Non-Human Primate Injuries in the Mefou Primate Sanctuary of Cameroon ()
1. Introduction
The 1973 Convention accord on the International Trade in Endangered Species (CITES) of wild fauna and flora was aimed at preventing the risk of extinction and limiting international movements. This convention addressed three groups of protected species: threatened species (those whose survival is compromised hence necessitate a high degree of protection), vulnerable species (not actually threatened towards extinction but may be if trade is not controlled) and registered species (species listed so as to control their trade). The endangered nature of species led to the creation of both in-situ and ex-situ conservation sites for these species [1]. Following this, National reserves, wildlife sanctuaries and zoos were created. An animal sanctuary is a facility where animals are brought to live and to be protected for the rest of their lives. The Pan African Sanctuary Alliance recognizes 3 sanctuaries in Cameroon; The Limbe Wildlife Centre (LWC), The Mefou Primate Sanctuary (MPS) and The Sanaga Young Chimpanzee Rescue Centre (SYCRC) [2]. Sanctuaries are different from Zoos in that, their goal is to rescue and rehabilitate injured or captured animals and give them a lifelong home while zoos focus more on human entertainment [3]. Primate sanctuaries rehabilitate and socially integrate rescued primates, by offering an environment suitable for the expression of species-typical behaviours, allowing for a gradual recovery and introduction in an adequate social network [4]. Nowadays, wildlife sanctuaries not only house and care for rescued animals, but also strive to advocate for improved captive animal welfare conditions, law enforcement, raising awareness and in-situ conservation [5]. Despite the multiple efforts put in place to secure these animals in these environments, there are still a lot of threats, amongst which, injuries are the most common.
Information on injuries and impairments of animal populations in the wild is important because these conditions can cause disability, affect reproduction and cause mortality [6]. Such information would also provide insight on how to minimize risks, the evolution of wound healing, and other adaptations to injuries. In primates, reported impairments include birth defects [7], consequences of diseases like arthritis [8] [9] or aging as well as the result of injuries that are inflicted by external agents and accidents [10]. The origin of injuries in NH primate sanctuaries are numerous. However, visitor access strategies and the variety of enclosure designs used are not expected to expose the animals to any potential threat from visitors. Enclosures are designed to maximize the possibility of spotting animals to increase the visitor’s satisfaction or to allow animals to easily retreat to off-display areas avoiding a forced on human presence [11]. In zoos as well as some primate rescue centres, animals are confronted with both familiar (caregivers, volunteers and researchers) and unfamiliar humans (visitors). Few systematic studies on the nature and frequency of injuries and impairments have been conducted on wild primates or on arboreal monkeys [12]. Data on the frequency and types of non-human primate injuries and primate-related human injuries, is grossly lacking in Cameroonian sanctuaries. The reasons for the occurrence of injuries amongst NH primates and in humans at the MPS are not fully understood but there are several speculations concerning the type, the degree and the causes of these injuries. The present study was designed to evaluate the injuries amongst non-human primates at the MPS by looking at the different types, associated factors and the causes of these injuries.
2. Methodology
2.1. Study Site and the Non-Human Primates
This study was carried out in the MPS) which is found in the Mefou and Afamba Division in the centre Region of Cameroon. It is located between longitude 13˚57’36” N and latitude 11˚55’48” E [13]. The captive animals included 277 NH Primates of twelve (12) different species; two (2) apes: Gorillas “Gorilla gorilla” and Chimpanzees “Pan troglodytes”, two (2) papionines: Olive Baboons “Papioanubis” and Mandrills “Mandrillus sphinx”, two (2) mangabeys: Redcap Mangabey “Cercocebus torquatus” and the Agille Mangabey “Cercocebus agilis” and six (6) guenons: Putty nosed monkey“Cercopithecus nictitans”, De Braza monkey “Cercopithecus neglectus”, Moustache monkey “Cercopithecus cephus”, Crown guenon “Cercopithecus pogonias”, Talapuin monkey “Miopithecus talapoin” and the Mona monkey “Cercopithecus mona”.
2.2. Data Collection
The parameters evaluated were based mainly on personal observation. This was done every day from morning to evening in various cages and enclosures of the sanctuary. With the help of the sanctuary Motorola (communication radio) information on injuries from other cages or enclosures could be received, facilitating follow-up. Information concerning individual animals was gotten from the keepers, the administration and the animal’s data base. NH primate injuries were documented, taking particular note of the type of injury, its severity, the cause and factors associated with the prevalence of injuries. Precise information on the individual; sex, age, species, group, rank and behaviour, date and outcome of injury was documented. The information on the housing, environment and other group members was also collected. Data from the sanctuary’s database on past cases of injuries was also included in this study. The sanctuary records every case of disease, injury, escape, arrivals and any other vital information related to each animal in the animal’s database.
2.3. Data Analysis
The data was computed in Microsoft Excel. Descriptive statistics were used to explore the data and a normal distribution test was performed. All statistical analyses were done using the SPSS (version 17.0) software while Excel (version, 2013) was used for graphs. Statistical significance was set at P < 0.05.
3. Results
Injuries assessed in non-human primates of the Mefou Primates Sanctuary were either wounds or traumas. The wounds recorded were either lacerations (Figure 1), incisions (Figure 2) or open wounds (Figure 3). The traumas (Figure 4) recorded in our study were either fractures, luxations, swellings, contusions or broken teeth.
Figure 1. (a), (b), (c), (d), (e), (f), (g), (h): various lacerations encountered in NH primates at the MPS (January - March 2020).
Figure 2. (a) (b): incised wounds encountered in NH primates at the MPS (January - March 2020).
Figure 3. (a), (b), (c), (d), (e), (f), (g): Opened wounds in NH primates at the MPS (January - March 2020).
Figure 4. (a) (b): Traumas encountered in NH primates at the MPS (January - March 2020).
Injury prevalence in NH primates
Amongst the twelve (12) species of NH primates, the overall prevalence of injuries was 59.57%, highest amongst Pan troglodytes (68.9%) (Table 1).
Table 1. Prevalence of injuries amongst captive NH primates at the MPS.
Prevalence |
Species |
N |
No injury (%) |
Injury |
(%) |
Gorilla gorilla |
24 |
11 (45.8) |
13 |
54.17 |
Pan troglodytes |
115 |
36 (31.3) |
79 |
68.69 |
Papio anubis |
27 |
11 (40.7) |
16 |
59.25 |
Mandrillus sphinx |
38 |
16 (42.1) |
22 |
57.89 |
Cercocebus tonquartus |
6 |
3 (50) |
3 |
50 |
Cercocebus agilis |
23 |
12 (52.1) |
11 |
47.82 |
Cercopithecus negletus |
3 |
1 (33.3) |
2 |
66.67 |
Cercopithecus nictitans |
20 |
10 (50) |
10 |
50 |
Cercopithecus mona |
9 |
4 (44.4) |
5 |
55.56 |
Cercopithecus pongonias |
3 |
3 (100) |
0 |
0 |
Cercopithecus cephus |
6 |
4 (66.6) |
2 |
33.33 |
Miopithecus talapoin |
3 |
1 (33.3) |
2 |
66.67 |
Total |
277 |
112 (40.4) |
165 |
59.57 |
Types of injury in NH primates
The injuries encountered in NH primates at the MPS were either wounds or the outcome of trauma. Majority of the wounds observed were lacerations, with very few open wounds. Traumas were more of swellings and a few contusions and fractures. In both cases, the prevalence was highest in Pan troglodytes (Table 2).
Table 2. Nature of injuries in NH primates at the MPS.
Specie |
Nature of injury |
Wounds |
Trauma |
|
lacerated w |
punctured w |
incised w |
open w |
fracture |
luxation |
swelling |
broken teeth |
contusion |
Total |
Gorilla gorilla |
27 |
11 |
9 |
4 |
1 |
5 |
6 |
0 |
2 |
65 |
Pan troglodytes |
58 |
22 |
11 |
5 |
5 |
5 |
23 |
6 |
3 |
138 |
Papio anubis |
34 |
11 |
7 |
5 |
0 |
3 |
1 |
1 |
0 |
62 |
Mandrillus sphinx |
25 |
1 |
9 |
1 |
0 |
1 |
1 |
4 |
0 |
42 |
Cercocebus tonquatus |
6 |
1 |
1 |
0 |
2 |
0 |
0 |
1 |
1 |
12 |
Cercocebus agilis |
10 |
2 |
3 |
0 |
0 |
1 |
0 |
0 |
0 |
16 |
Cercopithecus negletus |
1 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
1 |
Cercopithecus nictitans |
10 |
1 |
2 |
0 |
1 |
1 |
0 |
0 |
0 |
15 |
Cercopithecus mona |
2 |
2 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
4 |
Cercopithecus cephus |
0 |
0 |
1 |
0 |
0 |
0 |
0 |
0 |
0 |
1 |
Total |
173 |
51 |
43 |
15 |
9 |
16 |
31 |
12 |
6 |
356 |
X2 |
88,451 |
P |
0.091 |
Variation of injuries with sex, age and habitat of NH primates
Table 3. Variation of injuries with sex, age and habitat of NH primates at the MPS.
Factors |
Nature of injury |
|
|
|
|
Wound |
Trauma |
|
|
|
|
lacerated |
punctured |
incised |
open |
fracture |
luxation |
swelling |
broken teeth |
contusion |
Total |
χ2 |
P |
Sex |
male |
145 |
34 |
35 |
12 |
8 |
10 |
25 |
11 |
5 |
285 |
11,895a |
0.156 |
female |
28 |
17 |
8 |
3 |
1 |
6 |
6 |
1 |
1 |
71 |
|
|
Total |
173 |
51 |
43 |
15 |
9 |
16 |
31 |
12 |
6 |
356 |
|
|
Age |
adult |
155 |
47 |
32 |
12 |
9 |
10 |
18 |
10 |
4 |
297 |
38,497a |
0.001 |
adolescent |
13 |
2 |
8 |
2 |
0 |
3 |
6 |
1 |
1 |
36 |
|
|
juvenile |
5 |
2 |
3 |
1 |
0 |
3 |
7 |
1 |
1 |
23 |
|
|
Total |
173 |
51 |
43 |
15 |
9 |
16 |
31 |
12 |
6 |
356 |
|
|
Habitat |
satellite cage |
149 |
43 |
35 |
11 |
7 |
15 |
23 |
10 |
2 |
295 |
28,340a |
0.029 |
enclosure |
18 |
8 |
6 |
4 |
1 |
1 |
8 |
2 |
4 |
52 |
|
|
free ranging |
6 |
0 |
2 |
0 |
1 |
0 |
0 |
0 |
0 |
9 |
|
|
Total |
173 |
51 |
43 |
15 |
9 |
16 |
31 |
12 |
6 |
356 |
|
|
The type of injury varied significantly with the age of the NH primates’ P = 0,001 and χ2 = 38,497. Injuries were generally more frequent in adults compared to adolescents and juveniles. Injuries were significantly higher (p= 0.029, χ2= 28.34) amongst NH primates living in satellite cages compared to those in enclosures and those free ranging (Table 3).
Causes of injuries in non-human primates
The causes of injuries included fights, falls, bites, injuries from the cage, objects, during the introduction of a new animal or during an escape. Injuries caused by fights were significantly higher than those resulting from other causes (P = 0.002, χ2 = 62,951). Fighting was also the highest cause amongst the various species taken individually. All non-human primates that sustained only a single injury during this period was due to fighting (Table 4).
Table 4. Causes of injuries amongst different HN primate species at the Mefou Primates Sanctuary.
Specie |
Cause of Injury |
fight |
cage |
fall |
object |
bite |
introduction |
escape |
Total |
Gorilla gorilla |
44 (12.4) |
6 (1.7) |
4 (1.1) |
7 (2) |
3 (0.8) |
1 (0.3) |
0 (0.0) |
65 (18.3) |
Pan troglodytes |
93 (26.1) |
13 (3.7) |
7 (2) |
11 (3) |
6 (1.7) |
5 (1.4) |
3 (0.8) |
138 (38.8) |
Papio anubis |
56 (15.7) |
1 (0.3) |
1 (0.3) |
1 (0.3) |
0 (0.0) |
3 (0.8) |
0 (0.0) |
62 (17.4) |
Mandrillus sphinx |
33 (9.3) |
2 (0.6) |
1 (0.3) |
3 (0.8) |
2 (0.6) |
1 (0.3) |
0 (0.0) |
42 (11.8) |
Cercocebus torquatus |
7 (2) |
0 (0.0) |
0 (0.0) |
3 (0.8) |
0 (0.0) |
0 (0.0) |
2 (0.6) |
12 (3.4) |
Cercocebus agilis |
10 (2.8) |
0 (0.0) |
0 (0.0) |
3 (0.8) |
1 (0.3) |
0 (0.0) |
2 (0.6) |
16 (4.5) |
Cercopithecus negletus |
1 (0.3) |
0 (0.0) |
0 (0.0) |
0 (0.0) |
0 (0.0) |
0 (0.0) |
0 (0.0) |
1 (0.3) |
Cercopithecus nictitans |
14 (39) |
0 (0.0) |
0 (0.0) |
1 (0.3) |
0 (0.0) |
0 (0.0) |
0 (0.0) |
15 (4.2) |
Cercopithecus mona |
4 (1.1) |
0 (0.0) |
0 (0.0) |
0 (0.0) |
0 (0.0) |
0 (0.0) |
0 (0.0) |
4 (1.1) |
Cercopithecus cephus |
1 (0.3) |
0 (0.0) |
0 (0.0) |
0 (0.0) |
0 (0.0) |
0 (0.0) |
0 (0.0) |
1 (0.3) |
Total |
263 (73.9) |
22 (6.2) |
13 (3.7) |
29 (8.1) |
12 (3.4) |
10 (2.8) |
7 (2.0) |
356 (100)+ |
χ2 |
62,951 |
P |
0.002 |
4. Discussion
The overall prevalence of injuries in the Mefou Primate Sanctuary was 59.57 %. These injuries were more prevalent in Pan troglodytes though the difference was not significant. Our results show that NH primates’ species have little or no influence on the prevalence of injuries. This is contrary to the work of [14] who found that species differed in proportion of individuals with injuries and also in the types of injuries encountered. The nature of injuries; wounds (lacerated, incised, punctured and open) and trauma (fracture, luxation, swelling, contusion and broken teeth) varied significantly with the age of the NH primates. In all the cases, injuries were significantly higher amongst adult NH primates compared to adolescents and juveniles. These findings are similar to those of [14] who found that adult animals had more injuries than juveniles. This is probably due to the fact that adult animals are those frequently involved in competition for dominance, and dominance has typically been associated with aggression. Thus, primates that often compete become aggressive towards each other [15]. Mating is a common cause of aggression among adult animals. Conflicts due to mating are common, given that the males would generally mate with the females irrespective of whether they consent or not [16].
The number of injuries together with the nature of injuries; wounds and trauma did not vary significantly with the sex of non-human primates despite all injuries being higher among males. Males fight seriously when a solitary male tries to take over his group [14] and also compete for resources such as food or water; like amongst females, competition levels and frequency of aggressive interactions vary depending on food availability [17]. Aggression among males also frequently occurs in a mating context, as predicted by the theory of sexual selection.
Injuries varied significantly with the habitat of NH primates. In all the cases, injuries were higher amongst the NH primates housed in satellite cages compared to those in enclosures and free ranging. This could be explained by the fact that NH primates in cages are more stressed and more prone to aggression since cages have less space, little enrichment facilities and are different from their natural biome. It has been recognized that the welfare of environments and habitats are not just a conservation concern but also compromise the welfare of wild-living animals due to potential stressors [18]. In a study on non-human primate housing carried out by [19], they showed that the rhesus macaque group of the Monkey Temple at the Bristol Zoo, had a mean of 4.4 fights per hour when 41 animals were present, but only 1.5 fights per hour when half of the animals were removed. Based on this, they hypothesized that fighting was a social pathology in response to overcrowding. Extensive study of the chimpanzees in the naturalistic enclosure at Arnhem showed that aggression rose only slightly when the animals were crowded, and they used other social behaviours to maintain amicable social relationships when threatened by crowding-induced stress [20]. It is important to consider the characteristics and context of any aggressive interaction, as these will sometimes be determined by the species’ ecology and behaviour [21]. According to [22], auto aggression (self-mutilation) can be a significant problem in primates housed in cages. Enrichment is often used to increase the activity of the animals and decrease their abnormal behaviours, and a range of techniques is used which varies from manipulation of the social group to the provision of toys [23]. The most common method of providing enrichment is to modify the home (cage) environment in a manner that expands the range of behaviours that can be expressed by the animal. [24].
In the MPS, causes of injuries ranged from; fighting, cage-related causes, falls, objects, bites, during the introduction of new animals and during animal escapes. Amongst all these causes of injuries, injuries caused by fights were significantly higher than the others. Overall, fighting was the main cause of injuries in NH primates at the MPS. Hence, it was also highest amongst the various species taken individually [25]. In addition, NH primates who sustained only a single injury during the study period was due to fighting. These results are similar to those of [26] who found that the high number of injuries in adult males resulted mainly from fights with other males as a direct consequence of aggression or due to falls during chases. This shows that fighting amongst NH primates is a major concern in the MPS and the fights are mostly linked with aggressions, agonistic behaviours, stress and competition for food. In addition to fighting over specific resources, such as food and mates, primates frequently compete over status. In most primate species, individuals of one or both sexes can be ordered in a linear dominance hierarchy. Individuals generally appear keenly aware of their own place in the hierarchy [3].
5. Conclusion
The prevalence of injuries amongst NH primates’ species in the MPS was quite high. The prevalence of injuries was higher in adult non-human primates. There was no significant disparity in sex and species despite male non-human primates and the Pan troglodytes having more injuries respectively. Injuries were higher amongst the NH primates present in satellite cages. Fighting was the most important cause and the main factor associated with injuries amongst NH primates at the MPS. The fights were more frequent amongst adults, males and the Pan troglodytes. Fighting was associated with stress caused by the housing situation of the non-human primates and was the main cause of injuries of NH primates in the MPS.
Acknowledgements
We thank the administration of MPS (Mefou Primate Sanctuary) for permitting us to carry out this study in their site. We equally thank the entire staff for their support and collaboration.
Significant statements
This study uncovered a great variety of injuries of non-human primates together with the causes and the factors associated with these injuries.
Funding
This research received no external funding
Ethical Considerations
The necessary authorisations to carry out our survey were sought from the director and the management team of the Mefou Primates Sanctuary. The study protocol was approved by the department of Forestry and Wildlife management of the University of Dschang.
Conflicts of Interest
The authors declare no conflict of interest.