Background of the study area
The selected 60 homegardens are located in three villages in the Kandy district and they demonstrate the characteristics of typical KHs. These homegardens predominantly feature perennials crops, with spices being the dominant category, while fruits and vegetables are the secondary focus. The plant species within the homegardens are arranged in three distinct layers, showcasing a diverse range of annual and perennial crops, many of which hold economic potential. The owners of these homegardens maintain them as a subsistence farming model, relying on their produce to meet the household's food requirements and however, they contribute to their income as well. It is noteworthy that the respondents have extensive experience in managing homegarden crops, reflecting their deep knowledge and expertise gained over the years.
Risk Assessment
The severity index, incidence index, followed by risk index were calculated to identify the most visited and destructive wild animals in KHs. Based on that, ten animals were ranked (Tables 1 & 2) and a risk map was developed (Fig. 3). The wild boar (97%) and porcupine (97%) are the most reported wild animal (Incident Index) followed by torque monkey (83%) in the KHs. Indian peafowl has the highest Severity Index (2.00), but the lowest risk of crop damage. Because when the severity index increases, the severity of the damage is decreased. Though Indian peafowl damage is not significant in KHs, it might be a beginning of a severe problem in the future. The highest risk index was observed for wild boars (0.87), followed by torque monkeys (0.83), porcupines (0.79), and giant squirrels (0.55). Numerous reports suggest that, besides homegardens, torque monkeys and wild boars are causing significant damage to large-scale commercial cultivation in other parts of the country as well (Rudran et al. 2021). Though yield and economic losses have not been scientifically calculated, informal information reveals that the yield loss is over 30% due to torque monkeys damage.
The KHs system is considered one of the most sustainable agricultural systems which significantly contributes to present-day food and nutritional security. Hence, government and non-government organizations have introduced a number of programs to enhance the production and productivity of KHs while aiming for developing a sustainable food production unit. As respondents claimed neither such projects were effective nor successful due to high incidents of wild animal damage. In addition, some respondents noted that they have had to temporarily cease growing crops and managing homegardens due to the dangers posed by wild animals, specifically wild boars and torque monkeys. They also further expressed their displeasure towards the responsible organizations for not giving adequate attention to address this problem.
Table 1
Most distractive wild animal in KHs with their species and conservation status
Common name | Scientific name | Species status | Conservation status |
Wild boar | Sus scrofa | Native | Least concern |
Torque monkey | Macaca sinica | Endemic | Least concern |
Porcupines | Hystrix indica | Native | Least concern |
Giant squirrel | Ratufa macroura | Native | Near threatened |
Great yellow bat | Scotophilus heathii | Native | Vulnerable |
Flying squirrel | Petaurista philippensis | Native | Endangered |
Barking deer | Muntiacus malabaricus | Native | Near threatened |
Sri Lanka grey hornbill | Ocyceros gingalensis | Endemic | Least concern |
Greater bandicoot rat | Bandicota indica | Native | Least concern |
Indian peafowl | Pavo cristatus | Native | Least concern |
Since the KHs are rich in species diversity (Pushpakumara et al. 2016), it provides a diverse range of foods for the wild animal throughout the year. Moreover, the high density of perennial trees (e.g. fruits, spices, timber, etc.) provides favorable habitats and resting places for wild animals. Therefore, most of the torque monkey's and wild boar's corridors are running through the well-managed species-rich homegardens in the studied area. KHs resemble forest ecosystems due to their high species density, which includes multiple canopy layers and a diverse range of woody perennials. Thereby KHs provide hiding places for some wild animals during the day time, particularly barking deer, greater bandicoot rat, and porcupines. Within this background, controlling wild animal damage in KHs is a big challenge. However, more scientific investigations and community surveys are required to develop a comprehensive and long-term strategic plan to protect KHs from wild animal damages.
Table 2
Risk index for key species in KHGs
Wild animal | Severity index (Sj) | Incidence index (Ij) | Risk index (Rj) | Rank |
Wild boar | 1.11 | 0.97 | 0.87 | 1 |
Torque monkey | 1.00 | 0.83 | 0.83 | 2 |
Porcupines | 1.22 | 0.97 | 0.79 | 3 |
Giant squirrel | 1.33 | 0.73 | 0.55 | 4 |
Great yellow bat | 1.67 | 0.63 | 0.38 | 5 |
Flying squirrel | 1.56 | 0.52 | 0.33 | 6 |
Barking deer | 1.44 | 0.37 | 0.25 | 7 |
Sri Lanka grey hornbill | 1.78 | 0.40 | 0.23 | 8 |
Greater bandicoot rat | 1.89 | 0.35 | 0.19 | 9 |
Indian peafowl | 2.00 | 0.23 | 0.12 | 10 |
Nature and severity of crop damage
Figure 4 shows the most reportedly damaged fruit tree species in the assessed area. Out of the 60 homegardens assessed, over 45 homgardens reported coconut as the most vulnerable crop for wild animal damage (Fig. 4). The coconut (Cocos nucifera L.) is one of the main species found in almost all homegardens in the assessed area and it is one of the three main export crops and also important for the food and nutritional security of Sri Lankan families being an essential component of Sri Lankan cousins. It is also a highly susceptible species to wild animal damage, particularly torque monkeys, giant squirrels, and flying squirrels. The crop is damaged by wild boar and porcupines at the initial growth stage of the plant. Moreover, Annona (Annona muricata L.), Avocado (Persea Americana Mill.), Rambutan (Nephelium lappaceum L), Guava (Psidium guajava L.), and Durian (Durio zibethinus L.) have more than 70% of yield losses due to wild animal damage (Fig. 5). Though most wild animals feed on fruits, torque monkeys eat immature leaves and flower buds of some plants. The wild boars, greater bandicoot rats, and porcupines mostly damage root and tuber crops, particularly manioc and yams. It was interesting to observe that monkeys not only damage crops but also ornamental species. They pluck flowers, give them a sniff, and then crush them before discarding them.
Compared to other plant categories, fruits are the most vulnerable group of crops to wild animal damage. The KHs are rich in fruit species and they provide food and habitat for wildlife throughout the year. Torque monkeys, bats, giant squirrels, and flying squirrels are some of the animals that largely feed on fruit species. Out of them, torque monkeys are the most distractive animals highly damaged for fruit crops. However, according to our observations, we found that torque monkeys do not damage some crops (Citrus spp., some Solanum species, Ginger and Turmeric, etc.), due to some of their special characteristics. But such crops may be damaged by wild boars, porcupines, and rats. However, when selecting crop species for KHs, such crops can integrate with other species. Additionally, it is important to investigate whether these crops can serve as an effective barrier crops against torque monkeys.
Application of different control methods and their effectiveness
Despite numerous methods being used to control wild animal damage, there is currently no single, permanent solution that is consistently effective in minimizing crop damage. However, as mentioned by respondents, integration of several methods would be the most effective way of controlling wild animal damage in KHs. A list of currently applied methods along with their effectiveness and usage percentage is given in Table 3.
Table 3
Different control methods used with usage percentage and effectiveness
Control methods | Effectiveness according to household experience % | Usage % |
Solar power system | 90 | 7 |
Wire net | 73 | 12 |
Cover from barrel halves | 66 | 12 |
Hanging sarees | 65 | 5 |
Air rifle | 60 | 13 |
Using fish net | 60 | 3 |
Covering of seedlings | 60 | 3 |
Nickel wire | 60 | 2 |
White pollythen belts | 50 | 8 |
Use of dogs | 50 | 3 |
Cover using nylon threads | 48 | 3 |
Use of mask (Vesmuhuna) | 46 | 15 |
Use of Gliricidia fence | 45 | 17 |
Removing garbage from homegarden | 40 | 3 |
Use of scarecrow | 40 | 2 |
Hanging electric bulbs on tree | 34 | 8 |
Use of Takaya* | 33 | 17 |
Use of fire cracks | 30 | 33 |
Grow thorny grass/ crops as boundries | 30 | 3 |
Use of Catapult (Ketapola) | 29 | 28 |
Spread hair cut waste around crops | 25 | 3 |
Use of bamboo fence | 20 | 2 |
*Takaya is a locally developed simple tool which is making sounds and hanging on a tree.
The effectiveness of these control methods was assessed according to household experiences. The survey resulted that the use of a firecracker is the most used method, but its effectiveness is relatively less (30%). This control method is mostly used for controlling torque monkeys. However, currently, there is no effective and successful method for controlling these primates. Recently, some people have resorted to using air rifles and face masks (Wes muna) as a means of controlling them. However, some of these methods have proven to be largely ineffective, as monkeys can quickly adapt to any methods used against them.
Though solar power system is the most effective method (90%), its usage is less (7%) due to high installation cost. As respondents reported this method is highly effective for controlling wild boars and porcupines. But due to the high establishment cost, people use other alternative methods, such as hanging sarees, and covering the field using white polyethylene or nickel to control the wild boar damage, because such methods show more than 50% effectiveness to control wild boar damage. In addition, some traditional control methods such as covering the cultivated land using nylon threads, spreading hair cut waste around crops, removing garbage foods from a homegarden, and use of gliricidia or bamboo fences are used, but they were found to be less effective.
Within the Kandy district, porcupine damage is more dominant over other wild animals in some areas. Since there are no accepted and effective methods, people protect their cultivation by covering barrel halves, placing a cover around seedlings, and using of gliricidia fence. But none of these methods are successful and effective to minimize the visits of porcupines. One of the reasons for the failure of the gliricidia fence is that porcupine eats gliricidia roots and damage to the root system. While it is evident that giant squirrels cause significant damage to fruit trees, controlling their population remains a challenge. Developing effective measures to curb their behavior and the resulting damage is particularly challenging due to the unique characteristics of these creatures.
In the study area, a method for controlling flying squirrels and bats involves hanging light bulbs on trees. For instance, during the bearing seasons of Durian fruit, when flying squirrel attacks are prevalent, people will hang light bulbs on the trees to deter the animal. The survey reported damage by Sri Lanka grey hornbill for some crops which is uncommon but might be the beginning of severe problem in the future. The hornbill causes more damage to the nutmeg tree which is one of the most economically important crops in KHs. Currently, there was no record of any method used by the people to control the hornbill. Out of the 60 householders surveyed, only nine householders have been informed of the wild animal damage to their crops to responsible agencies. Only three homegardens had received subsidies to prevent their crops from wild animal damage. As interviewees claimed, the government is giving priority to only the wild elephants and human conflict and damage from other wild animals has not been seriously considered yet. The vast majority believe that controlling a growing population of wild animals, particularly, torque monkeys and wild boars by killing is the only successful method to protect their cultivation. However, it is not a realistic and viable solution due to not only the biological significance, but also cultural taboos, religious barrios as well as the resistance of animal welfare movements because most of the methods used (e.g. poisoning, shooting, electrocution, etc.) against them are injurious and lethal.
Since, wild boar, torque monkeys, porcupines, and barking deer are the most destructive animals in KHs, people used various methods to control them. To find the effectiveness of the control measures against them, six experimental plots were established in selected homegardens and made observations at regular intervals. In this study whether there is a relationship between the control methods and the number of visits or crop damage percentage was considered. This study only considers whether the number of visits and crop damage percentage change with the control method or no control method. Here animals or crops are not specified in relation to each control method. According to the results, the use of control methods has significantly minimized the number of visits of three animals other than wild boars (P < 0.05) (Table 4 and Fig. 6). Even when control methods are employed, such as fencing or other physical barriers, they are not always effective in preventing wild boar attacks. Because wild boars pose a significant challenge to effective control due to their strength and size, which allow them to break physical barriers. Additionally, these animals may be subject to attacks by other domesticated animals and even humans. Another difficulty in controlling wild boars is their nocturnal habits, which makes it challenging to implement effective control methods during the night.
Table 4
Results of Chi-Square test of study of effectiveness of control methods
| Monkey | Wild boar | Porcupine | Deer |
Chi-Square | 4.9181 | 2.5 | 5.5652 | 6.7209 |
DF | 1 | 1 | 1 | 1 |
Pr > ChiSq | 0.0266 | 0.1138 | 0.0183 | 0.0095 |
Following the same way, the effectiveness of control methods used to protect the highly damaged four crops was tested. Results revealed that except for cassava, the use of control methods has significantly minimized the crop damage for the other three crops (P < 0.05) (Table 5 and Fig. 7). Being a root crop, cassava is highly attractive to both wild boars and porcupines. Torque monkeys eat both tubers and immature leaves whereas barking deer prefer to have their immature leaves at the initial growing stage. Since the crop is attracted by four major and most destructive animals, the use of currently practiced control methods are less effective in homegarden cultivation of cassava. However, our experiment concludes that the practice of the commonly used control methods is less effective for controlling wild boar damage in homegarden crops and none of the methods works for protecting cassava from wild animal damage. Although these findings offer valuable insights, it's important to note that they are specific to the particular site under study. Thus, it's necessary to consider that control measures should be tailored to the unique characteristics of each location and not generalized to other homegardens in different parts of the county.
Table 5
Results of Chi-Square test of study of effectiveness of control methods for four selected crops
| Coconut | Chili | Papaya | Cassava |
Chi-Square | 12.6409 | 4.2222 | 14.8205 | 2.9919 |
DF | 1 | 1 | 1 | 1 |
Pr > ChiSq | 0.0004 | 0.0399 | 0.0001 | 0.0837 |
Use of Ethnobiological Knowledge
Though people used newly introduced and traditional control methods, none of such methods are supported to them as an effective solution for controlling wild animal damage completely. However, some people used their own methods that they experienced or handed down from their elders in order to address this particular issue. Such ethnobiological knowledge will help to understand the ground truth of this perennial problem as well as it will contribute to setting the appropriate control measures against damage caused by wild animals. Therefore, it is important to collect, document as well as to utilize their traditional knowledge related to wild animal damage aiming for developing of more effective and efficient methods. Because integration of traditional methods and modern scientific knowledge will be an effective tool to control wild animal damage in KHs system.
According to the respondents, wild animal damage has gradually increased over the last 5–10 years in KHs system. The survey reported that the torque monkey’s damage and their population has rapidly increased compared to other wild animals. The respondents have an idea on both vulnerable crops for torque monkey damage and most resistant crop to their attack. Drawing from their personal experiences, they are giving a high priority on cultivating the crops listed in the Table 6 in order to protect them from damage caused by torque monkeys.
According to several respondents, there was a time when wild boar damage was not a significant issue in the Kandy district. This was likely due to the fact that piglets were a primary food source for wild foxes, which helped to control the boar population. Furthermore, they believe that with the loss of fox habitats and the increased use of agrochemicals, the fox population in the area has declined and become concentrated in a few remaining forested areas. This has allowed the wild boar population to grow unchecked, leading to more frequent incidents of damage. Moreover, people believe that with the introduction of various agrochemicals, wild foxes were locally extinct due to the eating of crabs and frogs in polluted paddy fields and marshy lands. They experienced that wild boar and porcupines are mostly damaged for homegarden crops during the rainy seasons. Some of the cultural and religious norms associated with the traditional community (e.g. kem systems) have also been used to control wild animal damage. For example, Pirith written papers hang on trees to protect crops from animals. Pirith is verses and scriptures chanted by Lord Buddha to bless and safeguard people from disasters, crisis situations, invisible forces, etc. Moreover, the survey reported that some people spread Pirith pan (chanted water) in and around their homegarden to chase away wild animals from cultivated crops. As respondents mentioned they have observed that the number of visits is high during the flowering season of Kitul trees (Caryota urens L.) and there is a substantial yield reduction during their visits. However, it is important to understand the scientific background behind their observations, experience as well as traditional methods they used. Most of the respondents informed that wild animals moved from nearby forests to homegardens after clearing natural forests and replanting pine trees in and around the Kandy district. Furthermore, they believe that torque monkey are purposively introduced animals into Kandy the district two decades ago. However, the survey results highlighted the importance of knowledge of the traditional community and methods used by them based on their experiences and knowledge handed over from their elders. Because, such ethnobiological knowledge will be a good source of information to develop effective and efficient methods to overcome this problem.
Future prospects
The human and wild animal conflict in homegardens is not a newly immerged crisis, but it has intensified over the last two decades. The present survey also evidenced that the increasing wild animal population and their impact on homegarden crops are the major impediments to crop cultivation in KHs. Therefore, it is important to understand the driving triggers which contribute to the increase in the population growth of wild animals associated with homegardens and their impact on the production and productivity of homegardne crops. It is also important to recognize appearing of new macro pests, such as hornbills, Indian peafowl, etc. in Kandy district. However, it requires a national-level discussion with all stakeholders to find a solid and permanent solution for addressing this perennial problem. While there has been considerable research on human-element conflict and ample information is available on various aspects of it, the same cannot be said for human-monkey conflict, as there is a dearth of information on this topic. However, this knowledge gap has become a serious concern, as the involvement of monkeys in damaging crops and physical properties across the country has escalated to a critical level. The information on wild animal damage in KHs is scarce due to inadequate scientific investigation on this matter. It implies that without having baseline information, it is not possible to develop effective and efficient strategic plan to control wild animal population and their impact on homegarden crops. Apart from scientific research, conducting community survey and extracting ethnobiological knowledge are equality important to find most viable solutions.
The active involvement of the government and private sector play a crucial role for handling this problem. For example, the government and non-government organizations have significantly contributed to find the viable solution for minimizing human-elephant conflict. Despite the crucial role that KHs systems play in providing sustainable agriculture and ensuring local food security and environmental stability, the issue of wild animal damage to these systems has not received adequate attention from government authorities. This lack of attention is concerning, as it puts the livelihoods of farmers and the balance of local ecosystems at risk. The government involvement is highly significant to handle this issue, because sometimes it needs policy changes as well. For example, though the giant squirrel is a one of the most distractive animals in some areas of the county, the use of control measures are problematic, because the giant squirrel is the national animal of Sri Lanka. Moreover, though some animals are macro pests and largely damage for cultivations, they have declared as threatened and protected animals (Table 1). Despite their significance in biological diversity and being an endemic or protected animals, the threats by them for cultivated crops is more significant in present days. Since they are considerably effect on national economy as well as household economy and food security, it is important to consider the possibility of delisting them from various conservation lists and acts. The recent decision by the government to remove certain wild animals from protected lists is an important step towards mitigating this problem to some extent.
During the present survey, respondents categorically mentioned that due to decrease of forest cover and loss of other wildlife habitats, the damage was intensified in alarming rate. It implies that importance of conservation of existing natural habitats and establishing suitable habitats for them. Wijethilaka et al. (2021) is also reported that damage to crops and property was higher in the dry season compared to the wet season, because the wet season triggers flushing and fruiting of food sources in the forest, so the monkeys are able to get enough natural food at this time of year within the forest. But in the dry season, food sources are scarce inside the forest. According to them, this might be the reason for intensified foraging in the adjacent homegardens, resulting in high crop and property damages. It is further highlighted that importance of preserving wildlife habitats and minimizing damage to their habitats and species ecological niches. It also important to conduct a comprehensive environmental impact assessment before introducing new agricultural and industrial projects, and human settlements.
Due to the predominantly Buddhist population in and around the Kandy district, there is reluctance to implement many of the measures used to control wild animal populations. Furthermore, certain cultural, social, and religious barriers may limit the implementation of certain control measures, particularly those aimed at managing animal populations. In addition, it is crucial to address the concerns of various stakeholders, including government institutions and non-governmental organizations that advocate for animal rights and welfare. The effectiveness of any applied control measures largely depends on the contribution and active participation of the community. Thus, public awareness programs play a key role in mitigating wild animal damage for KHs. However, in conclusion, rather than focusing on single control method, it requires holistic approach with combination of several mechanisms in order to find a viable solution for this issue.
Table 6
List of species do not damage by torque monkeys
Species | Common name | Reasons |
Capsicum annuum L. | Miris | High pungency |
Citrus species | Dehi | Spines, unique citrus smell of fruits and leaves |
Curcuma longa L. | Kaha | Pungency and smell |
Raphanus raphanistrum subsp. sativus | Rabu | Unique smell |
Solanum insanum L. | Ela-batu | Spines, Pubescence in leaves |
Solanum torvum Sw. | Tibbatu | Spines, Pubescence in leaves |
Syzygium samarangense (Blume) Merr. & L.M.Perry | Jambu | Dark and shiny red colour fruits |
Zingiber officinale Roscoe | Inguru | Pungency and smell |