A new study reveals that Kangaroos appear to form tight social groups with other mothers when their young are in tow. These social gatherings keep their young joeys safe from predators and other troublesome males.
Ear Recognition Technology
Kangaroos are known for living in groups that can reach several hundred individuals. However, their one-on-one relationships have been a challenging area to study. This is because marsupials are more difficult to trap and tag than other animals, such as deer. Joeys hide in their mothers' pouches, while adult roo's powerful tails can get them injured or killed as they try to escape after being darted or trapped.
To address this challenge, ecologist Nora Campbell from the University of New South Wales Sydney turned to kangaroo ears, the body part with a unique outline and tuft pattern. Campbell collaborated with biologist Terry Ord, and together, they utilized artificial intelligence software that analyzes the distinct shapes of whale tails and polecat facemasks.
Every year, Ord counts and photographs a group of eastern gray kangaroos (Macropus giganteus) hiding in camouflage tents in southeastern Australia. Campbell sifted through more than 3,500 pictures captured by Ords from the past six years and chose those with a clear view of the roos' ears to be run through the software.
The software provided solid identification of the pictures of kangaroos and the other members of their 'club.' The marsupials rarely touch one another aside from their joeys, so the researchers defined the 'circle of friends' as any kangaroo standing within about 3 meters on at least two separate occasions.
The team used these identifications in mapping the social network of each of the 150 individuals seen in the group over the six years. From this analysis, they made a "social score" based on the number of kangaroos they associated with.
Biologist Rachel Bergeron from the University of Sherbrooke described this ear recognition technology as an ingenious concept. If further validated, this technique can provide an excellent, minimally invasive approach to studying kangaroo societies.
Tight-Knit Society
On average, female kangaroos with joeys tend to be twice as socially connected as the other kangaroos based on their social scores. It was found that those with the highest scores, considered the most popular females, also kept the same friends year after year. This behavior ends up being like a group of suburban mothers.
Kangaroo moms are shown to be antisocial in other studies. Bergeron was surprised to see them displaying the long-term female relationships usually found in dolphins, primates, and other highly cooperative, highly social species. It may be because the kangaroos in the new study live in an area with more harmful predators, making the mothers more likely to team up.
As vigilant moms try to protect themselves and their young, it makes sense to surround themselves with other vigilant mothers who do the same thing. According to zoologist Alan McElligott from the City University of Hong Kong, the findings of this study reflect just how sensitive and intelligent kangaroos are.
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