Introduction

On February 16th, 2026, the field staff from Budongo Conservation Field Station and Bugoma Primate Conservation Project met with each other to talk about their observations of chimpanzees in their respective forest. The main focus of conversation was nest building, and to some extent, tool use. Below is an edited transcript of the conversation between all field assistants. 

When and how do chimpanzees nest?

Budongo - Bosco: Nesting happens from 5–6pm. Nesting grunts are produced during nesting and is similar to a food grunt. Food grunt is a grunt produced by a chimp to attract other chimpanzees. The nest grunts are usually done by dominant males and dominant females. This is used to indicate that it is time to nest. Often, other more submissive individuals will then respond to this grunt. When the nesting grunt is produced, everyone chooses their tree where to nest.

Bugoma - Arua: Nesting usually begins with females, who sometimes nest very early, 5:30. It is the adult females actually that nest very first. But generally, females do tend to nest before males. But also depends on the weather, wet versus dry season. 

Bugoma - Owota: Sometimes males nest first actually. When we look at the chimps, it’s similar to humans. Sometimes women go first to sleep, sometimes it’s us men, it depends how I spent my day. Maybe I am tired and I go to bed earlier.

Bugoma - Abou: One day, I was following a group. It was around 5, some male chimpanzees were already in the nest. It may be that sometimes chimpanzees are just tired and decide to nest earlier than usual.

Budongo – Robert: During wet season, chimpanzees seem to nest much earlier than during dry season (as early as 5pm). In rain season, they also wake up and leave their nests a bit later (around 7am).

Bugoma – Kugonza: For us, we have  studied nesting since 2019 year or so. But last year, we nested the chimps sometimes around 5pm. But generally, females do tend to nest before males. But also depends on the weather, wet versus dry season.

Budongo – Jackson: For the nesting time also, age matters. Older ones will nest earlier. Chimpanzees also nest in the daytime, creating temporary nests. Several chimpanzees have been observed ground nesting; they just bring branches to the ground and stay there for about 30 minutes to an hour and then leave.

Bugoma: [in agreement] We have seen the same in our communities.

Budongo – Robert: Yes, on Waibira side, we have also seen chimps nesting during the day and night.

Where do chimpanzees nest? How low/high are the nests?

Bugoma - Arua: In Bugoma forest, the height of the tree nest start at around 3 or 5 meters, while some nests can be as high as 30 meters.

Budongo – Bosco: Following on this comment, the chimpanzees in Budongo can also nest quite low - sometimes as low as 2 meters. But some nests can also go up to 35 meters. Some chimps mainly choose strong trees to support their weight. Dominant males and females can nest low. The alpha particularly nests very low to guard and protect the females that nest high.

Budongo – Robert: In Waibira, they mainly nest in the middle of the tree, not so high in the trees.

Budongo – Bosco: The height of the nest can also depend on the layout of the forest in the area, i.e., is it more open or closed. This will influence where the chimpanzees nest.

Bugoma - Arua: Some chimps will nest on the ground very close to the tree where other chimpanzees are nesting, and they will be some of the last to nest. Those who ground nest don’t nest early, and mostly males show ground nesting behaviour (never females).

Budongo – Kiiza: In Waibira, nesting on the ground depends on individuals. There are very few individuals who do this, and it is always a temporary nest when they do this.

Bugoma - Arua: In dry season, that’s when we have a high number of ground nests.

Budongo – Gideon: Ground nesting can occur when the chimpanzee is sick. I have seen three nests made on the ground.

Bugoma - Kugonza: And also, on the ground nest they use a pillow sometimes also. 

Budongo - Jackson: In the tree nests, they also sometimes adjust the structure of the nest and put more leaves where they put their head. 

Budongo - Bosco: Also, the presence of food makes the chimpanzees choose where to nest. They choose specific trees, for instance Trichilia rubescens is an understorage tree species that chimpanzees commonly use to nest, with low canopy and branches. They use these to nest. Ficus is another example of trees that chimpanzees nest in.

Bugoma - Kugonza : According to me, it is not common to see chimps nest in the feeding trees. You may find a female and her infant nesting in the feeding tree when the bigger group is in nearby trees.

Budongo – Robert: In Waibira, they can make day nests in the feeding trees, but not night nests. They stay close by to that feeding tree to protect it from neighbours.

Budongo – Jackson: Chimps seem to nest less in fig trees or mango trees. They don’t want to contaminate the food by peeing or pooing on them. The chimps have a sense of protecting this food to be clean.

Budongo – Robert: This topic should be researched more. There must be a reason why chimpanzees don’t nest in the feeding trees.

Bugoma  - Arua: Also, on the ground nest, chimpanzees have been observed to leave the nest, just one or two meters away, to pee, and then they return to their nest.

Budongo – Bosco: Yes, we have also observed this in Sonso. When chimps pee, they don’t go directly in the nest, they instead put their butt out to pee.

Budongo – Jackson: They choose positions to avoid contaminating the nest or food below.

Do chimpanzees vary in their nesting behaviours/patterns?

Budongo – Bosco: In Sonso, we have categories of individuals: central and peripheral. Both of them sometimes nest close to the feeding trees, sometimes not. Differences are based on ranks and the presence of females in oestrus. The high-ranking male will nest close to popular females in oestrus to make sure the females are protected. He will nest next to the females in oestrus to avoid copulation with other males.

Bugoma - Owota: Yes, we also think ground nesting, mostly shown in males, is for protection – females nest up, and males on the ground for protection. But the question comes – what would the males be protecting them from? The only threats are humans and reptiles.

Budongo – Kiiza: During the rainy season, females nest very quickly – males in Waibira are always nesting around the females in oestrus, similar to what has been observed in Sonso.

Budongo – Gideon: We also have some females in Waibira, if they have infants, they go very far to nest. We have at least four individuals that do this: Nora, Bahati, Monika, and Keti. They like to nest in Maerua trees. 

Bugoma - Abou: It is the adult females that nest very first usually. Nesting time depends on the weather, age of the chimps, and how tired they are. 

Budongo - Jackson: Yes, age matters with nesting. Older chimpanzees will nest earlier.

Budongo – Mike: What about if a chimp is sick? Can another help make the nest?

Budongo – Robert: No, instead they use the old nest.

Budongo – Bosco: When chimps reuse nests, they can add leaves to make it more comfortable. And sick individuals can do ground nests, when they are close to grooming. 

Bugoma - Abou: Do the chimps share nests? I am asking this because recently I have seen whereby you find a nest with another nest nearby, or in the same nest, another nest that is like a room.

Budongo group: Yes! Mostly just mothers and infants.

What type of tools do chimpanzees use?

Budongo – Robert: In Waibira, chimps use leaves for drinking water. They take the leaves and chew them, then they put it in the water, then they suck, like a sponge.

Bugoma - Arua: The same has been seen in Bugoma. They also use leaf sponges to drink water.

Budongo – Robert: They also use moss, dip it in water, and squeeze it in the mouth to drink.

Bugoma - Kugonza: Not yet observed in Bugoma, only the leaves. Because our forest is thick, it is complicated to observe these behaviours.

Budongo – Kiiza: Chimps also make their own well for water by digging a hole.

Budongo – Robert: There is a spot where you can scratch and water comes a little bit. One female did this for about three years.

Budongo – Jackson: In Sonso, we also saw a juvenile, called Henri, digging repeatedly and cleaning the area to drink.

Bugoma - Kugonza: When we did honey experiments, we put honey in a wooden log. One chimpanzee used sticks to get the honey. This was only observed in this individual. This chimpanzee was called Engineer. He showed this behaviour twice.

Bugoma - Abou: Others came and watched him, but no one else used the stick.

Budongo – Jackson: So far in Budongo, they have never been seen to use sticks to access honey. 

General Reflections:

“I was happy to share our experience with a different field site on the two topics. I really enjoyed the trip”.

-Annonymous, (Bugoma)

“It was very special and interesting to interact with our colleagues from Bugoma. This was so impressive as one of our objectives to inspire other scientists in the world.  I have a feeling that this objective can be achieved. The interaction with the assistants has greatly paved way to cover a greater population of scientists and an inspiration to convince non-scientists.”

-Bosco (Budongo)

“I found it very interesting meeting the Bugoma team. Field assistants from Budongo know of many animals and different types of monkeys that the ones they have in Bugoma. Next time we could meet in Bugoma and have a look at their animals, also to have a look at their communities of humans and chimps. We never know in future, human beings move and we might meet in the future.”

-Robert (Budongo)

“It was interesting and at least I got a chance to get to know what I did not know. It created friendship between the two sets of field stations.”

-Annonymous (Bugoma)

“I was very happy to meet the guys from Bugoma, we had a lot of interactions. I came to learn that there are different tool uses in Budongo and Bugoma communities. I also came to understand that the forests in Budongo and Bugoma are different and many others. I am personally very happy to have met new friends and interacted with them and exchanged contacts. Next time I look for meeting them in Bugoma and interacting with them.”

-Patrick (Budongo)

“I liked the knowledge comparison and sharing and also it makes both sides put more effort in observing more from both the chimps and the forest at large.”

-Jackson (Budongo)

“As you know Budongo is older than Bugoma and Budongo has people who are experienced, who have knowledge on chimpanzee habituation, tracking and data collection, birding, phenology, everything. I stand to be one of the guys that has been in the field for many years. It is my wish that one day we might meet with you in Bugoma and we get to interact. We can learn from each other, as learning never ends. Thank you.”

-Monday (Budongo)