Wettedland

It had been six days since I’d been in the field. A combination of illness, injury, and three straight days of rain had prevented us from getting any work done, and I had barely left my room. The house was damp and musty. Everything was flooded. I was even starting to miss the monkeys. Well, almost.

So when a friend of a friend offered to take us to Palo Verde for the day, I jumped right into my boots. I had never been to the National Park despite its proximity and the fact that it’s the largest protected Wetland in Costa Rica.

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“Wetland” being somewhat of a joke in that it’s hard to find a place here where you are not, at some point, rather wet.

Tropical Ecology, regardless of environment, usually operates between extremes. Resources are only ever offered in abundance, or not at all. There is no middle ground, no moderation. Any addition–water, sunlight, etc, triggers a dramatic shift. Example: a Rainforest is nutrient-limited, and and addition of organic matter (animal carcass or fallen tree) causes an explosion of activity to reclaim it. A desert is water-limited, and any rainfall portends a mass emergence of sprouting plants and thirsty animals.

But Palo Verde is a Wetland surrounded by Dry Forest–an ecological oxymoron. And it doesn’t work the way you’d expect. Rather than mitigating each other, the two environments create a massive expanse of dynamic micro-habitats that push and pull at each others’ resources, constantly in flux and constantly disturbed. And if there’s one thing tropical biodiversity thrives off, it’s disturbance.

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And if there’s anything biologists thrive off, it’s disturbing.

 

We arrived after a long rainfall, but after enough time had passed that the flooded plains had shrunk to isolated pools. Vegetation had been uprooted and waterlogged, then left to decompose high and dry. Aquatic life had been allowed to flourish, then trapped and concentrated. It was textbook Trop Ecology. Life was busy here. Things were happening. Everybody was out and about.

Spiny-tailed iguanas basked on every available surface and only grumpily moved out of our way when we got close. I plucked one of the biggest milipedes I’ve ever seen off the middle of a trail. Ponds swarmed with fish, some of which were squirming through the mud or even across the roads to find new water.

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Making then easy prey for hungry birds and curious naturalists.

And the birds. My god, the birds. Palo Verde is a known birder’s Mecca in the dry season, but even now it didn’t disappoint. One spot, just off the road, was full of Wood Storks, White Ibis, several species of small heron, and all three species of egret. All perched together or wading through the flooded grass. I saw several Northern Jacana–small, delicate wading birds–along a boardwalk. We even caught a glimpse of Scarlet Macaws, something not often seen up North.

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The Jacana–I admit, I had to look most of these up. Birds are too mainstream for me.

Oh, there were mosquitoes, too. Like, swarms and swarms of them. It was awful. Some didn’t just itch–they actually stung a little when they bit. We couldn’t stop moving, and every retreat to the car was followed by a swatting party as we tried to massacre all the ones that had followed us into the car.

But one place we managed to escape them was a lookout, a high point on a pinnacle of karst limestone that overlooked the river and flooded plain. It was a great view, with perfect weather. We took advantage of the fact that both the weather- and mosquito- gods were showing us mercy and took it all in.

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It was almost enough to make me decide to invest in a new camera that isn’t several field seasons past its prime. Almost.

Return of the Queens

I know it’s a little soon to be doing another post about ants, but this is different. It’s not even a rant–this is something actually cool.

Returning from a night hike, several students started screaming, complaining of large flying insects crashing into them. I suggested they turn off their lights, which usually attract nocturnal bugs, and inspected the area, expecting maybe large beetles or moths.

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Understandably, not something you want flying into your headlamp.

What I saw were giant, winged ants, reddish and swollen, and covered with what looked like armored plates. Closer inspection proved them to be Atta sp, leafcutter ants, but of a caste that I had never seen before. They were queens. Thousands of them. All over the place.

I realize I may not have explained leafcutter ant ecology before. It’s truly fascinating, despite concerning ants. Leafcutters are the world’s oldest farmers. The leaves they clip and carry back to the colony are not for food–they are compost. The material is food for a certain strain of fungus that is harvested and eaten by the ants. Large chambers underground house huge, rotting masses of leaves, flowers, and fruit, covered with fungus, carefully tended by fungivorous ants.

The colony is divided into specialized subcastes. Large-headed soldiers guard the colony, and address any disturbance with massive jaws. Cutters clip segments of leaf and carry them back to the entrance. Once a cutter’s jaws become too dull, they are delegated to a different job of vetting leaves at the entrance and rejecting those of poor quality, a kind of ant retirement policy. Inside, there are more jobs for gardeners, nurses, and of course the queen. All of the above are female. Winged males live for short periods, and only only live to grow fat with sperm and fly around looking for mates.

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Insert your own jokes here.

Entire books can be, and indeed have been, written about leafcutters, so I won’t go into detail. But essentially, at times all the queens of nearby colonies take leave and take flight, taking with them a sample of the fungus. They find males by pheromones, mate, then find a place to start a new colony. They dig a hole, and inoculate the burrow with the fungus.

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Atta girl.

Which is what was going on. I had never seen this before, and didn’t realize the mass emergence was so…massive. Are there really this many colonies around? Are they from different colonies? How many will survive and succeed? Judging by the number around, it can’t be a high percentage, or we’re in for a lot of ants.

Final note: I watched one queen dig a brand-new hole near the station. The next day, there was a trail of cutters bringing leaves to it in a tidy line. Where did they come from so fast? There’s no way they could have hatched and metamorphosed so soon. Did the queen recruit them? From where?

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I can still hate ants and be curious about them, right?

Frogs That Grow on Trees

One of the few things I have the pleasure to say I’ve actually independently studied is the diversity of frog egg-laying strategies.  While there is the usual progression of eggs in water—tadpoles—froglets—frog, tropical species have a wider variety of techniques at their disposal.  For example, some lay eggs in a jelly mass that the males whip into a foam ball with their legs, leaving puddles full of amphibian meringues that resist drying out.  Some lay eggs in ponds, but then carry individual tadpoles into bromeliads in trees.  But my favorites are the ones that create thick, gooey egg masses that they glue onto leaves overhanging streams.

We’ve been seeing many of these on our transects while are, likewise, situated along rivers and streams.  The egg masses up to three meters above the surface, glistening with the consistency of tapioca pudding.  They’re from a few different families of treefrogs as well as glass frogs.  Since the eggs are transparent and develop and hatch in under a week, I’ve been able to get some good photos to document the process.  When the tadpoles are developed enough, they wriggle out of the goo and drop into the water below, where they continue to grow and metamorphosize.  This usually happens during heavy rain, when the jelly is softest.

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Like if you mixed chia seeds with Jell-O

The idea here is that, while suspended, the eggs are safe from most ground- or water-dwelling predators. If they get threatened by a tree climber—say a snake comes along to eat them—they sense the vibrations and can hatch prematurely.  The kicker is that, even as a developing embryo, the tadpoles are able to differentiate between the vibrations caused by a hungry predator and things like raindrops.  Anything shakes their leaf too much and they panic and jump for it.

Think about that: even before they’re born, frogs can recognize predator signs and have enough of a survival instinct to react to it.  Not only that, but for many of them, their first conscious thought is to fight free from the soft, wet, protective medium that is all they have ever known as home and drop several hundred times their own body size into what is, to them, a raging river.  Heck, even under normal, they force themselves to perform this leap of faith during thunder and lightning, wind and rain.  Man, frogs are freaking metal.

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You wouldn’t know it by looking at them.

A Change in the Winds, Maybe

I haven’t been here long enough to get a feeling for the phenology, the seasonal patterns of the ecology.  But I’ve noticed several first-time events for the region, and going through past studies and wildlife log books, I know these are special.  Even the locals have begun commenting on the changes going on, especially in regards to wildlife sightings.

For example, this year was the first time in recorded history where we had Resplendent Quetzals and Spider Monkeys seen on campus.  Those are species seen at higher or lower elevation, respectively, and have never been recorded in this valley since it was turned into a reserve.  And then today I had another sighting: Howler Monkeys.

This.
 It’s been a while.

These were a common sight in the lowlands.  And we often hear them calling from the next valley over.  But they are rarely, if ever, spotted on campus.  A friend and I caught these two hanging out in the trees, catching some rays.  Another first for the logbook.

Despite their calls, howler monkeys are more unagressive and easygoing than the capuchins, which tend to be more pee-happy and branch-throwy.
Despite their calls, howler monkeys are more unagressive and easygoing than the capuchins, which tend to be more pee-happy and branch-throwy.

And there have been more.  There was a tawny treefrog found sleeping on the sill of one of the office windows.  I had to look it up as it wasn’t on our species list.  I’ve made an unusual number of trips to the library to ID new insects lately.  Of course, there’s also the resident puma.  And it’s been a good month for snakes.

I believe this is preferable to finding either a snake or a puma in your office.
I believe this is preferable to finding either a snake or a puma in your office.

Is these just anomalies?  Is this a result of a changing climate?  Habitat loss elsewhere?  A simple observation bias?  Or is this a positive sign?  This reserve was once just cattle ranch and coffee farm.  What exists now is secondary forest, slowly recovering and restoring itself to a more natural state.  Maybe these sightings mark a return to a primary, original condition.  At least, I like to think so.  Time will tell.

Wide-Eyed and Jet Lagged

Mentoring of new hires and guiding new guests always forces me to reflect on just how accustomed I have become to the more unique aspects of life here.  But when these people have never been to Costa Rica before, or never even been to the tropics, then I really have to take a step back and try to see things for the first time again.

I’m not talking about being bored of coatis or cussing out monkeys.  I mean, I still do that, but I try not to in front of new people.  Especially ones trying to take a picture of an exotic animal without their guide spontaneously going berserk.

If this little punk woke you up at five in the morning every day, you'd feel the same.  Go to hell, monkey.  You know what you did.
If this little punk woke you up at five in the morning every day, you’d feel the same. Go to hell, monkey. You know what you did.

I mean the basics.  Going over weather patterns.  Forest structure.  How to deal with ants.  What the giant moths are called.  What the little yipping sounds are coming from the ceiling at night.

Answer: geckos.
                       Answer: geckos.

Today a tourist was gushing over epiphytes.  I had casually passed a tree on campus without a thought.  After all, I see those trees all the time.  But it was one of those that had so many epiphytes that they probably outweighed the tree.  It was a megalopolis of microhabitats.  We spent a good ten minutes going over all the botany and ecology involved, with everyone taking pictures.  It reminded me of when I had been so impressed.

This.  I have become disinterested in this.  What happened to me?
           This. I have become disinterested in this. What happened to me?

So it’s a good learning opportunity all around.  For some, a new experience, for others, a valuable reminder.  This is not a place to take for granted.

When a Tree Falls in the Cloud Forest

Last night I was awoken by a familiar sound, although one I haven’t heard in about three months.  It was a harsh cracking that grew above a low rumble, and culminated in a fantastic crash that shook the ground.  A tree had fallen over.

Back in the lowlands, we used to hear this all the time.  Once the rains hit, and the ground softened, many of the tall trees with shallow roots toppled over, pulling others down with them by the lianas that connected the complete canopy.  It happened about once a night.  It is that level of commonplace disturbance that characterizes tropical lowland forests, allowing for patchy regrowth in an otherwise primary forest.

Damn, was that really just three months ago?
Remember this place?  Damn, was that really just three months ago?

Which may be the primary distinction between that forest and the one I am in now.  For three months now, I have been trying to put my finger on it–why is this forest different?  I now think it has to do with disturbance.  Everything here is growing, yes, but it is growing steadily with no interruption.  Plants here seem more stable.  More complete.  There is less of a sense of frantic, chaotic climbing and spreading of leaves before the next tree fall of canopy closure.

I’m halfway through my post at this station, and it’s good to be still learning things.  Although I shouldn’t be surprised.  I haven’t even lived through a seasonal change at this climate yet, but already I’m noticing changes.  The rainy season is building up to a finale now.  There are fewer light showers and more heavy downpours that arrive, like clockwork, at almost exactly midday and continue on to early evening.  In between deluges, we get a thick fog that hides even the sides of the valley we’re in.

That is not lens flare.  It is actually that foggy.
That’s not lens flare. It is actually that foggy.

They say the rains hit their peak sometime in October.  So we can probably expect more wet ground and falling trees.  Let’s hope the guests come prepared.

Studyin’ About That Good Ol’ Way

I’ve been slacking on my posts because the office laptop I was using to upload pictures was loaned out to a visiting professor.  I should get it back in a few days.  Until then, however, I’ll do a couple picture-less posts so I don’t fall too far behind.  (Update: Pictures up Sep. 17)

Besides us “Resident Naturalists”, this place hosts voluntary interns for more specialized roles.  There’s a position for farm intern, one for photojournalism, one for water quality, and one for moths.  Yes, just moths.  Some positions are more specialized than others.

These interns tend to be younger, some still in college, and so they only stay for a semester or so.  However, they also have more day-to-day lab or office work than us guides who pretty much wait around until someone wants to go on a hike or has a snake they want removed.  Plus, the research interns get to be part of some long-term and occasionally interesting projects.

Pictured:  Something very interesting.
Pictured: Something very interesting.

Our water quality intern organized a bunch of field trips to collect biological and chemical samples from several streams, and conscripted the hypostimulated naturalists as assistants on different days.  But I’m not complaining.  The field trips were a lot of fun, and were a chance to do some actual research.

Ah, field research.  Ratty field notebooks.  Finicky GPS.  Crotchety old SUV with coolers full of sample bags.  Expensive equipment muddied and dented and repaired with duct tape.  Someone charging around with a sieve net, another on the bank with a notebook, and some poor sucker taking depth measurements while pits-deep in water cloudy with agricultural runoff.  It felt like being back in undergrad.

Tools of the trade.
Tools of the trade.  Ah, nostalgia

It’s funny–I, as well as the other naturalists, call myself a biologist.  But that suggests that I’m a scientist who studies living things, something I have not done in a formal setting in some time.  At least, not with any publications to show for it.  Most of my work recently has been more in education, or outreach.  So maybe we’re better described as nature guides who sometimes spend hours online looking up ant behavior and arguing over how to pronounce “-aceae”.

But anyway, a chance to bust out some good ol’ science felt good.  Even if it was just picking through gravel and dead leaves for wriggling larvae and insect nymphs.  No.  Especially if it was.  Plus, you can’t beat the location.

Four out of five stars.  Would sample again.
  Four out of five stars. Would sample again.

To Kill a Monocot

(Internet’s been down a while, so I have a few days’ worth of posts here)

Where I come from, it’s practically a sin to kill a tree.  You better have a pretty good reason for bringing that thing down, since it will be a while before one grows up again.

Less so here.  Some species just grow so fast, and the forest is so thick, that people here can cut with impunity.  Left alone, trees fall over all the time.  Soil layer is ridiculously low, and nothing has a tap root.  Wide buttress roots characteristic of the tropics help somewhat, but when old growths get loaded down with vines and epiphytes and rain…well, loud crashes from deep in the forests are a common sound some times of year.

I’ve been helping to make a new trail, and I’ve gotten used to thoughtlessly hacking away at thick vines and saplings.  They’ll grow back before you know it, and it’s barely any more damage than they would sustain in a bad windstorm.  This place just thrives off disturbance. Any dead wood quickly becomes termite food, or fungus nursery, and light gaps are regrown in days.  Sometimes even hours.

But I still get a little twinge of guilt every time I see a tree come down.  Which happens a lot here.  Ironically, this is not the place for a real treehugger.