History of movement and the dispersal of female southern elephant seals

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One of the most important behaviours shown by an animal, in terms of its survival and

reproductive success, is the selection or attempted selection of the site or sites that it will occupy during the various stages of its life (Caughley 1977; Manley et al. 1993). Accessibility to sites varies among species; many animals have a relatively limited ability to select sites and must rely on chance to place them and their offspring or propagules in a favourable habitat (Matthiopoulos 2003). Other animals, however, have remarkable abilities of movement. This group includes some of the larger vertebrates. Furthermore, some animals among this group are able to travel relatively efficiently for long periods and through media that provide few barriers (Schmidt-Nielsen 1972; Boyd 2002; Gleiss et al. 2011).*
Notable examples here are some species of birds and some species of marine vertebrates, such as various fish, turtles, cetaceans and pinnipeds (Boyd 2002; Gleiss et al. 2011). These animals frequently undertake long migrations between distant sites during the course of their lives. These animals are potentially able to move among a variety of habitats and to select those suitable or most suitable (Dingle 1996; Clobert et al. 2001). The ability to move among habitats is beneficial, because (1) animals change during the course of their lives, with concurrent changes in resource requirements, and (2) accessible environments change, with concurrent changes in the types and levels of resources available.
The selection of a site will depend on a number of factors (Figure 1.1). Among these are the accessibility of that site, the knowledge of its existence, location, and characteristics, and an ability to assess the characteristics of newly encountered sites (Greenwood & Harvey 1982; Manley et al. 1993; Matthiopoulos 2003). Therefore, in addition to an ability to move among sites, in order to survive in its environment, an animal will need to be able to assess the quality of a site, remember the quality of that site, remember the features of the site that will enable it to exploit resources at that site efficiently, and remember features in the vicinity of that site that will aid in locating that site.
During the course of its existence an animal may have built up a body of knowledge of previously visited sites that could aid it in the selection of a site. This knowledge may be modified by information gained concerning the current state of a site in terms of resources and perceived dangers, and the social environment present (Greenwood & Harvey 1982; Manley et al. 1993). Definitions The term dispersal has been used in a variety of ways (see Baker 1978; Dingle 1996; Clobert et al. 2001). I follow a common biological usage (for example Howard 1960; Greenwood 1980; Shields 1987) in defining it as the movement of individual animals from one location to another, where reproduction is attempted.
Reproduction, in this case, being either mating or parturition. Natal dispersal is movement in relation to the natal site, whereas breeding dispersal is movement in relation to a site used for reproduction. Another important definition is philopatry, which is defined as a return by an animal to its natal site to reproduce. A more broadly defined term is site fidelity, which is the return of an animal to any previously used site for any purpose. These definitions broadly follow Howard (1960), Greenwood (1980) and Shields (1987). Finally, history of movement describes the record of the interseasonal movements of an animal that result in a pattern of displacements between seasonally used sites over the course of its life.
History of movement does not refer to finer scale movements of animals on a day-to-day basis, or even within a season (for example Munyai 2006). Consequences of site fidelity and dispersal The fidelity of individual animals to a particular site or population and their dispersal to other sites or populations is important for a number of reasons, and on a number of levels. Firstly, it affects the distribution and size of populations through the colonisation of potential habitat and the rescue of small unviable populations (Matthiopoulos et al. 2005). Secondly, levels of dispersal lead to the movement of genetic material and thus influence the establishment of population genetic structure (Caughley 1977; Gaines & McClenaghan 1980; Lidicker & Caldwell 1982; Matthiopoulos et al. 2005). Thirdly, dispersal may influence individual survival through the levels of resource availability at a particular site and the disease, injury and mortality risks of a particular site (Caughley 1977; Gaines & McClenaghan 1980; Moore & Ali 1984). Finally, it may influence the reproductive success of individuals through the availability of potential mates and resources, and the risks of mortality faced by offspring and the potential resources available to those offspring (Caughley 1977; Beletsky & Orians 1991; Pärt 1994).

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Patterns of dispersal

Patterns of dispersal shown by animals vary among species, and within species among populations, and among age and sex classes (Greenwood 1980; Dobson 1982; Pärt 1991). These patterns of dispersal have been related to life history characteristics and to characteristics of the environment, including resource availability and distribution (Greenwood 1980; Dobson 1982). Immature animals typically disperse farther than adults for a number of possible reasons: 1. their lack of familiarity with their environment, 2. a need to assess their environment through exploration, and 3. they may be unable to compete with older animals (Greenwood 1980; Greenwood & Harvey 1982). Adult animals frequently show an increase in site fidelity as they age (Greenwood & Harvey 1982; Pärt 1995).

TABLE OF CONTENTS :

Abstract
Foreword
Acknowledgements
Table of contents
List of tables
List of Figures

Chapter 1 ▪ Introduction
- Dispersal and the history of movement
- Site selection
- Definitions
- Consequences of site fidelity and dispersal
- Patterns of dispersal
- The study animal – southern elephant seals
- Description
- Life history
- Distribution
- Study site
- Location
- Topography
- Climate
- The study of movement in pinnipeds
- Northern fur seals and Antarctic fur seals
- Other otariids
- Grey seals
- Weddell seals
- Harbour seals
- Other phocids
- Elephant seals
- Aims of the study
- Overview
- Key questions
- Null hypotheses
- Assumptions associated with this study
- References
Chapter 2 ▪ History of movement and the dispersal of female southern elephant seals
- A b s t r a c t
- Introduction
- Methods
- Definition
- Study location
- Fieldwork
- Data editing
- Statistical Approach
- Results
- Site fidelity in relation to a history of haulouts – Moult
- Site fidelity in relation to a history of haulouts – Winter
- Site fidelity in relation to a history of haulouts – Breeding
- Site fidelity and the age of breeding haulouts – First reproductive haulout
- Site fidelity and the age of breeding haulouts – Second reproductive haulout
- Site fidelity and the age of breeding haulouts – Subsequent reproductive haulouts
- Discussion
- Conclusions
- References
Chapter 3 ▪ History of movement and the dispersal of male southern elephant seals
- Abstract
- Introduction
- Methods
- Definition
- Study location
- Fieldwork
- Data editing
- Statistical Approach
- Results
- Moult haulout
- Winter haulout
- Breeding haulout
- Discussion
- Site fidelity of males
- Differences between the sexes
- References
Chapter 4 ▪ Natal site fidelity by breeding female southern elephant seals in relation to their history of participation in the winter haulout
- Abstract
- Introduction
- Methods
- Study site
- Field work
- Data editing and analysis
- Results
- Participation in winter and moult haulouts by immature animals at the study site
- Natal site fidelity and history of winter haulout participation of primiparous females
- Natal site fidelity and history of winter haulout participation of multiparous females
- Natal site fidelity and history of moult haulout participation of primiparous females
- Natal site fidelity and history of moult haulout participation of multiparous females
- Natal site fidelity and history of participation in all haulouts of multiparous females
- Discussion
Chapter 5 ▪ Do elephant seals forget? Loss of familiarity with terrestrial haulout sites over time
- Abstract
- Introduction
- Methods
- Study site
- Fieldwork
- Data editing
- Analysis
- Results
- Discussion
- References
Chapter 6 ▪ Conclusions
- Dispersal, site fidelity and site selection
- Site fidelity and history of movement
- Differences in site fidelity between males and females
- Familiarity with a site and the winter haulout
- Forgetful elephant seals
- A synthesis
- Further avenues for research
- Summary
- Introduction
- Methods
- Results