How do you first sass out your opponent before becoming involved in a potentially detrimental confrontation?
Well, if you were a female dwarf mongoose, then one way would be to check out the height of your rival's handstand scent marks.
Handstand scent marks?
Dr Lynda Sharpe, a behavioural ecologist from the Department of Botany and Zoology at Stellenbosch University, explains.
"Scent marking is an important means of communicating in mammals. Many species raise their marks up off the ground by smearing them on surrounding objects. This is thought to increase detectability because the scent wafts more widely."
But the height of an elevated scent mark usually reflects the height of the marker, so animals may employ elevated marks to transmit information about body size. This information would be hugely useful to a neighbour or rival thinking of mounting a challenge, she points out.
Since 2006, Dr Sharpe has been studying the social behaviour of four groups of wild dwarf mongooses at the Phuza Moya private game reserve outside Hoedspruit, Limpopo. Over time she managed to habituate the wild dwarf mongooses so that she can walk within one to two metres of them without disturbing their natural behaviour.
But while considerable research has gone into the information that can be extracted from the chemical composition of scent deposits (like identity, sex, reproductive status, social status, health and kinship), the relative height of the deposit has received virtually no scientific attention.
"In some species, like grey wolves and African wild dogs, elevated marking is largely restricted to dominant individuals, or to just one sex, such as females in bush dogs and males in giant pandas," she says.
"In these species, mark height clearly provides information about who has marked. But no one knows whether small differences in mark height – typical of markers of differing in size – are also important."
In the case of dwarf mongooses, they all display the handstand marking posture, pups included.
Dr Sharpe says dwarf mongooses are socially very sophisticated animals, living in cooperative groups where everyone chips in to rear the pups and guard against predators. She wanted to find out whether they are using their elevated scent marks to indirectly assess the size, and hence competitive ability, of rivals.
She found that female mongooses devoted more than twice as much time to sniffing scent deposits placed 16cm above the ground as compared with 10cm, even though the two were the same chemically: "Females were genuinely more interested in scent marks that were elevated above the average handstand mark height, and they (but not the males) appeared to actively seek out the highest deposits, stretching up on tip-toe to pass their noses along the entire length of the 20cm stick," she writes in an article published in the journal Animal Behaviour this month.
Dr Sharpe explains that competition among the females is extremely intense, because only those that are able to win the alpha position within a group get to breed. The highest female scent marks are normally deposited by the largest females, and, because body size is positively correlated with social rank in females, these large females pose the biggest threat to others.
The results of the study were published in the journal Animal Behaviour this month, with the title 'Handstand scent marking: height matters to dwarf mongooses'.
On the photo: Dwarf mongooses are small carnivores that live in territorial groups of six to 30 individuals. Groups are normally composed of an alpha pair, which largely monopolises breeding, and their adult offspring. There are strong, intrasexual, linear dominance hierarchies within groups and females normally queue for the alpha position within their natal group. Photo: Lynda Sharpe
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Dr Lynda Sharpe
M: +27 _76 013 9420
E: sharpelynda@hotmail.com
