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14 - Contest behaviour in ungulates
- Edited by Ian C. W. Hardy, University of Nottingham, Mark Briffa, University of Plymouth
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- Book:
- Animal Contests
- Published online:
- 05 June 2013
- Print publication:
- 30 May 2013, pp 304-320
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- Chapter
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Summary
Summary
This chapter reviews our current understanding of ungulate contest behaviour. Before proceeding to the meat and bones we offer a caveat: following Yeats’ question as to whether we can separate the dancer from the dance, we recognise that no single aggressive action employed by a contestant can be considered independent of all other actions. Nevertheless, for reasons of structure and economy we have presented an overview of the competitive process by portraying contests more as parts of their sum rather than vice versa. The reader should keep this in mind when considering the various sections on display behaviour, contest structure, assessment processes and opponent choice. Many ungulates vocalise and appear to show their body and weapon size to opponents during contests, and so we begin with a review of how ungulates communicate their competitive ability prior to physical confrontation. Following this, we consider factors that might affect how ungulates structure their fights: do body size, resource availability and the level of familiarity between opponents influence contest duration? What assessment processes might be driving the willingness of a competitor to engage in a fight and how might this influence contest structure and subsequent outcome? We conclude with a review of the literature concerning what factors might be involved in mediating the decision for one individual to escalate an interaction with a particular group member to fighting.
Introduction
Ungulates comprise approximately 257 species classified broadly within two different orders, the even-toed (order Artiodactyla) and uneven-toed (order Perissodactyla) ungulates. They represent the majority of large herbivores and, with the exception of the Antarctic, are currently resident in all continental regions. The numerous and diverse members of these orders and their wide geographic distribution is reflected in a complex range of social systems that extend from monogamous pair bonds to a variety of large group polygamous breeding systems. Despite the range and complexity of ungulate societies, competition to secure or defend access to resources is a common feature.
4 - Analysis of animal contest data
- Edited by Ian C. W. Hardy, University of Nottingham, Mark Briffa, University of Plymouth
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- Book:
- Animal Contests
- Published online:
- 05 June 2013
- Print publication:
- 30 May 2013, pp 47-85
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- Chapter
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Summary
Summary
In this chapter we outline and discuss statistical approaches to the analysis of contest data, with an emphasis on testing key predictions and assumptions of the theoretical models described in Chapters 2 and 3. We use examples from an array of animal taxa, including cnidarians, arthropods and chordates, to illustrate these approaches and also the commonality of many key aspects of contest interactions despite the differing life histories and morphologies (including weaponry) of these organisms. We first deal with the analysis of contest outcomes, a useful approach for determining which traits contribute to an individual's resource holding potential (RHP). Here we outline alternative statistical approaches that treat the outcome as either an explanatory (independent) variable or as the response (dependent) variable. In both cases, we treat a single contest as one ‘experimental unit’ and consider ways in which multiple measures taken from the same experimental unit should be accounted for in the analysis. Thus, we introduce paired and repeated measures approaches for contest data and also the calculation of composite measures. We then discuss more complex mixed models, which are particularly useful for dealing with multi-party contests when multiple individuals from the same group occur in more than one observation. Having established what factors influence RHP, one might then ask questions about the roles of information-gathering and decision-making during contests. These questions are prompted by the theoretical models of dyadic contests discussed in Chapters 1 and 2, and we consider the advantages and limitations of using analysis of contest duration to distinguish between ‘mutual-’ and ‘self-assessment’ type contests. An additional tool that we can use to address this question is the analysis of escalation and de-escalation patterns, and we thus shift the focus to within-contest behavioural changes.