TY - JOUR
T1 - Determinants of elephant foraging behaviour in a coupled human-natural system
T2 - Is brown the new green?
AU - Branco, Paola S.
AU - Merkle, Jerod A.
AU - Pringle, Robert Mitchell
AU - Pansu, Johan
AU - Potter, Arjun B.
AU - Reynolds, Alana
AU - Stalmans, Marc
AU - Long, Ryan A.
N1 - Funding Information:
National Science Foundation, Grant/Award Number: IOS-1656527 and IOS-1656642; Rufford Foundation; Save the Elephants; Campizondo Foundation
Funding Information:
We thank the Government of Mozambique and Gorongosa National Park for permission to conduct this research. We thank Rui Branco, Louis van Wyk and Mike Pingo for their skilled assistance in elephant capture and handling. This work and its participants were supported by the U.S. National Science Foundation (IOS-1656642 to R.A.L.; IOS-1656527 to R.M.P.). We also thank the University of Idaho, Gorongosa Restoration Project, Rufford Foundation, Campizondo Foundation, Artipopart, Save the Elephants, Sr. Jean-Marc Gr?n, Victria Branco, the Cameron Schrier Foundation, the Princeton Environmental Institute and the Becky Colvin Memorial Award for the financial support. We are grateful to our field assistants Castiano Lencastro, Michel Souza, Elyce Gosselin and Tosca Tindall. We also thank Dr. Janet Rachlow, Dr. Joyce Poole and Petter Granli for their comments and support. We are grateful to the Associate Editor and two anonymous reviewers for insightful comments that greatly improved the manuscript. The authors declare that they have no conflict of interest.
Funding Information:
We thank the Government of Mozambique and Gorongosa National Park for permission to conduct this research. We thank Rui Branco, Louis van Wyk and Mike Pingo for their skilled assistance in elephant capture and handling. This work and its participants were supported by the U.S. National Science Foundation (IOS-1656642 to R.A.L.; IOS-1656527 to R.M.P.). We also thank the University of Idaho, Gorongosa Restoration Project, Rufford Foundation, Campizondo Foundation, Artipopart, Save the Elephants, Sr. Jean-Marc GrD?n, Victria Branco, the Cameron Schrier Foundation, the Princeton Environmental Institute and the Becky Colvin Memorial Award for the financial support. We are grateful to our field assistants Castiano Lencastro, Michel Souza, Elyce Gosselin and Tosca Tindall. We also thank Dr. Janet Rachlow, Dr. Joyce Poole and Petter Granli for their comments and support. We are grateful to the Associate Editor and two anonymous reviewers for insightful comments that greatly improved the manuscript. The authors declare that they have no conflict of interest.
Publisher Copyright:
© 2019 The Authors. Journal of Animal Ecology © 2019 British Ecological Society
PY - 2019/5
Y1 - 2019/5
N2 - 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.
AB - 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.
KW - DNA metabarcoding
KW - Loxodonta africana
KW - Normalized Difference Vegetation Index
KW - behavioural plasticity
KW - crop raiding
KW - human–wildlife conflict
KW - movement ecology
KW - protected area management
UR - http://www.scopus.com/inward/record.url?scp=85063497830&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85063497830&partnerID=8YFLogxK
U2 - 10.1111/1365-2656.12971
DO - 10.1111/1365-2656.12971
M3 - Article
C2 - 30825191
AN - SCOPUS:85063497830
SN - 0021-8790
VL - 88
SP - 780
EP - 792
JO - Journal of Animal Ecology
JF - Journal of Animal Ecology
IS - 5
ER -