Introduction

The chimpanzee gestation time is estimated to be around 8-9 months. During those months the pregnant female behaves in a regular manner, however, her oestrous swelling is on and off. Furthermore, the pregnant female’s oestrous does not reach the full stage of swelling, and often remains only partial for extended periods of time. The irregular timing and nature of these swellings are one indicator that the female will soon give birth. As the pregnancy progresses the female will stop copulating with adult males and instead will transition to copulating with immature juveniles. On the side of the mature males, when the female approaches them, they will inspect and sniff her swelling. This inspection and sniffing action is also done by the adult males to check the female’s ovulation state even if the female is not pregnant. This copulation inspection behavior is also common in bovines and ungulates. It has been observed that males have also aggressed females when the male suspects the female is pregnant.

We have observed that chimpanzee female behavior can also change during pregnancy. One such change is that the Budongo chimpanzees can also become more peripheral when pregnant. If the female is pregnant, she may also act lethargic; her behaviors may include feeding bouts followed by resting bouts. Another clue that a female may be pregnant is her stomach size increases. Also, her hair texture may change, becoming smoother.

When a pregnant female already has a juvenile and is already lactating, she will wean her juvenile and stop breastfeeding that offspring when the new baby is born. To carry these two offspring she will  sometimes carry one on her stomach and one her back. In the early days following the arrival of the new infant the juvenile will force themselves into the mother’s nest with her new infant. Certain mothers have more tolerance toward their existing juveniles than others. Their tolerance level can depend on the interval between the subsequent babies which is dependent on the fertility of the female. The juvenile’s personality can also impact the amount they still rely on the mother. Importantly, how the central the female is in the group could impact weaning and tolerance toward the existing juvenile.   

While we have information on the behavior of wild chimpanzees before and after giving birth so far, not much information has been reported concerning live births in wild chimpanzees. This is because it is a very rare event which requires many years of experience and time in the field. This paper will report two novel events witnessed by the Budongo Conservation Field Station Primatologist Team and give an account of these observations.

Methods

Study Site

Budongo forest is a semi-deciduous tropical rainforest located in the western rift valley, Uganda. The forest is 793 km2 and is home to approximately 600 chimpanzees. Our observations occurred within the Sonso and Wabira communities which are located in south of the forest and have been studied systematically since 1990 and 2011 respectively. Both communities are considered to be habituated to human presence, although Sonso are regarded as being considerably more habituated to human presence than Wabira.

Budongo forest is divided into 7 blocks for manage purposes. Each block is divided into compartments. Our observations occurred within the Nyakafunjo block, in particular N3. Compartment N3 is the core of the Sonso community grid system. Sonso grid system is divided into research blocks of 100 metres by 100 metres. They are all systematically labelled. Both of our observations occurred in the block 0A. 0A is close to the centre of the territory, within 100 metres of BCFS camp. 0A has a mixture of trees, including two prominent Ficus Mucoso trees, a small number of brosounettia papyfyrus trees, and lantana camara, amongst others. When observation 1 occurred in 1998, Sonso had 54 individuals. When observation 2 occurred in 2019, Sonso had 65 individuals    

Subjects

Kewaya

At the time of observation, Kewaya was a core female in the Sonso community. Kewaya has a mutilated right hand due to a snare injury. She was not a shy individual because the mother was habituated. Her mother was Zimba, a high-ranking female, which is why we now take Kewaya to be high ranking. Kewaya can be aggressive to males and her fellow females. However, she often dislikes to be followed, especially when in estrus, and has been observed to produce bark vocalisations at human followers. Kewaya has had 5 offprings: Her first offspring, Katia, is the offspring observed being born in this paper. Since Katia, Kewaya then had a second infant who died on 21st November 2005 unsexed and unidentified. She then had Kox, another female who surivives today and has her own infant. Next she had another female infant who died through infanticide. Finally, Kewaya had a male offspring, Kavera who survives today. When Kewaya gave birth she was approximately 15 years at the time.

Kutu

At the time of observation, Kutu was a core female in the Sonso community. Her age was 40 years old and she had given birth to 8 infants, 4 of which survived. At the time of observation, she had a juvenile son, Keffa, who was 5 years old. She also had a sub-adult female daughter, Kathy, who was 11 years old. Finally, she also had an adult male son, Kato, who was 26 years old. Before our observations she had experienced infanticides previously. She is known to be a nervous individual around human observers and other chimpanzees, especially when she is on the ground. When followed by humans on the ground, she often moves in circles to dodge her followers. She has not had any snare injuries. She possesses many features that show she has been aggressed in the past such as her left-side ear which has a notch in it. She is a mid-ranking female.

Data Collection

The main method of data-collection in Sonso and Wabira is through focal following. Each day, once the chimpanzees have been located, the researcher chooses an individual, and follows that individual and systematically observes their behaviour for that day. In addition, observations for rare or unusual events are collected ad libitum. Both of our live birth observations were ad libitum. Data is collected between 7am and 4:30pm in Sonso and between 6am and 5pm in Wabira. Data collection occurs throughout the entire year.

Results

Observation 1

At 7:30 of 30/12/1998, chimpanzees of the Sonso community were heard calling. A tree of the species Ficus mucoso which was bearing ripe fruits was observed carefully in order to see whether the chimps of the Sonso community were feeding on its fruits. The individual named Kewaya (KY) was seen sitting on a branch of the fig tree at a height of 30 metres above the ground (1/2 way in the canopy). KY was not feeding, but according to the expression on her face she appears to be in pain. Observations of KY started at 08:07. At 08:38 she pushed her left hand into her vagina for 40 seconds. The left hand was used by KY because her right hand is deformed due to a snare injury. When she removed the hand it was visible and the hand was wet. She then licked her fingers. At this moment it was assumed that she might have been in labour. At 08:42 she pushed her hand again into her vagina. When she removed it, fluid came out from the vagina. It was thereafter assumed that the amniotic sac had broken. Then she became ‘unsettled’ (i.e. she was nervously moving around as if something was bothering her) and she moved ½ metre on the same branch and sat, moved back, then sat again and again moved back. Unfortunately a good report of the time from this moment onwards has not been recorded since priority was given in obtaining a good description of the event. KY kept pushing her hand into her vagina several times. At 08:50 while removing the hand from the vagina, fluid poured again. She kept being ‘unsettled’ and pushing her left hand into her vagina. At 08:55 when she removed the hand, some more fluid (a smaller amount than before) came out of the vagina. At this time she stopped pushing her hands into the vagina, but she placed/pressed the hand on the vagina as if she was waiting for something. KY kept on touching her vagina and moving about in the tree changing branch. At 09:12 she started having abdominal contractions with the right hand placed onto the vagina waiting for the infant to come out. At 09:15 other individuals of the Sonso community (KG adult female with KD, juvenile son and KT infant daughter) came onto the same branch. KG moved in the direction of KY but not showing any particular interest/concern. KG sat 1.5m away from KY and started feeding on figs. At 09:20 KY changed position facing KG’s side (KY was looking at KG but she appears not to request any help/assistance form her). At this time KY was seen to be in great pain (according to the way she was moving and her facial expressions) and to keep the hand on the vagina. The vagina at this moment opened widely: the infants head was seen to come out first. The infant was born at 09:23. As soon as the infant emerged fully KY caught it in the hand which was placed onto the vagina and she pulled the infant onto her belly and hugged it. After 4 seconds from the birth of the infant, blood started to come out for about 5 seconds. At 09:26 KD came close to see the newborn. KY did not pay attention to the interest of KD towards the new infant. At 09:40 she put her hand on her vagina, she collected the placenta and started to feed on it immediately. At 09:46 she finished feeding on the placenta and started licking blood from her hands. She did not eat the umbilical cord and she left it hanging. At 09:48 she grasped the umbilical cord from the end and started pulling it. Unfortunately, it was not possible to see what she was doing exactly, but it was assumed that she was using her teeth (incisors) to cut it, given that she was seen biting the umbilical cord when facing the observer. At 09:49 she stopped and after 30 seconds she started feeding on ripe fruits of the Ficus mucoso. At 09:53, NB and her offspring MS (juvenile male) and NO (infant female) joined the group on the tree. At 09:55, KU and her offspring KT (juvenile male) and KN joined the group. At 10:16 KL and her juvenile daughter BH joined the group. Later 2 adult males (MU and AY) and a sub-adult female (JN) joined in. None of the chimps present showed any particular attention/interest in the newborn infant. Observations were stopped at 11:00 when all the individuals left the tree and they were not visible to the observer anymore.

Observer: Zephyr T. Kiwede (ZK).

This observation has not been previously reported.

Observation 2

Chimps were feeding on ripe fruits of ficus mucoso tree near camp. There were quite a large group of individuals that day. Kutu was seen in her nest for about an hour. When she came out from the nest, we realised that we suspected that she was going to give birth, so we decided to reduce on the number of people present. We decided to do this to reduce her stress level so that she will engage in usual behaviours. The primatologist that left to reduce the group size was Bosco Chandia. She came out of her nest and started feeding, she then constructed a second nest, and then continued feeding. She then constructed a third nest, left and fed again. She then made a fourth nest. For the third and fourth nest she constructed it in a way that was more structured and sound than the others. She began groaning, a sound produced when chimps are not feeling well. During that period of groaning, she was pushing out the infant. The observers then saw the hand of the infant. The first individual to have a look at the baby was Keffa, Kutu’s young living juvenile. Following this, Kathy, her next in line before Keffa came to inspect the baby. GM had a sense, after she constructed her third nest, that Kutu might be in the position of giving birth.

Observers: Geresomu Muhumuza (GM) and Adrian Soldati (AS), joined by Bosco Chandia (BC) and Mael Laroux (ML).

This observation is previously reported by A. Soldati (Soldati et al. 2022, supplementary materials)

Discussion

In this paper, we decided to focus on live births in budongo chimpanzee communities. Live births are notoriously difficult to observe because they are rare and females often become reclusive during this time. Here, we report on two direct observations of live births in chimpanzees. In the two live births that we have observed, we found chimpanzees show unusual patterns of nesting and feeding behaviours during these events and use their own hands to deliver their offspring. Other chimpanzees were not observed to directly intervene in any way.

One surprising aspect of our observations of chimpanzee live births relates to nesting behaviour. Usually, a chimpanzee will make one nest and rest inside for an extended period of time before leaving. Once they leave they will usually engage in at least one other activity such as feeding or travelling before making another nest. One reason for this is that it is costly to individuals in terms of time and energy. We know this from observations of sick chimpanzees, who when they are weak, will often reuse old nests or instead decide to nest on the ground because of lacking energy. Since we observed a chimpanzee making multiple nests one after the other, this suggests she was in quite some discomfort and because of this was willing to invest time and energy in making new nests. The 5th nest was a reused night nest from the evening before. Night nests are often better built. We think this may show that towards the end of the birth Kutu was becoming more tired and weak and was unable to continue modifying more poorly built nests where the branches may not have been staying in place. It was reported that when Kutu was in the 4th and 5th nest that she made, groaning sounds were heard. This suggests that similar to humans throughout the birthing process, Kutu’s pain was progressively increasing. While Kewaya was not observed to nest during the birth, she was reported to repeatedly change branch in the tree, also suggesting an increasing level of discomfort.

We did not see anything especially unusual about either female feeding on ficus mucoso fruits, since this is a normal activity we see in chimpanzees. But, in both cases the females did feed for a short time, which again may suggest she was in some level of discomfort. On the topic of feeding behaviours during live births, one usual aspect was the feeding on the placenta. Many animals, in fact, eat the placenta (Farr et al., 2018). Placenta carries a lot of blood, protein, and nutrients. Since a lot of energy is spend during giving birth, Kutu and Kewaya may have decided to eat the placenta to replace blood, proteins and nutrients that were lost during the birth.

In most human communities, assistance is needed from other community members to give birth successfully. Even other species, for example goats, can often need human assistance in order to give birth successfully. Within Budongo forest, we have found even animals such as hyrax, bush buck, and red duikers have died during the process of giving birth alone. In our observations so far, chimpanzees gave birth without assistance from others and did not appear to seek it. In the future, it would be interesting to examine whether mothers with different levels of experience receive help from community members. 

There is still much more that is not known about live births in wild chimpanzees. For example, how is the umbilical cord removed. Kewaya was observed pulling the cord, suggesting that it is actively removed, although the actual removal was not directly observed. In the case of Kutu, she emerged from the nest with the placenta. So, we do not know how the umbilical cord was removed. Another aspect of behaviour during live births that is little known is the pushing behaviour. Because for Kutu the birth occurred inside of the nest high up in a tree, there was a lot that could not be observed. However, Kewaya was observed to use her hand to extract the baby from the vagina, suggesting chimpanzees may give birth more by using their hands instead of pushing as humans do. It is possible, that Kewaya was suffering from dystocia, which is a difficulty in giving birth due to slow cervical dialation often observed in animals (Mota-Rojas et al., 2020).

The fact that both of our observations occurred in Sonso, and even within Sonso, the first birth was not observed until 9 years after systematic studies began, suggests that habitation may play a role in the likelihood of observing such rare events. Wabira are far less habituated than Sonso, and a live birth has never been observed in the community there. In the future to better study this topic as well as the topic of pregnancy and the immediate period following birth in wild chimpanzees field primatologists can work together with veterinary teams to better track pregnant females. This will also increase our likelihood of observing future live births. Also, future studies should utilize long term data to examine diets of females 8 months before the birth was observed.

Conclusion

In conclusion, chimpanzees live births are very rare events to observe. In 30 years of observation in Sonso chimpanzee community and 10 years of observation in Wabira chimpanzee community of Budongo forest, we have observed only two live births directly which occurred in Sonso community. During these events, we observed unusual patterns of nesting behaviour as well as feeding behaviours, which provide new insights into how wild chimpanzees experience live births and the physical demands that live births put on them. Many things still remain unknown about live births in chimpanzees and more observations are needed. To gain this information, we recommend that field primatologists collaborate more closely with vetinary teams to monitor the pregnancy status of females and use this information to focus their attention.

References

Farr, A., Chervenak, F. A., McCullough, L. B., Baergen, R. N., & Grünebaum, A. (2018). Human placentophagy: a review. American journal of obstetrics and gynecology, 218(4), 401-e1.

Mota-Rojas, D., Martínez-Burnes, J., Napolitano, F., Domínguez-Muñoz, M., Guerrero-Legarreta, I., Mora-Medina, P., ... & González-Lozano, M. (2020). Dystocia: factors affecting parturition in domestic animals. CABI Reviews, (2020), 1-16.

Soldati, A., Muhumuza, G., Dezecache, G., Fedurek, P., Taylor, D., Call, J., & Zuberbühler, K. (2022). The Ontogeny of Vocal Sequences: Insights from a Newborn Wild Chimpanzee (Pan troglodytes schweinfurthii). International Journal of Primatology, 1-24.

CITE AS:

Perspectives Collective. (2023). Live Births in Budongo Chimpanzee Communities. Perspectives Collective Journal, 1(1). https://doi.org/10.5281/zenodo.8420143