African forest elephant social networks: fission-fusion dynamics, but fewer associations

Abstract

For animal species with dynamic interactions, understanding social patterns can be difficult. Social network analysis quantifies associations and their intensity between individuals within a population, revealing the overall patterns of the society. We used networks to test the hypothesis that the elusive African forest elephant Loxodonta cyclotis exhibits fission−fusion social dynamics, similar to other elephant species. We observed associations between individuals in savanna clearings in Lopé National Park, Gabon, in 2006Gabon, in , 2008Gabon, in , and 2010. When possible, dung was collected from individuals for genetic analyses using 10 microsatellite loci and the mitochondrial DNA control region. Using simple ratio association indices, networks were created for each year, wet and dry seasons, individuals detected at least twice, and for all females. We identified 118 unique adult females, for 40 of which we obtained genetic information. N etworks had low densities, many disconnected components, short average path lengths, and high clustering coefficients. Within components, average relatedness was 0.093 ± 0.071 (SD) and females appeared to share mitochondrial haplotypes. We detected 1 large component consisting of 22 adult females, but there were few preferred associations (8 of 65, 12.3%). No seasonal or yearly differences were observed. Our results substantiate fission−fusion dynamics in forest elephants; however, the networks are more disconnected than those for other elephant species, possibly due to poaching and ecological constraints in the forest environment. KEY WORDS: Social networks · Social structure · Loxodonta cyclotis · Fission−fusion · Elephants Resale or republication not permitted without written consent of the publisherEndang Species Res 25: [165][166][167][168][169][170][171][172][173] 2014 can be quantified and visualized (Croft et al. 2008, Wey et al. 2008, Sih et al. 2009, Croft et al. 2011. We used network analysis to elucidate the social structure of the African forest elephant Loxondonta cyclotis, an elusive species thought to have fission−fusion dynamics.Two species of African elephant are recognized: savanna and forest (Rohland et al. 2010). In savanna elephants, related females form family groups that repeatedly join and separate from other groups (Moss 1988, Wittemyer et al. 2005, Archie et al. 2006. Family groups are important for fitness. Females rear young as a group (Lee 1987), and intact groups are more effective at forming defensive postures in response to playback calls from lions (McComb et al. 2011). The oldest member, the matriarch, retains knowledge about the landscape important for the group's survival (McComb et al. 2001). In poached populations, where social structure is disrupted, groups have lower reproductive output and higher stress levels (Gobush et al. 2008), with potentially long-term negative consequences for decisionmaking abilities (Shannon et al. 2013).Less is known about forest elephant social structure, as their dense and remote habitat m...

Ecological consequences of forest elephant declines for Afrotropical forests

“…2). Although the better-studied savanna elephant (Loxodonta africana) is a major driver of vegetation structure, tree recruitment, and plant community composition (e.g., Laws et al 1970;Guldemond & Aarde 2008;Asner & Levick 2012), studies of savanna elephants provide limited inference for understanding how forest elephants interact with their environment because the 2 taxa have demonstrable differences in morphology, ecology, reproduction, and social structure (e.g., Roca et al 2001;Schuttler et al 2014;Turkalo et al 2017). This is a problematic knowledge gap because forest elephants are ecosystem engineers that control, directly or indirectly, the availability of resources to other organisms by causing physical state changes in biotic and abiotic materials.…”

Abundance, density, and social structure of African forest elephants (Loxodonta cyclotis) in a human-modified landscape in southwestern Gabon

“…Genetic studies have confirmed that individuals in these small groups are usually highly related 82 (Munshi-South 2011, Schuttler et al 2014a, Schuttler et al 2014b). Studies of forest elephants in 83 bais have also revealed that while forest elephant groups differ in size compared to savanna 84 elephant groups, both species exhibit fission-fusion social structure Lee 2013, 85 Schuttler et al 2014b).…”

Abundance, density, and social structure of African forest elephants (Loxodonta cyclotis) in a human-modified landscape in southwestern Gabon

“…Genetic studies have confirmed that individuals in these small groups are usually highly related [7,20,21]. Studies of forest elephants in bais have also revealed that while forest elephant groups differ in size compared to savanna elephant groups, both species exhibit fission-fusion social structure [2,7]. Collectively, these data have furthered our understanding of forest elephant sociality; however, many of these studies have relied on observations of forest elephants in bais.…”

“…Indeed, this last factor limits most behavioral observations of this species to time spent in bais (i.e. forest clearings around a water resource) [2][3][4], although observations have been possible when the elephants occupy coastal or savanna habitats [5][6][7][8]. Studies of African forest elephants are critical given their conservation status and recently documented population declines [9,10], as well as their relevance for understanding the evolution of proboscideans [11,12].…”

“…Direct observation of forest elephants has revealed that social groups are considerably smaller than those of African savanna elephants with groups typically composed of two to three individuals, often mothers and their dependent offspring [5,19]. Genetic studies have confirmed that individuals in these small groups are usually highly related [7,20,21]. Studies of forest elephants in bais have also revealed that while forest elephant groups differ in size compared to savanna elephant groups, both species exhibit fission-fusion social structure [2,7].…”