and pygmy rattlesnakes, the Mexican Horned Pitviper,
and, largest of the lot, the Bushmaster. Maybe it is a
good idea to keep an eye on your feet as you walk the
rain forest trails.Snakes: The Pitvipers
All pitvipers (subfamily Crotalinae), which range
throughout both the tropics and the temperate zone,
are venomous. North American rattlesnakes, plus
the well- known Copperhead (Agkistrodon contortrix)
and Cottonmouth, or Water Moccasin (A. piscivorus),
are pitvipers. The “pits” referred to in the name are
sensory depressions located between the nostrils and
eyes. They sense heat and aid the snake in locating
warm- blooded prey. Like other serpents and some
lizards, pitvipers use their forked tongues to detect
odors. The tongues, flicked in and out frequently, are
highly sensitive to molecules in the air. Pitvipers have
long hypodermic fangs in which a venom duct from
modified salivary glands can deliver a lethal dose of a
biochemically complex toxin that attacks blood cells
and vessels, surrounding tissue, and sometimes nerve
tissue. Pitvipers tend to rest in a coiled position, which
they also assume when danger threatens (plate 16- 64).
Any pitviper may be aggressive in display, raising its
head high and vibrating its tail. Rattlesnakes enhance
this position by shaking their noisy rattles. Pitvipers
normally have large, triangle- shaped heads, and catlike
eyes with vertical, slit- like, elliptical pupils, helpful
features in recognizing them.
The most well known Neotropical pitviper is the
Fer- de- lance (Bothrops asper; plate 16- 65), one of
31 species of lanceheads, all in the genus Bothrops.
Lanceheads are mostly lowland species found at
elevations below 1,500 m (approx. 5,000 ft). They
tend to bear a close resemblance to one another, and
it is often not possible to identify them to the species
level without a careful in- hand examination of the
animal (not recommended). The Fer- de- lance will
serve to introduce you to the group. Known variously
as the Yellow- tail, Yellow- jaw, or Tommygoff, as well
as by many Spanish and Portuguese names, it is best
known by its Trinidadian name, Fer- de- lance, though
its English name is actually Terciopelo. The name fer-
de- lance refers to the lancelike shape suggested by
the long, serpentine body and conspicuously large,
triangular head. In Brazil a very similar species is called
the Jararaca, a name meaning “arrowhead.” The Fer-Are Fer- de- lances Very Common?
Well, to speak the plain truth, yes. In a somewhat
courageous study performed at La Selva Biological
Station in Costa Rica, researchers D. K. Wasko and M.
Sasa used radiotelemetry to study the spatial ecology,
activity patterns, and habitat selection of 11 female and
five male Fer- de- lances. They brought captured snakes
to the lab, anesthetized them, and implanted radio
transmitters. They released the snakes back where they
were initially taken and monitored their movements,
attempting to relocate each animal at least once a day,
either during the day or at night. They documented the
snakes’ activity patterns, recording them as inactive if
lying coiled, active if moving, ambushing if lying coiled
and alert, head raised. The study was performed over
a two- year period. Each of the snakes had a relatively
small home range, and that, of course, allows for
numerous snakes to inhabit a forest tract. Habitat
preference was focused on swamps, although the
snakes were also commonly present in primary and
secondary forest— so they could show up pretty much
anywhere. The good news was that they generally
avoided developed areas, presumably to the relief
of humans who occupy such areas. However, I have
seen Fer- de- lances rather often around field stations
and lodges located within forest (plate 16- 66). So
be vigilant. Fer- de- lances and most other snakes are
primarily nocturnal in their activity patterns, spending
most of the daytime hours coiled and inactive.
Remember though, they are out there.Plate 16- 66. This small and deceased Fer- de- lance was
apparently the victim of an automobile. It was lying on a
gravel road adjacent to an ecotourist lodge. Even the small
ones are highly venomous. Photo by John Kricher.chapter 16 from monkeys to tarantulas: endless eccentricities 347