Introduction 

This is the third post on research exploring the interventions to improve the lives of urban wild vertebrate animals in South African cities. We are grateful for the support of a grant from EA Animal Welfare Fund. The aim of this post is to catalogue existing methods for managing the population of Cape chacma baboons living in the Cape peninsula, with a focus on welfare impacts for the baboons. Where appropriate, we indicate which existing methods might be prioritised or modified, to improve baboons’ welfare. Since urban baboon populations are not widespread globally, many of these insights are particular to the local context. However, some insights may be generalised to contexts where urban wildlife populations share certain characteristics with the Cape chacma baboon.

Relative to more numerous urban wild animal populations considered “pests” (e.g. rats and pigeons), we think that the importance of interventions to improve welfare of Cape baboons is low. Recent data (in the past ~5 years) indicates that annual baboon deaths are relatively low (and have been decreasing). The baboon population seems to be stabilizing around a suggested carrying capacity of ~480 baboons. Fewer baboons die from (direct or indirect) human causes than from natural causes (including infanticide). 

Neglectedness is also relatively low compared to rats and pigeons. The problem seems relatively well-recognised and researched. The City of Cape Town has devoted resources to the existing Urban Baboon Programme (see below), which seems to have been fairly effective at keeping baboons out of urban areas. The issue has received research and media attention. 

Nevertheless, Cape baboon welfare matters, and efforts to improve their welfare are worthwhile. Improving their welfare seems relatively tractable, e.g. there seems to be reasonably broad “buy in” for humane methods of keeping humans and baboons separate. 

Rationale

There are 12 troops of Cape chacma baboons in the Cape peninsula, with a total population of approximately 450-500, which is comfortably within the bounds of the suggested ~480 carrying capacity for the area. These baboons live close to urban areas and are often in contact and in conflict with human beings. This proximity and associated conflict is driven largely by the historical culling of baboon predators, reduction in baboon habitat due to urbanisation, and expanding baboon populations over the past approximately ten years. 

The majority of human-baboon conflict arises when baboons enter low-lying urban areas to source calorie-rich human food (“raiding”). Raiding is typically performed by lone male baboons, and research suggests that most raiding is undertaken by only a few members of a few of the Cape peninsula troops. These troops reside in areas with steep mountain slopes adjacent to urban areas (baboons typically need 2000-2500 hectares of “buffer” natural habitat, and prefer more digestible vegetation in low-lying areas). Human-baboon conflict has resulted in human-inflicted injury and death to baboons, and less frequently, baboon-inflicted injuries to humans. The leading causes of death and injuries for baboons in these conflicts are dog attacks, car accidents, poisoning, and shooting (Human Wildlife Solutions, 2020).

Although the most significant welfare considerations for baboons arise from human-baboon conflict, human-baboon spatial overlap also carries relatively low health risks to both humans and baboons due to the possible transmission of parasites (Trichuris) or hepatitis A virus between the species (Ravasi et al, 2012). 

Current interventions

Research indicates (typically lone young male) baboons continue to raid despite the risk of deterrence, because the rewards of calorie-rich human food are so great. Therefore it is widely accepted that (i) baboons spending more time in their natural habitats is associated with fewer human-caused injuries and deaths; and (ii) reducing contact with humans requires active monitoring and the use of aversive deterrents from human food/waste. Because the reward of human-food is so great, multiple interventions are required to make raiding undesirable to baboons.

The problem of human-baboon conflict in the Cape peninsula has received significant public attention (O’Riain, 2021). In 2009, the City of Cape Town implemented the well-resourced Urban Baboon Programme, which, via an outsourced service provider, manages the local baboon population, with the central goal of keeping baboons and human beings as separate as possible. The programme follows a set of guidelines and standard operating procedures which are the product of deliberation between public and private participants including research institutions, affected communities, and the organisations mandated to manage local and national parks (City of Cape Town, 2019). 

The baboon troops are actively monitored, which includes tracking their population, movement, and behaviour. Interventions such as electric fencing and “virtual fences” (predator sounds played via loud-speakers when baboons approach particular locations) are used in “no-go” buffer zones around the urban edge in order to make it more difficult for baboons to travel into urban areas (Human Wildlife Solutions, 2019). 

When necessary, baboon rangers are trained and permitted to use a variety of methods and tools to prevent conflict between humans and baboons and deter baboons from entering urban areas. These include the use of paintball markers, bear bangers and pepper balls.

• Paintball markers are shot from paintball guns in order to encourage a change in direction of baboons approaching urban areas, and afford the operator a wider sphere of influence (10-20 metres from the operator). When baboons are within a buffer zone,  rangers will prioritise firing no more than two warning shots into the ground in front of adult baboons. If warning shots fail to cause the baboons to retreat, operators may fire at adult baboons, but only at their central back and rump, with caution not to hit the facial region. If the baboons continue to approach or enter an urban area, the protocol changes. These changes however do not allow for more indiscriminate firing on baboon targets, but rather pertain to firing in such a way as to prevent the dispersion of the baboon troop as it is expelled from the area, as well as the prevention of harm to human beings.
• Bear bangers are “cartridges that are fired into the air…[which] explode with a loud bang that scare baboons” (Human Wildlife Solutions, 2015).
• Pepper balls are projectiles from paintball guns which “break upon impact and release a super-irritant powder called PAVA (capsaicin II) pepper. They are only used to chase baboons in extreme circumstances” (Human Wildlife Solutions, 2015), presumably because of the pain and suffering caused to baboons.

The above methods are designed to inflict as little physical harm to baboons as possible while achieving the desired effect of deterring them from urban areas.

In addition to active management and monitoring , legislation exists to reduce human-induced death and injury to baboons in the Cape peninsula, as well as to curb human behaviour that encourages human-baboon contact and conflict. It is illegal to feed,  hunt, poison, and shoot at baboons (including with non-lethal implements such as paintball guns), or otherwise intentionally harm baboons, without a permit (Cape Nature, 2010).

Apart from legal mechanisms to discourage inappropriate treatment of baboons, the Urban Baboon Programme also engages in routine public education campaigns to promote responsible human behaviour aimed at reducing human-baboon conflict. Communities are given information regarding how to make their environments less appealing and accessible to baboons, such as by installing baboon-proofing on windows, doors, and bins, and by planting indigenous trees instead of invasive garden plants that are appealing food sources for baboons. Electric fencing is also recommended in areas where baboon raiding occurs, especially for properties where food waste attracts baboons, such as restaurants and waste sites. The City of Cape Town requires residents in baboon raiding areas to use baboon-proof bins fitted with two padlocks. Such bins are made available by local government, and although they tend to be readily adopted, residents use the padlocks inconsistently, diminishing the overall efficacy of the intervention. 

Research by Fehlman et al (2017) used GPS tracking collars attached to baboons to show that raiding male baboons significantly changed their behaviours in urban spaces (relative to baboons living in more remote areas who adopted time-expensive low-risk foraging strategies), in order to exploit calorie-rich human food sources. Specifically, raiders spent almost all of their time at the urban edge, engaging in short, high-activity forays into the urban space. Despite the risks of being deterred by rangers, occasionally getting into urban areas to raid is incentive enough to persist with raiding attempts. This suggests that the above baboon-proofing interventions are essential in tandem with the ranger activities outlined above, in order to deter raiding baboons. 

The programme also includes protocols for the euthanasia of baboons who are identified as habitual raiders and this is used as a last resort. Baboons who have been seriously injured by human-interactions are also sometimes euthanised under this protocol.  

Research indicates that these interventions have been fairly effective in deterring baboons from entering urban areas. Between 2013 and 2020 managed troops spent around 95% of their time outside of urban areas (Human Wildlife Solutions, 2020). 

In addition, fewer baboons are currently being euthanised under the programme’s protocols compared to when the programme commenced, even though the baboon population has grown. For example, between 2013 and 2015, 35 habitual raiders were euthanised, as opposed to only 17 being euthanised in the period between 2018-2020, while the population has grown by 25.7% (Human Wildlife Solutions, 2020).  

Potential improvements on current interventions

The current management strategy implemented under the Urban Baboon Programme has been largely successful where it has been enforced, and is routinely scrutinised and revised both internally and via external stakeholder engagement (O’Riain, 2021). One reasonable improvement, therefore,  is to extend the programme’s operational sphere to other areas in the Western Cape province (and South Africa) with significant human-baboon interactions. Another improvement might be to introduce audits or other mechanisms to ensure community compliance with the programme. Another  urgent additional intervention will be contraceptives and sterilisation in order to control the Cape peninsula population as it approaches and/or breaches the carrying capacity of the region. Finally, further research could be productive in assessing new and existing interventions to better understand their efficacy and short- and long-term impacts on baboon welfare.

Consider contraceptives and sterilisation options

Due to the historic culling of baboon predators (and their resultant absence), it is possible that in the future the baboon population may grow to exceed the region’s carrying capacity. This may in turn increase competition for resources and lead to an increase in human-baboon conflict (or increase non-anthropogenic baboon suffering due to e.g. starvation or intra-troop conflict) .  

There is some evidence to suggest that the Cape baboon population might already be approaching its carrying capacity. A report by Human Wildlife Solutions (the company  contracted to manage the Urban Baboon Programme at the time), noted that baboon deaths caused directly by interactions with human beings (such as being killed by a dog or a car) doubled between 2017 and 2020 (Human Wildlife Solutions, 2020). In the same period, infanticides committed by baboons also doubled, suggesting that human-baboon conflict and intra-baboon conflict are both increasing. Hoffmann and O’Riain (2012) suggest that capturing and removing troops is not recommended as a viable long-term solution to this conflict, because neighbouring troops are likely to usurp the territory vacated by removed troops.

Sterilisation and contraceptive measures for baboon populations were considered in response to the damage baboons have caused to commercial plantations, especially in Mpumalanga (Institute for Commercial Forestry Research, 2012). A number of significant welfare consequences of these interventions were raised. It was noted that sterilisation by surgical means is exceptionally costly, would cause significant distress to the baboon being sterilised as well as its troop, and may cause unforeseen behavioral and social consequences such as the dissolution of troops (Institute for Commercial Forestry Research, 2012). 

The use of contraceptives also has unknown social consequences for baboons, but may be more cost-effective and easier to implement. Effective use of contraceptives would require repeated administration of hormones to known individual baboons, which in the Cape peninsula may be reasonable as the troops are very well-monitored. Further research is required to assess baboon welfare effects and  potential costs and benefits.

Extend formal protection of baboons and baboon management programmes

A notable shortcoming of the current strategy is its scope. Outside of the rural and urban areas of the Cape peninsula, the active management of baboon troops is generally absent, and there are fewer legal constraints on the treatment and killing of baboons who are in conflict with human beings (Winchester, 2019). In other parts of the Western Cape, such as the Cape winelands, hunting season for baboons runs throughout the year, and farmers are permitted to kill one baboon per day. Unlike in the Cape peninsula, communities have largely been left to navigate the management of local baboon troops without support or coordination, which has resulted in inflated baboon deaths caused by humans (Winchester 2019).

A first step to decreasing the number of baboons being killed by humans in these regions is to extend the formal protection of baboons that exists in the Cape peninsula, thereby prohibiting members of the public from killing any baboons without a permit. However, in absence of a concrete management strategy, human-baboon conflict is likely to persist in these regions.

Extending the Urban Baboon Programme, or establishing similar regional programmes in other parts of the Western Cape, would ameliorate this chaotic situation, but would require significant investment by the provincial government.

Create alternatives to euthanasia for habitual raiders

One of the most significant welfare costs to baboons of the present programme is the euthanasia of habitual raiders. While it is not recommended to relocate entire troops, relocating these habitual raiders to appropriate wildlife sanctuaries or rehabilitation centers (that meet the regulatory requirements of the Cape nature conservation authority, CapeNature) may be a feasible alternative.

Conduct more concrete field-based trials of baboon deterrents

Marginal improvements to baboon welfare could be achieved by conducting more concrete field-based trials of new baboon deterrents, to assess marginal effectiveness over existing deterrents; and making the results of such trials available to decision-makers in a centralised database. Ideally, new deterrents should prima facie be (i) at least as effective at keeping baboons out of human areas; and (ii) have a lower impact on baboon welfare.

Audit and draft legislation to improve compliance with guidelines for reducing food attractants for baboons

As underscored by Fehlman et al. (2017), the high-reward of calorie-rich human food for raiding baboons is so high that a critical aspect of mitigating baboon presence in urban areas is to decrease the amount of human food accessible to baboons, and  increase the cost for baboons of accessing these human food sources (City of Cape Town, 2021). 

The City of Cape Town could perform audits in baboon hotspots to ensure that baboon-proofing is in place on human properties, and that waste management procedures are conducted so as to minimise baboons being lured and having access to waste as a food source. Areas already identified as having low rates of adoption of baboon-proofing should be prioritized for auditing. In addition, the city may consider introducing by-laws or other legislative mechanisms to ensure compliance with these measures. 

Expand use of baboon-proof electric fencing 

While we could find little existing research regarding the efficacy of electric fencing as a deterrent to raiding baboons, their installation has been frequently recommended in the annual and monthly reports produced by the Urban Baboon Programme, especially in situations where paintball markers are not being used. This suggests that adequate roll-out of electric fencing may be a viable alternative to paintball markers and other interventions that impose greater welfare costs to baboons. 

Lessons for other cities

A key driver of human-baboon conflict in the Cape peninsula is the lack of natural baboon predators due to historic culling of these species. Other cities should be keenly aware of the importance of preserving existing predator populations and biodiversity in order to minimise conflict between humans and urban wildlife species (especially wildlife populations that interact/conflict frequently with humans).

In the case of baboons, research has shown that most conflict with humans is caused by particular troops and particular individuals within those troops. This may be true of other urban wildlife species who come into conflict with human beings. It is therefore advisable to conduct monitoring and research to identify problematic groups or individual animals that may be driving conflict, such that management interventions can be targeted at these animals, as opposed to applied generically. This is especially important in the case of more extreme measures such as culling.

References

Beamish, E. 2009. Causes and consequences of mortality and mutilation in the Cape Peninsula baboon population, South Africa. University of Cape Town.

Bentley S., Kaplan, M., Justin O'Riain "Shedding Light on Reflective Prisms as Potential Baboon (Papio ursinus) Deterrents in the Cape Peninsula, South Africa," African Journal of Wildlife Research, 45(1), 117-121, (1 April 2015). 

Cape Nature. (2010). Understanding Baboons [Pamphlet]. https://www.kbrc.org.za/imgs/biodiversity/baboons/understanding-baboons-a3-leaflet.pdf

City of Cape Town. (November, 2019). 2019 Guidelines for Baboon Management. https://www.baboons.org.za/images/Protocols/Guidelines_for_Baboon_Management_Nov_2019.pdf

City of Cape Town. (May, 2021). Urban Baboon Programme May 2021 Monthly Report. https://resource.capetown.gov.za/documentcentre/Documents/City%20research%20reports%20and%20review/Baboon-Mngt-monthly-report-NCC_2021-05.pdf.

Drewe, J. A., O'Riain, M. J., Beamish, E., Currie, H., & Parsons, S. (2012). Survey of infections transmissible between baboons and humans, Cape Town, South Africa. Emerging infectious diseases, 18(2), 298–301. https://doi.org/10.3201/eid1802.111309

Fehlmann, G., O’Riain, M.J., Kerr-Smith, C. et al. Extreme behavioural shifts by baboons exploiting risky, resource-rich, human-modified environments. Sci Rep 7, 15057 (2017). https://doi.org/10.1038/s41598-017-14871-2

Hoffman, T. S. and M. Justin O'Riain. 2012. Monkey management: using spatial ecology to understand the extent and severity of human–baboon conflict in the Cape Peninsula, South Africa. Ecology and Society 17(3): 13. http://dx.doi.org/10.5751/ES-04882-170313

Human Wildlife Solutions. (2015). Tools used by HWS [Pamphlet]. http://www.baboons.org.za/index.php/2015-04-02-12-21-19/brochures/send/2-brochures/114-tools-used-by-hws

Human Wildlife Solutions. (August, 2019) Baboon Management: Past, Present and Future. https://resource.capetown.gov.za/documentcentre/Documents/Graphics%20and%20educational%20material/PresentationCARBS-BaboonMngt_PastPresentFuture_2019-08-29.pdf

Human Wildlife Solutions. (2020) Cape Peninsula Baboon Management Annual Report July 2019 to June 2020. https://resource.capetown.gov.za/documentcentre/Documents/City%20research%20reports%20and%20review/Baboon-Mngt-2019-20-annual-report-HWS.pdf

Institute for Commercial Forestry Research. (August, 2012). Causes, consequences and solutions to baboon induced damage within commercial plantations in southern Africa [Workshop summary]. https://www.forestry.co.za/uploads/File/Industry%20News/2013/Oct%202013%20-%20Baboon%20damage%20symposium%202012.pdf

Kaplan, B.S., O’Riain, M.J., van Eeden, R. et al. A Low-Cost Manipulation of Food Resources Reduces Spatial Overlap Between Baboons (Papio ursinus) and Humans in Conflict. Int J Primatol 32, 1397–1412 (2011). https://doi-org.ezproxy.uct.ac.za/10.1007/s10764-011-9541-8

O‘Riain, J. (2021) Cape Town’s baboon programme. Daily Maverick (19 July 2021).  https://www.dailymaverick.co.za/article/2021-07-19-cape-towns-baboon-programme-successful-coexistence-between-wildlife-and-urban-communities-through-trial-and-error/

Ravasi DF, O’Riain MJ, Davids F, Illing N (2012) Phylogenetic Evidence That Two Distinct Trichuris Genotypes Infect both Humans and Non-Human Primates. PLoS ONE 7(8): e44187. https://doi.org/10.1371/journal.pone.0044187. 

Winchester, Madelyn. (July, 23, 2019). Barrydale at war over growing baboon problem. IOL.  https://www.iol.co.za/capeargus/news/barrydale-at-war-over-growing-baboon-problem-29682582.