Determinants of elephant foraging behaviour in a coupled human‐natural system: Is brown the new green?

Abstract

Crop raiding by wildlife poses major threats to both wildlife conservation and human well‐being in agroecosystems worldwide. These threats are particularly acute in many parts of Africa, where crop raiders include globally threatened megafauna such as elephants, and where smallholder agriculture is a primary source of human livelihood. One framework for understanding herbivore feeding behaviour, the forage‐maturation hypothesis, predicts that herbivores should align their movements with intermediate forage biomass (i.e., peak green‐up); this phenomenon is known as “surfing the green wave.” Crop‐raiding elephants, however, often consume not just foliage, but also fruits and tubers (e.g., maize and potatoes), which generally mature after seasonal peaks in photosynthetic activity. Thus, although elephants have been reported to surf the green wave in natural habitats, they may utilize a different strategy in cultivated landscapes by selecting crops that are “browning down.” We sought to understand the factors that underpin movement of elephants into agricultural landscapes. In Mozambique's Gorongosa National Park, we used movement data from GPS‐collared elephants, together with precipitation records, remotely sensed estimates of landscape greenness (NDVI), DNA‐based diet analysis, measurements of plant nutritional quality and survey‐based metrics of crop availability to understand spatiotemporal variation in elephant crop‐raiding behaviour. Elephants tracked peak NDVI while foraging inside the Park. During the dry season, however, when NDVI within the Park declined and availability of mature crops was high, crop raiding increased dramatically, and elephants consistently selected crop plants that were browning down while foraging in cultivated landscapes. Crops contained significantly higher digestible energy than wild food plants, but comparable (and sometimes lower) levels of digestible protein, suggesting that this foraging strategy maximized energy rather than protein intake. Our study is the first to combine GPS tracking data with high‐resolution diet analysis and community‐based reporting of crop availability to reveal fine‐scale plasticity in foraging behaviour of elephants at the human–wildlife interface. Our results extend the forage‐maturation hypothesis by showing that elephants surf waves of plant brown‐down in cultivated landscapes. These findings can aid efforts to reduce human–elephant conflict by enabling wildlife managers to prioritize mitigation actions in time and space with limited resources.

Climatic and Resource Determinants of Forest Elephant Movements

“…Similarly, knowledge of key stands of fruiting trees visited by elephants could orient seasonal anti-poaching patrols and efforts. Most elephant follows occurred within relatively pristine protected areas: future work should investigate drivers of elephant movement around settlements as forest elephants may alter their foraging behavior at humanwildlife interfaces (see Branco et al (2019) where this was demonstrated for savannah elephants). In the same way that responses to fruit availability and rainfall vary among individuals, elephants may also demonstrate individual behavior in their tendency to approach settlements and raid crops (Swan et al, 2017).…”

Spatiotemporal Distribution of Human–Elephant Conflict in Eastern Thailand: A Model-Based Assessment Using News Reports and Remotely Sensed Data

“…Nevertheless, EVI slope had the highest predictive power among all EVI variables, implying possible importance of vegetation phenology. A study of crop raiding behavior in African elephants identified crop availability and ripening timing as important indicators for predicting crop damage [82]. Therefore, variables related to crop types along with its phenology, which can be detected from remotely sensed satellite data, should be further studied.…”

An experimental test of community‐based strategies for mitigating human–wildlife conflict around protected areas

“…Elephants are now recovering under the auspices of the Gorongosa Project (Pringle, 2017), and the most recent aerial census counted roughly 600 individuals (Stalmans et al, 2019). After the war, however, much of the buffer zone has been converted to agricultural lands ( Figure S1, Appendix S1), which strongly attract elephants (Branco et al, 2018).…”

“…(Male elephants are generally more prone to crop-raiding behavior: Hoare, 1999. ) A detailed description of our capture and handling procedures is provided by Branco et al (2018); all procedures were approved by the Animal Care and Use Committee at the University of Idaho (protocol #2015-39). In addition, our research was certified as exempt from continuing review by the Institutional Review Board at the University of Idaho.…”