If you’re a wee carnivore living out in the wooded savannas of Africa, it might be a bit difficult to intimidate your rivals. But with a bit of balance and agility, wild dwarf mongooses have found a way. These little predators, who weigh around half a kilogram (or about a pound), elevate their scent marks way up high by doing handstands. After all, higher marks typically suggest a taller mark maker. The findings were published online in Animal Behaviour last month.
Researchers used to think that when mammals elevate their scent marks – by leaving them on vertical objects, like trees – they’re doing it to increase detectability. These marks contain a lot of information, from age to sex and how receptive they are at the time. But recent work hinted that these elevated markings evolved to convey the size of the marker to potential competitors. Being able to assess rivals indirectly can be a huge advantage if it helps to avoid potentially dangerous encounters with a big bully, for example. But whether or not size is something mammals can extract from scent marks had remained unconfirmed until now.
Dr Lynda Sharpe of Stellenbosch University conducted tests with wild dwarf mongooses (Helogale parvula) in northeastern South Africa to see if they discriminate between scent deposits at different heights. These tiny mongooses live in territorial groups of between six and thirty animals and they engage in a pretty extreme form of elevated marking using handstands. The mongoose balances on its forepaws while flinging its hind legs into the air and smearing its “anogenital secretions” one full body length above the ground, she writes. You can see mongooses doing handstands and smearing their anal scent glands on vegetation in this great video. Both males and females engage in the scent marking.
Sharpe swabbed 10 anal-gland secretions left by wild dwarf mongooses, and each sample was used to mark bamboo sticks at 10 and 16 centimeters. With the stick standing straight up, these would correspond to the heights of small and large adult mongooses. The sticks were then left out in the wild.
As it turns out, height matters to dwarf mongooses. Females spent twice as long investigating deposits positioned at 16 centimeters above the ground than those positioned at 10 centimeters – even though the two were swipes of the same scent deposit and were likely to be chemically identical. “Presumably, finding out information about big animals is more important than finding out information about small animals,” Sharpe tells New Scientist.
In a separate “feces presentation” experiment, females were more interested in obtaining information about other females than males. This is probably because female dwarf mongooses experience extreme competition with others of the same sex. Sharpe thinks that, since females spend their entire lives in the same territory, they use scent marks to assess the risk of nearby groups encroaching on their land. The heights of handstand scent marks help them to size up potential rival females and gather information on those that pose the greatest threat.