Biology Reference
In-Depth Information
A placid stretch of the Puerto Viejo in front of the station was popular for swimming,
and no doubt many a problem has been deciphered there over beer and a quiet sunset.
Nonetheless, at times the river was rebellious, reminding us that life wasn't always tran-
quil. One afternoon it rose so fast from storms upslope that I measured an inch every
five minutes as water lapped up the steps; watching its contradictory moods, I more
easily understood how Latin American writers so persuasively blur what gringos distin-
guish as reality and magic. Huge trees roared by in the foamy brown current; on one of
them was a dead pig, with skin discolored and parched ears erect, facing downstream
as if on some hellish last journey. Then, in 1982, the station gained a touch of modern-
ity with construction of a suspension footbridge, after which everyone walked back and
forth to take meals in a shiny new
comedor
on the north bank. Some older hands resen-
ted these changes, but the flora and fauna probably benefited from concentrating our
activities away from the forest.
Five years later, on sabbatical leave from Berkeley, I sought fresh perspectives from
the bridge. Ringed kingfishers, keel-billed toucans, and other flying dinosaurs perched
on the spits and tree limbs that extended from the downstream riverbanks. Surrepti-
tious squirrel cuckoos with lemon bills and sorrel plumage scoured foliage for lizar-
ds and caterpillars, and a king vulture soared overhead, recognizable even to novice
birders like me. The only prominent asymmetry was a fallen tree reaching from the
south bank into midriver, where it snared logs and other debris. Green ibises perched
there in misty dawn light, whacking their turquoise bills in social ritual; later on, spec-
tacled caimans, close kin of our alligators, basked on the toasty sunlit lounge. One morn-
ing a Neotropical river otter lay on the logjam and groomed her svelte belly, swollen
nipples visible, then rubbed her rump against a stump and stretched out for a nap. I
stopped again after lunch and observed two of the willowy weasel relatives hunting
around the submerged trunk, after which each emerged crunching a large crustacean.
The bridge also offered an excellent vantage for watching arboreal vertebrates, most
of which are difficult to see and poorly known. Three-toed sloths were sometimes vis-
ible in nearby
Cecropia
trees, and one morning I photographed them waging “hand-
to-hand” combat. A sloth was curled up asleep as I trudged over for breakfast, and
a couple of hours later it was leisurely eating new, orange-brown leaves in the same
tree. After eighteen minutes a second animal emerged from adjacent vegetation, ascen-
ded the
Cecropia
at twice normal sloth speed, and pummeled the resident with heavily
clawed forefeet. Both were males, judging from their yellow and black dorsal markings,
and after a surprisingly vigorous and noisy struggle, resident chased intruder from his
tree at
three
times normal speed. Sloth sociality, my serendipitous observations implied,
is more complex than previously recognized.
5
Until that year my visits had been between February and August, when green
iguanas are dull olive and well camouflaged. In late November, however, the sides and
dorsal spines of males had turned an electric coppery-orange, and from the bridge I eas-
ily counted more than a dozen sunning along a quarter mile of riverbank. Basking was
followed by head-bobs and dewlap shakes that established who was most attractive to
females, and by noon their abdomens bulged with a morning's meal of leaves. One day
Isaías Alvarado, station foreman and lifelong area resident, walked up as I was contem-
plating iguanas. “Those lizards are always easier to see during these weeks,” he noted
matter-of-factly, and then asked, “Do you know why?” I'd just been thinking about how
