Biology Reference
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small plane between volcanic peaks that rise to more than eight thousand feet around
San José, with a little girl in front of me screaming throughout the stomach-churning
ride. There followed a dirt-strip landing, billowing red dust and flapping banana leaves,
and an hour's drive on a horrible road to La Selva. For the next few years I traveled
back and forth to the field station in ElRápido, a dilapidated red bus that required nine
hours to traverse the pot-holed highway; by 1991, however, we'd get there in an hour,
winding down a freeway through the sparkling mountain scenery of Braulio Carrillo Na-
tional Park.
Travelers often speak as if “rainforest” and “jungle” were synonymous, whereas bio-
logists restrict the latter to regenerated vegetation after forest has been cleared, either
naturally, as with a wind-toppled tree, or by humans. Also known as second growth,
jungle is of short stature, with a dense understory and difficult to walk through without
cutting trail. Mature rainforests are multilayered, reaching, in the case of the La Selva
canopy, upward of 160 feet. Shorter trees shade a fairly open understory, within which
trails are constructed more for navigation than access. Woody vines and epiphytes
are obvious but not abundant; palms are common and diverse, encompassing emerald-
leaved Geonoma the size of small shrubs as well as big, spiny-trunked and stilt-rooted
Iriartea. Only about 1 percent of sunlight reaches the forest interior, as irregular solar
flecks and blotches, with temperatures generally mild by tropical standards.
La Selva appealed to me for its mature rainforest, almost sixty species of snakes, and
other researchers who might help me find vipers. I especially wanted to study bushmas-
ters and terciopelos (often inappropriately known as fer-de-lance), among the largest
venomous serpents, and rumor had it they were common. Soon after my arrival, though,
I found carnivore droppings and hatched a plan to assay all predator diets, parallel-
ing the Chilean studies with Rob's and my student Fabián Jaksic but in a much richer
tropical assemblage. Typically I'd set out after breakfast, sometimes accompanied by
an assistant and others who hoped to see snakes. We wore light pants and long-sleeved
shirts, rubber boots, and bandana sweatbands. My pack bulged with camera and tele-
metry gear, other research gadgets, and water bottles. We'd walk all morning, paying
special attention to long dark objects, because sometimes instead of roots that might
trip us they were snakes that could bite. For weeks on end, during some dozen trips, I
recorded observations, collected scats, and marveled at my good fortune.
Arthropods, birds, and mammals are the most obvious animals at La Selva, with
many insects distinguished by dazzling colors, nasty stingers, or both. Inch-long, shiny
black bala (“bullet”) ants abound, and wasp nests seem preferentially hidden under
leaves at face height. During our walk an electric whine crescendos, then ebbs as a ci-
cada chorus goes briefly quiet. The Costa Rican avifauna encompasses plenty of small
drab birds but also gaudy toucans and plump tinamous, their haunting calls like flute
music at dusk. We'd occasionally get a glimpse of collared peccaries and rarely find
the dinosaurlike tracks of Baird's tapir. Among otherwise ratlike rodents are pacas and
agoutis the size of house cats, and who can deny the appeal of wild primates? From
time to time white-faced capuchins chattered threateningly from nearby trees, while
cartwheeling spider monkeys high overhead left our necks aching from watching them.
And I was never too tired to enjoy the roaring howlers as darkness fell in the forest.
As for the surrounding greenery, certain easily identified species make exceptionally
high plant diversity palpable even for those focused on vertebrates. Monkey pot trees,
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