Macaques Reveal Insights into Foraging Strategies

Monkeys use different methods to find Food, especially in places where food is hard to find. Some monkeys remember where food was before and return to those places, while others change their approach depending on the season. Macaques, a type of monkey, are especially good at living in many different kinds of places. They often travel long distances each day, sometimes even several kilometers, to search for food. Young male macaques sometimes leave their group to join others or start their own.

Macaques often encounter new and unknown areas while searching for food. This situation makes them look for information to help them decide where to go. The way they make decisions can change based on how much they know or don’t know about their surroundings. When they have unclear options or uncertain outcomes, macaques tend to explore new choices or look for more information. Studies have shown that macaques, along with other primates, can recognize potential rewards from these unclear choices. Interestingly, macaques prefer choices that have some uncertainty rather than those that are either completely certain or completely random, especially if there is enough food available. They seem to be motivated to decrease their uncertainty about food locations.

Sampling and Exploring for Food

When macaques search for food in unfamiliar areas, they may try different strategies to gather useful information about where food might be hidden. For example, when looking for food that is randomly distributed, animals may take a flexible approach to find food scattered around different spots. It’s thought that macaques, like other animals, have a tendency to spend more time searching in places where food has been found in the past. This might help them find more food in future Searches.

Searching through an area with hidden food can be seen as a challenge where the forager needs to figure out the best spots to look. The search strategy can involve making choices that minimize effort and time by avoiding places that are less likely to have food. For example, when searching for food hidden in a challenging environment, some animals may wait to gather information before moving to another location.

When searching randomly, some animals, including macaques, tend to follow a pattern called a Lévy walk, where they take steps of varying lengths in different directions. This means they sometimes travel short distances between food searches and occasionally take longer steps. However, whether this pattern is due to their search decisions or the actual distribution of food in the area is still not completely clear.

Balancing Search Strategies

Even though random searching can be beneficial, it doesn't explain how animals change their paths when they encounter food-rich areas. For example, animals like gophers may dig more tunnels in areas with a lot of their favorite plants. Some dolphins spend time in ocean spots where they’ve found food moments before. This search strategy, known as area-restricted search, is beneficial when food is concentrated in certain places.

When animals find food, they often adapt their searching behavior. For example, if a small worm finds food in a petri dish, it initially moves in a straight line but starts to move more slowly and carefully once it finds food. This change in behavior might indicate a switch from searching broadly to focusing on a smaller area with food. However, many foragers, including humans, may balance exploration and exploitation throughout their search, meaning they continue to look for more food while staying aware of their surroundings.

The Experiment Setup

In this study, researchers wanted to learn how macaques search for food in an uncertain environment. They designed a controlled setting called the Exploration Room where macaques could search for hidden food on a grid of woodchip piles. The setup allowed researchers to monitor and record how the monkeys moved and what paths they chose while Foraging.

In each session, the monkeys searched through a grid with piles of woodchips. Some of these piles hid pieces of food, which were placed according to a specific pattern. The researchers ensured that the monkeys had no prior knowledge of where food was located, making it a fair test of their searching strategies.

Macaque Foraging Behavior

The monkeys started searching the terrain without any particular order. Across different sessions, they found between 42% and 100% of the food hidden under the piles. Interestingly, the first food hit was sometimes found on the first attempt, showing the unpredictability of foraging in an unfamiliar area.

The researchers looked closely at the monkeys’ foraging paths to see if they resembled any known patterns of searching for food. They found that the distances the monkeys traveled between searches followed a heavy-tailed distribution, similar to a Lévy walk. This indicates that the monkeys sometimes traveled long distances between their searches. The monkeys favored searching nearby piles after finding food but did not limit their exploration to just those areas.

Searching Near Food Sources

To better understand how finding food influenced the monkeys' search patterns, the researchers compared their movements after finding either food or an empty pile. After encountering food, monkeys tended to choose piles that were closer compared to when they had just found an empty one. This behavior suggests that they may expect to find more rewards near the places they have already successfully searched.

Interestingly, while the monkeys temporarily shortened their search distance after finding food, they did not completely stop exploring. Instead, they continued to adapt their foraging strategy, showing an inclination to maintain a balance between searching nearby and exploring further away.

Information-seeking in Foraging

Finding food provided the monkeys with valuable information about the surrounding area. When they searched a pile, they learned whether it contained food and could make decisions based on that knowledge for their next search. This information allows them to focus on piles that might be more promising based on their previous experiences.

Researchers developed a model to better understand how information-seeking, along with reward-seeking and energy preservation, played a role in the monkeys’ foraging patterns. By simulating different strategies based on these factors, they were able to see how the monkeys made their choices and how it affected their paths.

Simulating the Foraging Process

Using the model, researchers could generate different foraging paths based on how much the monkeys weighed information, rewards, and proximity. They found that macaques adjusted their strategies based on the environment they were in. For example, when the landscape had food scattered throughout, the monkeys displayed more exploratory behavior compared to when they foraged in areas where food was grouped closely together.

When comparing the results from the monkeys to the outcomes produced by the model, researchers noticed individual differences in the foraging strategies of each monkey. Some monkeys seemed to prioritize information-seeking more than others, which highlighted unique foraging strategies based on their past experiences or behavior tendencies.

Adapting to Different Food Distributions

The study also examined how the structure of food distribution affected the monkeys’ searching behavior. When the food was grouped together, the monkeys showed a tendency to stay closer to that area after finding food. However, when the food was scattered, their behavior shifted to become more exploratory, allowing them to seek out new food sources more effectively.

By simulating the monkeys’ behaviors in both localized and scattered food distributions, researchers found that encountering food influenced their search distances in similar ways across different terrains. This finding indicated that monkeys assumed some level of continuity in how food was distributed, regardless of the randomness of its location.

Conclusion

The findings from this study reveal that macaques incorporate information-seeking into their foraging strategies while searching in unfamiliar environments. The monkeys demonstrated Lévy-like search patterns, indicating that they balance their search efforts between exploring for new food sources and exploiting the areas where they’ve already found food. The use of a spatial model helped explain their behavior and showed that different individuals adapted their searching strategies based on their past experiences and the nature of food distribution.

As a result, the research contributes to our understanding of how individual differences in foraging behavior can arise and how monkeys, like other animals, can effectively navigate and adapt their strategies when seeking food in uncertain environments.