It is important to understand how marmosets perceive the world if we are to be able to cater for their welfare needs.
Vision
Like other primates, including ourselves, marmosets rely mainly on their sight
Vision is used to look out for possible threats, to find fruits, and catch prey and to watch other marmosets
High acuity and binocular vision, with overlapping visual fields, allows them to judge depth and distance
Colour-blind Vision
All males are dichromatic – what we would call “colour blind” although they can see colour. They confuse reds, greens, browns and oranges that all look similar. Females have either trichromatic vision (like most humans), or dichromatic vision like the males
Remember this when selecting coloured targets for training marmosets
Hearing
Marmosets can hear higher frequencies (higher pitches) than humans
Sources of ultrasonic frequencies in the captive environment can worsen welfare
(e.g. dripping tap, overhead lights, some computer monitors)
Some of the calls made by marmosets are too high-pitched for humans to hear
(some of their seep and tsik calls)
Music is not necessarily enriching for marmosets. When given a choice between music and silence, monkeys prefer silence
Smell
Marmosets have a keen sense of smell, with specialised scent organs
Smell can lead them to food, provide information on the ripeness of fruits and alert them to predators
Scent markings are used to communicate
Scent marks provide information about the identity of the marker and may also have a territorial role
Taste
Taste (along with smell) helps marmosets to identify and select foods
Providing tasty (but healthy) food is a good way to enrich marmosets
Touch
Receptors in their skin cells respond to touch, pressure and temperature
These sensations guide marmosets’ behaviour
Access to a wide range of different textured surfaces (hard, soft, spongy, smooth, rough etc.) is rewarding to them
Touching contact with other marmosets (grooming, huddling, nuzzling etc.) is very important
Social relationships are formed and maintained through friendly tactile behaviours
However, there is no evidence that marmosets enjoy being stroked or directly touched by humans. For this reason, handling should be restricted to the absolute minimum necessary
It may also help marmosets cope better with stress
