'The bigger, the better' according to bonobos

In 2020, the bonobo group in ZOO Planckendael was joined by five new females. With the arrival of the new animals, the group is one of the largest bonobo groups in Europe. This group expansion is beneficial for intelligent primates that also live together in large groups in nature according to the fission-fusion principle. “Bonobos live in large groups that split into smaller subgroups during the day. In the evening, the small groups often come back together to make a nest close to each other, in a large group,” explains curator Sarah Lafaut. “The larger the group, the better we can mimic that principle.”

Never before have so many great apes roamed around the bonobo enclosure. In the summer of 2020, five females from German zoos arrived. Nayembi (°2006) and daughter Nila (°2015) stayed at the Frankfurt zoo, Binti (°1995) moved with little ones Bina (°2015) and Balina (°2019) from Cologne. Not much later, two new youngsters were born, Vyombo (°2020) and Wakati (°2021). The latter is the 20th bonobo born in ZOO Planckendael. The bonobo family now has 20 members, 13 women and 7 men.

“The introduction of animals from other zoos does not happen overnight, but follows a well-thought-out process. For this, ZOO Planckendael appeals to decades of experience with great apes,” says curator Sarah Lafaut.


“The European breeding programme (EAZA Ex Situ Programme) knows the genetic background of all animals. The programme aims to preserve at least 90% genetic diversity in 100 years so that these animals can serve as a back-up population should it ever be necessary to release them into the wild. In order to guarantee this genetic diversity of 90%, it is examined which animals breed best together. In addition, just like in nature, we try to follow the natural course of events. For example, the women move away from their family group around the age of eight or nine. We imitate that. With one difference: we choose, on their behalf, where they will go.”

“In addition to genetic diversity, we also look at the characters of the animals. If an animal does not feel well in a certain group, we intervene. We don’t only look at the numbers but also at the individual. When groups are not assembled as in nature, problems arise. That is why it is so important to be able to do research in zoos as well as in Africa. By studying the species in depth, we can provide the best care for the animals in zoos.”


Today the group in ZOO Planckendael consists of twenty animals. This makes the group one of the largest bonobo groups in Europe. The group expansion is beneficial for the intelligent primates that also live together in large groups in nature according to the fission-fusion principle. “This means that the large group splits up into smaller subgroups during the day. In the evening the small groups often come back together to make a nest close to each other, in a large group. The next day, the composition of those subgroups may look different again,” says curator Sarah Lafaut. “The larger the group, the better we can mimic that principle.”

The social bonobos need to be mentally challenged. Their residence, which was renovated in 2019, has seven locations for the animals to choose from. In this way they decide for themselves whether they sit together in a group or whether they want to isolate themselves for a while, just like in nature.


 “The introduction of new residents does not happen overnight,” says Sarah Lafaut. “First, the new animals are kept separately for a short time to relax and get used to their new environment. When a bonobo arrives without family members, we will immediately introduce it to a group member. Bonobos are social animals and segregating them for too long could have a major emotional impact.”

“We observe their behavior and make sure that they are eating well and that they are comfortable. Only when all signs are favorable will we continue the introduction. We look at the character of the newcomer and decide, in consultation with the animal's caretakers, which individuals of our group they can meet first.”

The animals can see and touch each other, but are still separated by a barrier. Their behavior is monitored by a caretaker on site and by the cameras in the building. Doctoral students and master's students are often also involved in the observations. Sarah: “We can see every corner of the residence. The team observes all the animals' reactions and behaviors. If the interaction is positive (or not negative), we open the slider. Sex often follows, which is a good sign.”

In general, the introduction to bonobos goes smoothly. With chimpanzees it sometimes takes months, but Nayembi and Nila quickly felt at home in their new group. A week after the great apes arrived at Planckendael ZOO, they were introduced to the rest of the group. “Everything went very smoothly, the introduction was completed after one day. With Binti, Balina and Bina, the process was a little more difficult. However, it can take months before the group structure is established. Conflicts are therefore not uncommon.”


Sarah is clear: “That is determined by the animals themselves. The breeding program coordinator, caretakers, scientists from the CRC (the Antwerp ZOO Center for Research and Conservation) and I may give a recommendation, but if the animals don't want to be together, they quickly make that clear.”

“We do a thinking exercise beforehand and try to estimate which characters would fit well together. We put those animals next to each other. If the interaction is negative, however subtle, we choose another animal. Negative signs are for example bullying behavior, such as pushing each other, or taking away food. If a new animal is not supported by another individual in the group, the situation can quickly escalate. In short: in the end, the animals themselves choose who they want to be with. We physically open the door but will never force them to interact with each other.”

“We had correctly assessed the situation with Nayembi and Nila. Binti needed more time to get used to the size of the accommodation and the group. In that case, we wait until Binti has a good relationship with one of our women so that they support her if a conflict should arise during the further course of the introductions.”


“Bonobos are very important to ZOO Planckendael. They are a crowd favourite and the zoo is studbook keeper for all bonobos in zoos worldwide, as well as coordinator of the European breeding program. For bonobos in European zoos, the coordinator determines which bonobo may have offspring with which other bonobo. Since 1992, scientists from our own research center (CRC) have been studying the behavior of bonobos in ZOO Planckendael. Nowhere in the world can so much information be collected.

We are the first zoo in Europe to conduct structural scientific studies on bonobos from the start. The way we keep the animals is based on the results of research,” says Sarah. We can safely call ourselves an authority in the field of bonobos.”