Deterrents for testing

8.3.1.1 Field guarding: making improvements

Field guarding is the most straightforward method used to prevent crop raiding, involving a person simply chasing animals away from the crops (Sillero-Zubiri & Switzer 2001). The advantages of guarding are that it is simple, low-tech and if carried out by farmers alone does not involve any additional financial costs. However, one farmer on his own is unlikely to be effective on large commercial crop farms, where guarding then becomes labour intensive (Sekhar 1998; Lee & Priston 2005; Wang et al. 2006; Marchal & Hill 2009; Mackenzie &

Ahabyona 2012). Since foraging efficiency is so much greater when feeding on crops, primates can wait many hours for the opportunity to raid (Strum 1994); successful guarding therefore requires people to be in the fields for long periods of the day and whenever crops are vulnerable throughout the year (Hill 2000). For those who do guard themselves, guarding can result in missed opportunity costs, through reduced time to complete other work with consequently lost income or missed schooling if children must guard fields (Treves 1997; Naughton-Treves 1998; Woodroffe et al. 2005). Guarding can also lead to increased risks of being injured by wild animals (Sillero-Zubiri & Switzer 2001). Lastly, as with most deterrent methods, chasing animals from one field can simply result in raiding of a nearby field (Wang et al. 2006; Warren 2008; Warren et al. 2010).

Despite its drawbacks, guarding is the most commonly used deterrent method in many wildlife crop raiding areas (Naughton-Treves 1997; Hill 2000; Sillero-Zubiri & Switzer 2001; Tweheyo et al. 2005; Wang et al. 2006; Warren 2008; Mackenzie & Ahabyona 2012), including the current study area. It is considered to be the most successful strategy in some areas (King & Lee 1987;

Studsrød & Wegge 1995; Sekhar 1998) and the only remaining viable option in others (Nijman &

Nekaris 2010). Field guarding is considered to be around 70-90% effective at reducing crop damage by raiding animals in the study area.

The guards more or less 70% [effective]. (F12)

I would say about 80% [effective], because now they don’t just come in, now they sit there and wait, so where they would have been in for half an hour now they will just run in and run out and then she’ll go there and chase them off, so they have less time eating.

(F06)

The guards are quite effective, but they do still come in and they do still make problems

so I’d say about 80% for the guards. (F04)

163 I think the guards are quite effective… the guards I would say are 90% effective. (F02) Other studies report that guarding may reduce, but not necessarily prevent damage to crops by wildlife (Warren 2008).

It is clear from data collected on primate crop raiding behaviour in Chapter 5, section 5.3.5 that there is scope to improve the effectiveness of guarding in the study area; detection rates for vervets are low, and departure times for baboons after chasing begins are slow. Further investigation into improving effectiveness of guards is also encouraged in other studies (Strum 1994; Naughton-Treves 1998; Hill 2000). The key to successfully guarding crops involves early warning systems, vigilance, and active response (Sitati & Walpole 2006; Hedges & Gunaryadi 2010); the data collected in this study show that guarding has the potential to be improved in two ways: through the use of early warning systems to increase detection and increasing the perceived fear of guard response.

Early warning alarm system

While the field guards in the current study responded to 81.7% of baboon raids, they only chased 15.5% of vervet raids (Chapter 5, section 5.3.5). As explained in Chapter 5, such a low response rate to vervets is more likely due to the vervets’ discrete raiding style rather than guard negligence; difficulty detecting raiding animals by guards has been reported elsewhere (Warren 2008; Wallace 2010). Some form of early warning system that alerts guards to the presence of vervets entering crop fields could therefore drastically improve guarding against vervet crop raiding. In this situation, the system itself would not be intended to work as a deterrent, but instead work alongside the guard, providing an alarm to any approaching raiders. This could increase detectability of inconspicuous species and therefore raise field guard response rates.

Cow bells or tin-can-and-stone noise makers are the most common methods used for providing early warning systems; these are tied to fences, making noise any time an animal moves against the fence (Osborn & Parker 2002; Graham & Ochieng 2008; Hedges & Gunaryadi 2010). Osborn

& Parker (2002) recorded an increase in farmer detection of elephants entering crop fields from 42% to 67% with the use of cow bells as an early warning system, while Hill & Wallace (2012) found that a net with bells attached effectively alerted farmers to the presence of crop raiding primates. Conversley, Graham & Ochieng (2008) report that bells are ineffective as an alarm system for elephants.

During discussions at the mitigation workshop, the farmers present were not keen on the idea of bells used as an alarm system. One farmer expressed his view that raids are not chased because of guard negligence:

164 You know what, they [guards] know that they [primates] are in there anyway. (F06) The results from Chapter 5 may have given farmers a better understanding of the nature of vervet raiding and the difficulty in detecting every raid when guards have multiple fields to protect, and that alarm systems could increase the effectiveness of their field guards. However, when the method was explained to a field guard, she was very enthusiastic about the idea and believed it would help her protect the crops more efficiently.

There was also concern with the expense of this method:

It would be cheaper to lose one tomato seed out there, than buy 11 or 12 of these to

cover kilometres [of fence]. (F06)

Disadvantages of using bells as an alarm system include the number of bells required for such large farms, and the potential for bells being stolen (Graham & Ochieng 2008). However, cattle bells are relatively inexpensive (ZAR61 per bell in the study area) and the cost would be a one-off purchase. They are also readily available within the area and many farmers already possess a number of bells. Furthermore, they require very little maintenance or further effort once they are attached to the fence.

Despite the farmers’ disenchantment with the idea, the data on such a low response rate by guards to vervet raiding as well as the simplicity of the method encouraged me to select an early warning system using bells for trialling. The reaction from the field guard and the belief that it would aid her deter vervets provided further encouragement for the trial. This method will therefore be tested in Chapter 9, section 9.2.

Bear bangers

Field guarding is effective as long as primates are afraid of people (Lee & Priston 2005); adding elements to guarding that increase risk perceived by primates will therefore improve its deterrent efficiency (Strum 1994). King & Lee (1987) suggest that guards known to carry threats are more effective. Baboons in particular are more afraid of men than women or children and those carrying weapons pose more of a risk than those that do not (Box 1991; Strum 1994; Hill 1997; Sillero-Zubiri & Switzer 2001). Many weapons are already in use by guards with mixed effectiveness, including drums, throwing stones, slingshots, spears, bow and arrow, whips, torches, airguns, bells, and dogs, among others (Maples et al. 1976; King & Lee 1987; Tchamba 1996; Hill 1997, 2000, 2005; Knight 1999; Hill et al. 2002; Hurn 2005; Lee & Priston 2005;

Webber 2006; Nahallage et al. 2008; Warren 2008; Arlet & Molleman 2010; Warren et al. 2010;

Mackenzie & Ahabyona 2012; Lemessa et al. 2013). Guards within the study area used sticks to

165 bang on fences, buckets to drum on and picked up stones from the ground to throw at the primates.

Data from Chapter 5, section 5.3.5 show that the time delay from the onset of chasing by guards to the termination of raiding by baboons ranged from 0 to 6 minutes 35 seconds, with a mean of 26.8 seconds. Increasing primates’ perceived risk of guarding is predicted to decrease the delay between the onset of chasing and raid termination, and thus shorten raid duration.. Given the strong positive correlation between raid duration and number of food items removed (Chapter 5, section 5.3.2), this will ultimately lead to a reduction in crop damage.

Kaplan (2013) provides convincing evidence that bear bangers are effective at deterring baboons. Bear bangers are small cartridges fired into the air using a pen-sized launcher.

Originally designed as bear deterrents, they make an audible pop when fired and a loud gunshot style noise a few seconds later about 20-30m away in the direction fired (for example, see Mountain Equipment Co-op 2016). Kaplan (2013) used bear bangers to deter baboons from entering residential areas in Cape Town with immediate success that showed no decline over a 10-month period; four years later they remained successfully in use. Kaplan reports that lack of habituation, which was unexpected, may have been due to pairing bangers with human presence, making their spatial and temporal deployment unpredictable, as well as the production of two noises, the second often directly above the group. He also suggests that the bear bangers efficacy may additionally be in part due to the history of conflict in the area, with many baboons having been shot in the past – as is also the case within the study area. Harris &

Davis (1998) also suggest that the resemblance to a gunshot sound no doubt enhances the effectiveness of the bear banger in scaring animals that are already hunted or shot at with firearms.

The use of bear bangers was suggested to the study farmers at the mitigation workshop, and the farmers were interested in the idea. However, there were a few restrictions farmers placed on the use of bear bangers, which rendered it unfeasible for use in this area. The first was the fire risk that firing a cartridge posed. Although there have been no incidences of fire caused by the use of bear bangers in Cape Town (Professor Justin O’Riain, personal communication), bear bangers do pose a potential fire risk, especially in dry vegetation (Brooks et al. 1990; Kaplan 2013). It was felt that fire was too big a risk in such a dry area.

If you could remove the fire risk that it imposes, particularly in a dry area like this. (F17) The second restriction with the bear banger was the risk of injury that it could potentially cause another person. Bear bangers can be dangerous if used improperly, but with correct use are not

166 usually hazardous (Kaplan 2013). Given pre-existing racial attitudes, farmers feared that guards may misuse the device to deliberately harm one another or the farmers themselves.

A pencil flare is very dangerous. (F10)

They [guards] are going to argue around the campfire, then there will be a lot of issues [if

they have bear bangers]. (F18)

Lastly, farmers were concerned over the range of the device:

They’ll [baboons] soon learn the range if the thing. I take my gun with me when I can, they know that within 400m they are in trouble, after 400m they will sit at the top of a baobab and look at you. They just know what the range is. (F17) However, Kaplan (2013) suggested that the guard can affect the unpredictability of the noise by changing the direction and flight path of the cartridge; this may have increased the bear bangers efficacy relative to a static noise or one associated exclusively with a person, such as blanks from a fire arm. Furthermore, as long as the range at which baboons perceive to be outside of danger is beyond the crop fields, then the banger is doing its job. Not mentioned by the study farmers, but an additional disadvantage is that loud noises produced by bear bangers may disturb people, domestic animals and non-target wildlife (Gilsdorf et al. 2002). At the Mountain Equipment Co-op (2016), a single launcher costs $16.50 CAD (ZAR191.78/£8.24) while a pack of six cartridges cost $17.75 CAD (ZAR206.31/£8.87). Depending on deployment frequency, which may or may not decline over time, this deterrent method could potentially be quite expensive. Advantages on the other hand are that bear bangers are easy to use and place the explosion closer to baboons, rather than originating at the guard (Harris & Davis 1998; Kaplan 2013).

Study farmers discussed the possibility of further altering the bear banger design, to include for example a smell that accompanied the explosion to reinforce the danger perceived by baboons.

If you perhaps replace the flare component with something like pepper, a pepper mist or something like that, that you could fire into the troop and it would cover them all with

chilli powder. (F17)

An adaptation that removes all risk of fire and harm to people, and incorporated a secondary sensory deterrent (such as the inclusion of pepper mist) may prove effective in this rural area, and would certainly be socially acceptable to the people involved. Unfortunately, although trials on this mitigation method were planned, it was not possible to find a device with these adaptations before the time of trialling, and it was therefore not tested in this study. There is nevertheless opportunity here for further investigation.

167

8.3.1.2 Acoustic repellent: motion-activated sound

Agriculturalists have used many kinds of sound-producing techniques to repel vertebrate crop raiders from their fields, including shouting, drumming, commercially available noise making devices, and recorded animal sounds (Koehler et al. 1990). A commonly used acoustic repellent is the gas gun, a propane or acetylene powered mechanical device that produces a periodic loud, banging noise to frighten animals away (for example, see EnviroGuard 2016). The bangs are produced by igniting gas, which resembles the noise of a shotgun. Designed specifically for agricultural use, it was originally built as a bird-scaring device and is now also employed to reduce aeroplane collisions with birds, by scaring birds away from runways at airports (Harris &

Davis 1998).

A number of studies report the gas gun to be effective at reducing crop damage (Stickley et al.

1972; Conover 1984; Cummings et al. 1986), most reporting effectiveness against birds, but it has also been reported as ineffective by others (Harris & Davis 1998; Gilsdorf et al. 2004). A major drawback of the device is that animals quickly adapt to the sound, especially without the use of other techniques that reinforce the threat of the cannon; as such it becomes ineffective after a short while (Harris & Davis 1998; Steensma 2009). When discussing the use of gas guns in the study area, the problem with habituation was iterated many times by farmers.

Gas guns work, but only for a while… I’ve seen steenbok, duiker, warthog underneath it, literally under the gas gun and it doesn’t even pick its head up, it’s still feeding and

eating. (F01)

No, they’ll get used to that as well, so no. (F12)

The length of time for which the gas gun effectively deters animals varies from study to study.

Pfeifer & Goos (1982) report that gas guns deter coyotes from depredating ranches for an average of 31 days, while Belant et al. (1996) found that systematic detonations every 8-10 minutes deterred deer for only two days. The duration for which gas guns are reported to be effective on baboons in the study area also varies from one farmer to another.

We tried it last year, it doesn’t work. It worked for the first few days, but then it doesn’t

work. (F05)

It will maybe work for a week, two days, three days and then they just get used to the sound because even when they’re not at the field the gas gun goes and he gets used to

the sound of it and then he just comes in. (F15)

168 For the first week it worked, the next week they ran close to the gas gun and played with

it. (F08)

If it’s not dry and there is food… it’ll be effective for maybe 2 months… when it’s dry then it’s effectiveness is gone, they’ll start taking chances and getting used to it, and just go

past it, because they are hungry. (F01)

Effectiveness of the gas gun varies with methods of presentation. It can be improved if the frequency of explosions and number of shots per firing sequence varies, as well as if the device is moved to a different area and the direction of firing is changed every second or third day (Koehler et al. 1990; Hygnstrom et al. 1994; Harris & Davis 1998). Shorter periods between shots keeps animals more easily dispersed, at least for birds (Harris & Davis 1998), although this can speed up habituation (Gorenzel et al. 1994). Furthermore, effectiveness can be maximised through incorporation of additional control techniques, especially those that reinforce the threat of the cannon (Koehler et al. 1990; Belant et al. 1996). These techniques essentially prolong habituation.

The main advantage of the gas gun is that it is not labour-intensive; it is simply placed within the crop field and left to operate on its own, requiring only daily checks (Koehler et al. 1990). It can also be moved and the direction, timing and volume of the blasts can be controlled (Harris &

Davis 1998). Furthermore, they can be used both day and night. However, the units are very loud, which can cause problems when being deployed near residential areas, and disturb domestic and non-target animals (Gilsdorf et al. 2002). The affected area is relatively small, and as such the gas gun is more practical for small acreages; it is generally impractical and too expensive for large areas (Koehler et al. 1990).

Study farmers were also concerned about the cost of the device, mentioning that the device is very expensive and has to be filled every three to four days, which will cost at least ZAR1,000 a month. Also mentioned was that people steal the device. The product advertised on EnviroGuard’s website (EnviroGuard 2016) sells for £275 (~ZAR6500.00) plus VAT, while 10 litres of propane fuel costs around £35 (~ZAR835).

When asked whether they thought the gas gun was something that would work as a deterrent against baboons, study farmers were split in their opinions. Many (53.8%) felt that the gas gun is not an option because it simply does not work. Others, however, suggested that it may work for a short time and could be used alongside field guarding.

If you could give a gas gun to the guards that would help them a lot, not having to run all

that much but shooting and making a noise. (F02)

169 During discussions at the mitigation workshop, it was unanimously agreed that the gas gun isn’t worth trying. However, building on the gas gun’s design, adaptations were suggested and discussed with the farmers. In an attempt to reduce habituation, two amendments were considered. The first is to incorporate the use of a motion detector, so that sound is triggered whenever, and only when, an animal is detected entering the crop field. Motion-activated explosions reduce habituation, probably because detonations are less predictable than systematic explosions, and have been shown to increase habituation time from two days to one to two weeks (Belant et al. 1996). The second adaptation involves playing a range of different sounds rather than using a single ‘explosion’, which is likely to increase its effectiveness as a deterrent (Bomford & O’Brien 1990). These adaptations generated positive responses from farmers, who thought they might work and were worth trialling.

That will be something that will affect them. (F18)

I think that would definitely be worth trialling. (F17) A device such as this is not currently available on the market, so the cost of such a device is unknown. However, it is likely to have similar drawbacks to the gas gun in terms of cost. To cover an area as large as these commercial farms, a number of the devices may be required,

I think that would definitely be worth trialling. (F17) A device such as this is not currently available on the market, so the cost of such a device is unknown. However, it is likely to have similar drawbacks to the gas gun in terms of cost. To cover an area as large as these commercial farms, a number of the devices may be required,