Researchers report rarity of chimpanzee 'hunting' for food with spearlike tool


DES MOINES, Iowa Researchers report witnessing a
chimpanzee skewering a tree creature for supper with a spearlike
tool, a rare observation of a long-studied primate in the wild.

``It's not uncommon to have chimps use tools. But to use them in
the context of hunting'' is nearly unheard of, said Jill Pruetz, an
anthropology professor from Iowa State University who led the
research team.

The chimp's actual spearing of a bushbaby, a lemurlike creature
that lives in hollow branches or trunks, was only seen once,
however. So some primate experts said it was unclear whether the
spectacle was a bit of luck or an indication that chimps have a
more advanced ability to hunt than was thought.

The observations were made in Fongoli, Senegal, from March 2005
to July 2006. Pruetz's team documented cases of the chimps using
the spears in a study released in the online version of
the journal Current Biology.

Pruetz said the practice is most common among adolescent
females, ages 10 to 13, which must compete against physically
superior males.

``It's a way of accessing protein or meat that is a creative
solution to this problem,'' she said.

Pruetz said the chimpanzees stripped leaves from tree branches
and modified the tip with their incisors, ``effectively making a
point.'' Then the chimpanzees jabbed the tool into a cavity to snag
a bushbaby.

Chimpanzees commonly use sticks to get food, such as termites,
said Ian Gilby, a postdoctoral fellow who studies chimpanzee
hunting at Harvard University.

``You frequently see chimps sticking sticks into holes or trees,
so they can make the hole bigger so they can put their arm in,''
said Gilby, who hadn't read the study.

Gilby said he's seen this tactic used to get honey and small
birds from holes in his work in Gombe, Tanzania.

``If it's clear they're making a point'' on a branch tip, he
said, then that ``does appear to be slightly different from what we
see at other sites.''

David DeGusta, an assistant professor of anthropological
sciences at Stanford University, lauded Pruetz's work because of
the rarity of studying chimpanzees outside Gombe, where renowned
researcher Jane Goodall did her work. It's hard to get animals
accustomed to human presence and willing to carry on naturally,
DeGusta said.

``The more populations that are studied, the more we learn about
how their behavior can vary,'' said DeGusta.

Pruetz's study was funded by Iowa State University and the
National Geographic Society.

Her Iowa State graduate students continue to observe other
emerging patterns among chimpanzees in Senegal.

``In a million years I never would've predicted that I would've
seen (hunting),'' she said. ``I'm going to plug along and see what