WHAT SENSES DO VERVET MONKEYS USE?
Understanding how vervet monkeys use their senses helps campers predict their behaviour and secure their campsites.
Vervet monkeys rely on a combination of sight, hearing, smell, touch, and taste to move around, find food, and detect danger. Their sensory priorities differ slightly from humans, giving them advantages in certain situations.
1. Sight: Primary Navigation Tool
Sight is the vervet monkey’s most important sense.
Their eyes are positioned at the front of the head, similar to humans, providing binocular vision and depth perception. This helps them judge distances accurately when moving through trees or across the ground.
Vervets rely on sight to:
- Identify safe routes between branches and objects.
- Recognise food sources such as fruits, insects, or human food.
- Monitor troop members through visual signals and gestures.
- Detect predators like eagles, leopards, or snakes.
Compared to humans, vervets have excellent motion detection. Their peripheral vision is slightly wider, and they are quicker to notice sudden movements.
For campers, this means monkeys often spot unattended food or open bags long before people notice them.
2. Hearing: Early Warning and Communication
Hearing plays a major role in a vervet monkey’s daily activity.
Their ears are tuned to a wide range of frequencies, including high-pitched alarm calls and subtle rustling noises.
Troops rely on distinct vocal signals to alert one another to specific threats:
- Short “chutter” calls often indicate snakes.
- A specific bark alerts others to eagles.
- A different alarm call signals leopards or ground predators.
This precise auditory communication allows them to react fast and coordinate movement. They also use hearing to detect approaching humans or animals before they become visible.
For campers, this means vervet monkeys often hear you unzip a tent, open a packet, or start preparing food well before you see them nearby. Their ability to recognise these sounds makes them efficient at approaching campsites at the right time.
3. Smell: Secondary, but Useful
Smell is less dominant than sight or hearing, but vervet monkeys still use it effectively.
Their sense of smell helps them:
- Identify ripe fruit or other food sources.
- Recognise individuals in their troop.
- Detect predators through scent cues.
Humans generally have a weaker sense of smell compared to many animals, but vervet monkeys’ olfactory abilities are moderate – stronger than ours for natural scents, but not as advanced as dogs or some other primates. They may smell food items like fruit or cooked meals from a moderate distance, but usually rely on sight and sound first.
For campers, food scents can draw their attention once they’re already in the area. If they’ve seen movement or heard packaging, smell reinforces their decision to investigate.
4. Touch: Close-Range Information
Touch becomes important when vervet monkeys are close to objects or other individuals. They use their hands to explore food, assess ripeness, and remove outer layers like peels or packaging.
Their tactile sense is highly developed in their fingers, allowing them to open containers, peel fruit, and manipulate objects quickly.
Social grooming also relies on touch. It reinforces bonds within the troop and helps remove parasites. Campers who leave zips or containers unsecured may find monkeys quickly figuring out how to open them, as their fine motor skills are excellent.
5. Taste: Final Evaluation
Taste is usually the last sense vervet monkeys use.
After locating food through sight, confirming through sound or smell, and handling it, they taste it to decide whether to eat. Their taste preferences lean toward sweet, ripe fruits, but in campsites, they often sample anything that resembles food, including bread, snacks, and cooked meals.
Unlike humans, vervet monkeys are less cautious about trying unfamiliar food, though they often discard items they don’t like after tasting.
This behaviour is why campers may find bits of packaging and half-eaten items scattered around after a troop visit. It is not that monkeys waste food.
Sensory Order: How Vervets Navigate
When vervet monkeys move through an area, their senses engage in a predictable sequence:
- Sight — scanning for movement, food, other monkeys, or predators.
- Hearing — detecting subtle signals and communication within the troop.
- Smell — confirming potential food or identifying familiar scents.
- Touch — exploring objects at close range, opening or peeling.
- Taste — final stage, determining edibility.
This sequence allows them to react quickly and make efficient decisions. For example, a monkey in a tree might first see a plastic bag on a table, hear wrappers being opened, smell fruit or bread, climb down to touch the bag, and finally taste its contents.
Humans also rely heavily on sight and hearing for navigation, but vervets are faster at switching between these senses and reacting to subtle cues. Their attention to motion and sound gives them a tactical advantage in busy campsites.
Implications for Campers
Understanding this sensory order helps campers manage interactions with vervet monkeys:
- Reduce visual cues: Keep food out of sight, preferably in closed containers or inside the car.
- Limit sound signals: The sound of packets, zips, and coolers can draw their attention even if they cannot see the food.
- Manage smells: Dispose of food waste properly and clean up immediately after meals.
- Secure tactile access: Use containers or coolers that are difficult to open. Vervet monkeys are skilled with simple latches and zips.
- Avoid tasting opportunities: Don’t leave plates, cups, or utensils with leftovers lying around.
This sensory-based approach can reduce campsite conflicts and protect both campers and wildlife.
Conclusion
This explains how Vervet monkeys rely mainly on sight and hearing, supported by smell, touch, and taste, to navigate their environment.
Their ability to detect subtle cues makes them highly efficient at spotting opportunities around campsites.
By understanding their sensory order, campers can secure food, minimise attractants, and enjoy peaceful wildlife interactions.
“Vervet Monkeys as Travelling Salesmen”
The research on “Vervets as travelling salesmen” by Audrey E. Cramer and C. R. Gallistel investigates how vervet monkeys (Cercopithecus aethiops or Chlorocebus pygerythrus) solve complex foraging routes that are mathematically analogous to the Travelling Salesman Problem (TSP).
The TSP requires finding the shortest path among multiple destinations before returning to the start.
The researchers aimed to determine how many future destinations influence a vervet monkey’s decision on its next step.
Key Findings:
- Distance Minimization: The captive vervet monkeys were shown to ignore the order in which food (grapes) was hidden and instead consistently chose routes that minimized the total distance travelled among the food sites.
- Planning Ahead: While a simple “nearest neighbour” algorithm (always choosing the closest unvisited site next) could largely account for the vervets’ overall efficiency, specialized tests were conducted to see if they were considering sites beyond the immediate next one.
- Three-Step Planning: The results demonstrated that the choice of the next destination was strongly influenced by at least two further destinations along the route. This indicates that the monkeys were capable of planning at least three steps ahead when navigating, a remarkable cognitive capacity given the limited number of destinations (never more than six) in their excursion.
Acknowledgement
This summary is based on the article “Vervets as travelling salesmen” by Audrey E. Cramer and C. R. Gallistel, published in Nature (Vol. 387, No. 6632, p. 464) in June 1997.