written by Chris Hirsch, a volunteer field assistant on the project
White-Faced Capuchin Monkeys (Cebus capucinus)
are widely accepted as some of the most intelligent monkeys in the
entire New World. Personally there is no doubt in my mind that these
monkeys are much more intelligent than we give them credit. There wasn’t
a day that went by, during the year that I spent in Lomas, that I
wasn’t impressed by their inventiveness and problem solving abilities.
Whether it was navigating complex social hierarchies or foraging
dangerous prey, the variation of solutions among individuals, to these
common challenges, suggests an impressive level of cognitive reasoning.
This fact was never as evident to me as it was while working with the
Musketeers group during wasp breeding season.
 |
| Chris Hirsch |
The
beginning of the wet season (July-August) in Lomas Barbudal Biological
Reserve is the breeding season for several different migratory wasp
species. One of these species is Polistes instabilis or
as we call them in our coding system, “PI”. These little bundles of joy
are a constant source of anxiety for moneros working in Lomas because
of their habit of making hidden nests, on the undersides of leaves, at
exactly face height. My personal record is seven stings in one day. PI
larvae are a prized delicacy for those capuchins daring enough to risk a
few stings. Foraging wasp larvae involves a monkey running past a nest
and snatching it before the unsuspecting wasps know what hit them.
Luckily for the monkeys, PI wasps don’t pursue their attackers for more
than a few feet before returning to the site where their nest used to
be. At first it is almost sad to see newly homeless wasps pathetically
hovering around the branch where their nest and offspring once resided.
This empathy quickly fades as your sting count rises, and most moneros
cheer the monkeys on as they clear the forest of these pesky wasps.
(sgm).jpg) |
| Waldo |
Most
capuchins forage wasp nests by conventional means. First, the monkey
catches a glimpse of its unsuspecting prey. The monkey will then run at
full speed and reach out with its highly skilled hand to snatch either
the wasp nest itself or snap off the limb that the nest is hanging from.
The conventional technique exposes a monkey’s face and hands to the
possibility of painful stings. Although it never happened in the year I
was in the field, other moneros told tales of extremely unlucky monkeys
receiving a vision-impairing sting to the eye. The danger of PI stings
is made all the more apparent when you observe the fearful and
threatening reactions of onlooker monkeys, as an exceptionally large
nest is foraged. The hand foraging technique can be seen in all of the
Lomas study groups; however in the Musketeers study group, a few
individuals have invented a new foraging technique.
Waldo
was a brand new migrant adult male when I began my year term with the
Lomas Barbudal Monkey Project. He had migrated from one of the many
unhabituated groups that neighbor our study population. Waldo was also
the first monkey that I noticed using a novel wasp foraging technique.
Instead of grabbing the nests with his hands; Waldo runs completely past
the nest, reaches back with his prehensile tail, snaps the branch off,
and drags it behind him to safety. Breaking the branch off with the tail
instead of the hand allows the rest of a monkey’s body to be out of
danger by the time the wasps are alerted. Waldo isn’t the only monkey in
Musketeers to employ this technique. Tamarindo and Sapporo, both adult
females, also forage wasp nests with their tails. It was immediately
apparent to me after observing this behavior that using the tail was a
much safer method of wasp nest foraging compared to hand foraging. I
cannot recall ever seeing any of these three monkeys scratching stings
or swatting away wasps after using the tail technique. Capuchin monkeys
use their tails constantly as a “fifth limb”, so I was very surprised to
find out that the tail foraging technique wasn’t widespread in our
study population.
