Crop‐raiding elephants and the moon

Barnes, R. F. W.; Dubiure, Umaru-Farouk; Danquah, Emmanuel; Boafo, Yaw Agyeman; Nandjui, A.; Hema, E. M.; Manford, M.

doi:10.1111/j.1365-2028.2006.00689.x

Cited by 26 publications

(24 citation statements)

References 5 publications

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“…Weaver, Paquet & Ruggiero, 1996). Inferential studies of crop raiding suggest that African elephants move into and through cultivated fields at night (Bell, 1984;Thouless, 1994;Hoare, 1995;Osborn, 1998;Sitati et al, 2003;Barnes et al, 2006). This apparent behavioural strategy of risk avoidance through spatial partitioning in time, while obvious, has been difficult to demonstrate directly as nocturnal observation data were difficult to collect until recent advances in radio telemetry.…”

Section: Introductionmentioning

confidence: 94%

The movement of African elephants in a human‐dominated land‐use mosaic

Graham

Douglas‐Hamilton

Adams

et al. 2009

Animal Conservation

193

225

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Land outside of gazetted protected areas is increasingly seen as important to the future of elephant persistence in Africa. However, other than inferential studies on crop raiding, very little is understood about how elephants Loxodonta africana use and are affected by human-occupied landscapes. This is largely a result of restrictions in technology, which made detailed assessments of elephant movement outside of protected areas challenging. Recent advances in radio telemetry have changed this, enabling researchers to establish over a 24-h period where tagged animals spend their time. We assessed the movement of 13 elephants outside of gazetted protected areas across a range of land-use types on the Laikipia plateau in north-central Kenya. The elephants monitored spent more time at night than during the day in areas under land use that presented a risk of mortality associated with human occupants. The opposite pattern was found on large-scale ranches where elephants were tolerated. Furthermore, speed of movement was found to be higher where elephants were at risk. These results demonstrate that elephants facultatively alter their behaviour to avoid risk in human-dominated landscapes. This helps them to maintain connectivity between habitat refugia in fragmented land-use mosaics, possibly alleviating some of the potential negative impacts of fragmentation. At the same time, however, it allows elephants to penetrate smallholder farmland to raid crops. The greater the amount of smallholder land within an elephant's range, the more it was utilized, with consequent implications for conflict. These findings underscore the importance of (1) land-use planning to maintain refugia; (2) incentives to prevent further habitat fragmentation; (3) the testing and application of conflict mitigation measures where fragmentation has already taken place

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Section: Introductionmentioning

confidence: 94%

The movement of African elephants in a human‐dominated land‐use mosaic

Graham

Douglas‐Hamilton

Adams

et al. 2009

Animal Conservation

193

225

View full text Add to dashboard Cite

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“…It has been well-documented that stimuli from human-induced disturbance are perceived as a form of threat or predation risk (Frid & Dill, 2002). Elephants being cathemeral animals, the almost exclusive pattern of raiding crops at night observed in both African and Asian elephants reflects their human-avoidance behaviours to lower human-associated threats (Sukumar, 2003;Barnes et al, 2006;Graham et al, 2009;Gunn et al, 2014). Elephants being cathemeral animals, the almost exclusive pattern of raiding crops at night observed in both African and Asian elephants reflects their human-avoidance behaviours to lower human-associated threats (Sukumar, 2003;Barnes et al, 2006;Graham et al, 2009;Gunn et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Lower levels of glucocorticoids in crop‐raiders: diet quality as a potential ‘pacifier’ against stress in free‐ranging Asian elephants in a human‐production habitat

Pokharel

Singh

Seshagiri

2018

Animal Conservation

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Overlapping habitats and sharing of resources between elephants and people has led to intense elephant-human conflicts, especially crop depredation by elephants, across elephant-range countries. While raiding agricultural crops, elephants face numerous threats from people through chase, injury and the risk of death which could enhance the associated energetic costs, ultimately elevating their stress levels. We hypothesized that crop-raiders (in the human-production habitat) would show higher faecal glucocorticoid metabolite (fGCM) levels, a proxy of stress-response, as compared to nonraiders (in protected forests). To study this, 208 faecal samples were collected from crop-raiding elephants in a human-production habitat and 394 samples from nonraiding elephants in protected forests during 2013 and 2015. Contrary to our expectation, fGCM levels were significantly higher in nonraiding than in crop-raiding elephants of both sexes. As one of the possible factors for lower fGCM in elephants inhabiting the human-production habitat, the influence of benefits obtained from foraging here was assessed. For this, the difference in vegetation greenness (standing biomass) between the human-production habitat and the protected forests was analysed from remotely-sensed Normalized Differential Vegetation Index (NDVI), and further confirmed by measuring dietary quality (faecal nitrogen (N) content and C:N ratio as proxies for crude protein). Interestingly, higher NDVI values (greater biomass availability), higher N content and lower faecal C:N ratio (indicating higher protein content in the diet) of elephants in the human-production habitat suggested enhanced nutritional levels here as compared to protected forests. Further, there were significant correlations between faecal C:N ratio (positive) or N content (negative) and fGCM levels. These findings suggest that crop-raiding comes with the benefits of a superior quality diet which may help in reducing human-induced stress-response in elephants inhabiting or foraging within human-production habitats.

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“…Elephant crop consumption depends on both the spatial distribution of agricultural fields and elephant movement patterns (Cook, Henley, & Parrini, 2015;Sitati, Walpole, Smith, & Leader-Williams, 2003;Songhurst & Coulson, 2014). Rainfall generates seasonal changes in both the movements of elephants (Barnes et al, 2006;de Boer et al, 2013;Hoare, 1999;Osborn, 2004), and crop consumption (Chiyo, Cochrane, Naughton, & Basuta, 2005;Hoare & Du Toit, 1999;Jackson et al, 2008;Sukumar, 1990). For example, in northern Botswana, at the start of the wet season from mid-October to March crops and grasses start to grow and most crop consumption in the area occurs between March and April, when crops are maturing (Songhurst, 2017;Songhurst & Coulson, 2014).…”

Section: Introductionmentioning

confidence: 99%

“…The intensity of crop raiding also depends on the time of day and individual elephants' characteristics. For example, most crop consumption takes place at night (Barnes et al, 2006;Hoare, 1999;Jackson et al, 2008;Sitati, Walpole, & Leader-Williams, 2005;Sukumar, 1990), and males typically raid fields more often than females (Chiyo et al, 2005;Hoare, 1999;Songhurst, 2017;Von Gerhardt et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Exploring movement decisions: Can Bayesian movement‐state models explain crop consumption behaviour in elephants (Loxodonta africana)?

Vogel

Lambert

Songhurst

et al. 2020

Journal of Animal Ecology

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Animal movements towards goals or targets are based upon either maximization of resource acquisition or risk avoidance, and the way animals move can reveal information about their motivation. We use hidden Markov models (HMMs) fitted in a Bayesian framework and hourly Global Positioning System fixes to distinguish animal movements into distinct states and analyse the influence of environmental variables on being in, and switching to, a particular state. Specifically, we apply our models to understand elephant movement decisions around agricultural fields, and crop consumption. As it is unclear what the role of habitat features are on this complex process, we analyse whether elephants target agricultural crops for consumption, or simply pass through them in search of water. Our HMMs separate elephant movements into two states: exploratory movements that are fast and directional, and encamped movements that are slow and meandering. For each elephant, we ran 16 models with each possible combination of selected habitat features (river, elephant corridor, agricultural field, trees), and repeated these analyses including interaction effects with both season and time of day. We used cross‐validation to select the best model. In corridors, exploratory movements are dominant. Elephants mainly showed encamped movements at the river during the dry season, when temporary water sources have dried out and elephants relied on this permanent water source. In fields, males most often exhibited exploratory movements to and from the river, while females showed an increase in the frequency of encamped behaviour during the dry season and at night—the times when most crop consumption and movements through fields occur. Adaptation to risk could explain this behaviour, since foraging in fields is likely less risky under the cover of darkness and during the dry season when farmers are absent. This sex segregation in elephant movement decisions highlights the importance of predation risk in shaping movement patterns, which can result in sex segregation in responses to mitigation methods. The increase in encamped movements in the dry season suggests the importance of agricultural timing, and shows the potential for early ploughing and early‐harvest crop types in order to reduce elephant crop consumption. Taking this into account could increase efficiency of elephant crop consumption mitigation.

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Crop‐raiding elephants and the moon

Cited by 26 publications

References 5 publications

The movement of African elephants in a human‐dominated land‐use mosaic

The movement of African elephants in a human‐dominated land‐use mosaic

Lower levels of glucocorticoids in crop‐raiders: diet quality as a potential ‘pacifier’ against stress in free‐ranging Asian elephants in a human‐production habitat

Exploring movement decisions: Can Bayesian movement‐state models explain crop consumption behaviour in elephants (Loxodonta africana)?

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