I'm happy to share my co-authors and I have published a new article on the Burgers' Zoo chimpanzees in a special issue on anecdotes in Behaviour, which you can read here.
In this article, we describe how an immigrant female chimpanzee adopted a local female-specific tradition after introduction to the Burgers' Zoo group. The behavior in question (the "crossed arm walk") has been present in this group for over 20 years, but had never been written about before. It appears to serve no function, yet the immigrant female copied it within days after meeting a resident female who often performs the behavior.
Extra interesting is that another female who was introduced at the same time never showed the crossed arm walk during our study period, and that the female who copied appeared more integrated two years after the introduction. This highlights how, depending on circumstances and background, individuals vary in their behavioral response to an integration. Possibly, copying the behavior of your new group mates can be one 'strategy' you can use to fit in and minimize the risk of being excluded. In humans, it is well known that similarity breeds connection, perhaps a similar mechanism is at play here.
If you are interested to read more about our observation of this behavior, do check out the article! I am very grateful to all of my co-authors, Kayla Kolff for her help during data collection, and the zoo keepers for all the knowledge and assistance they contributed during the process!
Morami (likely the inventor of the behavior) doing the crossed-arm walk while holding sticks