Modelling large herbivore movement decisions: Beyond food availability as a predictor of ranging patterns

Abstract

The ability of animals to adapt to their changing environment will depend in part on shifts in their ranging patterns, but when and why individuals choose to move requires detailed understanding of their decision-making processes. We develop a simple decision-making model accounting for resource availability in habitually used ranges. We suggest that disparities between model predictions and animal tracking data indicate additional factors influencing movement decisions, which may be identified given detailed system-specific knowledge. The model was evaluated using movement data from satellite-tracked elephants (Loxodonta africana) inhabiting the Amboseli Ecosystem in Kenya, moving from savannah areas with low quality but constant resource availability, to areas with temporally-constrained higher nutrient availability. Overall, the model fit the data well: there was a good correlation between predicted and observed locations for the combined data from all elephants, but variation between individuals in how well the model fits. For those elephants where model predictions were less successful, additional factors likely to affect movement decisions, reproduction, anthropogenic threats, memory and perception, are suggested. This protocol for building and testing decision-making models should contribute to success in attempts to preserve sufficient space for large herbivores in their increasingly human-dominated ecosystems.

Supporting Zoo Asian Elephant (Elephas maximus) Welfare and Herd Dynamics with a More Complex and Expanded Habitat

“…Increased walking distance in both African and Asian zoo-housed elephants has been associated with feeding diversity and unpredictable feeding schedules [ 37 ]. In free-ranging elephants, walking activity and patterns are affected by a variety of factors, including the distribution and availability of resources, season, age, sex, reproductive state, presence of calves or juveniles in a group, ranking of social groups, and human activities [ 14 , 38 , 39 , 40 , 41 , 42 , 43 , 44 ]. The relationship between resource availability and walking distance suggests that walking varies in response to external conditions.…”

Elephant population responses to increased density in Kruger National Park

“…Like most large herbivores, elephants choose landscapes based on water, food, comfort and safety (Boult et al 2019;Chamaillé-Jammes, Valeix & Fritz 2007;Kinahan, Pimm & Van Aarde 2007;Wittemyer et al 2017) and make large seasonal movements (e.g. Cook, Henley & Parrini 2015).…”

Agent-based modelling as a tool for elephant poaching mitigation

“…Each elephant is part of a specific herd and follows a specific matriarch. Each day, females and young (<14 years old) male elephants follow their assigned matriarch and move as a herd, according to a seasonal migratory pattern following resources (Boult et al, 2019) such as food (Bohrer et al, 2014;Loarie, Aarde, & Pimm, 2009), water (Chamaillé-Jammes, Valeix, & Fritz, 2007;Redfern et al, 2003), and social partners (Chiyo et al, 2014). Elephant herds aggregate near water sources for seven months of the year (the 'dry season') and then disperse and move randomly throughout the landscape for the remaining months (the 'rainy season').…”

“…3.6.1 Elephant Migration and Dispersal Each day, females and young (<14 years old) elephants follow their assigned matriarch and move as a herd, following a seasonal migratory pattern following resources (Boult et al, 2019) such as food (Bohrer et al, 2014;Loarie, Aarde, & Pimm, 2009), water (Chamaillé-Jammes, Valeix, & Fritz, 2007;Redfern et al, 2003), and social partners (Chiyo et al, 2014). Water availability is a major driver of seasonal patterns in elephant migrations; elephants concentrate at permanent water during the dry season and then disperse after the rains (Western, 1975).…”

“…Our model incorporates aspects of elephant ecology and behaviour in order to assess how these factors impact the system and how they can inform law enforcement strategies. Each elephant is part of a specific herd; female and young male elephants follow the matriarchal herd, according to a seasonal migratory pattern following resources (Boult et al, 2019) such as food (Bohrer et al, 2014;Loarie, Aarde, & Pimm, 2009), water (Chamaillé-Jammes, Valeix, & Fritz, 2007Redfern et al, 2003), and social partners (Chiyo et al, 2014). Spatio-temporal differences in behaviour were included, as matriarchal herds aggregate near water sources during the dry season and then disperse during the rainy season (Moss & Poole, 1983;Western, 1975).…”