African savanna elephants (Loxodonta africana) as an example of a herbivore making movement choices based on nutritional needs

Abstract

BackgroundThe increasing human population and global intensification of agriculture have had a major impact on the world’s natural ecosystems and caused devastating effects on populations of mega-herbivores such as the African savanna elephants, through habitat reduction and fragmentation and increased human–animal conflict. Animals with vast home ranges are forced into increasingly smaller geographical areas, often restricted by fencing or encroaching anthropogenic activities, resulting in huge pressures on these areas to meet the animals’ resource needs. This can present a nutritional challenge and cause animals to adapt their movement patterns to meet their dietary needs for specific minerals, potentially causing human–animal conflict. The aim of this review is to consolidate understanding of nutritional drivers for animal movement, especially that of African savanna elephants and focus the direction of future research. Peer reviewed literature available was generally geographically specific and studies conducted on isolated populations of individual species. African savanna elephants have the capacity to extensively alter the landscape and have been more greatly studied than other herbivores, making them a good example species to use for this review. Alongside this, their movement choices, potentially linked with nutritional drivers could be applicable to a range of other species. Relevant case study examples of other herbivores moving based on nutritional needs are discussed.MethodsThree databases were searched in this review: Scopus, Web of Science and Google Scholar, using identified search terms. Inclusion and exclusion criteria were determined and applied as required. Additional grey literature was reviewed as appropriate.ResultsInitial searches yielded 1,870 records prior to application of inclusion and exclusion criteria. A less detailed review of grey literature, and additional peer-reviewed literature which did not meet the inclusion criteria but was deemed relevant by the authors was also conducted to ensure thorough coverage of the subject.DiscussionA review of peer reviewed literature was undertaken to examine nutritional drivers for African elephant movement, exploring documented examples from free-ranging African savanna elephants and, where relevant, other herbivore species. This could help inform prediction or mitigation of human–elephant conflict, potentially when animals move according to nutritional needs, and related drivers for this movement. In addition, appropriate grey literature was included to capture current research.

Differing physiological and behavioral responses to anthropogenic factors between resident and non-resident African elephants at Mpala Ranch, Laikipia County, Kenya

“…The fact that migrant elephants had lower FGM concentrations than residents suggests they may be tracking vegetation quality to improve bioenergetics. A wide-ranging foraging strategy may better meet nutritional demands (Parker, Barboza & Gillingham, 2009;Sach et al, 2019), thus reducing GC output.…”

Climatic and Resource Determinants of Forest Elephant Movements

“…Forest elephants can move over 2800 km annually with average home ranges of ∼700 km 2 (Mills et al, 2018). Like savanna elephants (Loxodonta africana), forest elephants show patterned preferences for various habitats, potentially moving to fulfill their energy and nutrition needs (Sach et al, 2019). The ranging behavior of forest elephants has been linked to resources such as browse abundance, mineral deposits, water resources, and the physical and seasonal distribution of ripe fruit (Blake, 2002;Blake et al, 2006;Buij et al, 2007;Mills et al, 2018), but the relative importance of these resources on their movements is largely unknown.…”

Potential bio-indicators for assessment of mineral status in elephants

“…Dietary provision compared to published recommendations. Calcium, Fe and Zn all have published recommended dietary intakes for elephants 4 . Figure 1 shows a comparison of mineral levels in keeper-fed diets from each zoo to captive recommendations produced by Ullrey et al 34 .…”