The influence of life history milestones and association networks on crop-raiding behavior in male African elephants

Factors that influence learning and the spread of behavior in wild animal populations are important for understanding species responses to changing environments and for species conservation. In populations of wildlife species that come into conflict with humans by raiding cultivated crops, simple models of exposure of individual animals to crops do not entirely explain the prevalence of crop raiding behavior. We investigated the influence of life history milestones using age and association patterns on the probability of being a crop raider among wild free ranging male African elephants; we focused on males because female elephants are not known to raid crops in our study population. We examined several features of an elephant association network; network density, community structure and association based on age similarity since they are known to influence the spread of behaviors in a population. We found that older males were more likely to be raiders than younger males, that males were more likely to be raiders when their closest associates were also raiders, and that males were more likely to be raiders when their second closest associates were raiders older than them. The male association network had sparse associations, a tendency for individuals similar in age and raiding status to associate, and a strong community structure. However, raiders were randomly distributed between communities. These features of the elephant association network may limit the spread of raiding behavior and likely determine the prevalence of raiding behavior in elephant populations. Our results suggest that social learning has a major influence on the acquisition of raiding behavior in younger males whereas life history factors are important drivers of raiding behavior in older males. Further, both life-history and network patterns may influence the acquisition and spread of complex behaviors in animal populations and provide insight on managing human-wildlife conflict.     

Seasonal variation of feeding patterns and food selection by crop-raiding elephants in Zimbabwe

Elephants and humans are increasingly coming into conflict because of the conversion of elephant habitat into agricultural areas. In order to identify trends that influence raiding behaviour, the nutritional makeup of food items consumed by crop‐raiding elephants over a 2‐year period were analysed and a trigger for crop raiding was identified. The point at which the quality of wild grasses declines below the quality of crop species corresponded to the movement of bull elephants out of a protected area and into fields. This finding may have wider implications for developing predictive models of elephant/human interactions.     

The influence of lunar cycles on crop‐raiding elephants; evidence for risk avoidance

Long‐term solutions to crop raiding by elephants (Loxodonta africana) should be based on an understanding of their behaviour and ecology. The real and perceived risks from humans have been shown to affect elephant behaviour. This is evidenced by elephants predominantly raiding crops at night, avoiding the height of human activity. If such human avoidance behaviours are apparent, it might also be expected that elephants avoid risks associated with higher visibility and increased human activity as may occur during the full moon. However, elephant nocturnal crop‐raiding behaviour in relation to lunar cycles has largely been a neglected factor in studies of human–elephant interactions. In this study around Mikumi National Park, Tanzania, we apply circular statistics in this context for the first time to show a significant decrease in crop raiding during the full moon and apply this method retrospectively to data from another site in West Africa with similar results. Additionally, a greater proportion of farms raided was guarded during the full moon than any other moon phase. Our results indicate that variations in crop raiding with lunar phase could be a general feature of elephant behaviour and thus could be used to design and time mitigation efforts.     

Population structure and behaviour of crop-raiding elephants in Kibale National Park, Uganda

We examined patterns of crop raiding by elephants across gender and age classes in relation to elephant life history and sociobiology and estimated the quantitative contribution of crops to elephant diet in Kibale National Park (KNP). Elephant dung‐boli sizes were used to estimate age and sex, while the presence of crop remains in the dung of crop‐raiding elephants was used as evidence of repeated raiding. To estimate the expected proportion of elephants raiding per age class, the age distribution of raiders was compared with the age distribution of all KNP elephants. Elephants raiding crops were predominantly males. They began raiding in expected proportions at 10–14 years while a higher than expected proportion raided crops at 20–24 years. These results suggest that crop raiding is initiated at an age when male elephants leave their families and a large proportion of elephants raid when they are approaching reproductive competition. Evidence from dung of crop raiders, suggests that repeated raiding increases with age. Crop raiders derived 38% of their daily forage from the short time spent raiding, consistent with expectations of foraging theory. Males may be more likely to learn crop raiding because they are socially more independent and experience intense mating competition than females.     

Spatial Variation in Army Ant Swarm Raiding and its Potential Effect on Biodiversity

Invertebrate communities of the tropical rain forest floor are highly diverse, characterized by patchy species distribution patterns and high variation in species density. Spatial variation in the foraging activity of swarm raiding army ants, prime invertebrate predators in tropical rain forests, is discussed as a mechanism contributing to these patterns, but highly resolved long‐term data on army ant raiding on the local and landscape scale are hitherto lacking. In this study, 196 positions in 11 study sites in a tropical rain forest in western Kenya were continuously monitored over ~4 mo for the occurrence of swarm raids of army ants. Using population simulation analyses, the consequences of army ant raiding for prey communities were assessed. We found an unexpectedly high variation in raid rates at the study site and landscape scale. The weekly chance of communities to become raided by army ants was on average 0.11, but ranged from 0 to 0.50 among the 196 positions. Simulating population developments of two Lotka–Volterra species—showing slight trade‐offs between competitive strength and resistance to army ant raids—in the real raiding landscapes showed that the observed spatial variation in raid rates may produce high prey diversity at larger spatial scales (due to high β‐diversity) and strong variation in species density. Our results indicate that high spatial variation in army ant swarm raiding is a mechanism capable of generating patchy species distribution patterns and maintaining the high biodiversity of invertebrate communities of the tropical rain forest floor.     

Does traditional and advanced guarding reduce crop losses due to wildlife? A comparative analysis from Africa and Asia

Crop damage caused by herbivorous wildlife species on farms located within conservation landscapes, is a driver of human-wildlife conflict (HWC). Guarding of farms, whereby farmers spend the night out in the fields, in areas adjacent to protected areas is, therefore, very common in many African and Asian countries. Furthermore, guarding is often combined with other crop protection measures, but little is known about the efficacy of these measures.We examined the effect that different traditional and advanced crop protection measures (active and passive guarding strategies, barriers and combinations of measures) had on the magnitude of damaged crops. For this, we examined the cost of crop damage caused by a total of 20 wildlife species in two African and two Asian study areas, where different protection types were applied. Data was compared with the cost of crop damage on unprotected fields. We continuously used a standardised HWC assessment scheme over six years (2009–2014), based on site observations and measurements in addition to interviews with victims.The analysis of crop damage costs revealed substantial losses, especially from that caused by elephants (Loxodonta africana and Elephas maximus) and other large herbivores, such as zebra (Equus quagga) and common eland (Taurotragus oryx). Once wildlife had entered the farms, it was found that crop protection measures by farmers were only able to reduce damage costs when applied as a communal, strategic guarding system. Surprisingly, all other traditional crop protection strategies have proven ineffective in reducing crop damage costs. Electrical fences actually increased the risk of crop damage when combined with guarding and the chasing of wildlife strategies. Therefore, we recommend reviewing the practice of traditional guarding strategies and the effectiveness of fences. Furthermore, we emphasise the need for objective evaluation of HWC mitigation strategies in the long-term.     

Patterns and perceptions of wildlife crop raiding in and around Kerinci Seblat National Park, Sumatra

Crop raiding can reduce farmers' tolerance towards wildlife. Despite higher human population densities in rural areas, and more rapid conversion of forest to farmland, much less is known about crop raiding in Asia than in Africa. Over 14 months, we identified perceived and actual crop pests, and their patterns of crop raiding from farmland in and around Kerinci Seblat National Park, Sumatra. Farmers named either the wild boar Sus scrofa (80%) or the pig-tailed macaque Macaca nemestrina (20%) as the two most destructive crop pests. From 5125 crop raids by 11 species of mammal, most raids were indeed made by the wild boar (56%) and the pig-tailed macaque (19%). For all species combined, temporal crop raiding peaks were positively correlated with periods of high rainfall. Spatially, most crop raids occurred nearest to the forest edge and the local guarding strategies used were ineffective. However, raids by wild boars were more extensive than raids by pig-tailed macaques, which caused much greater crop damage (73%) than wild boars (26%), contrary to farmers' perceptions. Our research suggests that alternative mitigation strategies need to be trialed over dry and rainy seasons to identify the most effective strategies and that guarding effort should be increased during the rainy seasons and tailored towards specific crop raiding species based on their unique spatial patterns.     

空间尺度对地形异质性-物种多样性关系的影响:粒度和幅度

空间尺度是影响我们理解生态学格局和过程的关键因素.目前已有多种关于物种多样性分布格局形成机制的假说且研究者未达成共识,原因之一是空间尺度对物种多样性分布格局的环境影响因子的解释力和相对重要性有重要影响.地形异质性是物种多样性分布格局的重要影响因素.本文综述了在地形异质性-物种多样性关系的研究中,不同空间粒度和幅度对研究...     

Assessing the cost of living with elephants (Loxodonta africana) in areas adjacent to Meru National Park,Kenya

Crop raiding by the elephants is a serious and recurring management problem around protected areas in Kenya such as Meru National Park. Crop-raiding menace is one of the most significant of human–elephant conflicts in Meru National Park. The distribution, impact, and conservation implications of the increased elephant crop raiding in areas adjacent to Meru National Park is attributed to the changes in land use systems within these areas. Crop raiding by African elephants (Loxodonta africana) was monitored in the area adjacent to Meru National Park between August 2010 and July 2011. From the study, 144 farms were raided and farmers lost crops amounting to USD 120,308.60. Crop raiding was higher during the month of August 2010 (KES 2,714,295 or USD 33,928). The study suggests capacity building for communities in order to safeguard their crops against elephant raiding. Other probable measures put forward to mitigate this include the development of alternative water sources and the need to implement electric fence around the remaining section of the Park boundary which is affected by elephant.     

The spatial scale of homogenisation and differentiation in Chihuahuan Desert fish assemblages

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Ecological function losses caused by monotonous land use induce crop raiding by wildlife on the island of Yakushima,southern Japan

Mass production is a logical outcome of price competition in a capitalist economy. It has resulted in the need for large-scale logging and planting of commercial crops. However, such monotonous land use, or monoculture, has damaged various ecological functions of forests and eroded the beneficial public service provided by forests. In Japan, the most widespread monotonous land use is associated with coniferous plantations, the expansion of which was encouraged by Forest Agency policies from 1958 that were aimed at increasing wood production. By 1986, half of all forested lands had been transformed into single-species conifer plantations. These policies may damage the ecological functions of forests: to provide stable habitats for forest wildlife. In particular, food supplies for wildlife have fluctuated greatly after several decades of logging. Some species have therefore changed their ecology and begun to explore novel environments proactively in order to adapt to such extreme fluctuations. Such species have started to use farmlands that neighbor the plantations. In this sense, crop raiding by wildlife can be regarded as a negative result of monotonous land use due to the loss of ecological functions. Therefore, habitat management to rehabilitate ecological functions and to reorganize the landscape will be required in order to resolve the problem of crop raiding by wildlife. This study examines crop raiding by Japanese deer (Cervus nippon) and monkeys (Macaca fuscata) on the island of Yakushima, which typifies crop-raiding situations in Japan.     

Large Mammal Distribution in a Transfrontier Landscape: Trade‐offs Between Resource Availability and Human Disturbance

Understanding factors that affect the persistence of charismatic megafauna in human‐dominated landscapes is crucial to inform conservation decision‐making and reduce human‐wildlife conflict. We assessed the effect of environmental and anthropogenic factors at different landscape and management scales in predicting the distribution of African elephant (Loxodonta africana) within the Greater Mapungubwe Transfrontier Conservation Area in Southern Africa. We combined aerial distribution counts over a 12‐yr period with 14 variables, representing food availability, landscape, and anthropogenic effects, into generalized linear models. Generalized linear models were run for the broader landscape, as well as three separate management units within the broader landscape, namely ecotourism, trophy hunting, and a combination of hunting and ecotourism. Human activities within different management units forced elephant to trade‐off between disturbance avoidance, and good food and water availability. In addition, the important predictors of elephant distribution within each of the management units differed from the predictors at the broader landscape. Overall, our results suggest that at the fine scale, elephant are constraint by factors that may be masked at the broader landscape scale. We suggest that accounting for anthropogenic disturbance is important in determining the distribution of large, wide‐ranging, mammal species in increasingly human‐dominated landscapes, and that modeling needs to be done at the spatial scales at which conservation decisions are made.     

Patterns of spatial and temporal variation of macrofauna under boulders in a sheltered boulder field

Abstract Spatial and temporal patterns of abundance of animals and plants must be quantified before models to explain distributions can be developed. These patterns also provide essential data for measuring potential effects of environmental disturbances. Studies in many different habitats have shown that most organisms, particularly invertebrates, have highly variable and interactive patterns of abundance, with much variability at the smallest temporal and spatial scales. Intertidal boulder fields in New South Wales, Australia, support a diverse fauna, many species of which are relatively rare. These habitats are commonly found near rock‐platforms and in sheltered estuaries and are subjected to many human disturbances. Although there have been a few studies on the fauna in boulder fields, none has documented variability of the assemblage using multivariate and univariate techniques and most studies have not incorporated different spatial and temporal scales. This study quantifies spatial variation at three scales (metres, tens of metres alongshore and tens of metres upshore) and temporal variation at two scales (3 months and 2 years) of the assemblage of molluscs and echinoderms in a sheltered boulder field subjected to little natural or human disturbance. Multivariate analyses revealed that each site contained a distinct assemblage, mainly due to the relative abundances of a few species. Most species, those generally only found under boulders and common, widespread species, had considerable spatial variability in abundances, with more than 90% measured at the smallest scale, that is metre to metre within a site. Changes in abundances over 3 months or 2 years varied among species and sites in unpredictable ways. These data show that sampling designs to measure impacts on these fauna will need to be complex and must incorporate a number of spatial and temporal scales if they are to be able to detect impact against such a variable background.     

Assessment of Crop Damage by Protected Wild Mammalian Herbivores on the Western Boundary of Tadoba-Andhari Tiger Reserve (TATR), Central India

Crop raiding by wild herbivores close to an area of protected wildlife is a serious problem that can potentially undermine conservation efforts. Since there is orders of magnitude difference between farmers’ perception of damage and the compensation given by the government, an objective and realistic estimate of damage was found essential. We employed four different approaches to estimate the extent of and patterns in crop damage by wild herbivores along the western boundary of Tadoba-Andhari Tiger Reserve in the state of Maharashtra, central India. These approaches highlight different aspects of the problem but converge on an estimated damage of over 50% for the fields adjacent to the forest, gradually reducing in intensity with distance. We found that the visual damage assessment method currently employed by the government for paying compensation to farmers was uncorrelated to and grossly underestimated actual damage. The findings necessitate a radical rethinking of policies to assess, mitigate as well as compensate for crop damage caused by protected wildlife species.     

空间粒度变化对景观格局分析的影响

认识空间异质性的多尺度依赖性和景观格局特征对尺度效应关系的影响是进行空间尺度推绎的基础。以2种真实景观(中国广东粤北植被景观与美国凤凰城城市景观)和SIMMAP景观中性模型产生的27种模拟景观为对象。利用景观格局分析软件FRAGSTATS对18种常用景观指数的尺度效应进行了系统的分析。根据这些指数对空间粒度变化的响应曲线和尺度效应关系,18种景观指数可分为3类。第1类指数随空间粒度的增大单调减小。具有比较明确的尺度效应关系(幂函数下降),尺度效应关系受景观空间格局特征的影响较小;这类指数包括缀块数、缀块密度、边界总长、边界密度、景观形状指数、缀块面积变异系数、面积加权平均缀块形状指数、平均缀块分维数和面积加权平均缀块分维数。第2类指数随空间粒度的增大将最终下降。但不是单调下降的;尺度效应关系比较多样,可表现为幂函数下降、直线下降或阶梯形下降。主要受缀块空间分布方式和缀块类优势度的交互影响;这类指数有5种：平均缀块形状指数、双对数回归分维数、缀块丰度、缀块丰度密度和Shannon多样性指数。第3类指数随空间粒度的变粗而增加。随缀块类优势度均等性的增加。尺度效应关系由阶梯形增加、对数函数增加、直线增加向幂函数增加过渡。尺度效应关系主要受缀块类优势度的影响;此类指数包括平均缀块面积、缀块面积标准差、最大缀块指数与聚集度。景观指数随空间粒度变化是一种1临界现象,当粒度大于或小于1临界值时,景观指数对空间粒度变化非常敏感。变化速率非常大。绝大部分情况下。真实景观粒度效应关系和曲线形状与模拟景观所得分析结果相似。说明模拟景观具有很好的代表性。文中也讨论了本研究结果与前人研究的异同。分析了造成差异的原因。景观指数的粒度效应关系与指数本身所反映的景观格局信息有一定关系,总体上来说。随粒度增加。缀块数、边界长度、缀块形状的复杂性、多样性将减小,而平均缀块面积和聚集度将增加。一系列的尺度效应图和不同景观指数的尺度效应关系可作为景观格局分析时指数选择、分析结果的解释和进行空间尺度推绎的参考。     

The conflict between vervet monkeys and farmers at the forest edge in Entebbe, Uganda

Forty‐seven property owners in Entebbe, Uganda were questioned about vervet monkey activities on their property. Our main objective was to investigate the interactions between humans and vervet monkeys in an agricultural area adjacent to a forest zone. Other studies have reported that farms located within 300 m of a forested boundary probably incur the greatest risk of crop‐raiding. Two other factors that may influence susceptibility to vervet crop‐raiding were also examined: the types of crops grown and the types of direct preventative measures used. The effect of these two factors on vervet crop‐raiding is not straightforward. However, the distance a property is located from the forest edge is an important factor influencing vervet crop‐raiding. Surveyed gardens 200 m from the forest edge received significantly less crop‐raiding than farms located 100 m or 50 m (P = 0.040, < α = 0.05). We suggest that the development of nonagricultural activities on land directly adjacent to forested areas may reduce vervet crop‐raiding by deterring vervets from travelling greater distances from the forest edge due to increased obstacles or risks.     

Spatial scale and benthic community organisation in the littoral zones of large oligotrophic lakes: potential for cross-scale interactions

1. We studied the spatial organisation of littoral, benthic invertebrate communities in two large oligotrophic lakes with very extensive heterogeneous littoral zones, and report that littoral communities show significant variation in their structure at multiple spatial scales. 2. At coarser scales, littoral zone topography, riparian inputs and exposure may be important drivers of community spatial structure. At finer scales, the composition of substrates, particularly macrophytes and inorganic sediments, may be drivers of community spatial structure. 3. The effects of substrates on community spatial patterns were non‐additive across scales; community‐habitat correspondence became very noisy when we attempted to extrapolate results throughout the littoral. We present some evidence to suggest that this non‐additivity is because of the interaction among structuring processes that operate at different scales.     

Exploring the drivers of wildlife population dynamics from insufficient data by Bayesian model averaging

A long-standing interest in ecology and wildlife management is to find drivers of wildlife population dynamics because it is crucial for implementing the effective wildlife management. Recent studies have demonstrated the usefulness of state-space modeling for this purpose, but we often confront the lack of the necessary time-series data. This is particularly common in wildlife management because of limited funds or early stage of data collection. In this study, we proposed a Bayesian model averaging technique in a state-space modeling framework for identifying the drivers of wildlife population dynamics from limited data. To exemplify the utility of Bayesian model averaging for wildlife management, we illustrate here the population dynamics of wild boars Sus scrofa in Chiba prefecture, central Japan. Despite the fact that our data are limited in both temporal and spatial resolution, Bayesian model averaging revealed the potential influence of bamboo forests and abandoned agricultural fields on wild boar population dynamics, and largely enhanced model predictability compared to the full model. Although Bayesian model averaging is not commonly used in ecology and wildlife management, our case study demonstrated that it may help to find influential drivers of wildlife population dynamics and develop a better management plan even from limited time-series data.     

Mitigating crop raiding by forest elephants and baboons at Kibale National Park

In Africa, most protected forests are in densely human-dominated landscapes where human–wildlife conflict is intense. We documented farmer perceptions and responses to crop-raiding wildlife from Kibale National Park, Uganda. Crop raiding was mostly (95%) by baboons (Papio anubis) and elephants (Loxodonta africana). While the financial loss caused by baboons and elephants did not differ, elephants were perceived as more damaging. Guarding and trenches were perceived as the most effective deterrent strategies for baboons and elephants, respectively. Distance from the park boundary and household income were significantly associated with a greater likelihood of crop raiding. Distance from the park, household head age and the species that raided crops, influenced whether a household applied one or more deterrent strategies. Households headed by women or older adults were most vulnerable, experiencing greater losses to raiding. Patterns of human–wildlife conflict around Kibale forest are complex, but the extent of crop damage was mostly determined by distance from the park and farm socio-economic status and thus their ability to mitigate or deter raiding. Managing crop raiding requires collaboration between the park and affected farmers to ensure that mutually managed deterrent methods, such as trenching (elephants) and guarding (baboons), are effectively shared, applied and maintained.