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Exploring movement decisions: can Bayesian movement-state models explain crop consumption behaviour in elephants (Loxodonta africana)?
J Anim Ecol. 2020 Jan 20 [Online ahead of print]JA

Abstract

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 fitted in a Bayesian framework and hourly GPS-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 hidden Markov models 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.

Authors+Show Affiliations

Department of Zoology Research and Administration Building, University of Oxford, 11a Mansfield Road, Oxford, United Kingdom. Ecoexist Trust, Lions Gate, Boseja, Maun, Botswana. Center for Biodiversity Dynamics in a Changing World (BIOCHANGE), Department of Bioscience, Aarhus University, Ny Munkegade 114, DK-8000, Aarhus C, Denmark. Section for Ecoinformatics and Biodiversity, Department of Bioscience, Aarhus University, Ny Munkegade 114, DK-8000, Aarhus C, Denmark.Department of Zoology Research and Administration Building, University of Oxford, 11a Mansfield Road, Oxford, United Kingdom. Department of Infectious Disease Epidemiology, Imperial College London, St Mary's Campus, Norfolk Place, London, W2 1PG.Department of Zoology Research and Administration Building, University of Oxford, 11a Mansfield Road, Oxford, United Kingdom. Ecoexist Trust, Lions Gate, Boseja, Maun, Botswana. Agriculture and Life Sciences, Texas A&M, 600 John Kimbrough Blvd, MS-2261, College Station, Texas, United States.Department of Zoology Research and Administration Building, University of Oxford, 11a Mansfield Road, Oxford, United Kingdom. Ecoexist Trust, Lions Gate, Boseja, Maun, Botswana. Agriculture and Life Sciences, Texas A&M, 600 John Kimbrough Blvd, MS-2261, College Station, Texas, United States.Ecoexist Trust, Lions Gate, Boseja, Maun, Botswana. Agriculture and Life Sciences, Texas A&M, 600 John Kimbrough Blvd, MS-2261, College Station, Texas, United States.Department of Zoology Research and Administration Building, University of Oxford, 11a Mansfield Road, Oxford, United Kingdom.

Pub Type(s)

Journal Article

Language

eng

PubMed ID

31960413

Citation

Vogel, Susanne Marieke, et al. "Exploring Movement Decisions: Can Bayesian Movement-state Models Explain Crop Consumption Behaviour in Elephants (Loxodonta Africana)?" The Journal of Animal Ecology, 2020.
Vogel SM, Lambert B, Songhurst AC, et al. Exploring movement decisions: can Bayesian movement-state models explain crop consumption behaviour in elephants (Loxodonta africana)? J Anim Ecol. 2020.
Vogel, S. M., Lambert, B., Songhurst, A. C., McCulloch, G. P., Lee Stronza, A., & Coulson, T. (2020). Exploring movement decisions: can Bayesian movement-state models explain crop consumption behaviour in elephants (Loxodonta africana)? The Journal of Animal Ecology. https://doi.org/10.1111/1365-2656.13177
Vogel SM, et al. Exploring Movement Decisions: Can Bayesian Movement-state Models Explain Crop Consumption Behaviour in Elephants (Loxodonta Africana). J Anim Ecol. 2020 Jan 20; PubMed PMID: 31960413.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Exploring movement decisions: can Bayesian movement-state models explain crop consumption behaviour in elephants (Loxodonta africana)? AU - Vogel,Susanne Marieke, AU - Lambert,Ben, AU - Songhurst,Anna Catherine, AU - McCulloch,Graham Paul, AU - Lee Stronza,Amanda, AU - Coulson,Tim, Y1 - 2020/01/20/ PY - 2020/1/22/entrez KW - conservation KW - crop raiding KW - hidden Markov models KW - human-elephant conflict JF - The Journal of animal ecology JO - J Anim Ecol N2 - 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 fitted in a Bayesian framework and hourly GPS-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 hidden Markov models 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. SN - 1365-2656 UR - https://www.unboundmedicine.com/medline/citation/31960413/Exploring_movement_decisions:_can_Bayesian_movement-state_models_explain_crop_consumption_behaviour_in_elephants_(Loxodonta_africana) L2 - https://doi.org/10.1111/1365-2656.13177 DB - PRIME DP - Unbound Medicine ER -
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