Graduate School - Tracks and Shadows: Field Biology as Art - page 54

coralsnake, released in the yard-wide arena after the alley and smaller snake had been
removed, inevitably followed the invisible spoor of its prey. Trailing behavior was espe-
cially obvious at the turns, which coralsnakes overshot by a few inches, then relocated
by side-to-side head movements and tongue-flicking. After a few minutes an undulating
coralsnake looked like lacquer-banded sine waves moving around an octagon. 12
My captive coralsnakes seized other snakes willy-nilly but always swallowed them
headfirst, as had been the case with 96 percent of 150 prey items in preserved spe-
cimens. The advantages seemed straightforward—a blunt head was easier to grasp
than a slender tail, jaws more easily passed over backward-projecting scales and body
parts—but how, I wondered, do beady-eyed coralsnakes distinguish the head and tail of
their prey, hidden a foot or more away in leaf litter? Captives ingested short pieces of
prekilled snakes from the front, proving that neither head nor tail was necessary and
that a directional cue existed all along the prey's body. Next I removed skins of dead
snakes, in the manner of peeling of a stocking, and replaced them on the carcasses
backwards. Coralsnakes moved to the “front” of those experimental items—actually the
prey's tail—supporting my hypothesis that they used backward-overlapping belly scales
to find a prey snake's head. 13
Fitch had whetted my wanderlust with publications from his Latin American so-
journs, and Bill enthralled me with tales of driving a pickup from Texas to Colombia—his
wife, Wanda, teenage daughter, Karen, and three students cramped in among supplies.
The Pyburns spoke of exotic birds, strange night sounds, and rainforest trees so large
they camped among the wall-like trunk buttresses. Ever the careful observer, Bill wrote
in one letter from the field of a tiny green kingfisher flying low over a puddle, catch-
ing a single tadpole on each pass. And once, attracted to a commotion in the canopy,
he watched an agitated woolly monkey snatch something off a branch and hurl it down-
ward, stared as what looked like monkey shit materialized into a blob with outstretched
limbs, then caught what proved to be a much sought-after canopy treefrog!
My own first tropical adventures were modest—a driving marathon to Guatemala
with new friend Jonathan Campbell from the Fort Worth Zoo, a trip to Veracruz with
two other Pyburn students—and exemplified the mystical allure that draws naturalists
toward the Equator. Now I remember tense border crossings and vividly garbed Indian
women, crested basilisk lizards and mosslike treefrogs, and one prophetic incident. On
my knees in wet pasture, tearing open rotten logs with a potato rake, I spied the thrash-
ing orange coils and black spots of a Tuxtla coralsnake. Having seen similarly “ab-
normally colored” specimens in museums, I used tongs on the snappy, eighteen-inch-
long serpent, whereas my companions, unaware that not all coralsnakes are banded,
would have simply grabbed it, with potentially lethal consequences. For me that animal
sparked a new research interest.
In 1867 Alfred Russel Wallace, building on his fellow explorer Henry Bates's dis-
covery of noxious “models” and palatable but protected “mimics” among butterflies,
suggested that the brightly ringed colors of venomous coralsnakes warn predators and
that harmless serpents gain protection by looking like those deadly species. 14 I'd read
Wolfgang Wickler's Mimicry in Plants and Animals, however, and was impressed by his
argument that coralsnakes couldn't be models because fatally bitten predators wouldn't
survive to later avoid nonvenomous mimics. 15 By then Jay Cole, my friend from K.U.,
was at the American Museum of Natural History, and when I voiced skepticism about