Biology Reference
In-Depth Information
The unusual flash of brightly colored birds in an all-green realm triggered a raft of in-
triguing questions that had been lingering in my mind for years: Why might such species be
rare? And why are rare creatures as different as macaws, monkeys, cats, and rain forest trees
so similar in the character of their spacing patterns? Was one single factor the cause, tran-
scending whether an organism was covered in fur, feathers, or leaves? And why do biologists
believe that some of the scarcest species exert a tremendous influence on the workings of the
rain forest?
Up in the Manu viewing tower, the distant sound of communal throat clearing caught Sue's
attention: the hubbub was a troop of capuchin monkeys expressing their displeasure at an in-
truder lurking nearby. Perhaps a jaguar had walked past and settled along the riverbank or
a forest eagle or falcon had passed overhead. “As long as the capuchins stay hidden in the
branches, they're generally safe from aerial predators,” Sue related. “But they're scared to
death of an opportunistic spotted margay cat that could climb up after them.” At all costs,
capuchins and other monkeys avoid the ground, where they would be an easy mark for a jag-
uar. This largest of South American cats is known by its local name,
yaguara
, which means
“to kill with one pounce.”
Consistently locating jaguars was central to George's research project. He sought to an-
swer one of the most pressing questions of tropical biology: How much is enough? He wanted
to know how much habitat area was needed to conserve jaguars, pumas, peccaries, tapirs,
and other locally rare Amazon species. Up to now, scientists could only guess or shrug in
response.
Sue had spent the previous five years searching these forests for wild primates, the little-
known saki in particular, so she knew all about the wariness of monkeys. The bald-faced
saki, part of an unusual-looking group of primates, the pithecians, is distinguished by its
long, coarse fur, a pelage seemingly out of place in the tropical rain forest but quite use-
ful as camouflage, an important feature for canopy residents that weigh only two kilograms.
Their very long, black-and-white mottled hair not only makes these monkeys appear twice
their size but also resembles the shape, color, and texture of the branches of their home in
the lower canopy. Their unusually bushy tail only adds to the strange silhouette, although it
is not prehensile like the tails of larger-bodied New World monkeys. Rather than hang from
tree branches as do some other primates, they scamper over canopy limbs like giant squirrels.
When they reach a tree laden with unripe fruit, sakis use their massive (for their size) canines
to pry, rip, or split open the often hard-coated fruits to reach the soft young seeds. But few
primatologists had ever seen bald-faced sakis for very long, let alone studied them. Even their
weird vocalizations seemed like part of the “camouflage” adaptation: their birdlike sounds,
on top of their secretive behavior, contributed to Sue's own ecological name for this group:
stealth monkeys.
