By Dr Matt McLennan, BCCP Director
In chimpanzee society, young females normally leave their birth community when they reach adolescence and join another group to begin their reproductive lives, avoiding breeding with close male relatives such as their fathers, uncles, and brothers. As highlighted in previous posts, setting out alone in search of other chimpanzees is a risky undertaking for young females in Bulindi and elsewhere in Uganda’s Budongo–Bugoma Corridor. The network of riverside forests and swamps that once served as their migration routes has mostly been cut down and replaced by farmland, villages, and towns, and the landscape is now crisscrossed with busy tarmac roads. As we expand our monitoring and conservation programme to more communities of “village chimpanzees” in the corridor, we are learning more about the fascinating migration patterns of young females, and the huge challenges they face as they navigate this human-transformed landscape.
Our free eBook, The chimpanzees next door, explains how this landscape has changed for chimpanzees and the people who live alongside them.
Juvenile Jackie in Kasongoire (March 2026).
Over the last decade, we have confirmed that a number of young females successfully migrated between the chimpanzee communities we monitor. More often, however, these females simply disappear from their birth groups during adolescence, and we never find out what happened to them. Did they find another community to join and start a family, or did they run into trouble in the human-dominated landscape along the way?
While most wild female chimpanzees seem intrinsically driven to migrate, a minority become pregnant and give birth in their birth communities. Once they have offspring of their own to care for, these females seem to lose the urge to migrate, and most stay in their birth community for life. This seemed to be true for Jemima of the Bulindi chimpanzee community.
Jemima and her new infant in Kasongoire (January 2026).
We first got to know Jemima in 2012, when she was a juvenile. She is the presumed firstborn of Bulindi matriarch Mirinda. In 2016, Jemima gave birth when she was around 10 years old, a very young age for a wild female. Most likely, she became pregnant before she had a chance to consider migrating. Sadly, her first infant died during an outbreak of coughing in early 2018. Still, Jemima stayed in Bulindi, and by the end of that year she had given birth to a second infant, whom we named Jackie. Jemima was close to her mother, Mirinda, and the two females were always found together with their infants. It seemed certain that Jemima would spend her whole life in Bulindi.
In September 2021, Jemima gave birth for a third time. This time, her newborn disappeared on its second day. Jemima had been fearful of the group’s males, especially aggressive young male Jack, and had tried to stay close to BCCP Chimpanzee Monitors Tom and Johnmary, apparently for protection. We suspect Jemima’s baby was a victim of infanticide, an adaptive (though, for researchers, unsettling) strategy for some male chimpanzees. Less than two months later, as Jemima was coming back into season, she disappeared from Bulindi, along with Jackie, then almost three years old. We believe the suspected infanticide made Jemima reconsider her options and prompted her to leave her birth community to seek a new life with other chimpanzees.
For four years, we didn’t know what had happened to Jemima and Jackie. In 2022, there were reports that farmers had killed a female chimpanzee with an infant in Masindi, some way across the district border from Bulindi, and we wondered whether it could have been Jemima and Jackie. Either way, it seemed unlikely we would ever know for certain whether Jemima’s migration had succeeded.
From late 2025, we began expanding our monitoring programme to include the Kasongoire chimpanzees, who range about 13 km from Bulindi. Given the relatively short distance between the two communities, we wondered whether females occasionally migrated between them. I visited Kasongoire in November 2025, and while studying the photos and videos taken on that first day, I was intrigued by a young adult female who looked a lot like Jemima. As more photo and video evidence built up over the following days and weeks, it became clear that this female was indeed Jemima, and that she had a new infant, a boy, evidently fathered in Kasongoire. It was a great relief to confirm that Jemima had made it!
Jemima and her new infant in Kasongoire (March 2026).
Jackie’s fate was far less certain. While the Kasongoire males would certainly have welcomed a young breeding female like Jemima, they may have been more ambivalent about her daughter, fathered by rival males. Kasongoire is a relatively large community, with over 40 members, including many juveniles, and it can take time to match juveniles, who are often quite independent, to their mothers with confidence. Slowly, though, it became clear that one juvenile female, aged around seven, which is exactly Jackie’s age now, associates with Jemima and her infant. We are pleased to conclude that this must be Jackie, and that she made it to Kasongoire too!
Now that our monitoring programme includes Kasongoire, we hope to follow the lives of Jemima, her infant, and Jackie for years to come. Sign up for our newsletter to follow their story.
Rediscoveries like this are only possible because our Chimpanzee Monitors follow the chimpanzees every day. Your donation helps keep them in the field as we follow Jemima, Jackie, and many other chimpanzees.