Little research has been conducted on the senses of sengis (elephant-shrews, Macroscelidea, Afrotheria, Mammalia); behavioural investigations about the animals’ vision are completely missing. Other Afrotheria (manatees, elephants, tenrecs, rock hyraxes) are dichromats, having two types of cone photoreceptors in the retina. We tested the hypotheses of dichromatic colour vision in sengis. With choice experiments, we examined the potential of two sengi species to discriminate between trained colours (blue, green, red) and different shades of grey, and to differentiate between trained UV-reflecting (high UV reflectance) and UV-absorbing (low UV reflectance) plates. Both sengi species recognised blue and green and could distinguish them from all shades of grey. The ability to perceive red and ultraviolet could not be proven. Thus, the sengis are most likely dichromats based on green and blue sensitive receptor types. We discuss protective mechanisms in the lens as a UV filter explaining maximum sensitivity in the UV suggested for another sengi species after in vitro expression assays.

Beside insects, sengis also consume plant material such as leaves, fruits, seeds and floral nectar. It is known that they use olfaction for foraging, but little is known about their vision and visual learning capabilities. Colour vision has been tested in two species, showing that they are likely dichromats (green- and blue-sensitive retinal cone-photoreceptors, meaning red-green colour blind). Our aim was to examine the learning and colour discrimination abilities of another species, Elephantulus edwardii. Using training procedures and choice experiments, we tested the hypotheses that the animals can associate a reward with trained colours and that they can discriminate between different colour hues. The sengis preferred the trained colours over the others, indicating associative learning. They could discriminate between all tested colours (blue, red, green, yellow). The sengis’ colour choice behaviour indicates that the animals can use also colour features to find food plant material. Additionally, learning abilities most likely are essential for the sengis’ foraging activities, for instance by associating floral or fruit shape, colour or scent with nectar or ripe fruit, to increase the efficiency to locate food sources.