Elevated levels of stress hormones in crop-raiding male elephants

Ahlering, Marissa A.; Millspaugh, J. J.; Woods, Rami J.; Western, David; Eggert, Lori S.

doi:10.1111/j.1469-1795.2010.00400.x

Cited by 49 publications

(31 citation statements)

References 44 publications

(42 reference statements)

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“…In many parts of Africa, managers are concerned with elephants leaving core protected areas and damaging agricultural crops (or crop raiding), a behaviour that in itself can result in elephants entering elevated physiological states (Ahlering et al . ). Our findings suggest that elephants in an elevated physiological state are more likely to use refugia and less likely to make exploratory movements.…”

Section: Discussionmentioning

confidence: 97%

Unravelling complex associations between physiological state and movement of African elephants

et al. 2013

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Summary1. Despite the identification of internal state as a fundamental component of animal movement, the effect of an individual's internal physiological state on movement remains poorly understood. African elephants (Loxodonta africana) alter their behaviour in response to their physiological state, and elevated stress hormone concentrations have been associated with reclusive behaviour and aggression towards humans. Thus, a better understanding of the link between internal physiological state and movement is important in advancing the field of movement ecology, and the ecology and management of elephants. 2. We compared the movement paths of African elephants in two physiological states (basal and elevated stress hormone levels) to understand the variation in the use of space in relation to the proximity of environmental features and refugia. 3. We documented differences in the elephants' use of space along movement paths by physiological state. Elephant family groups in a basal physiological state tended to venture away from refugia and commercial tree plantations, and use areas in closer proximity to fresh water. In contrast, elephant family groups in an elevated physiological state tended to use areas near refugia and commercial tree plantations. The use of commercial tree plantations during elevated states highlights an important concern for human safety in the context of humanelephant conflict. 4. Synthesis and applications. Our findings suggest that fine-scale movement patterns and the use of specific environmental features by elephants are associated with differences in elephant physiological state. Therefore, future attempts to describe or predict typically complex animal movement could be enhanced by incorporating measures of their physiological state. Given that elephants are more prone to habitat disturbance and aggression when in an elevated physiological state, information about elephant movement behaviour could be used in combination with real-time tracking data to predict when and where elephants are potentially in elevated physiological states and limit human access to these areas, which might mitigate humanelephant conflict.

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Section: Discussionmentioning

confidence: 97%

Unravelling complex associations between physiological state and movement of African elephants

et al. 2013

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“…African elephants with high stress (fGCM) levels exhibited streaking (rapid unidirectional movement) and refuge behaviours along with restricted and altered habitat preferences (Jachowski et al, 2012(Jachowski et al, , 2013. Ahlering et al (2011a) showed, on the basis of limited sampling, elevated fGCM levels in crop-raiding male African elephants than those in nearby protected areas. Season (dry season as 'D' and wet season as 'W').…”

Section: Discussionmentioning

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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“…Similar results have been reported from Kasungu (Malawi) where high levels of poaching, of mainly bulls, led to additional males continuously moving into the area (Bell ). Younger bulls are more often responsible for crop raiding (Chiyo et al , Ahlering et al ), but the older bulls are required for a good trophy income (Hurt and Ravn , Festa‐Bianchet , Milner et al , Slotow et al ). Regulations on damage causing animals differ between Botswana and South Africa.…”

Section: Discussionmentioning

confidence: 99%

Sustainability of elephant hunting across international borders in southern Africa: A case study of the greater Mapungubwe Transfrontier Conservation Area

et al. 2013

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Trophy hunting of African elephant is often implemented as an income generator for communities surrounding protected areas. However, the sustainability of hunting on elephant populations, especially with regards to international cross‐border populations has not previously been evaluated. We assessed the effects of trophy hunting on the population dynamics and movements of elephant in the Greater Mapungubwe Transfrontier Conservation Area, which is spread across the junction of Botswana, South Africa, and Zimbabwe. Currently, no common policy exits in quota setting for cross‐border species, and each country determines their own quota based on limited data. Using VORTEX, we determined the sustainability of current quotas of elephant off‐take under different ecological and hunting scenarios. We used distribution data from 6 aerial surveys and hunting data per region to determine the disturbance effect of hunting on bulls and breeding herds separately. Hunting of bulls had a direct effect in reducing bull numbers but also an indirect effect due to disturbance that resulted in movement of elephants out of the areas in which hunting occurred. The return interval was short for bulls but longer for females. Only a small number of bulls (<10/year) could be hunted sustainably. At current rates of hunting, under average ecological conditions, trophy bulls will disappear from the population in less than 10 years. We recommend a revision of the current quotas within each country for the Greater Mapungubwe elephant population, and the establishment of a single multi‐jurisdictional (cross‐border) management authority regulating the hunting of elephant and other cross‐border species. © 2013 The Wildlife Society

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Elevated levels of stress hormones in crop-raiding male elephants

Cited by 49 publications

References 44 publications

Unravelling complex associations between physiological state and movement of African elephants

Unravelling complex associations between physiological state and movement of African elephants

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

Sustainability of elephant hunting across international borders in southern Africa: A case study of the greater Mapungubwe Transfrontier Conservation Area

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