Chamberlain team up to trap tree crabs lurking in liverworts.


When she retires she says she’s going to work on a plant called Jack-in-the-pulpit, which was found recently to be pollinated by thrips. She finds that an interesting interaction—thrips are normally thought of as pests, not beneficial pollinators. “I don’t want to publish, just to know,” she says. “I like the idea of pushing my walking frame into the garden and studying wildflowers.”

Watching Candy in the field, I’m pretty sure the walking frame is a long way in the future. By midday I’m wilting in the heat, with Noel Coward’s lyrics about mad dogs and Englishmen running through my head, but Candy, mud-spattered and sweating, presses ahead with the work. She doesn’t miss much, either. Today she found a fish I had been hoping to see: the mangrove killifish, or Rivulus. It was swimming in a shallow puddle in the Pelliciera forest, darting down fiddler crab burrows when it was disturbed.

We bought the sweetest pineapples I've ever tasted from these paddlers passing our research site.

KENNEDY WARNE
We bought the sweetest pineapples I've ever tasted from these paddlers passing our research site.


Rivulus is the only known vertebrate capable of breeding without a mate. It can develop male and female sex organs and fertilise its own eggs. What’s more, it can breathe air through its skin, like a frog, and one specimen spent 66 consecutive days out of water, living in a hole in a tree. The fish’s ability to survive out of water comes in handy for Rivulus researchers, Candy said—they swap live specimens through the post.

When the field work was over for the day we explored a new river system. We passed groves of Pelliciera where the buttress roots and their reflections produced rows of diamonds at the waterline. Candy stood in the bow of the boat, surveying the forest, enthusing about the epiphytic orchids, wondering out loud why the Pelliciera on this coast seem to reach a certain height and then stop growing. The birders in the group had eyes only for trogons, toucans and other avian exotica, but I suspected that Candy’s mind was on the mangroves, pondering how they fit into the complex ecological pattern she is helping define.

When the collecting finishes, the analysing begins.

KENNEDY WARNE
When the collecting finishes, the analysing begins.


I came across a statement from the late great US writer John Updike. His goal as a writer, he said, was “to give the mundane its beautiful due.” It seems to me that this is what Candy Feller is doing for mangroves, and I admire her for it.

Ay caramba! A caterpillar that thinks it’s a snake

June 22nd, 2009

Today we found a caterpillar that belongs in the Guinness Book of Records in the “most bizarre” category. About 8 cm long and as thick as my little finger, it had a head like a snake, which it would lift up if you breathed on it. The tail end had a single Cyclops eye in the middle of it, complete with a fake eyelid that blinked.

The creature was positioned head-down on the trunk of a Pelliciera (perhaps so that a predatory bird would be attracted to the eye, the “decoy”). Pelliciera trunks here are covered with mats of tufting liverworts, which are favourite haunts of tree crabs. The trunk was bare around the caterpillar’s head, and looked to have been grazed by the animal.

I’m working on finding out what sort of moth or butterfly this magnificent beast turns into, but if it’s even half as spectacular as its larvae it must be quite a sight.*

(Click photo to see more pictures of the “snake caterpillar of Valiente.”)

Contender for the 'most bizarre' award?

KENNEDY WARNE
Contender for the 'most bizarre' award?

*UPDATE Annette Aiello, an entomologist with the Smithsonian, has provided me with the following excellent information:

“My guess is that your spectacular caterpillar belongs to the moth family Sphingidae, the sphinx moths, which include the well-known ‘tomato horn worm.’ Several sphingid genera are snake mimics, and in most of the cases I’ve seen so far, it is the ventral surface of the body that is displayed to resemble a snake. You can see that in the attached photograph of a species of Hemeroplanes. The head, mostly hidden, forms the blunt nose of the snake, then behind that you see the ventral surface of the thorax with its three pairs of true legs folded against the body, and the large, dark, false eyes (that can be opened and closed with blood pressure) on the sides of the third thoracic segment. Continuing back, you see the first three pairs of false legs (prologs), which are the large black structures on the ventral surface of the abdomen. The larva is holding on to the substrate with its fourth pair of prologs. In contrast, your caterpillar presents its dorsal surface during the display. The only record I can find of a similar caterpillar is Pholus labruscae, shown figure d, plate xiii of Miles Moss (1912) publication “On the Sphingidae of Peru,” Transactions of the Zoological Society of London 20(2): 73-134. Moss describes the final stage larva as ‘Remarkably snake-like, either end appearing as the head of a snake.’ He reports that the caterpillar eats members of the grape family (Vitaceae).”

Pholus labruscae

Pholus labruscae

Among the Pelliciera

June 21st, 2009

Here are a few more glimpses of the magic forest. (Click on photograph to start slide sequence.)

Bromeliad on a Pelliciera trunk.

KENNEDY WARNE
Bromeliad on a Pelliciera trunk.

Forest of flowers

June 21st, 2009

We’re off again, as Candy Feller says, “like a herd of turtles.”

Emily Dangremond (right) with Pelliciera blooms. Anne Chamberlain looks on.

KENNEDY WARNE
Emily Dangremond (right) with Pelliciera blooms. Anne Chamberlain looks on.


With us today are a couple of Smithsonian communications people, filming a documentary piece on Candy, and David Luther, a bird expert who works on the conservation of endangered species at the University of Maryland. A paper of David’s on vertebrates which rely on mangroves is about to be published in the journal Bioscience. This is good news for me, because I was hoping to find a list of mangrove-dependent creatures, and David has produced that very list—for vertebrates, at least. David says that almost half of these mangrove endemics—48 birds, 14 reptiles, 1 amphibian and 6 mammals—are endangered, many of them critically so.

One of his mangrove species is chattering in the branches as we wheelbarrow our gear to the boat: the mangrove yellow warbler, a canary-sized bird with canary-coloured plumage. The male has a rusty red head, as if it had been dipped in paprika.

Village in Peninsula Valiente.

KENNEDY WARNE
Village in Peninsula Valiente.


We weave our way through the Bocas archipelago and cross the bay to the Peninsula Valiente. The sea is silky calm and dotted with the canoes of the Ngöbe Buglé people native to this area. They are fishing, diving or just commuting; rivers and sea are the only roads in this area.

We stop at a village which looks like a film set: rough timber buildings on stilts at the water´s edge, blue smoke drifting through almond trees, jungle rising thickly behind. Half an hour further on and we come to Candy’s site: a forest which includes the mangrove species known as Pelliciera rhizophorae.

Candy Feller takes nectar from a Pelliciera flower.

KENNEDY WARNE
Candy Feller takes nectar from a Pelliciera flower.


Candy has a special affection for Pelliciera, which has one of the most restricted distributions of any mangrove. It occurs on the Pacific coast of Latin America from Costa Rica to northern Ecuador, and in just a few spots on the Caribbean coast. The trees have elegant fluted buttresses, straightish trunks and long spindle-shaped leaves. But their flowers are what set them apart. Almost all mangroves have small, unspectacular flowers—except Pelliciera, which breaks ranks by producing flamboyant, star-shaped, nectar-filled blooms. The nectar attracts hummingbirds (believed to be the main pollinator) as well as many insects. We even find tree crabs taking a dram. Pelliciera blooms year-round, but when flowering is at its peak the forest is alive with the whirring wingbeats and squeaking calls of hummingbirds. “Imagine being strafed by hummingbirds,” Candy says.

On a previous trip Candy discovered something unusual: when she shone a UV light on the flowers the nectar fluoresced. Today she wants to take nectar samples and have them analysed in a lab that specialises in fluorescence. This turns out to be too easy. The flowers produce so much nectar that she can fill a glass capillary tube in seconds—if, that is, she beats me to it. I’ve been in a sugar desert lately, and am making up for it by licking Pelliciera nectar (it has a delicate caramel flavour).

The fabulous blue morpho, with the fabulous blue hidden inside folded wings.

KENNEDY WARNE
The fabulous blue morpho, with the fabulous blue hidden inside folded wings.


I walk through the forest, scouting for flowers and for the peacock flash of blue morpho butterflies, whose seemingly random fluttering always seems to be out of camera range. For a while, the best I can achieve photographically is a morpho at rest on a mangrove leaf, when the heavenly blue is hidden, and all you see are an eye-patterned grey and black. Then I find a butterfly trapped in a golden orb spider’s web, with the spider feeding on its dead body. It seems unsporting to photograph the iconic creature’s demise, but it could be my only chance to record the wing colour, so I shoot a few frames. “Frames”—the old film terminology lingers. “Files” doesn’t have the same magic.
Blue morpho, golden orb.

KENNEDY WARNE
Blue morpho, golden orb.


We eat lunch of boiled eggs, tomatoes and bread, and are treated to the sight of a basilisk, or “Jesus Christ lizard” running across the river and up a mangrove tree. “Basilisk,” I learn, comes from the Greek for “little king,” a name bestowed by none other than Carl Linnaeus, father of taxonomy.

Candy, Emily and Anne follow a similar collecting pattern as yesterday, gathering seedlings, twigs and flowers, collecting crabs and, on this occasion, measuring the salinity of the peaty mud in which the trees are growing. I help with the fiddler crabs, whose large claw has an off-puttingly wide set of pincers at the tip. I find that their posture is worse than their pinch, and manage to collect several without being nipped.

Young basilisk, or Jesus Christ lizard.

KENNEDY WARNE
Young basilisk, or Jesus Christ lizard.


We arrive back at the lab at sunset, and though it’s been a long, hot day Candy can’t resist putting in a couple of hours in the lab, slicing into the twigs and seedlings with a knife to see what’s living inside.

In front of the main building two bat researchers have set up a mist net and are catching bats at a rate of one every couple of minutes. Just as in nature, institutions like the Smithsonian have their diurnal and nocturnal residents. We mangrovistas are winding down, thinking of gin and tonics and what’s for dinner, while the bat brigade is gearing up for a night of excitement. The main researcher thinks he may have captured a new species.

Night belongs to the bats . . . and their captors.

KENNEDY WARNE
Night belongs to the bats . . . and their captors.


I take a torch down to the boat ramp and spotlight the mangroves, watching tree crabs chomping leaves and flowers. Howler monkeys are making a racket in the jungle beyond the lab, while poison dart frogs keep up a constant chirruping. It’s a great life, and tomorrow I get to do it all over again!

The nutrient economy

June 20th, 2009

It takes an hour by speedboat from Isla Colón, where the Smithsonian research station is located, to reach Isla Popa, where Candy Feller has one of her experimental sites.

Anne Chamberlain (left) and Emily Dangremont tickle the mangrove roots for crabs on Isla Popa.

KENNEDY WARNE
Anne Chamberlain (left) and Emily Dangremont tickle the mangrove roots for crabs on Isla Popa.


Candy’s main project in Bocas is to look at how nutrients affect mangrove growth. “Nutrients are the currency of food webs,” she says. She studies how that currency moves through a mangrove ecosystem in the same way that economists study how money moves through an economy. The three major elements she’s interested in (the dollars and cents) are carbon, nitrogen and phosphorus. She compares the ratios of each element in the mangrove trees in her study plots, and also in the herbivores that eat mangroves. Those consumers include everything from tree-climbing crabs to twig-boring miners. Candy has found more than 100 species which feed on mangrove twigs alone.

Some of the associations are intricate and fascinating. For example, the exit hole of one borer may be the entrance way of the next species in the chain. One of Candy’s favourites is a nemertine worm which takes up residence in an empty beetle gallery. The worm traps its prey by everting its insides. Charming!

Candy Feller in the dwarf mangrove forest.

KENNEDY WARNE
Candy Feller in the dwarf mangrove forest.


So thoroughly do creatures use the mangrove habitat that a seedling with its leaves in the air and its roots in the water will have terrestrial borers burrowing down from the top and marine borers burrowing up from the bottom.

As well as measuring the nutrients in an undisturbed system, Candy has added nutrients in the form of fertilisers to see how the mangroves and their associated flora and fauna respond. This is an important line of research because nutrient over-enrichment is a growing problem for marine ecosystems around the world. As fertilisers run off the land and into the sea, the delicate nutrient balance of mangrove and other communities (seagrass beds, coral reefs) can be thrown into disarray.

As we step off the boat there’s a surprise: a golden orb web spider has spun a metre-diameter web at head height just to one side of our access point. I hope I don’t forget its location. The spider is close to 15 cm from leg tip to leg tip, and I don’t fancy the thought of it falling down the back of my shirt. (The spider gets its name from the fact that the silk of its web is a golden colour, not white.)

Golden orb web spider near the boat.

KENNEDY WARNE
Golden orb web spider near the boat.


At Isla Popa there is a marked difference in height between the mangroves on the shore and those inland. The shore mangroves are five or six metres tall, while those inland are a bonsai forest of dwarf trees less than a metre high. Candy has found that the shore mangroves are limited by nitrogen while the dwarf mangroves are limited by phosphorus. Adding phosphorus to the dwarf trees results in dramatic growth increases, but adding nitrogen to the shore trees has much less impact.

I head into the dwarf forest with Candy while Emily Dangremont, a graduate student from Berkeley, and Anne Chamberlain, one of Candy’s associates at the Smithsonian, work on the shoreline mangroves. Our tasks include counting seedlings (living and dead) and collecting leaves, seedlings, winkles and two sizes of crab from around the fertilised trees. These will all be physically and chemically analysed back at the lab.

Leaf scars provide an estimate of the age of the dwarf mangroves—as much as 300 years old.

KENNEDY WARNE
Leaf scars provide an estimate of the age of the dwarf mangroves—as much as 300 years old.


The dwarf mangroves (which Candy refers to affectionately as “Charlie Brown trees”) are a revelation. Candy points to the leaf scars on the branches. Each time a leaf falls, a permanent record of its existence is left on the branch. Between two and three leaves fall off per year, so the number of leaf scars gives an estimate of the age of the tree. (You can’t use the normal method of counting rings because mangroves don’t lay down rings annually, but on a more irregular basis.) Though these dwarf trees are smaller than a metre in height, it turns out they are several hundred years old. They grow in a layer of peat that is close to two metres thick, which has formed from the fine roots of generation upon generation of mangroves.

In Bimini, similar dwarf mangrove forests were denigrated as “stunted mangroves” by the Bimini Bay Resort development company, which justified its plan to destroy such stands on the grounds that they were biological rejects—losers in the game of life. Seeing these ancient forests in Bocas, collecting the crabs that nestled in their leaf bases and the molluscs that clung to their branches, underscored the crassness of the developer’s rhetoric. Who can say how much life owes its existence to these trees? And who has the right to deny it?

Further inland still, where the mangroves mudflats meet the terrestrial soils of the jungle, the mangroves are much higher—10 metres or more—and festooned with epiphytes. Bromeliads, orchids and arum lilies perch and twine on trunks that are felted with moss, liverwort and filmy fern. Candy thinks of the epiphytic community as a separate freshwater ecosystem suspended over the saltwater mangrove one. It is sustained by the high humidity and rainfall of Panama. (Bocas receives up to five metres of rainfall annually, spread throughout the year—but, luckily for us, not on the days we are in the field.) The epiphytes provide yet another level of complexity in an already complex system.

Epiphytes on the mangroves are a feature of Panama.

KENNEDY WARNE
Epiphytes on the mangroves are a feature of Panama.


I walk back to the shore mangroves to help Emily and Anne catch crabs. The most effective method is to “tickle” the algae-covered roots at the water line with your fingers, hoping to flush the crabs from their hiding places and cause them to climb up the tree. If you’re quick enough, you can grab the crab before it realises its danger and jumps into the water.

Aratus, the tree-climbing crab we’re going after, has an infuriating knack of staying on the opposite side of the branch to the side its pursuer is on. This isn’t such a problem if the branch is narrow, but on a thick trunk I sometimes circled round and round (with occasional feints in the opposite direction) and only glimpsed bits of disappearing leg or pincer as the crab kept deftly out of sight.

It’s great to be in the company of scientists again, sharing a quest for knowledge. Je ne regrette rien, but at times like this the scientific career path I set aside for journalism has the allure of the road not taken.

Slothful in Panama

June 19th, 2009

Soon after I arrived at the Smithsonian Tropical Research Institute in Bocas del Toro, there was a commotion outside the lab. People were gathering on the balcony with cameras and tripods. A sloth had assumed a photogenic position in the fork of a tree a dozen or so metres away. I ran to the house where I was staying to get my binoculars. As I was running I thought, “Why am I running? It’s a sloth, for goodness’ sake!”

Three-toed sloth at Smithsonian research centre in Bocas del Toro.

JP LAWRENCE
Three-toed sloth at Smithsonian research centre in Bocas del Toro.


Sure enough, when I arrived back at the balcony I hadn’t missed anything. The sloth was resting its head on its arms, entirely placid and apparently asleep. After a while it favoured us with a view of its face, which is dramatically marked with a black eye mask. It began to scratch its fur with its scimitar-like claws, revealing itself to be a three-toed sloth. Panama has three species: a three-toed variety (diurnal and nocturnal), a two-toed (nocturnal) and a rare pygmy sloth which lives solely in the mangroves.

I was intrigued to see that the fur had a distinctly greenish hue. One of the researchers told me that sloth hair follicles are hollow, and that algae get into them, turning them green. From an information panel directly below the sloth’s tree (clearly this was a favourite roost) I learned that sloths come down from the treetops only once a week—to defaecate. This struck me as extremely well-mannered, though inherently unslothful, behaviour.

That night we had a discussion about whether one should pronounce sloth with a long “o” as in slow or a short “o” as in top. I said I preferred the long-“o” sloth for the animal and the short-“o” sloth for the vice, but needed to investigate the matter further—which I guess would make me a sleuth.

Even a sloth needs to take time to smell the flowers.

KENNEDY WARNE
Even a sloth needs to take time to smell the flowers.


I have come to Bocas, in the north-west corner of Panama, with a mangrove expert I first met in Belize in 2005. Candy Feller adores mangroves, and particularly a species that is found in only a few locations in Central America, known as Pelliciera rhizophorae. Over the coming days I will accompany her and her research associates Emily Dangremond and Anne Chamberlain to their study sites in the Bocas archipelago, exploring the mangrove forests and looking for pygmy sloths and any other creature that favours us with a sighting in this biodiversity hotspot.