Detecting changes in elephant body condition in relation to resource quality

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Detecting changes in elephant body

condition in relation to

resource quality

By

Christelle de Klerk

Submitted in fulfillment of the requirements

for the degree of Magister Scientiae in the Faculty of Science

at the

Nelson Mandela Metropolitan University

Supervisor: Prof G.I.H. Kerley

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ACKNOWLEDGEMENTS

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This project was made possible through funding by the National Research Foundation (NRF), a NRF grantholders bursary through Prof. Graham Kerley, and NMMU postgraduate bursary.

I’d like to thank my supervisor, Prof. Graham Kerley, for the opportunity to work on this project. Thank you for all your input, guidance and support throughout, as well as the time spent reading drafts of this document.

I’d also like to thank all the owners, managers and staff of the various game reserves for always being ready to accommodate and assist me with my project. Specifically, I’d like to thank John O’Brien and Bruce Main from Shamwari, Warrick Barnard from Blaauwbosch, Jennifer and Mike Fuller from Kariega, and Richard and Kitty Viljoen from Asante Sana for always welcoming me and going out of their way to make sure I had everything I needed. It was a fantastic experience. I’d also like to thank SANParks for the opportunity to work in the Addo Elephant National Park.

My sincerest thanks to Marietjie Landman and Craig Tambling for assistance with my statistics. I would definitely have been very lost indeed without your help!

I’d also like to thank my two field assistants, Alexander Finger and Francesca Lyndon-Gee, for their company, friendship and help during my field trips. You guys just made the whole experience that much better.

Lastly, I’d like to thank all my friends and family who embarked on this journey with me. Thank you for your understanding, support and encouragement throughout this entire project. I would not have been able to do it without you. A special thank you to my mom, dad and Philip- your continued encouragement, love and belief in me is what got me this far.

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Acknowledgements i Contents ii Abstract v Chapter 1 General introduction 1.1 Introduction 1

1.2 The elephant problem 1

1.3 Elephant life history and population regulation 4

1.4 Caughley’s framework 6

1.5 Body condition as indicator of response 7

1.6 Elephants as herbivores 7

1.7 Measuring diet quality 8

1.8 The elephant problem in the Eastern Cape 8

1.9 Rationale, objectives and research approach 9

Chapter 2

General description of the study sites and populations

2.1 Background and elephants in the Eastern Cape 11

2.2.1 Historic populations and distribution 11

2.2.2 Decline of the elephant 13

2.2.3 Current populations and distribution 14

2.2 Study sites and populations 15

2.2.1 Addo Elephant National Park- Main Camp 15

2.2.1.1 Site description, topography and geology 15

2.2.1.2 Climate 16

2.2.1.3 Vegetation 17

2.2.1.4 Elephant population history 18

2.2.1.5 Elephant diet 18

2.2.2 Addo Elephant National Park- Nyathi Concession Area 19

2.2.2.2 Climate 19

2.2.3 Asante Sana Private Game Reserve 21

2.2.3.2 Climate 22

2.2.4 Shamwari Private Game Reserve 24

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2.2.4.2 Climate 25

2.2.5 Kariega Private Game Reserve 27

2.2.5.2 Climate 28

2.2.6 Blaauwbosch Private Game Reserve 31

2.2.6.2 Climate 31

Chapter 3

Life history variation in body condition

3.1 Introduction 34

3.1.1 Body condition 34

3.1.2 Body condition over lifetime 34

3.1.3 Condition measures 35

3.2 Hypotheses and aims 36

3.3 Materials and methods 37

3.3.1 Selection of life-history groups 37

3.3.2 Data collection 38

3.3.3 Data analysis 40

3.4 Results 40

3.5 Discussion 45

3.5.1 Condition and life stage 45

3.5.2 Condition and season 48

Chapter 4

Site-specific variation on body condition

4.1 Introduction 50

4.1.1 Spatial variation in forage resources 50

4.1.2 Impacts of herbivores on forage resources 50

4.1.3 Effects on body condition 52

4.1.4 Diet quality and its assessment 52

4.1.5 Elephant nutrient requirements 55

4.2 Hypotheses and aims 56

4.3 Materials and methods 56

4.3.1 Choice of sampling method 56

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4.3.3 Sampling procedure 58 4.3.4 Data analysis 59 4.3.4.1 Body condition 59 4.3.4.2 Dietary quality 60 4.4 Results 61 4.4.1 Body condition 61 4.4.2 Dietary quality 74

4.4.2.1 Precision of sample analysis 74

4.4.2.2 Faecal dietary quality 74

4.4.2.3 Plant dietary quality 80

4.5 Discussion 81

4.5.1 Population specific patterns 81

4.5.2 Dietary quality variation 87

Chapter 5

Concluding discussion

5.1 Body condition scores 91

5.2 Responses in body condition 91

5.3 Future Research 94

References 97

Appendix 1 – Sample sizes obtained for the various sites, seasons and

life stage stages 111

Appendix 2 – Results of the log-linear analysis of body condition and

life stage in the Addo Main Camp 112

Appendix 3 – Results of log-linear analysis of body condition for all

sites and seasons 113

Appendix 4 – Results of the multinomial regression model 114

Appendix 5 – Results of the ANOVAs for faecal dietary quality 115

Appendix 6 – Plant dietary quality (protein, phosphorus and NDF) values and results of overlapping plant species and

PDI’s 116

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ABSTRACT

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Elephants, as megaherbivores, are known to have extensive impacts on vegetation, especially in enclosed areas. This raises the issue that elephants in enclosed areas may become limited by resource availability. Resource limitation is generally expressed via density dependence, but elephants, due to their slow demography, may not be affected by initial changes in resource availability. This highlights the need for a more sensitive measure of resource limitation to allow for the detection of energy stress within a population before changes in vital rates occur. This study investigated visual changes in elephant body condition in relation to resource availability in a number of Eastern Cape reserves to assess whether body condition could be used to detect life stages, as well as seasons and sites which may be resource limited. Elephant life stages were divided into energy stressed (newly weaned calves, lactating females, and old females) and non-energy stressed classes (sub-adults and non-lactating females) to determine whether energy stressed life stages were more vulnerable to resource limitation. In the AENP it was found that lactating and old females exhibited significantly poorer body condition than non-energy stressed individuals, but that weaned calves had body conditions similar to non-energy stressed individuals. Comparisons between seasons revealed that all life stages exhibited better condition in winter than summer or spring, with lactating females showing little recovery of condition over time. Seasonal body conditions were correlated with rainfall recorded in the Addo Elephant National Park. Comparisons of elephant body condition between sites (n = 6) revealed that body condition varied across sites, with poorer body condition associated with areas of higher elephant density and low rainfall during the study period. Comparisons with faecal dietary quality data both between sites and seasons indicated that body condition also responded to changes in the availability of protein and neutral detergent fibre (NDF) of plant resources, with higher protein and lower values associated with better condition. Based on condition estimates of elephants occurring in the Addo Main Camp, it was established that this population is experiencing nutritional stress, with energy stressed individuals exhibiting the lowest body conditions. This was supported by dietary quality measures. Our findings suggest that elephant body condition is a good measure for detecting resource limitation, both within populations and between seasons, and that elephant body condition respond to relatively small changes in resource conditions, thus making it an effective measure for the detection of nutritional stress. Additionally, our findings show that energy stressed individuals, particularly lactating and old females are more vulnerable to resource limitation. This demonstrates the importance of monitoring these life stages for the detection of density dependence within populations. Finally, our data suggest that threshold values of faecal dietary quality may exist at which body condition within a population begins to deteriorate, making it possible to determine the condition of a population through values obtained in faecal samples.

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Keywords: Body condition, dietary quality, protein, phosphorus, NDF, life

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CHAPTER 1 GENERAL INTRODUCTION

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1.1 Introduction

One of the major concerns regarding elephant conservation and management is the impact that they have on vegetation in enclosed areas. This issue can be extended to the problem that elephants, both individually and as populations, may become limited by resource availability. In accordance with optimal foraging theory, elephants should consume the highest quality food sources first, switching to lower quality foods as the abundance of the higher quality foods decreased. This would result in them consuming food of declining quality over the years, possibly to the point where sufficient nutrients to maintain condition are no longer available, thereby resulting in a decrease in body condition. This may then extend to reduced fitness, as predicted by density dependence. This project addresses this hypothesis.

1.2 The elephant problem

The concept of the “elephant problem” was first introduced by Caughley (1976a), referring to the trend of elephants transforming forest to open savannah or grassland. The concern was that elephants were destroying trees faster than they could regenerate, thereby altering habitats irreversibly. This concern was based on the idea that ecosystems should be maintained at some balanced state, and that any changes would negatively affect biodiversity. Although the idea of a stable equilibrium in ecosystems has since been replaced with the view that disturbances are essential to the maintenance and generation of biodiversity (Connell 1978), these disturbances must still be assessed to ensure they comply with the general primary objective of biodiversity conservation across a range of organizational levels.

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Due to their large body size, elephant feeding and breakage impact on plants are much more severe than smaller-sized herbivores (Owen-Smith 1988). These impacts can also extend over larger areas than those by other herbivores, and due to their longevity, can occur for much longer time periods (Laws 1970). Although elephants have a relatively low specific metabolic rate and therefore their relative daily dry weight food intake is low, their large size and low digestive efficiency results in them requiring up to 180 kg of wet weight in food on a daily basis (Owen-Smith 1988). In addition to this, elephants are known to be very wasteful feeders, sometimes discarding the equivalent of between a quarter and a half of the mass consumed (Paley 1997; Lessing 2007). They have been recorded to fell and uproot trees with basal diameters of up to 60cm, only to feed on the branch tips or roots, if at all (Chafota 2007).

Their tusks and trunks are well-adapted to feeding and allow them to access plants and plant parts that would otherwise be unavailable to them. They use

their tusks to strip bark from trees, to dig into the trunks of baobabs (Adansonia

digitata) or to dig up roots (Barnes 1982; Lessing 2007). Their trunks allow them

to obtain very high intake rates (up to 2 kg.min-1 in thicket; Lessing 2007) by

enabling them to handle and chew food simultaneously. It also allows them, combined with their shoulder height, to feed up to 8m above the ground (Croze 1974).

Elephants consume a varied diet which includes a range of plants and plant parts, and their feeding is generally presumed to be an important mechanism in

structuring plant communities (Laws 1970; Stuart-Hill 1992; Trollope et al. 1998;

Lombard et al. 2001). This emphasises the importance of understanding

elephant diets and dietary preferences. Numerous incidences of elephant-induced vegetative changes have been recorded in both savannah and thicket

ecosystems (Savidge 1968; Laws 1970; Penzhorn et al. 1974; Barratt &

Hall-Martin 1991; Barnes et al. 1994). They are also known to severely impact the

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Barratt & Hall-Martin 1991). Their impact on plant communities are not only a matter of food requirements, however, as these do not account for their wasteful feeding or their indirect impact on non-browsed species through trampling and path formation (Landman et al. 2008).

In addition to their effects on plant communities, elephants also impact individual plant and animal species. Elephants are the only herbivores capable of killing adult baobab trees and have been linked to the decline in their numbers

(Swanepoel 1993; Barnes et al. 1994). They also have been linked to the decline

of several Acacia species (Van Wyk & Fairrall 1969; Pellew 1983; Barnes 2001),

marula trees (Sclerocarya birrea) (Jacobs & Biggs 2002), Aloe africana

(Penzhorn et al. 1974), mistletoes (Magobiyane 2006) and geophytes and dwarf

succulent shrubs in thicket (Moolman & Cowling 1994). In addition, they negatively impact a wide range of animal species including rhino (Kerley &

Landman 2006), ants, birds, bats (Cumming et al. 1997) and ungulates

(Owen-Smith 1988; Fritz et al. 2002).

The degree to which elephants impact their environment is a function of their movement and density. Elephants do not use the landscape in a uniform fashion, thereby varying their impacts across the landscape and creating heterogeneous

patterns of biodiversity (Owen-Smith et al. 2006). Movement, and thus impacts

across the landscape is determined by topographic relief (Wall et al. 2006), the

utilization of different vegetation types (Guldemond & Van Aarde 2007), as well as the distribution of surface water (Laws 1970; Owen-Smith 1996). Higher densities are also associated with more rapid rates of biodiversity loss and

habitat degradation (Laws 1970; Cumming et al. 1997).

Elephants are often confined to relatively small conservation areas. This further amplifies their effect on the environment, as it does not allow for their impacts to be distributed through space and time, thereby hampering vegetation recovery

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species (O’Connor et al. 2007). Additionally, the lack of space for range expansion often results in the formation of larger family groups, creating very high local densities with subsequent catastrophic effects on the resource base (Laws 1970).

The nature of their diet, their large size and food requirements, feeding behaviour and adaptations, as well as their movement patterns thus allow elephants to influence various aspects of their environment in a unique way. Their impacts on populations and species subsequently affect ecosystem patterns and processes, such as nutrient cycling, soil resources, vegetation structure and dynamics (Hatton & Smart 1984; Owen-Smith 1988; Kerley et al. 1999; Cowling & Kerley

2002; Skarpe et al. 2004; Lessing 2007), and ultimately influence biodiversity

(Van Wyk & Fairall 1969; Penzhorn et al. 1974; Barratt & Hall-Martin 1991;

Moolman & Cowling 1994; Lombard et al. 2001; Kerley & Landman 2006). This

demonstrates the vital importance of understanding elephant populations in order to manage them.

1.3 Elephant life history and population regulation

Elephant are characteristic of long-lived (K-selected) species with a low intrinsic rate of increase, low reproductive rates, low mortality and low rates of population turnover (Laws 1981). The mean age of first reproduction in South Africa averages 11.3 years, with females reaching sexual maturity from the age of

seven onwards (Van Aarde et al. 2007). Gestation lasts for 22 months, with a

mean intercalving interval of 3.6 years in South Africa (Van Aarde et al. 2007).

Females may remain reproductively active well into their 50’s (Whitehouse & Hall-Martin 2000) with life expectancies of over 60 years (Van Aarde et al. 2007). There is a high level of maternal investment and survival rates are generally high

among all age classes (Van Aarde et al. 2007).

Large mammal population regulation generally occurs via one of two mechanisms- either through resource limitation (bottom-up) (Fowler 1987) or

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predation (top-down) (Messier 1994). Predation works via the direct reduction of population size through the killing of individuals. Due to their large size, however, elephants have few predators, and it thus unlikely that predation plays an

important role in population regulation (Van Aarde et al. 2007). Resource

limitation, on the other hand, works via density dependence where, as population size increases, the availability of resources declines (Klein 1968; Sinclair 1974; Owen-Smith 2002). As resources become limiting, population growth is slowed due to changes in vital rates. According to Fowler (1987) vital rates have different sensitivities to changes in population density, with an increase in juvenile mortality usually being the first response, followed by an increase in the age at first reproduction, an increase in the intercalving interval and finally an increase in the mortality rate of adults. This is supported by Eberhardt (2002), who found similar sensitivities in vital rate responses. For large mammal populations, these changes occur at densities close to the carrying capacity (Fowler 1981) and have

been demonstrated in numerous studies (Buss & Savidge 1966; Laws & Parker

1968; Laws 1969; Corfield 1973; Hanks & McIntosh 1973; Sinclair 1974;

Clutton-Brock et al. 1983). Such density dependent effects are also often exacerbated by

the heterogeneous distribution of resources through space and time (Chamaillé-Jammes et al. 2008).

It has been suggested that, in open systems, elephant populations may respond to increased density and food limitation primarily through dispersal, with changes

in reproduction and survival rates occurring more slowly (Chamaillé-Jammes et

al. 2008). However, reserve sizes in South Africa preclude the possibility of

dispersal as a mechanism of response. Additionally, although some evidence in

support of density dependence in Kruger has been found (Van Aarde et al. 1999),

Van Jaarsveld et al. (1999) found no evidence of density dependence on

population growth in 5 recovering populations in South Africa based on survival rates. This is supported by Gough & Kerley (2006), who found no evidence of density dependence at the population level in the Addo Elephant National Park (AENP), even at densities far exceeding the suggested carrying capacity.

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This raises the issue that elephants are able to impact and alter their environments with seemingly no ill effect on their own current wellbeing and survival, and highlights the need to investigate elephant populations more closely in order to detect small, but critical responses to resource limitation. This is especially true for populations in which other methods of control, i.e. culling, contraception or translocation, are not possible.

1.4 Caughley’s framework

According to Caughley’s (Caughley 1976b) plant-herbivore framework, an interferential model would best explain the interactions between elephants and their environment (Fig. 1.1).

Fig. 1.1 A graphical representation of Caughley’s interferential plant-herbivore framework.

It suggests that elephants, through their nature as large herbivores, would have an impact on their plant resource base, and that this impact would also affect other associated herbivores and biodiversity (as has been illustrated by numerous cited studies above). Through increased density and impact on their resources, there should then also be an effect of plants on elephants through resource limitation. One such way in which interaction would become apparent is through density dependent effects on population performance. As has been

Associated herbivores/

biodiversity

Interferential

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noted above, however, little evidence of such processes has as yet been documented in elephant populations.

1.5 Body condition as indicator of response

Another way in which resource limitation could be detected is by monitoring changes in the body condition of individuals within a population. As resource availability and/or quality declines beyond the level of maintenance requirements there should be an associated decline in the body condition of the individuals. This is based on one of the characteristics of inanition, whereby an animal tends to become thin as it drops in condition (Harris 1945; Riney 1960; Hanks 1981). By monitoring body condition over time it may be possible to detect periods, populations or segments of populations that are resource limited. This will allow for the identification of opportunities when management interventions may most effectively influence demographics.

1.6 Elephants as herbivores

Elephants are classified as large, generalist mixed feeders, consuming different proportions of browse and graze according to their availability (Owen-Smith 1988;

Ulrey et al. 1997; Codron et al. 2006). They are hindgut fermenters, and as such

make use of a large caecum inhabited by microorganisms to digest plant fibre (Ulrey et al. 1997). They have a rapid gut transit time (~24hrs; Clauss et al. 2007), and dry matter (DM) digestibility in free-ranging elephants has been estimated to

be 30-45% (Meissner et al. 1990), with an adult daily dry matter intake

requirement of 1-1.5% of body weight (Ulrey et al. 1997). The natural diet is

characterized by a very high fibre content, with a neutral detergent fibre (NDF) content of 50-70% DM, and a crude protein content of 6-12% DM (McCullagh 1969b; Meissner et al. 1990; Hatt & Clauss 2006), although calculations by Ulrey et al. (1997) based on extrapolations from nutrient requirements of horses estimated crude protein requirements of up to 14% for lactating females and growing juveniles.

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Due to their gut morphology they are able to ingest large amounts of fibre without slowing the throughput (Janis 1976) and this, combined with their rapid gut transit time and large size (and thus low specific metabolic rate), enables elephants to persist on a very low-quality diet (Demment & Van Soest 1985; Owen-Smith

1988; Duncan et al. 1990). As generalists they feed on a large variety of plant

species. A study in the AENP found 143 species included in their diet, five times more than coexisting ruminant browsers (Kerley & Landman 2006). This enables them to affect more plant species than any other mammal herbivore in the Eastern Cape thickets (Kerley & Landman 2006).

1.7 Measuring diet quality

Although various other methods for the determination of diet quality exist, faecal analysis has proven to be the most practical for the study of wild herbivores as it is non-invasive and samples are easy to collect (Leslie & Starkey 1985). Faecal samples are also representative of the diet consumed within the last day or two (taking into consideration gut-transit times), allowing it to be used to assess diet over time (Rees 1982). Diet quality is generally related to the amount of nitrogen (i.e. protein), fibre and minerals (e.g. phosphorus, calcium) present in forage, and studies have shown that values obtained in faecal samples are correlated with

those found in the diet (Moir 1966; Leslie & Starkey 1987; Ulrey et al. 1997).

Faecal analysis is therefore an easy and effective way of determining the diet quality of elephants.

1.8 The elephant problem in the Eastern Cape

Despite the fact that the Addo elephant population density has more than doubled since the fencing of the park and resource availability is seriously declining (Kerley & Landman 2006), the elephant population continues to grow at a mean rate of 5.8% per annum (Gough & Kerley 2007). This is thought to be due to the nutritious, evergreen, drought-resistant nature of the thicket vegetation which dominates the Eastern Cape (Everard 1987; Seydack & Bigalke 1992;

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Stuart-Hill & Aucamp 1993). It has been predicted that the Addo elephant population will continue to increase at a high rate at the expense of biodiversity until such a point at which they irreversibly damage the accumulated resource base (Gough & Kerley 2007).

The Addo elephant population is the longest established and best studied in the Eastern Cape, and as such provides a good benchmark for the management of other, more newly established populations within the province. Although these other populations are presently still limited in size, they have the ability to increase in the future (Kerley 2006). Their occurrence at various densities and in areas differing in productivity provides me with an excellent opportunity to investigate the effects of seasonal and site-specific changes in resource quality on the body condition of elephants in both energetically and non-energetically constrained life stages.

1.9 Rationale, objectives and research approach

The use of body condition indices may be a powerful approach to detecting dietary resource limitation in elephants. This is particularly relevant in a species of such large body size and slow demographic responses to environmental perturbations. These body condition responses may reflect life-history, seasonal and site specific foraging and resource constraints. This project therefore sets out to address the following objectives:

1. Determine whether energetically constrained elephant life stages (i.e. weaning, lactation and loss of tooth function) are more vulnerable to resource limitations compared to non-energetically constrained life stages (i.e. sub-adults and non-lactating females) in order to identify critical periods of elephant life history.

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2. Determine how seasonal changes in the quality and availability of resources affect elephant body condition in order to identify critical periods of resource limitation.

3. Determine how site differences in productivity and elephant density affect elephant body condition in order to identify populations that may be resource limited.

The research approach was to use the well-studied Addo elephant population to identify life stage variation in body condition, and to use this and other Eastern Cape populations to assess seasonal and site specific body condition responses of elephant.

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CHAPTER 2 GENERAL DESCRIPTION OF THE STUDY SITES AND

POPULATIONS

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2.1 Background and elephants in the Eastern Cape

2.2.1 Historic populations and distribution

The presence of elephants in the broader Eastern Cape region is well documented over the last few centuries, with archaeological discoveries providing evidence of their occurrence within the province up to 1000 years before present (Plug & Badenhorst 2001). These discoveries are supported by more recent (during the last 100 years) evidence, consisting mostly of bone material, some rock paintings and sightings, and the extensive hunting records of the occurrence of elephants within the thicket and thicket-associated habitats in

the Eastern Cape (Boshoff et al. 2002a; Skead 2007).

Fig. 2.1 Map illustrating the historic distribution of elephants in the broader Eastern Cape region (from Skead 2007).

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The first written records of elephants for most parts of the region date from the late 1700’s when ivory became a valuable commodity in great demand in Europe, causing elephant hunting to increase in popularity. From all the available records it would appear that elephants were once widespread throughout the Eastern Cape (Fig. 2.1) occurring in the Thicket, Forest, Grassland and Savanna biomes, and on a patchy basis in the Fynbos and Nama-Karroo biomes (Hall-Martin 1992; Skead 2007), and that numbers in the order of 100 000 animals is likely to have been present before 1652 (Hall-Martin 1992).

Fig. 2.2 Map illustrating the three zones of density distribution of elephants in the Eastern Cape region (from Boshoff et al. 2002a).

Most accounts of high elephant densities are from areas of thicket. Thicket was also the dominant vegetation type, comprised of evergreen trees and shrubs high in nutrients (Boshoff et al. 2002a). This was found to be especially true for the coastal and mesic succulent thicket, and where these thickets formed mosaics with forest and savanna vegetation- conditions that were prevalent along the coastal belt. A reconstruction of relative elephant densities, status and habitat

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types for the Eastern Cape was mapped by Boshoff et al. (2002a), indicating the three likely zones of elephant occurrence in the broader Eastern Cape, with high densities of resident populations occurring along the coastal belt, lower densities of mostly migrant and nomadic populations occurring in the sub-coastal belt, and very low densities or absence in the inland zone (Fig. 2.2).

2.2.2 Decline of the elephant

The near demise of the Eastern Cape elephants was indisputably caused by the arrival of European settlers, as the San, the Khoi and the Bantu-speaking people only utilized elephants at very low levels (Boshoff et al. 2002a). The first group of European hunters arrived in Algoa Bay in 1702 in search of ivory, and by the mid

1700’s hunting activity had spread as far east as Pondoland (Boshoff et al.

2002a). By the late 1700’s and early 1800’s hunting had all but destroyed the populations in the Peddie-King William’s Town area, and by the mid 1800’s

elephants were “rarely seen” in the Albany and Bathurst districts (Boshoff et al.

2002a). Ivory markets were established at various locations in the early to mid 1800’s, and large amounts of ivory were exported from Port Elizabeth (Hall-Martin 1992).

By 1850 the Addo and Zuurberg populations had been significantly reduced, and elephants were no longer found in the areas of the Great Kei and Great Fish

rivers (Boshoff et al. 2002a). The last of the elephants in the Bathurst district

were shot during the first decade of the 20th century, and the last known account

of elephants in western Pondoland was in 1860 (Boshoff et al. 2002a). The

remaining Addo elephants (about 130) were directly persecuted in 1919 when Major P.J. Pretorius was hired by the government to eradicate the herd, as they were in conflict with local farmers and human settlements (Hoffman 1993). He proceeded to kill about 120 individuals between June 1919 and July 1920, sparing only 16 individuals. By the time the Addo Elephant National Park (AENP) was proclaimed in 1931, the Addo population had declined to 12 individuals (Whitehouse & Hall-Martin 2000). Of these, 11 individuals went on to form the

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founding population, representing the sum total of elephants in the Eastern Cape at that time (Hall-Martin 1992; Whitehouse & Hall-Martin 2000).

2.2.3 Current populations and distribution

Since the establishment of the AENP the presence of elephants in the Eastern Cape has changed significantly. The Addo population has flourished, with the construction of elephant-proof Armstrong fencing in 1954 (Whitehouse 2000), several expansions of the park and maintenance of perennial water sources allowing the population to increase to its current number of 415 as at 30 November 2008 (K. Gough, pers. comm.). Additionally, with the development of technology to translocate elephants over long distances, new populations were established in the Eastern Cape. The first of these was in Shamwari Private Game Reserve in 1992, followed by a small population in the Double Drift Game Reserve in 1995, and two more populations in Kwandwe Private Game Reserve

and Bayethe Private Game Reserve in 2001 (Hall-Martin et al. 2002). Since then,

these populations have grown in size and more populations have been established across the Eastern Cape, with population sizes ranging from 3 to 415 individuals (Fig. 2.2).

Fig. 2.2 The rate of establishment of elephant populations in the Eastern Cape over the last 15 years (from Kerley 2006).

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Six of these populations were used in the current study (Fig. 2.4).

Fig. 2.4 Map showing the locations of the six study sites (ArcGIS 9.2; map units: decimal degrees; not projected).

2.2 Study sites and populations

2.2.1 Addo Elephant National Park- Main Camp

2.2.1.1 Site description, topography and geology

The Addo Main Camp (AMC) is located at 33°31’S, 25°24’E, approximately 60

km north east of Port Elizabeth, south of the R342 road from Paterson to

Kirkwood (Fig. 2.4). It spans an area of 103 km2, and forms part of the Addo

Elephant National Park (AENP). The topography of the AMC is characterized by a series of valleys and gently undulating ridges, which rise from 71 m.a.s.l. to 354 m.a.s.l. (Paley & Kerley 1998), with the Zuurberg limestone plateau dominating the eastern edge of the AMC (Barratt & Hall-Martin 1991).The dominant substrate on which the AMC lies is sandstone and mudstone from the Uitenhage

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Series, which is covered by a layer of red-brown granular clay loam soil rich in humus (Archibald 1955). The soils formed are neutral, fine-grained and relatively fertile (Hoffman 1989). The Zuurkop plateau is covered by grey calcrete and red-brown aeolian sands (Toerien 1972; Barratt & Hall-Martin 1991). A number of small, natural pans and waterholes are scattered throughout the park, although these only hold water for short periods after rain. Permanent water is supplied by means of three artificial water holes and two dams.

2.2.1.2 Climate

The AMC is located within the semi-arid region of South Africa, with a mean annual rainfall of 396 mm recorded between 1961 and 1990 at the Citrus Research Station, approximately 3 km south-west of the AMC (SA Weather Service 2008). Rainfall occurs throughout the year and is mostly associated with post-frontal events (Hoffman 1989), with peaks in late summer (February-March) and spring (October-November) (Fig. 2.5). Prolonged droughts occur on a regular basis (Barratt & Hall-Martin 1991).

0 5 10 15 20 25 30 35 40 45 50 J F M A M J J A S O N D Months R a in fa ll ( m m )

Fig. 2.5 Average monthly rainfall recorded at the Citrus Research Station for the period 1961-1990.

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Mean maximum temperatures range from c. 29°C in the summer to c. 22°C in the winter, although temperatures in excess of 40°C are often recorded in summer (Stuart-Hill 1992).

Fig. 2.6 Map of the Addo Main Camp depicting the five main vegetation types (ArcGIS 9.2; map units: decimal degrees; not projected, Mucina & Rutherford 2006). See Fig. 2.4 for location.

2.2.1.3 Vegetation

The AMC vegetation is classified as Xeric Succulent Thicket, which in its undisturbed state is characterized by a dense tangle of succulent and spinescent shrubs and lianas reaching 2-4 m (Paley & Kerley 1998; Henley 2001). Sundays

Thicket, dominated by Spekboom (Portulacaria afra), covers more than 66% of

the AMC (Fig. 2.6). Coega Bonteveld, consisting of a mosaic of low thicket with secondary open grassland, Albany Coastal Belt, dominated by short grassland with scattered bush clumps, and some Albany Alluvial Vegetation and Kowie Thicket is also present (Mucina & Rutherford 2006). Dominant shrubs and low

trees include Azima tetracantha, Capparis sepiaria, Carissa haematocarpa,

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incidence of Cynodon dactylon and Platythyra haeckeliana in the grassland

dominated areas (Landman et al. 2007).

2.2.1.4 Elephant population history

The establishment of the AENP in 1931 allowed for the allocation of 22.7 km2 for

the conservation of the 12 remaining elephants, although one was killed when the animals were herded into the park area, leaving a founder population of 11 (Whitehouse & Hall-Martin 2000). This number increased very slowly to 22 elephants in 1954, at which time elephant-proof fencing was introduced (Whitehouse & Hall-Martin 2000). After 1954 the population grew at an exponential rate, reaching 284 individuals in 1998 (Whitehouse & Hall-Martin 2000), and currently numbering 415 (K. Gough, pers. comm.). During this time there have been five expansions of the AMC, as well as the translocation of 4 Kruger bulls into the camp in 2002, and 63 individuals out to the Nyathi Concession Area (NCA) in 2003, with corresponding changes in elephant density (Gough & Kerley 2006). For most of the history of the park, the elephant density

has remained well above the 2 elephants/km2 estimated ecological carrying

capacity for subtropical thicket vegetation (Barratt & Hall-Martin 1991; Novellie et al. 1996), as well as the 0.54 elephants/km2 calculated by Boshoff et al. (2002b).

The current density stands at 4.03 elephants/km2 (K.Gough, pers. comm.).

2.2.1.5 Elephant diet

The most recent elephant dietary study was conducted by Landman et al. (2007).

From this 13 Principal dietary items (PDI- species contributing 3% or more to the diet) were identified, which made up 66.5% of the total diet. Of these, 7 species

contributed more than 3% each, namely Cynodon dactylon (19.6%), Portulacaria

afra (9.3%), Carissa haematocarpa (6.1%), Panicum deustum (4.5%), Azima tetracantha (4.4%), Schotia afra (3.4%) and Eragrostis obtusa (3.2%).

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2.2.2 Addo Elephant National Park- Nyathi Concession Area

The Nyathi Concession Area (NCA) is located to the north of the Addo Main Camp and also forms part of the AENP (Fig. 2.4). It lies in the Coerney River

Valley, spanning an area of approximately 114 km2, and includes the southern

slopes of the Zuurberg Mountains (Davis 2005). For this reason, the terrain is more rugged and mountainous than the AMC. The geology of the Zuurberg Mountains is dominated by sandstones and quartzites of the Tafelberg and Witteberg Series (Mucina & Rutherford 2006), with the south being dominated by mudstones and shales of the Uitenhage group. Sandy soils dominate the northern section of the park, with red loamy to clayey soils found throughout most of the rest of the park (Mucina & Rutherford 2006). Water is supplied by the Courney River, which runs in a south-westerly direction, as well as two artificial dams and a couple of natural pans within the concession area.

2.2.2.2 Climate

The NCA also falls within the semi-arid region, with temperatures similar to the Addo Main Camp, but is thought to receive more rainfall on average than the AMC due to orographic effects (Davis 2005).

According to Mucina & Rutherford (2006) the vegetation of the NCA is dominated by Sundays and Kowie Thicket, with Albany Alluvial Vegetation in the south. The Zuurberg Mountain in the north is covered by a small section of Southern Mistbelt Forest and Zuurberg Fynbos, characterized by grassy fynbos on the quartzite dominated soils and closed ericoid shrubland/grassland on the shale dominated soils (Fig. 2.7, Mucina & Rutherford 2006). The Sundays Thicket is predominantly found on the low mountains and foothills, and is characteristically tall and dense with many trees and shrubs (Mucina & Rutherford 2006). Succulents and spinescent species, as well as a variety of lianas are common (Mucina & Rutherford 2006). Kowie Thicket is found mainly on the drier,

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north-facing slopes and is dominated by succulent euphorbias and aloes with a thick understory of thorny shrubs, woody lianas and shrubby succulents (Mucina & Rutherford 2006).

Important plants include Schotia afra, Cussonia spicata, Euclea undulata, Olea

europaea, Azima tetracantha, Portulacaria afra, various Viscum and asparagus species, as well as numerous woody succulent and woody climbers (Mucina &

Rutherford 2006). Dominant grasses include Cynodon dactylon, Eragrostis

obtusa, Panicum maximum and P. deustum (Mucina & Rutherford 2006). A large

number of herbs, succulent herbs and geophytes are also present.

Fig. 2.7 Vegetation map of the Nyathi Concession Area showing the six main vegetation types (ArcGIS 9.2; map units: decimal degrees; not projected, Mucina & Rutherford 2006). See Fig. 2.4 for location.

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The NCA was first stocked with elephants from the Addo Main Camp in May 2003, when 63 individuals were moved across the R342 Paterson to Kirkwood

road and fenced in (K.Gough, pers. comm.). The group consisted of 17 mature

females, nine sub-adult females, one sub-adult male, 20 calves, and 15 mature bulls. An additional four males were introduced into the park from Kruger in 2003, but one subsequently died in 2004. At the time of stocking the density was 0.45

elephants/km2. Before this, elephants had been absent from the NCA for more

than 50 years (Davis 2005). Since then the population has grown to 88 (K.

Gough, pers. comm.) and a density of 0.77elephants/km2.

According to Davis (2005), eight plant species were found to make up the

principal dietary items (PDI) of the elephants in the NCA, and included Azima

tetracantha, Cynodon dactylon, Panicum deustum, Cussonia spicata, Viscum sp., Rhiocissus digitata, Schotia afra and a category made up herbaceous plants which could not be identified to the genus level.

2.2.3 Asante Sana Private Game Reserve

Asante Sana Private Game Reserve (ASPGR) is located at 32° 18’ S, 24° 58’ E, approximately 40 km east of Graaff-Reinet in the basin of the Sneeuberg

Mountains (Fig. 2.4). It spans an area of 108 km2, and includes mountains

reaching up to 2 100 m.a.s.l. with slopes of varying steepness, as well as the basin floor, lying at approximately 1000 m.a.s.l. (Boshoff & Kerley 1997). The geology consists of the Beaufort Group of the Karroo Sequence, with greenish grey and red mudstones and sandstones of the Middleton formation overlain by greenish grey and red mudstones and shales and sandstone of the Balfour formation, with dolerite sills of varying thickness intruding the Balfour Formation (Boshoff & Kerley 1997). The basin floor consists mainly of alluvial soils, which are thought to be important from an agricultural point of view (Hill 1993 as cited

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by Boshoff & Kerley 1997). These are dominated by loamy sand to loamy duplex type soils, with high amounts of potassium, copper and boron, and low levels of zinc (Boshoff & Kerley 1997).

2.2.3.2 Climate

ASPGR occurs in a region where most rainfall is received in the summer months

(October – March) (Venter et al. 1986). The mean annual rainfall recorded for the

closest town, Graaff Reinet was 361 mm for the period 1961-1990 (Fig. 2.8, SA Weather Service 2008). It is thought that the rainfall on the higher slopes of the reserve should fall within the 600-700+ mm range (Boshoff & Kerley 1997). Extended periods of drought are often experienced in this region, however, this is partially alleviated by infrequent winter rains and run-off from melting snow (Boshoff & Kerley 1997).

0 10 20 30 40 50 60 70 J F M A M J J A S O N D Month R a in fa ll ( mm)

Fig. 2.8 Average monthly rainfall recorded at Graaff Reinet for the period 1961-1990.

The mean annual temperature ranges between 15 and 17.5°C, although temperature extremes are experienced both in summer (< 30°C) and winter

(>0°C) (Venter et al. 1986). Frost is occasionally recorded (mean annual

frequency of 5 days) on the basin floor and valley bottoms (Boshoff & Kerley 1997).

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According to Mucina & Rutherford (2006) two vegetation types can be discerned in Asante Sana, namely Camdeboo Escarpment Thicket and Karoo Escarpment Grassland (Fig. 2.9).

Fig. 2.9 Vegetation map of Asante Sana illustrating the two main habitat types (ArcGIS 9.2; map units: decimal degrees; not projected, Mucina & Rutherford 2006). See Fig. 2.4 for location.

Merxmuellera disticha and Themeda triandra dominate the grassland, whilst the

Escarpment Thicket is dominated by Acacia karroo, Celtis africana and Grewia

robusta (Mucina & Rutherford 2006). Pentzia incana, Pentzia spinescence and Eriocephalus ericoides dominate the Karroid Dwarf Shrubland, whilst the

dominant species in the Riverine Thicket include Acacia karroo, Rhus lancea and

Cynodon dactylon (Boshoff & Kerley 1997), with Portulacaria afra, a characteristic of this vegetation type, only occurring sparsely.

After an initial study by Boshoff & Kerley (1997) to investigate the suitability of the area to elephants, a small family group of nine elephants was translocated to the

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area from Sabi-Sands Private Game Reserve in 2004. The group consisted of three mature females, four sub-adult females, as well as two calves (both about two years old). Shortly after translocation one of the sub-adult females as well as a male calf died. A calf was born on the reserve in June 2004, followed by another calf in January 2005 to bring the population back up to nine individuals. Due to the lack of a sexually mature bull in the group and the unchanged reserve size, the population size and density, has remained constant at 0.083 elephants/km2.

According to a dietary study by Minnie (2006), 66 species make up the elephant diet in the ASPGR, with 17 species being identified as PDI. These PDI were

dominated by three species, namely Acacia karroo (24.7%), Cynodon dactylon

(8.5%) and Grewia robusta (8.3%), contributing 42.7% to the total diet.

2.2.4 Shamwari Private Game Reserve

Shamwari is located at 33°20’S, 26°01’E, along the N2 national road to Port Elizabeth, approximately 11 km east of Paterson (Fig. 2.4). It spans an area of

approximately 200 km2, of which 180 km2 is available to elephants. It is

characterized by a series of undulating hills ranging from 196 m.a.s.l. in the south to 628 m.a.s.l. in the north. According to O’Brien (2004), the main geological formations found in Shamwari include Bokkeveld Series Shale, Witteberg Quartzites, Karroo Sandstone and Sundays River Formations. Because of the steep elevation gradient four main substrate types are exposed and available to plant communities, namely shale, sandstone, quartzite and calcrete. Some deeper alluvial soils also occur on the lower lying land (O’Brien 2004). Water is supplied by the semi-perennial Bushman’s River, which flows through the reserve, as well as numerous other pans and dams scattered throughout the reserve.

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2.2.4.2 Climate

Shamwari falls between the summer and winter rainfall areas of the Eastern Cape and thus receives rainfall throughout the year (Fig. 2.10), with peaks in March (63.3 mm), August (63.5) and November (58 mm). Annual precipitation for the period 1999 to 2007 averaged 550 mm (Shamwari rainfall records).

0 10 20 30 40 50 60 70 J F M A M J J A S O N D Month R a in fa ll ( m m )

Fig. 2.10 Average monthly rainfall recorded at Shamwari for the period 1999-2007.

Temperature data for Shamwari, or the nearest town, Paterson, were not available, and therefore temperature data from Addo (approximately 40 km south-west of Shamwari) were used. As indicated above (AMC section) the mean

maximum temperatures ranged from approximately 29°C in summer to

approximately 22°C in winter, although temperatures in excess of 40°C are often

recorded in summer (Stuart-Hill 1992).

Shamwari encompasses 5 vegetation types, including Kowie Thicket, Bisho Thornveld, Suurberg Quartzite Fynbos, Albany Coastal Belt and Suurberg Shale Fynbos, with Kowie Thicket being the dominant vegetation type (Fig. 2.11; Mucina & Rutherford 2006). A study done by O’Brien (2004) identified a further 8 vegetation types, including Grassland, Bushclump Savanna and Riverine Thicket.

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Fig. 2.11 Vegetation map of Shamwari depicting the five major vegetation types (ArcGIS 9.2; map units: decimal degrees; not projected, Mucina & Rutherford 2006). See Fig. 2.4 for location.

According to O’Brien (2004) the thicket is characterized by a dense tangle of evergreen succulent and woody shrubs and trees dominated by species such as Schotia afra, Carissa bispinosa, Cussonia spicata, Pappea capensis, Euclea undulata, Aloe africana, A. ferox, and Portulacaria afra. The grasslands are

dominated by Themeda triandra, Heteropogon contortus and Eragrostis curvula,

while species such as Pennisetum clandestinum, Cenchrus ciliarus and Cynodon

dactylon can be found on the old farm lands. The composition of woody species is similar in the bushclump savanna as in the subtropical thicket, with

bushclumps being interspersed with grasses such as Digitaria eriantha, Setaria

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(O’Brien 2004). The Albany coastal belt includes species such as Erythrina caffra, Euphorbia triangularis, Grewia occidentalis and Rhus lucida, whilst the fynbos areas support ericoid shrubland and grassland species (Mucina & Rutherford 2006).

According to O’Brien (2002) the first elephants were introduced between 1992 and 1993, when 14 orphans were translocated from the Kruger National Park, consisting of seven males and seven females. An additional group of eight orphans were introduced from Mpongo Park in East London in 1994, comprising four males and four females. In 1997 a family herd of nine elephants were reintroduced, with only seven surviving (two males and five females). Two females were subsequently brought from Knysna in 1999. In 2003, 13 individuals were relocated to Bushman Sands Game Reserve and Sanbona Wildlife Centre, and two adult bulls were euthanased. Between 2003 and 2008 another 25 individuals were translocated out of the park, six to Sanbona Wildlife Centre, five to Mpongo Parks, three to Kamala Game Reserve, six to Bushman Sands Game Reserve and five to Rippons Game Reserve. The current population stands at 47 individuals and a density of 0.26 elephants/km2.

According to Roux (2006) the elephant diet in Shamwari consists of 23 species

from 19 families, with the bulk of the diet made up of Acacia karroo (36%), Rhus

spp. (11%), Opuntia ficus-indica (10%), Azima tetracantha (9%), Gymnosporia

spp. (6%), Pappea capensis (3%), Schotia afra (3%) and Combretum caffrum

(3%).

2.2.5 Kariega Private Game Reserve

Kariega is located in the Kariega River Valley (Fig. 2.4), along the R343 regional road, approximately 45 km south of Grahamstown (33°35’S, 26°37’E). It spans

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an area of 190 km2 and ranges from an altitude of 23 m.a.s.l. at the base of the Kariega River Valley to 262 m.a.s.l. at the northwest corner of the reserve. The northern half of the reserve is located on a plateau situated above the Kariega River Valley, with the southern half consisting of undulating hills in the west and flat, low-lying ground in the east. The principal geological formations of the reserve include Beaufort Group shale, mudstone, solonetic soils and sandstone, and Cape Supergroup sandy clays and lithosoils (Low & Rebelo 1996). Apart from several small dams, water in the park is mainly supplied by the perennial Kariega River, which runs through the park for 11 km.

2.2.5.2 Climate

Kariega falls within the spring-dominated rainfall area of the Eastern Cape, but has a pronounced bi-modal rainfall pattern (March-April and

November-December) (Stone et al. 1998). The average annual precipitation for the closest

town for which data were available, Port Alfred, for the period 1936 to 2003 was 640 mm (Fig. 2.12; SA Weather Service 2008). Its close proximity to the coast results in Kariega having a slightly higher average rainfall than other reserves in the Eastern Cape due to coastal fog, where moist air from the sea moves over the cold land surface (Stone et al. 1998).

Kariega’s close proximity to the coast also results in it being affected by land and sea breezes in the late afternoons/evenings, caused by differential heating and

cooling of the land and sea (Stone et al.1998). These breezes moderate the

temperatures by decreasing day time temperatures and increasing night time temperatures, thereby also decreasing the amount of frost exposure in the reserve. Temperature data were not available for Kariega, or the closest town, Bushman River’s Mouth, and therefore data from Port Alfred were used. The

mean maximum temperature for summer was approximately 27°C and

approximately 20°C for winter, with temperatures in excess of 30°C and below

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0 10 20 30 40 50 60 70 80 J F M A M J J A S O N D Month R a in fa ll ( mm)

Fig. 2.12 Average monthly rainfall recorded at Port Alfred for the period 1936-2003.

Three major vegetation types are present on the reserve (Fig. 2.13), namely Kowie Thicket, Albany Coastal Belt and Cape Estuarine Salt Marshes (Mucina & Rutherford 2006), with Kowie thicket being the dominant vegetation type, occurring on most of the slopes in the reserve (Parker 2004).

Characteristic species include Cassine aethiopica, Euphorbia triangularis, E.

tetragona and Plumbego auriculata (Low & Rebelo 1996). Acacia cyclops has also invaded some of this vegetation type on the reserve. Some old farm land occurs on the flood plains of the Kariega River, and is characterized by grass

species such as Panicum stapfianum, Eragrostis curvula and Themeda triandra,

with some planted exotic trees also present (Parker 2004). Albany coastal belt

occurs along the eastern and western boundaries of the reserve in deep valleys,

and includes species such as Mimusops caffra, Apodytes dimidiata, Sideroxylon

inerme and Cassine aethiopica (Low & Rebelo 1996). Cape salt marshes make up only a small fraction of the reserves southern boundary.

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Fig. 2.13 Vegetation of Kariega showing the three main vegetation types (ArcGIS 9.2; map units: decimal degrees; not projected, Mucina & Rutherford 2006). See Fig. 2.4 for location.

Elephants were introduced to Kariega in 2004 when a family group of 11 individuals were translocated from the Sabi-Sands Private Game Reserve. The group consisted of seven females and four males, of which three were adults, six were sub-adults, and two were 5 year-old calves. Additionally, two adult bulls were introduced in 2005 from the AENP, and six calves have since been born on the reserve (one each in 2005, 2006, and 2007, and three in 2008). In early 2008 one of the adult bulls died from a tooth abscess, leaving the current population of 19 elephants at a density of 0.1 elephants/km2.

Wolmarans (2006) identified 15 PDI’s in the elephant diet. These included Cynodon dactylon (7.8%), Rhus crenata (5.6%), Azima tetracantha (5.3%) and Schotia afra (5.3%) as the dominant species. With the exception of the high

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2.2.6 Blaauwbosch Private Game Reserve

Blaauwbosch is located at 33°21’S, 24°49’E, approximately 5 km SW of Wolwefontein on the R75 road from Port Elizabeth to Graaff-Reinet (Fig. 2.4). It

spans an area of 45 km2 with mountainous terrain dominating the northern and

eastern sections with slopes of varying steepness, with the south being characterized by a typical Karroo basin. Altitude ranges from 854 m.a.s.l. in the north east to 420 m.a.s.l. in the south. The geology consists of shales and quartz sandstones of the Witteberg group in the northern and central regions of the park, with the southern half of the park dominated by conglomerates and sandstones of the Uitenhage group (Mucina & Rutherford 2006). The soils are predominantly red, acidic, fine-grained clay soils with a high phosphorus and low nitrogen content (Hoffman 1989). Water in the park is supplied by a number of ground and cement dams fairly evenly distributed across the park.

0 5 10 15 20 25 30 35 40 45 50 J F M A M J J A S O N D Month R a in fa ll ( mm)

Fig. 2.14 Average monthly rainfall recorded at Pinelands Farm (33°19’S, 24°51’E) for the period 1951-2006.

2.2.6.2 Climate

Blaauwbosch falls within the semi-arid region of South Africa and receives an average of 300 mm rain per annum (Fig. 2.14, calculated from rainfall records from a neighbouring farm spanning from 1951 to 2006). Although rain is recorded

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throughout the year, there is a distinct bimodal pattern (Stone 1998), with peaks in March (44 mm) and November (33 mm). Extended periods of drought are not uncommon.

As no temperature data were available for the park or the closest town, average temperatures were calculated from 29-year temperature data for Jansenville, approximately 50 km north east of Blaauwbosch, and Uitenhage, approximately 100 km south east. Average maximum temperatures for summer and winter were 31.2°C and 21.3°C respectively, with minimum temperatures recorded at 17.1°C and 6.3°C (SA Weather Service 2008).

Fig. 2.15 Vegetation map of Blaauwbosch Private Game Reserve illustrating the three dominant vegetation types (ArcGIS 9.2; map units: decimal degrees; not projected, Mucina & Rutherford 2006). See Fig. 2.4 for location.

Three major vegetation types are present in Blaauwbosch (Fig. 2.15), namely Lower Karroo Gwarrieveld in the north, Groot Thicket in the central regions and Sundays Thicket in the south. The Gwarrieveld vegetation is predominantly

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shrubland with a sparse canopy of Euclea undulata, Boscia oleoides and Schotia

afra with isolated outcrops of Portulacaria afra, whereas the Groot Thicket is

found on moderate to steep slopes of the mountain, dominated by fairly dense and closed low succulent thicket with a poorly developed grass component

(Mucina & Rutherford 2006). Species include Euclea undulata, Grewia robusta,

Carissa bispinosa, Portulacaria afra, Crassula ovata and Viscum spp.. The Sundays Thicket is as described in section 2.2.1.3 and 2.2.2.2.

A family group of eight elephants were translocated from the Sabi-Sands Private Game Reserve to Blaauwbosch in 2005. The group was comprised of four males and four females, of which three were adults, two were sub-adults and three were calves. Two calves were subsequently born in 2006, bringing the total population number up to 10 individuals. With the absence of an adult bull for

breeding, the density has since remained stable at 0.22 elephants/km2.

No elephant dietary study has yet been conducted in Blaauwbosch. Therefore the observations of the reserve manager and field rangers were used as an

indication of the species most utilized by elephants. These included Acacia

karroo, Azima tetracantha, Opuntia ficus-indica, Euclea undulata and Pappea capensis.

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CHAPTER 3 LIFE-HISTORY VARIATION IN BODY CONDITION

¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯

3.1 Introduction

3.1.1 Body condition

The condition of an animal can be defined as a measure of the variation of its body fat reserves and is essentially a reflection of its energetic state (Pitt et al. 2006). A minimum amount of energy is needed for maintenance, with any surplus energy being allocated to growth, reproduction and storage (fat deposits). An individual with a larger energy reserve will thus have more energy to allocate to reproduction and fat storage, thereby increasing its chances of survival and reproduction, and will thus ultimately experience increased fitness (Klein 1968; Sinclair & Duncan 1972; Miller & Hickling 1990; Choquenot 1991; Hodges et al. 1998). Factors that may affect the condition of an individual can broadly be classed into two categories, namely intrinsic and extrinsic. Intrinsic factors include factors that are an inherent part of the animal, i.e. life-history stages (i.e. pregnancy, lactation, weaning & loss of tooth function) and genetics, whilst extrinsic variables refer to those factors independent of the animal, i.e. population density, stress, forage quality production and rainfall (wet/drought periods).

3.1.2 Body condition over lifetime

During its lifetime an individual may be subjected to many changes in extrinsic (ecological) variables. These include periods of changeable rainfall (drought/wet periods) with associated changes in vegetation quality (Phillipson 1975; Malpas 1977; Grant et al. 1995). It may also be subjected to periods of stress (predation, disease, human conflict), and variations in population density with associated effects on food availability (Klein 1968; Skogland 1985; Choquenot 1991; Hodges et al. 1999; Gough & Kerley 2006). Depending on the duration and severity, these periods may impact the body condition of the individual through a decrease in the quality and quantity of available food (Phillipson 1975; Grant et al. 1995).

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An individual is also likely to experience periods of increased nutritional requirements during certain life stages. These include weaning, when the dependent calf is slowly weaned from its mother and is forced to start foraging for itself whilst still maintaining a high growth rate (Lochmillar et al. 1982; Robbins 1983; Hayssen 1993), lactation, when the adult female bears the cost of the nutrient-rich milk for her calf (Young 1976; Malpas 1977; Robbins 1983;

Clutton-Brock et al. 1989; Hayssen 1993; Reuter & Adcock 1998) and old age, when the

tooth surface starts wearing down, hampering forage mastication and thus nutrient absorption (Laws 1981; Price & White 1985; Skinner & Chimimba 2005). If there is not sufficient quality and quantity of forage available during these times to meet the increased nutritional requirements, the animal will be forced to mobilize body fat reserves and metabolize muscle tissue (Price & White 1985). This will cause a decline in body condition and make the individual increasingly more vulnerable to environmental stressors (McGregor & Butler 2008). This is known as the “multiplier effect”, whereby a small deficiency in resources can become lethal through the intercession of predators and pathogens (Owen-Smith 2002). An example of this increased vulnerability at these life stages can be found in the Tsavo elephant die-off of 1970/71, where neonates, mothers with calves and old individuals were the first to succumb to starvation during the drought (Corfield 1973).

3.1.3 Condition measures

Various indices have been developed to measure the condition of an animal. The majority of these use the amount of fat in various deposits throughout the body as an index of body condition. This is based on the assumption that the quantity of fat in a specific area of deposition is proportional to the total body fat reserves

in some predictive way (Sharp 1982). These indices include measures such as

the Kidney Fat Index (Malpas 1977; Choquenot 1991; Gallivan et al. 1995) and

Bone Marrow Fat (Malpas 1977). A number of other indices have also been used to assess condition, namely blood chemistry and haematology (Malpas 1977; Gallivan et al. 1995), adrenal cortical hypertrophy (Anderson et al. 1971), urinary

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excretion of hydroxyproline (McCullagh 1969a; Malpas 1977), bioelectrical

impedance (Pitt et al. 2006) and body growth (Hodges et al. 1999). Many of

these methods are, however, invasive or impractical for studies on large mammals. This has led to the development of visual body condition indices for

some mammals (Riney 1960; Albl 1971; Poole 1989; Grant et al. 1995; Reuter &

Adcock 1998; Wemmer et al. 2006), which have been found to give a reliable

reflection of overall condition. Additionally, visual condition estimations do not only consider deposited fat reserves, but are partially dependent on changes in muscle volume, thereby incorporating the deposition and mobilization of protein resources (Sharp 1982). This is important, as animals losing condition will catabolize muscle as well as fat reserves to meet their nutritional demands, even in the early stages of weight loss (Price & White 1985; Owen-Smith 2002).

3.2 Hypotheses and aims

By comparing the body condition of energetically constrained life stages to non-energetically constrained life stages (i.e. sub-adults and non-lactating females), I am able to test the hypothesis that elephant body condition will vary as a function of life stage, which can be visually represented (Fig. 3.1). Specifically, I predict that individuals that are being weaned, lactating, or experience loss of tooth function will have lower body conditions than those that are not energetically constrained.

This will enable me to determine whether energetically constrained elephant life stages (i.e. weaning, lactation and loss of tooth function) are more vulnerable to resource limitations compared to non-energetically constrained life stages (i.e. sub-adults and non-lactating females) in order to identify critical periods of elephant life history.

Additionally, by comparing the body condition of individuals (within their respective life stages) across seasons, I am able to test the hypothesis that elephant body condition will vary seasonally. Specifically, I predict that there will

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be a decrease in condition in seasons when resources may be limiting, and that this seasonal variation will be reinforced by the various life stages.

Fig. 3.1 Expected changes in the body condition of a female elephant over her lifetime.

3.3 Materials and methods

3.3.1 Selection of life-history groups

Only the AMC population was used to investigate the effect of individual life stage on body condition. This was the only population for which all individuals and their life histories are known (Whitehouse & Hall-Martin 2000; Gough & Kerley 2006), and was also the only population large enough to allow statistical analyses on the various life stages. A list of all the elephants was obtained (K. Gough, unpubl. data) and these were sorted into the four categories investigated, i.e. weaning, lactation, loss of tooth function, and sub-adults and non-lactating females (pooled). Individuals were classified as weaning if they were under 4 years and had a younger sibling no older than 1 year, as the initial period of weaning is thought to be the most energetically stressful. Although suckling up to the age of 8 years has been recorded (Lee & Moss 1986), only adult females

Detecting changes in elephant body condition in relation to resource quality