Hot Wet Places - Tracks and Shadows: Field Biology as Art - page 91

dices threaten snakes everywhere, but under the spell of this magnificent creature we
all slipped into a sort of naturalists' trance.
After a few minutes the bushmaster began inching toward the sprawling, buttressed
trunk of a nearby tree. Two keel-billed toucans landed on an overhead limb and howler
monkeys roared from back in the forest, reminding us that the day was under way. One
woman pointed out how well the snake's blotched color pattern and keeled scales blen-
ded into its forest-floor carpet of leaves and branches, and her companion added that
such effective camouflage was all the more impressive given that the animal's midbody
was as big around as his arm. A Costa Rican student mentioned its Spanish name, mat-
abuey, and asked whether a bushmaster can really “kill an ox.” Everyone knew that few
biologists have seen this species in the wild, that we were privileged.
I squatted and looked at the serpent's onyx eyes and forked tongue, which serve
perceptions plausibly similar to ours. Its pitviper namesakes, like sunken radar screens
between the eyes and nostrils, were even more intriguing. One of my early reptile
topics showed blindfolded rattlers striking hot-water-illed balloons, 13 and subsequent
research revealed that sensory receptors in the pits are spatially represented relative to
each other by cells in the brain. Spatial patterns of nerve firings thus create infrared im-
ages, allowing these snakes to evaluate enemies or prey by combining information from
pits and eyes. 14 Perhaps that bushmaster saw me as a dark blob silhouetted against
cooler vegetation, and because I neither moved nor came closer, I wasn't a threat. After
brief inspection of my size, shape, and surface chemistry, I became irrelevant back-
ground. Within minutes the viper was asleep, shaded by a fallen log, and as shafts of
sunlight warmed the foliage our handful of bipedal primates set about daily tasks, ever
more alert for venomous snakes.
Predator-prey interactions remind us that nature is exuberantly complex as well as
brutally indifferent. She is also sexy. One night at La Selva, Carole Farneti and Richard
Foster showed Secrets of the Mangroves, a film they'd made about Bornean wildlife.
Two dozen field biologists had put in a sweaty day's work and filled their bellies with
dinner; rain pounded the tin roof as Richard fiddled with the projector and we sipped
beers and chatted, a little black bat hawking insects among the rafters only a few feet
over our heads. Then we sat enthralled by footage of crab-eating frogs, proboscis mon-
keys, and other Asian treasures. After half an hour the story line turned nocturnal, and
suddenly a cinnamon brown bat, head strangely primatelike, hovered down onto an ex-
travagant white flower. Most of us had learned in zoology classes that the wings of bats
are suspended mainly on bones of their hands and thus are unlike those of birds, whose
flight structures are supported mostly by their arms. Now, though, without consciously
thinking about anatomy, we understood that this gorgeous creature was reaching out
for the flower with its fingers.
At first the bat awkwardly grasped the curved and densely spaced outer petals, but
then its membranous hands delicately enveloped the inflorescence, as one might cradle
a lover's face. Next the flying mammal pushed its furry muzzle into the lush blossom,
snaked out a reddish tongue, and began lapping nectar with insistent, slaking strokes.
Flecks of pollen glistened on its snout. As well-read tropical biologists, we knew that
those tiny grains would rub of on the female parts of other flowers, that this bat would
inadvertently facilitate plant sex. Our minds reflected on those details as our hearts
wandered elsewhere. I heard a murmur or two in the darkness. Someone coughed