Howler monkeys are a noisy bunch, and their deep holler vocalization (which seems to be associated with small testicles) can travel extraordinary distances through the canopy. New research published in the Journal of Animal Behavior has revealed another way for these roaring monkeys to adapt perfectly to the life of the rainforest, as they have found that Howler has incredible navigation skills. Not only did they remember the location of their favorite food (and when they were in season) they knew important locations to remind neighboring soldiers to call out alerts outside their territory.
The study, led by Oxford Brooks University, looked at black holler monkeys (Alouatta pigra) in the south-south Planck National Park. After analyzing nearly 3,000 hours of field observations, the researchers found that these monkeys were deliberately looking for ripe fruit trees. Researchers have revealed that monkeys on targets indicate that they have enjoyed these fruits in the past and are able to guess when they will found.
Fruits are a valuable product in this environment. Rain haulers have many mature leaves in their diet, which is effective because they are everywhere but they have high concentrations of toxins and tannins, which are not ideal in large quantities. To get ahead of their fruit-loving competitors, the monkeys select a few handfuls of trees with easy ripening cycles to remember and return to them when they are good to eat.
“Spider monkeys are traditionally considered more sophisticated than howler monkeys in terms of their local skills,” said Dr. Evolutionary Anthropologist. Miguel de Guinea says,
in an email to Oxford Brooks University IFLScience. “This is because the spider monkeys are very indifferent and the diet of the holler monkeys is largely made up of leaves: it is very difficult to identify the fruits on the top of the rainforests fruit (because they are the smallest). For the first time, I found that holler monkeys remember where and when to find the fruits of their cognitive skills with spider monkeys. “
In addition to cashing in on a few premium products, the study found that the Hollers were going through long rainforests through the rainforest until they reached a stage where they clashed with neighboring troops. Even in the absence of competitors, monkeys seen returning to these spots loudly, marking their territorial boundaries with higher warnings. Although violence rarely caused by the collision of a holler troupe, deciding whether they can continue to inspect the fruit trees of their choice to win or lose such a battle is at risk while protecting your patch.
The next step in this group is to work on establishing the best tools for use when studying individual primate species in the natural environment, hopefully this will reveal new insights into the evolution of primate spatial knowledge.
Guinea writes, “Perhaps visible, black holler monkeys are able to adapt the structure of these route networks over time, taking into account not only the cost of travel to certain areas, but also the most useful set of communication between relevant places.” “I am working with a team of experts to create a set of multiple approaches to comparing primate cognitive skills in population and field locations working with Sari Van Bell and Dr. Carlin Public Opinion (co-authors of this study).
Although multiple primate groups currently tracked in the wild, most of their data not analyzed or limited to descriptive metrics. Our goal is to provide a set of tools for creating a clear framework for the evolution of primitive spatial knowledge using naturalistic observations. “
