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McComb K.,University of Sussex | Shannon G.,University of Sussex | Shannon G.,University of KwaZulu - Natal | Durant S.M.,UK Institute of Zoology | And 4 more authors.
Proceedings of the Royal Society B: Biological Sciences | Year: 2011

The value of age is well recognized in human societies, where older individuals often emerge as leaders in tasks requiring specialized knowledge, but what part do such individuals play in other social species? Despite growing interest in how effective leadership might be achieved in animal social systems, the specific role that older leaders may play in decision-making has rarely been experimentally investigated. Here, we use a novel playback paradigm to demonstrate that in African elephants (Loxodonta africana), age affects the ability of matriarchs to make ecologically relevant decisions in a domain critical to survival- the assessment of predatory threat. While groups consistently adjust their defensive behaviour to the greater threat of three roaring lions versus one, families with younger matriarchs typically under-react to roars from male lions despite the severe danger they represent. Sensitivity to this key threat increases with matriarch age and is greatest for the oldest matriarchs, who are likely to have accumulated the most experience. Our study provides the first empirical evidence that individuals within a social group may derive significant benefits from the influence of an older leader because of their enhanced ability to make crucial decisions about predatory threat, generating important insights into selection for longevity in cognitively advanced social mammals. © 2011 The Royal Society.

Shannon G.,University of Sussex | Shannon G.,University of KwaZulu - Natal | Slotow R.,University of KwaZulu - Natal | Durant S.M.,UK Institute of Zoology | And 4 more authors.
Frontiers in Zoology | Year: 2013

Background: Multi-level fission-fusion societies, characteristic of a number of large brained mammal species including some primates, cetaceans and elephants, are among the most complex and cognitively demanding animal social systems. Many free-ranging populations of these highly social mammals already face severe human disturbance, which is set to accelerate with projected anthropogenic environmental change. Despite this, our understanding of how such disruption affects core aspects of social functioning is still very limited. Results: We now use novel playback experiments to assess decision-making abilities integral to operating successfully within complex societies, and provide the first systematic evidence that fundamental social skills may be significantly impaired by anthropogenic disruption. African elephants (Loxodonta africana) that had experienced separation from family members and translocation during culling operations decades previously performed poorly on systematic tests of their social knowledge, failing to distinguish between callers on the basis of social familiarity. Moreover, elephants from the disrupted population showed no evidence of discriminating between callers when age-related cues simulated individuals on an increasing scale of social dominance, in sharp contrast to the undisturbed population where this core social ability was well developed. Conclusions: Key decision-making abilities that are fundamental to living in complex societies could be significantly altered in the long-term through exposure to severely disruptive events (e.g. culling and translocation). There is an assumption that wildlife responds to increasing pressure from human societies only in terms of demography, however our study demonstrates that the effects may be considerably more pervasive. These findings highlight the potential long-term negative consequences of acute social disruption in cognitively advanced species that live in close-knit kin-based societies, and alter our perspective on the health and functioning of populations that have been subjected to anthropogenic disturbance. © 2013 Shannon et al.; licensee BioMed Central Ltd.

Okello M.M.,Center for Wildlife Management Studies | Kioko J.M.,Amboseli Elephant Research Project
Open Conservation Biology Journal | Year: 2010

A majority of large mammals from Amboseli National Park rely on group ranch wildlife dispersal areas for wet season dispersal. However, the contraction of wildlife dispersal areas around Amboseli may be increasing, but the extent is unknown. This study investigated the contraction of wildlife dispersal area by human infrastructure in Olgulului-Ololorashi Group Ranch, which surrounds over 90% of Amboseli Park. Global Positioning System (GPS) was used for location and Geographical Information System (GIS) was used for spatial analysis to determine the area occupied by the structures. The minimum distance of wildlife kept away from institutions was 275 ± 20 m, followed by bomas (214 ± 16m), roads (163 ± 9 m), and livestock (192 ± 12 m). The minimum distance of wildlife from human infrastructure was used as an index of wildlife displacement. All infrastructure occupied an actual area of 66 km2 (5%) of the group ranch. This increased to 281 km2 (23%) with wildlife displacement. Of the area occupied by human infrastructure, fourteen settlement clusters (199 km2, 10.82%) were located. Bomas covered 10% of the group ranch area, followed by institutions (6%), roads (5%), and agriculture (2.13%). The infrastructures were widely distributed in the group ranch and around the Amboseli. Although more dispersal space was available, the spatial distribution of clusters and infrastructure threaten wildlife dispersal. If the obstruction of dispersal routes is not addressed, the group ranch will be compromised as a wildlife dispersal area for Amboseli National Park. © Okello and Kioko; Licensee Bentham Open.

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