Analysing and Modelling the Ecological Requirements of Reptiles and Large Arachnids: a Study of the Leeuspruit Private Nature Reserve
ANALYSING AND MODELLING THE ECOLOGICAL REQUIREMENTS OF REPTILES AND LARGE ARACHNIDS: A STUDY OF THE LEEUSPRUIT PRIVATE NATURE RESERVE.
BY
PAUL SEBASTIAN RABIEGA
Minor-Dissertation submitted in partial fulfilment of the requirement for the degree
MASTER OF HUMANITIES
In
ENVIRONMENTAL MANAGEMENT
In the
Faculty of Humanities
at the
UNIVERSITY OF JOHANNESBURG
Supervisor: Dr. Isaac T. Rampedi Co-supervisor: Dr. Francois Durand
October 2013 Dedication
This study is dedicated to all the people that have a deeper and fulfilling fascination in our indigenous reptile and large arachnids
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Acknowledgements
The following persons I owe my gratitude and sincere appreciation for all they have done to facilitate the completion of this study.
To my mother, Bozena and brother, Patrick for the never ending field trips, patience, understanding and support they have offered whilst conducting this research. This research could not have been completed without your motivation. To my grandparents, Siegmund and Helena for their allowing me to pursue my ambitions in life and further education. To my late father, Andzej may you rest assured that I have made a success of my life. To my supervisor, Dr. Isaac Rampedi (Department of Geography, Environmental Management and Energy Studies, University of Johannesburg) for providing me the opportunity to conduct research in my chosen field and monitoring my progress with exceptional input to grant this research a success. To my co-supervisor, Dr. Francois Durand (Department of Zoology, University of Johannesburg) for his expertise and knowledgeable input in guiding and facilitating this research to grant it a meaningful and fruitful output. To Johan van Wyk (Environmental Scientist, Sasol Ltd.) for his agreement in accepting and facilitating the advancement of this research in the study area. To Japie Strydom and Sampie van der Merwe (Game rangers, Sasol Ltd. Nature Reserves) for their time spent in accommodating me in the study area and providing useful discussions. To Mariana van Wyk (Botanist) for her enthusiasm and time spent in the identification and processing of numerous plant species present in the study area. To Johan Marais (Herpetologist: African Snake Bite Institute/Reptile Ventures) for his expert advice and help in answering a series of questions.
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To Ian Engelbrecht (PhD Candidate: Researcher at the University of Pretoria) for his insight and help in scorpion taxonomy. To the National Research Foundation (NRF) for their financial contribution.
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Abstract
Reptiles are internationally one of the least studied taxa compared to all other vertebrates, and even less is known about the large arachnids. This proves problematic as the environmental management of reptile and large arachnid species is generally neglected or only partially considered in environmental impact studies and conservation. Consequently, there is a considerable lack of knowledge on the ecological requirements (dietary and habitat requirements) of reptiles and invertebrates. Furthermore, the environmental management of reptiles and large arachnids in the Leeuspruit Private Nature Reserve is restricted as no data exists on the assemblage of these taxa in the study area.
A model based approach was used to examine the ecology of species of reptiles and large arachnids (scorpions and baboon spiders) that were found in the Leeuspruit Private Nature Reserve during this study. The study proposes a baseline analysis between the species found in the study area and the suitability and availability of the ecological requirements necessary to their survival. The ecological requirements of each species were noted and utilised as the variable input categories in a scoring model developed for this study. Each species identified in the study area was allocated points from the scoring model based on favourable ecological requirements for that particular species.
Field work was conducted in the Leeuspruit Private Nature Reserve in the northern Free State Province (March 2012 – March 2013) to do a survey on reptile and large arachnid diversity and to record the habitats in which they occur.
A list of the reptiles and large arachnids found in the Leeuspruit Private Nature Reserve was compiled. One of the significant results which came to light during this study is that the diversity and abundance of reptiles and large arachnids are dependent on the availability and diversity of habitats with the necessary ecological requirements for those species. For example, the distribution of snake species was largely dependent on the abundance of amphibians and birds for food which coincided with a seasonal wetland in the study area; while rocks and detritus proved imperative to the seasonal functionality of the reptiles.
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During this study it was determined that 23 reptiles, four scorpion species and a baboon spider species occur in the study area. Fourteen of the reptile species found were not previously recorded from the Sasolburg 2627DD quarter degree grid cell map area; which constitutes a 61% increase of known reptile diversity in this area. The four scorpion species and one baboon spider found in the study area are all new records and the unexpected extensions of the geographical distribution ranges of a species of burrowing scorpion (Opistophthalmus glabrifrons) and a species of bark scorpion (Uroplectes triangulifer marshali) in the Free State Province were a key finding.
The findings of this study facilitated a discussion on recommendations proposed to Sasol Ltd. on how to facilitate the environmental management of the Leeuspruit Private Nature Reserve in order to preserve the biodiversity and abundance of indigenous reptile and large arachnids. The new species records have been submitted to ReptileMAP, ScorpionMAP and SpiderMAP which are projects of the Animal Demography Unit of the University of Cape Town to improve the national indigenous reptile database.
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TABLE OF CONTENTS
CHAPTER 1: INTRODUCTION AND RESEARCH BACKGROUND 1
1.1. INTRODUCTION 1
1.2. ORGANISATION OF THE DISSERTATION 2
CHAPTER 2: STATEMENT OF THE RESEARCH PROBLEM 5
2.1. INTRODUCTION 5
2.2. RESEARCH PROBLEM STATEMENT 5
2.3. AIM OF THE STUDY 6
2.4. OBJECTIVES OF THE STUDY 6
2.5. LIMITATIONS OF THE STUDY 7
2.6. SCOPE OF THE STUDY 8
CHAPTER 3: DESCRIPTION OF THE STUDY AREA 10
3.1. INTRODUCTION 10
3.2. HISTORY OF THE STUDY AREA 10
3.3. LOCATION OF THE STUDY AREA 11
3.4. CLIMATE 13
3.4.1. Rainfall 13
3.4.2. Temperature 14
3.5. GEOLOGY AND SOILS 16
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3.6. HYDROLOGY 17
3.7. TOPOGRAPHY 17
3.8. VEGETATION 18
CHAPTER 4: LITERATURE REVIEW 21
4.1. INTRODUCTION 21
4.2. REPTILES AND LARGE ARACHNIDS POTENTIALLY FOUND IN THE LEEUSPRUIT PRIVATE NATURE RESERVE 21
4.2.1. Reptiles 23
4.2.1.1. Tortoises and terrapins 26
4.2.1.2. Snakes 26
4.2.1.3. Lizards 30
4.2.2. Large Arachnids 32
4.2.2.1. Baboon Spiders 33
4.2.2.2. Scorpions 34
4.3. REPTILE AND LARGE ARACHNID BIOLOGY 35
4.4. ALIEN INVADER RISKS 37
CHAPTER 5: RESEARCH METHODOLOGY 39
5.1. INTRODUCTION 39
5.2. DEVELOPMENT OF SPECIES INVENTORIES 39
5.3. FIELD WORK AND DATA CAPTURE 45
5.3.1. Primary Method 46
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5.3.2. Pitfall trap and funnel trap arrays 48
5.4. ECOLOGICAL REQUIREMENTS 54
5.5. THE SCORING MODEL 61
CHAPTER 6: RESULTS 65
6.1. INTRODUCTION 65
6.2. METHODOLOGICAL APPROACHES 65
6.3. SPECIES CONFIRMED TO OCCUR IN THE LEEUSPRUIT PRIVATE NATURE RESERVE 66
6.4. COMPARISON OF SPECIES ECOLOGICAL REQUIREMENTS 72
6.4.1. Species dietary requirements comparison 72
6.4.2. Species habitat requirements comparison 76
CHAPTER 7: DISCUSSION OF RESULTS 82
7.1. INTRODUCTION 82
7.2. SPECIES ABSENCE AND UNCERTAINTY 82
7.3. EXTENSION OF SPECIES DISTRIBUTION RANGES 87
7.3.1. Tread snake (Leptotyphlops sp.) 87
7.3.2. Scorpions (Opistophthalmus sp. and Uroplectes sp.) 88
7.4. BEHAVIOUR, ECOLOGY AND FIELD OBSERVATIONS 89
7.5. RECOMMENDATIONS 94
7.5.1. Vegetation litter 94
7.5.2. Fires 94
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7.5.3. Moribund termitaria 95
7.5.4. Amphibians and water quality 96
7.5.5. Rocks, stones and building rubble 96
7.5.6. Manhole 96
7.5.7. Human impacts 97
7.5.8. Environmental legislation 97
7.5.9. Further research 97
7.5.10. Push factors 98
CHAPTER 8: CONCLUSION 99
CHAPTER 9: REFERENCES 101
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LIST OF FIGURES
Figure 3.1: A pan occurring in the Leeuspruit Private Nature Reserve. 11
Figure 3.2: The location and boundary of the Leeuspruit Private Nature Reserve. 12
Figure 3.3: Mean monthly rainfall (mm) for the Leeuspruit Private Nature Reserve
(Sasolburg). 14
Figure 3.4: Mean monthly maximum temperatures for the Leeuspruit Private
Nature Reserve (Sasolburg). 15
Figure 3.5: Mean monthly minimum temperatures for the Leeuspruit Private
Nature Reserve (Sasolburg). 15
Figure 3.6: Plant samples that were taxonomically identified. 19
Figure 4.1: Predation chart of snakes and their eggs. 25
Figure 4.2: Trachemys scripta elegans (Red-eared slider) are known to be persistent alien invaders. 38
Figure 5.1: Protective gear and equipment utilised in the capture of reptiles and
large arachnids. 47
Figure 5.2: Overview array of pitfall traps and funnel traps. 49
Figure 5.3: Cross-section view of pitfall trap and funnel trap array. 50
Figure 5.4: Basic design of a funnel trap. 50
Figure 5.5: Equipment needed to construct pitfall trap and funnel trap arrays. 52
Figure 5.6: The manhole that serves as a permanent ‘pitfall trap’. 53
Figure 5.7: The proposed model based on dietary and habitat requirements. 63
Figure 6.1: Dietary requirements of all potential species found in the Leeuspruit
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Private Nature Reserve. 74
Figure 6.2: Dietary requirements of species found to occur in the Leeuspruit Private Nature Reserve. 75
Figure 6.3: Habitat requirements of all potential species found in the Leeuspruit
Private Nature Reserve. 78
Figure 6.4: Habitat requirements of species found to occur in the Leeuspruit Private Nature Reserve. 79
Figure 7.1: A fire break on the boundary of the study area. 95
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LIST OF TABLES
Table 5.1: Species potentially occurring in the Leeuspruit Private Nature Reserve with key notes. 42
Table 5.2: Species potentially occurring in the Leeuspruit Private Nature Reserve with dietary and habitat requirements. 55
Table 6.1: Species occurring in the Leeuspruit Private Nature Reserve and
picture reference. 68
Table 6.2: Species occurring in the Leeuspruit Private Nature Reserve with
points allocated on ecological requirements. 70
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LIST OF APPENDICES
Appendix 1: Plates 1 - 15. 111
Appendix 2: Agreement letter from Sasol Ltd. to conduct research in the
Leeuspruit Private Nature Reserve. 127
Appendix 3: Field Guide Association of Southern Africa (FGASA) approved
snake identification, snake bite first aid and venomous snake
handling course certificate. 129
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LIST OF PLATES
PLATE 1 112
Figure 1: Bitis arietans arietans (Puff adder). 112
Figure 2: Hemachatus haemachatus (Rinkhals). 112
Figure 3: Homoroselaps lacteus (Spotted harlequin snake). 112
Figure 4: Aparallactus capensis (Black-headed centipede-eater). 112
Figure 5: Psammophis crucifer (Cross-marked grass snake). 112
Figure 6: Psammophylax rhombeatus rhombeatus (Spotted grass snake) . 112
PLATE 2 113
Figure 7: Crotaphopeltis hotamboeia (Red-Lipped snake). 113
Figure 8: Boaedon capensis (Brown house snake). 113
Figure 9: Lamprophis aurora (Aurora house snake). 113
Figure 10: Lycodonomorphus rufulus (Brown water snake). 113
Figure 11: Pseudaspis cana (Mole snake). 113
Figure 12: Lycophidion capense capense (Cape wolf snake). 113
PLATE 3 114
Figure 13: Dasypeltis scabra (Rhombic egg-eater) – Colour and pattern
variations. 114
Figure 14: Dasypeltis scabra (Rhombic egg-eater) – Rare patternless
variety. 114
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Figure 15: Dasypeltis scabra (Rhombic egg-eater) – Plain phase. 114
Figure 16: Dasypeltis scabra (Rhombic egg-eater) – Uncommon striped
variety lacking most characteristics rhombic markings. 114
Figure 17: Afrotyphlops bibronii (Bibron’s blind snake). 114
Figure 18: Afrotyphlops bibronii (Bibron’s blind snake) – Xanthis phase due to
a genetic pigment anomaly. 114
PLATE 4 115
Figure 19: Leptotyphlops scutifrons scutifrons (Peters’ thread snake). 115
Figure 20: Leptotyphlops scutifrons conjunctus (Eastern Cape thread snake). 115
Figure 21: Acontias gracilicauda (Thin-tailed legless skink). 115
Figure 22: Trachylepis capensis (Cape skink). 115
Figure 23: Trachylepis capensis (Cape skink) – Specimen lacking characteristic
markings. 115
Figure 24: Trachylepis punctatissima (Speckled rock skink) . 115
PLATE 5 116
Figure 25: Agama atra (Southern rock agama). 116
Figure 26: Lygodactylus capensis capensis (Common dwarf gecko). 116
Figure 27: Pachydactylus capensis (Cape gecko). 116
Figure 28: Pelomedusa subrufa (Marsh terrapin). 116
Figure 29: Uroplected triangulifer (Bark scorpion). 116
Figure 30: Uroplectes triangulifer (Bark scorpion) with brood on back. 116
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PLATE 6 117
Figure 31: Opistophthalmus pugnax (Burrowing scorpion). 117
Figure 32: Opistophthalmus pugnax (Burrowing scorpion) – Heavily gravid
female. 117
Figure 33: Opistophthalmus glabrifrons (Burrowing scorpion). 117
Figure 34: Harpactira hamiltoni (Common baboon spider). 117
Figure 35: Harpactira hamiltoni (Common baboon spider) – Juvenile. 117
PLATE 7 118
Figure 36: Crotaphopeltis hotamboeia (Red-lipped snake) – In threat pose. 1
Figure 37: Communal egg deposition site under a flat rock – presumably
of Psammophylax rhombetus rhambeatus (Spotted grass snake) or
Psammophis crucifer (Cross-marked grass snake). 118
Figure 38: Psammophylax rhombeatus rhombeatus (Spotted grass snake) –
A good example of egg deposition sites being utilised communally
by members of the same species. Two Psammophylax rhombeatus
rhombeatus utilise the same concrete slab, one female with her batch
of eight eggs and the other female heavily gravid. 118
PLATE 8 119
Figure 39: Bitis arietans arietans (Puff adder) – Skin shedding of Bitis arietans
arietans evident from markings. 119
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Figure 40: Bitis arietans arietans (Puff adder) – Head of a deceased specimen. 119
Figure 41: Entrance to a burrow of Harpactira hamiltoni (Common baboon spider). 119
Figure 42: Eggs of a Gekkonidae species, presumably Pachydactylus capensis
(Cape gecko). 119
Figure 43: Egg-sack of a Harpactira hamiltoni (Common baboon spider). 119
Figure 44: Parasite infestation in Uroplectes triangulifer marshali
(Bark scorpion). 119
PLATE 9 120
Figure 45: Communal egg deposition – The batch on the left is of Psammophylax
rhombeatus rhombeatus (Spotted grass snake) evident from the
female remaining with the eggs, the batch on the right is of an
unknown species. 120
Figure 46: Close-up of egg batch of unknown species. 120
Figure 47: Close-up of Psammophylax rhombeatus rhombeatus (Spotted grass
snake) eye. Note the large pupil due to a diurnal existence. 120
Figure 48: A pair of Pachydactylus capensis (Cape gecko) found under the
same rock. 120
Figure 49: All three of these Crotaphopeltis hotamboeia (Red-lipped snakes)
where found under the same rock, although not of breeding size.
This poses the question of communalism. 120
Figure 50: Close-up of Psammophylax rhombeatus rhombeatus (Spotted grass
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snake) eggs – Decalcified eggs shells reveal visible embryonic
development. 120
PLATE 10 121
Figure 51: Archive of collected hatched eggs, snake sheddings, reptile remains
and regurgitated bird’s eggs from Dasypeltis scabra (Rhombic egg-
eater). 121
Figure 52: Psammophylax rhombeatus rhombeatus (Spotted grass snake) –
Aggressively biting leather glove. 121
Figure 53: Psammophis crucifer (Cross-marked grass snake) – Hatchling
mortality. 121
PLATE 11 122
Figure 54: Amietophrynus gutturlis (Guttural toad) – One of many amphibian
species available as a dietary source. 122
Figure 55: Xerus inauris (Cape ground squirrel) – Small terrestrial mammal
available as a dietary source. 122
Figure 56: Streptopelia capicola (Cape turtle dove) – One of many bird
dietary sources. 122
Figure 57: Ploceus velatus (Masked weaver bird) nests – Bird’s eggs as a
dietary source. 122
Figure 58: Centipede as a specialised dietary source for Aparallactus
capensis (Black-headed centipede-eater). 122
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Figure 59: Ants with their eggs and lava as a dietary source. 122
PLATE 12 123
Figure 60: Slugs as a specialised dietary source for Duberria lutrix lutrix
(South African slug-eater). 123
Figure 61: Evidence of moles that serve as a dietary source for many snake
species. 123
Figure 62: Vegetation as a dietary source for herbivorous and omnivorous
reptile species. 123
Figure 63: Grasshoppers are common invertebrate dietary items 123
Figure 64: Rodent nest – Rodents and nestlings are taken by many species as
a varied dietary source. 123
PLATE 13 124
Figure 65: Fissures in exposed dolerite provide excellent retreats for scorpions
and reptiles. 124
Figure 66: Building rubble (bricks and concrete) utilised as retreats by reptiles
and arachnids. 124
Figure 67: Trees and bushes utilised by arboreal and semi-arboreal species. 124
Figure 68: Soft soil utilised by species that require specific soils for burrowing.
a heavily gravid Afrotyphlops bibronii (Bibron’s blind snake) was
found in this soil with a very complex array of burrows. 124
Figure 69: Exfoliating bark is a commonly utilised retreat for arboreal and semi-
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arboreal species. 124
Figure 70: Dolerite boulders from exposed outcrops occur in large numbers all
over the study area. 124
PLATE 14 125
Figure 71: Logs from fallen trees offer a cool and humid habitat. 125
Figure 72: Vegetation from mowed grass fire breaks are scattered all over the
study area and offer ideal egg deposition sites due to moisture and
heat retention. 125
Figure 73: Disused mammal burrows accommodate large snake species such
as Hemachatus haemachatus (Rinkhals). 125
Figure 74: Active termitaria. 125
Figure 75: Moribund termitaria with access holes exposed. 125
Figure 76: Exposed dolerite outcrops over the winter months. 125
PLATE 15 126
Figure 77: Seasonal wetlands appear after heavy rainfall over the summer
months. 126
Figure 78: Winter landscape. 126
Figure 79: Summer landscape. 126
Figure 80: Vegetation available as cover for diurnal species. 126
Figure 81: The Leeuspruit flowing through the study area. 126
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CHAPTER 1 INTRODUCTION AND RESEARCH BACKGROUND
1.1. INTRODUCTION
Research on conservation and nature reserve management tends to be focused mainly on large animal species and the management of mammals (Sparling et al., 2000; Blanc et al., 2007; Craigie et al., 2010). This trend is not limited to overseas countries but is also evident in South Africa. For instance, the conservation strategies on African wild dogs as well as the role that the Cape mountain zebra is playing in ecotourism have been examined in a greater detail (Lindsey et al., 2005; Watson et al., 2005; Bach et al., 2010). On the other hand, research on reptiles and large arachnids is generally limited in South Africa.
Reptiles and large arachnids play a crucial role in ecosystems where they form an integral part of food webs (Sparling et al., 2000). The growing impact of urbanisation, habitat fragmentation and environmental change in many parts of the world today necessitate a deeper understanding of the habitat requirements of such species in order to design successful conservation strategies (Souter et al., 2007). However, the impact of land use on reptiles is not always similar to the trends noted for plants and arthropods (Fabricius et al., 2003). For instance, reptiles may be deprived from competing successfully by the absence of dense vegetation and shade, besides not deriving any direct benefit from vegetation for their existence (Souter et al., 2007). Thus, without empirical research on the ecological requirements of reptiles and large arachnids, it is neither possible to identify and protect conservation areas undergoing environmental stress, nor undertake meaningful searches for populations facing environmental risks.
A number of reptile and large arachnid species have undergone red data evaluation to determine their conservation status. Although some species are legally protected, most species have not been adequately evaluated and as a result there is a need for determining their ecological status. The Leeuspruit Private Nature Reserve is
1 considered to be an ecological island that is surrounded by urbanisation, industry and mining operations. To successfully maintain reptile and large arachnid species diversity in the study area, a thorough species and habitat survey had to be done.
Pienaar (1966) did herpetological studies in southern Africa which formed a background for this research. Pienaar (1966) addressed the question of whether the factors governing the distribution patterns of indigenous reptile species are dependent on adaptability, climatological, geographical, vegetational or other aspects of the habitat, or whether species are more dependent on the availability of food, water and/or shelter.
1.2. ORGANIZATION OF THE DISSERTATION
The dissertation is presented in eight chapters. This section briefly highlights the structure, organisation and layout of the research conducted.
Chapter 1 provides an introduction and a brief background on the research topic. The chapter includes a description of the selected research focus as well as providing a rationale for the study and emphasising the importance of the research conducted.
Chapter 2 comprises of a description of the research problem which includes a motivational summary for doing the research following the studies conducted by Pienaar (1966) and de Waal (1978). The research aim includes a number of research objectives which correlate with the methodological approaches discussed in Chapter 5. The chapter ends with a brief contextualisation of the limitations and scope of the study.
Chapter 3 entails the description of the study area (Leeuspruit Private Nature Reserve). The introduction includes some context on the different historical land uses that the study area has undergone over the past years and is given by means of a brief historic background of the Leeuspruit Private Nature Reserve. The geographical location and biophysical aspects such as the climatic conditions, 2 geology and soil characteristics, hydrological processes, topographic data and the vegetation class of the study area are described.
Chapter 4 consists of a review of the relevant literature pertaining to the broader setting of study area as well as the ecology of reptiles and large arachnids. The core aspect of this chapter is a literature review of the ecological requirements of reptiles and large arachnids of this region. Aspects such as red data species, the ecological roles and ecological requirements of reptiles and large arachnids are highlighted, thus providing background knowledge on these species and their ecological dependency. Lastly, the possibility of alien invader species, both indigenous and exotic is discussed as a potential threat to homeostatic ecological functioning.
Chapter 5 provides a description of the research methodology utilised in obtaining and analysing the primary data. The various data collection processes and field work approaches are discussed, namely; the physical search and identification of the species of interest and the utilisation of trapping methods. The development of species inventories is discussed in detail as these inventories form the backbone of this research. The ecological requirements (dietary and habitat variables) on site were noted as these factors are the input variables in the development of the scoring model. The utilisation of the simple scoring model is explained and the advantages of such a model are discussed.
Chapter 6 deals with the presentation of research results. The chapter begins with an analysis of the methodological approaches utilized in the study and the overall success of each approach. The allocation of points based on the scoring model was awarded to all the species found to occur in the study area during the duration of this research. The discussion proceeds with the ecological requirements that were identified as being most significant to ensure species survival. The chapter also covers a comprehensive description on the comparisons made between all the species that could potentially occur in the study area and the species that were found to occur in the study area in relation to their key ecological requirements. The dominant habitat and dietary requirements (ecological requirements) are discussed and supporting reasons are specified as to the significance of ecological requirement availability as a deciding factor in species occurrence and abundance. 3
Chapter 7 presents a discussion based on research findings. This discussion includes a reflection on the reasons why there is an absence or uncertainty in the literature of the presence and distribution of certain species. The reptiles and large arachnids of the Leeuspruit Private Nature Reserve has proven to be rather diverse and the question on the absence of certain species which were expected to occur or the uncertainty about their distribution needed to be explained. The following sub- section focuses on the occurrence of scorpion species (Opistophthalmus glabrifrons and Uroplectes triangulifer marshalli) which have not previously been recorded from the broader region of the study area although they were found to have an extended distributional range in the northern Free State Province. Lastly, a comprehensive summary on suggested recommendations is provided to help facilitate the environmental management of current species abundance and ecological requirements in the study area.
The dissertation ends with Chapter 8, which comprises of concluding remarks based on the outcome and overall success of the conducted research. The concluding remarks allow an opportunity to set research goals for further studies in environmental management and other natural science fields pertaining to the ecology, conservation and management of reptiles, large arachnids and other animals.
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CHAPTER 2 STATEMENT OF THE RESEARCH PROBLEM
2.1. INTRODUCTION
The following section explains the research problem, thereby providing the motivation for conducting the research in the selected study field. The problem statement is followed by the underlying aim of the study and the research objectives are then listed. The limitations to the study are mentioned and briefly discussed followed by a paragraph delineating the scope of the study.
2.2. RESEARCH PROBLEM STATEMENT
Efforts to manage and protect indigenous fauna in South African nature reserves are hampered by inadequate records of species occurring within areas of environmental concern (Branch, 1998; Smart et al., 2005). Consequently, there is a lack of knowledge on the environmental needs, habitats and ecological niche requirements that are species specific. Environmental studies in the identification of species of fauna that occur in these reserves constitute the first step in designing a successful conservation strategy. Fragmentation of reptile populations following habitat degradation within a landscape can lead to the extirpation of species (Branch, 2008), while the loss of suitable habitat is the single biggest cause of terrestrial reptile biodiversity loss in South Africa (Alexander & Marais, 2007). For these reasons, it was considered important to conduct the current study, the goal being to contribute towards the development of a better understanding of reptile and large arachnid diversity within the study area.
This research was inspired by the paucity of scientific literature and knowledge on the reptiles and large arachnids in the region in which the Leeuspruit Private Nature Reserve is situated. A fundamental aspect of environmental management is that, ‘one cannot conserve and environmentally manage what one does not know is
5 there’, which is an empirical basis for conducting environmental monitoring and quantitative measurements (Porteous, 2000; Strangeways, 2003). This statement confirms the need for the identification of the reptiles and large arachnid species occurring in the Leeuspruit Private Nature Reserve as well as their ecological requirements in an attempt to contribute towards a better understanding and implementation of environmental management plans and conservation tools.
Pienaar (1966) conducted herpetological studies in the southern Africa region. Further motivation for research of this nature is emphasised by Pienaar (1966, p. 18): “Whether the factors governing the distribution patterns of our indigenous reptile species inhere primarily in the adaptability of the species to particular climatological, geographical, vegetational or other aspects of the habitat, or are more dependent on the availability of food, water and/or shelter or the relative abundance of their natural predators, is not clear in many instances. Basically however, it has been found that certain species may almost invariably be associated with particular environmental conditions existing in the habitat. The underlying causal factors and intricate ecological interrelationships involved here offer a fascinating field for further research.”
2.3. AIM OF THE STUDY
A model-based approach was used for the study of the presence of reptiles and large arachnids in the Leeuspruit Private Nature Reserve in an effort to determine the ecological status of these species in the study area by analysing the interrelationships between these species and their ecological requirements.
2.4. OBJECTIVES OF THE STUDY
Research objectives associated with the research problem are specified as follows: Compile an inventory of the reptiles and large arachnids that could potentially be found within the geographical location of the Leeuspruit Private Nature Reserve. 6
Identify the conservation status of each species of reptile and large arachnid potentially found in the study area.
Perform a complete assessment of all the necessary dietary and habitat requirements of the species which could be found in the study area.
Identify and photograph all species of reptiles and large arachnids found in the Leeuspruit Private Nature Reserve during the duration of the field work.
Compile a list of the reptile and large arachnid species that have been found in the Leeuspruit Private Nature Reserve.
Develop a model to assess the relationship between the species found in the Leeuspruit Private Nature Reserve and their ecological requirements by means of a scoring system.
Determine which of the species found in the study over the duration of the conducted research are new records for the quarter degree grid cell of the study area (2627DD).
Provide a discussion on the recommendation of how to manage the ecological variables required by the reptiles and large arachnids in the study area.
2.5. LIMITATIONS TO THE STUDY
No major limitations were present during the duration of the research. The landowner, Sasol Ltd., granted permission for the research and no limitations or hindering factors were experienced (Appendix 2). The Agreement Letter regarding access and permission to conduct the study was compiled and provided by Sasol Ltd.
The research was conducted during all seasons and therefore most seasonal ecological activities with regards to the reptiles and large arachnids in the study area were investigated. Literature and professional advice was readily available.
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Limitations that were of a low concern included some constraints around the limited utilisation of trap arrays, especially during times of excessive precipitation (discussed in Chapter 5). Another limitation was that the locating and capturing of sought after species was restricted due to the concern over environmental degradation and habitat destruction potentially caused whilst conducting field work.
2.6. SCOPE OF THE STUDY
Only the reptiles and large arachnids occurring in the Leeuspruit Private Nature Reserve and their ecological requirements were considered for this study. All reptile suborders are included in the research, whilst with regards to large arachnids, only scorpions (Neoscorpionina) and baboon spiders (Mygalomorphae) are considered.
The research has been limited to reptiles and large arachnids because these classes of the animal kingdom have been largely ignored by previous research. A further motivation to conduct research on reptiles and large arachnids stems from the fact that many species have not been recently evaluated in terms of their conservation status or their actual usefulness in ecological food-webs. Reptiles and large arachnids usually occupy similar habitats and therefore these two groups complement one another in ecological investigations.
The study utilises a model-based approach to identify the key dietary and habitat requirements of the reptile and large arachnid species occurring in the study area. All dietary and habitat requirements have been listed in a scoring model and each identified species is allocated points based on their utilisation or dependence on a specific ecological requirement. The first accomplishment is that an inventory of the reptile and large arachnid species that occur in the Leeuspruit Private Nature Reserve was compiled. Secondly, the scoring model offers a better insight into the current condition of the species, their ecological needs and aspects to be considered by environmental management related to these species. Recommendations and insights are then offered to the landowners (Sasol Ltd.), with a view that they may provide useful guidelines to enhance environmental management in the study area.
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The study does not include any form of genetic research, analysis in morphological characteristics (unless for the identification of a species) or taxonomy. The research is focused on reptiles and large arachnids as well as their habitat and dietary requirements. The research focus was to identify species, and thereby contribute to the distribution and certain ecological requirements of these species that occur in the Leeuspruit Private Nature Reserve. Furthermore, it is important to note that no specimens were preserved, donated, collected, kept in captivity, killed or harmed in anyway.
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CHAPTER 3 DESCRIPTION OF THE STUDY AREA
3.1. INTRODUCTION
This chapter provides a description of the study area and is presented in seven sections. The history of the study area deals with the promotion and transformation of the study area into a private nature reserve. The location of the study area is discussed in terms of geographical orientation, followed by the climatic characterisation which incorporates rainfall and temperature data. The other sections provide detailed discussions on the geology and soils, hydrological processes, topographical layout and vegetation of the study area.
3.2. HISTORY OF THE STUDY AREA
The Leeuspruit Private Nature Reserve falls within the boundaries of Sasolburg (Metsimaholo Municipality) in the far north of the Free State Province. Sasolburg owes its existence to the petro-chemical industry (Sasol Ltd.) that was established in 1954 (Scholtz, 2006).
The northern and eastern parts of the Free State Province have been extensively mined for their low grade coal reserves. The area, including the Leeuspruit Private Nature Reserve, has been subjected to subsurface coal mining in the past before becoming one of Sasol Ltd.’s many private and rehabilitated nature reserves (Strydom, 2012).
There is very little evidence of mining disturbance above the ground surface (Figure 3.1) which was one of the reasons why Sasol Ltd. decided to promote the area as a private nature reserve (Van Wyk, 2012a), which is currently utilized for game farming.
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Figure 3.1: A pan occurring in the Leeuspruit Private Nature Reserve.
3.3. LOCATION OF THE STUDY AREA
The Leeuspruit Private Nature Reserve is situated along the western boundary of Sasolburg in the far northern Free State Province (Figure 3.2). The quarter degree grid cell that the study area occupies is 2627DD. The total area of the Leeuspruit Private Nature Reserve is 423 hectares (Scholtz, 2006).
The Leeuspruit Private Nature Reserve is situated as follows: 26°48ʹ07.95ʺS and 27°47ʹ56.28ʺE at its most northerly point (1434 masl).
26°49ʹ34.57ʺS and 27°48ʹ51.72ʺE at its most easterly point (1461 masl).
26°49ʹ59.91ʺS and 27°48ʹ0712ʺE at its most southerly point (1458 masl).
26°48ʹ31.33ʺS and 27°47ʹ20.04ʺE at its most westerly point (1459 masl).
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Figure 3.2: The location and boundary of the Leeuspruit Private Nature Reserve (Adapted from: Google Earth, 2012).
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3.4. CLIMATE
In a broader climatic view, the Leeuspruit Private Nature Reserve is situated in a rainfall region that receives a mean annual rainfall of between 500 – 750mm (South African Weather Services (SAWS) (2012), or 580 – 705mm of annual rainfall in its quaternary catchment (Surface Resources of South Africa (SRSA), 2000a) which predominantly falls in January (SAWS, 2012). The study area is situated in an isotherm region of a mean annual temperature of 17.5°C (SAWS, 2012). In summer, the wind generally blows most frequently from the southwest, westerly, north- westerly, north-easterly and easterly directions. In the winter months (May - August), the wind is more prevalent from the south-westerly, westerly and north-westerly directions.
The following climatic discussion and graphs have been based on data that has been collected over a period of 11 years (2000 – 2011) for Sasolburg, Free State Province (Figure 3.3, Figure 3.4 and Figure 3.5) (SAWS, 2012).
3.4.1. Rainfall
The Leeuspruit Private Nature Reserve receives a mean annual rainfall of about 550mm which in good rainfall seasons can peak with a mean annual of 640mm (SAWS, 2012). The Leeuspruit Private Nature Reserve is situated in a summer rainfall region where the majority of rain falls in the form of convectional thunderstorms. Mean monthly rainfall increases in the spring and summer months (October – March) and decreases over the autumn and winter months (April – August) (Figure 3.3).
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Mean monthly rainfall 120
100
80
60 Millimeters 40
20
0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Figure 3.3: Mean monthly rainfall (mm) for the Leeuspruit Private Nature Reserve (Sasolburg). (Adapted from: SAWS, 2012).
Mean monthly rainfall increases from December to January before decreasing as the weather cools in late summer. The month of January may be regarded as the highest peak of the rainy season with a mean rainfall of 103mm and July is the driest month.
3.4.2. Temperatures
The highest mean maximum (midday) temperatures experienced in the Leeuspruit Private Nature Reserve are in the summer months of December, January and February with the peak of 28°C in January (Figure 3.4). Temperatures have been known to reach up to 35°C. Summer mean maximum temperatures remain above 20°C from August to May, with two winter months (June and July) dropping to a mean maximum temperature of 17°C.
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Mean maximum temperatures 30
25
20
15
Degrees celcius Degrees 10
5
0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Figure 3.4: Mean monthly maximum temperatures for the Leeuspruit Private Nature Reserve (Sasolburg). (Adapted from: SAWS, 2012).
Mean minimum temperatures 16
14
12
10
8
6
Degrees celcius Degrees 4
2
0
-2 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Figure 3.5: Mean monthly minimum temperatures for the Leeuspruit Private Nature Reserve (Sasolburg). (Adapted from: SAWS, 2012).
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The lowest mean minimum (midnight) temperatures experienced in the Leeuspruit Private Nature Reserve are in the months of May, June, July and August with the lowest being 0°C in June and July (Figure 3.5). Temperatures have been known to decrease below freezing during the cold winters but this is usually over a short interval. Frost occurs rather frequently with an average of 43 days per annum. Mean minimum temperatures remain above 10°C from October to March, with two summer months (January and February) peaking to a mean minimum temperature of 14°C (SAWS, 2012).
3.5. GEOLOGY AND SOILS
The dominant rock type in the Leeuspruit Private Nature Reserve is sandstone, which forms part of the Ecca Group (Council for Geoscience, 2000a). The Ecca Group was deposited between 280-240 million years ago during the Palaeozoic (Council for Geoscience, 2000b). The Ecca Group forms part of the Karoo Supergroup (Council for Geoscience, 2000c). The underlying rocks are mainly sedimentary sandstones, mudstones and shales in which seams of low grade coal occur. There are primarily vertic, melanic and red soils in the area which are derived from the weathering of the parent material and are strongly structured with a marked clay accumulation of which the typical forms are Arcadia, Bonheim, Kroonstad, Valsrivier and Rensburg (Institute for Soil, Climate and Water (ISCW), 2000a).
A ridge of intrusive Jurassic Karoo dolerites protrudes as an outcrop along the eastern section of the study area. This dolerite ridge runs for approximately 340 meters. A number of smaller outcrops of dolerite are present throughout the study area. These dolerites weather into dry clayey soils. Sandstone outcrops are also present but to much less of an extent. It is very evident that the soils are very directly associated with the underlying parent geology.
According to ISCW (2000b), the soil depth class of the Leeuspruit Private Nature Reserve is <450mm. The soil is non-calcarious (ISCW, 2000c) and the clay classes of the topsoil range between 15% and 35% (ISCW, 2000d).
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3.6. HYDROLOGY
The Leeuspruit runs through the Leeuspruit Private Nature Reserve in a south-north direction and occur throughout the entire length of the study area. The Leeuspruit is a non-perennial stream and its flow conditions are dependent on seasonal variations (Jansen, 2009). A number of pans and wetlands form in the summer rainfall months due to the continuous supply of water from the Leeuspruit as well as the undulating landscape. The primary catchment of the Leeuspruit Private Nature Reserve is the Vaal River Catchment (SRSA, 2000b).
The runoff of the Leeuspruit Private Nature Reserve can be summarised as follows, based on catchment order: Primary catchment runoff (mean annual runoff 10x m³ per primary catchment) is 3990.96 - 4567.41 (SRSA, 2000a).
Secondary catchment runoff (mean annual runoff 10x m³ per secondary catchment) is 560 – 1135 (SRSA, 2000c).
Tertiary catchment runoff (mean annual runoff 10x m³ per tertiary catchment) is 1 – 12 (SRSA, 2000d).
Quaternary catchment runoff (mean annual runoff 10x m³ per quaternary catchment) is 55 – 233 (SRSA, 2000b).
Tests on the pH of the various water retention features in the seasonal wetlands of the study area indicate that pH ranges from 7-10, depending on the time of day. Diurnal pH fluctuations are dependent on respiration and photosynthesis of aquatic plants during diurnal rhythms (Tucker & D’Abramo, 2008). Many animals have evolved to manage and survive such fluctuations (Tucker & D’Abramo, 2008).
3.7. TOPOGRAPHY
The Leeuspruit Private Nature Reserve is an area that is relatively flat and featureless. The far eastern section of the study area has a mean height of 1464m
17 above sea level. A belt of dolerite rock outcrops runs the length of the eastern section that is 1446m above sea level. Several dolerite outcrops are also present in the study area. The lowest elevation in the Leeuspruit Private Nature Reserve is the far northern corner with a mean elevation of 1433m above sea level. The study area is characterised by slightly undulating plains (ISCW, 2000e).
3.8. VEGETATION
The Leeuspruit Private Nature Reserve has an intermediate vegetation or ecotone that is found between two different vegetative zones; namely the Central Free State Grassland and Soweto Highveld Grassland (Acocks, 1988). The Central Free State Grassland is the dominant vegetation classification of the study area yet it is important to note that the Soweto Highveld Grassland literally boarders the western boundary of the Leeuspruit Private Nature Reserve (Acocks, 1988). The vegetation type of the Leeuspruit Private Nature Reserve is known as the Transitional Cymbopogon Themeda Veld according to Acocks (2000) and Moist Cool Highveld Grassland according to Low & Rebelo (1996).
The Central Free State Grassland occurs largely in the Free State Province and only marginally in Gauteng Province in a broad zone that stretches from Sasolburg in the north to De Wetsdorp in the south (De Wet, 2012a). A number of abundant species of plant were taken as samples to a botanist for identification (Figure 3.6).
In a natural state, the Leeuspruit Private Nature Reserve is dominated by Themeda triandra grass and Eragrostis curvula, E. chloromelas may rapidly dominate due to anthropogenic degradation in the region (Mucina & Rutherford, 2006). This domination is not yet evident in the study area. Dwarf Karoo bushes are established in the degraded clayey regions and Acacia karroo encroachment is prone in the upper elevated regions on heavy clayey soils.
Grass species that were recorded in the Leeuspruit Private Nature Reserve include Aristida diffusa, Brachiaria eruciformis, Cloris virgata, Cymbopogon plurinodis, C. excavates, Cynodon dactylon, Ennaepogon scoparius, E. chloromelas, Eragrostis 18 plana, Helictotrichon turgidulum, Panicum repens, Paspalum dilatatum, Pennisetum clandestinum, Phragmites australis, Setaria sphacelata, Sporobolus festivus, Sporobolus sp. and Themeda triandra (De Wet, 2012a; Van Wyk, 2012b).
Figure 3.6: Plant samples that were taxonomically identified.
Shrub species that were recorded in the Leeuspruit Private Nature Reserve include Asteraceae sp., Berkheya rigida, B. carlinopsis, Cirsium vulgare, Cruciferae sp., Dicoma sp., Flaveria bidentis, Helichrysum aureonitens, Helichrysum sp., Leonotus microphylla, Nasaea sp., Protasparagus laricinus, Protasparagus sp., Schkuhria pinnata, S. pinnata, Stoebe vulgaris, Tagetes minuta, Verbena bonariensis, V. brasiliensis and Walafrida densiflora (De Wet, 2012a; Van Wyk, 2012b).
Tree species that were recorded in the Leeuspruit Private Nature Reserve include Eucalyptus tereticornis, Ligustrum lucidum, Maytenus heterophylla, Salix babylonica and Ziziphus mucronata (Van Wyk, 2012b). Reed species recorded in the
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Leeuspruit Private Nature Reserve include Cyperus esculentus and Mariscus congestus (Van Wyk, 2012b).
Exotic woody species have been established at high densities in the central northern region (Eucalyptus tereticornis) of the study area and some exotics (Salix babylonica) are also seen along the Leeuspruit.
The Weedy Forb ecological unit of the Leeuspruit Private Nature Reserve is severely disturbed with poor observed grass basal cover. The entire study area holds spatially poor vegetation cover that is followed by degraded decreaser-dominated grasslands; especially on dolerite clays around the Weedy disturbed grasslands and wetlands. From this it is evident that the high proportion of pioneer grasses is no coincidence over this degraded landscape. The ecological status of the grassland is generally low to medium.
Serious exotic invader flora has been observed such as Eucalyptus tereticornis, Flaveria bidentis, Ligustrum lucidum, Schkuhria pinnata Tagetes minuta and Verbena brasiliensis (Van Wyk, 2012b). Dwarf Karoo shrubs seem to be multiplying and could pose an environmental degradation problem in the future.
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CHAPTER 4
LITERATURE REVIEW
4.1 INTRODUCTION
Chapter 3 provides a summary of the review of the literature associated with the research problem. This review is presented in two main sections followed by an overview of key findings, gaps in the literature as well as lessons learnt to inform current research. Section 4.2 provides an overview of reptiles and large arachnids that may potentially occur or be associated with the location of the Leeuspruit Nature Reserve. The section also examines some of the ecological requirements of these organisms. Section 4.3 analyses some of the trends associated with the environmental risks linked to the dissemination of alien invaded species in general and specifically to the study area.
4.2. REPTILES AND LARGE ARACHNIDS POTENTIALLY FOUND IN THE LEEUSPRUIT PRIVATE NATURE RESERVE
Economic growth results in an increased utilisation of natural resources that consequently lead to habitat destruction and the loss or fragmentation of suitable habitat (Shanas et al., 2006; Egoh et al., 2011; SAEO, 2012a). The Leeuspruit Private Nature Reserve seems to be an ecological island because all land surrounding the site has been transformed by mining, agricultural or urban activities. The study area itself has been subjected to sub-surface coal mining. This activity occurred mainly in the Free State Province within the grassland biome where large coal deposits exist (National Grassland Biodiversity Programme, 2006 as cited in SAEO, 2012b). This statement is supported by Shanas et al. (2006) and Egoh et al. (2011) which state that a major factor in habitat destruction is the transformation of natural lands into agricultural fields, mining practices and the increase in urban development. Anthropogenic influences on the environment are often inter-related and complex so that the impact on the status of indigenous species and the state of
21 the ecosystem is usually not immediately apparent (Egoh et al., 2011; Zeitsman, 2011 as cited in SAEO, 2012b). The grassland biome is regarded as the heartland of South Africa and therefore under immense developmental pressure that leads to habitat destruction and fragmentation (SAEO, 2012b).
Human induced habitat change is the leading factor in large-scale biodiversity loss and dramatic changes in species diversity and abundance (Shanas et al., 2006). Croplands cover large areas in the Free State (SAEO, 2012a) and therefore endemic species populations are increasingly fragmented and run the risk of expiration.
A number of species potentially occur in the Leeuspruit Private Nature Reserve that are of conservation concern. These species are listed as ‘vulnerable’, ‘near threatened’ or ‘rare’ in the South Africa Red Data Book (McLachlan, 1978; Branch, 1988) or by the International Union for Conservation of Nature (IUCN). Species of concern are as follows (as indicated by Branch, 1998; Marais, 2004; Alexander & Marais, 2007 and Leeming, 2008):
Homoroselaps dorsalis (Striped harlequin snake). IUCN - Near Threatened; Branch (1988) – Rare.
Lamprophis aurora (Aurora house snake). IUCN - To be classified.
Smaug giganteus (Giant girdled lizard). IUCN – Vulnerable; McLachlan (1978) and Branch (1988) – Vulnerable.
Varanus albigularis albigularis (Rock monitor). CITES Appendix ii.
Varanus niloticus (Nile monitor). CITES Appendix ii.
Harpactira spp. (Common baboon spider). Protected, in risk of extinction.
Opistophthalmus spp. (Burrowing scorpion). Protected, in risk of extinction.
An aspect to consider is work conducted by Gauteng Department of Agriculture, Conservation and Environment (GDACE) (2009) which deals with rare species that may be present in the Leeuspruit Private Nature Reserve. However, the occurrence of such rare species has not yet been verified in any clearer detail, even if they can
22 be used as indicators of ecosystem’s health and integrity. For example, in 100 hectares of continuous untransformed grassland in and around the Leeuspruit Private Reserve, the occurrence of Homoroselaps dorsalis (Striped harlequin snake) has not yet been described and quantified (GDACE, 2009).
Internationally, reptiles are the least studied taxon when compared to all other fauna (Bonardi et al., 2011). With regard to reptiles and large arachnids in the Leeuspruit Private Nature Reserve and pertaining to the grassland biome, the species richness is medium to low and endemism is low (Alexander & Marais, 2007). Due to the degradation of the grassland biome, a number of species are of conservation concern (Alexander & Marais, 2007).
4.2.1. Reptiles
Reptiles play several extremely important ecological roles in which they range from primary consumers to top carnivores and occupy a wide range of niches and habitats (Branch, 1998; Sparling et al., 2000; Marais, 2004; Alexander & Marais, 2007). Reptiles are the only group of vertebrates that have not recently undergone a conservation assessment in South Africa (Kearney & Porter, 2009).
Reptiles play an important role in the food webs within the ecosystems in which they exist (Figure 4.1). Reptiles, especially snakes, play a significant role in preserving the balance in nature as many prey on rodents and other vertebrates and insects and other invertebrates; some of which are considered to be pests by humans (FitzSimons, 1974). This important role in controlling pests has been identified by humans to the extent that certain snake species, especially Boaedon capensis (Brown house snake) and Pseudaspis cana (Mole snake), may be periodically released in a problematic area to successfully reduce pest populations (FitzSimons, 1974). For example, Aparallactus capensis (Black-headed centipede-eater) and Duberria lutrix lutrix (South African slug-eater) are encouraged in urban gardens to assist in controlling centipede, termite larvae, snail and slug populations, and Pseudaspis cana (Mole snake) and Boaedon sp. and Lamprophis spp. (House snakes) have been introduced by farmers and grain merchants into their grain sheds
23 with remarkable results (FitzSimons, 1974). Reptiles therefore deserve and require the fullest protection.
According to South African Environmental Outlook SAEO (2012b), 36 indigenous reptile species (8.6% of the total herpetofauna) are listed as threatened by the National Biodiversity Assessment of 2011. Two reptile species are extinct or suspected to be extinct taxa (National Biodiversity Assessment, 2011 as cited in SAEO, 2012b). Although not all the taxa given here occurs in the geographical boundaries of the research site it is none the less an important indicator of biodiversity decline. There are about 384 reptile species found in South Africa of which 43 species are highly dependent or exclusively found in the grassland biome (Steyn et al., 2007; SAEO, 2012b). The grassland biome is a niche habitat that contains many habitat specific species. The grasslands of South Africa are one of the most threatened biomes, with 35% being transformed beyond repair and only 2% formally protected (Egoh et al., 2011; SAEO, 2012b). Land-cover changes as determined by changes in land use are therefore an important indicator of the condition of ecosystems (SAEO, 2012a). Land use changes therefore need to be understood and managed. It is therefore important to note the pioneer work by De Waal (1978), in that no matter how well evolution has moulded the anatomy, physiology and behaviour of reptiles and large arachnids to cope with their environment, they are unable to adapt to rapid change. Ecosystems that retain their balance of biodiversity are more resilient to factors that can degrade them (SAEO, 2012b).
Private land owners are increasingly setting land aside for conservation purposes, where they maintain ownership of their property whilst obtaining formal protected area status according to the National Environmental Management: Protected Areas Act (Act No. 57 of 2003) (SAEO, 2012b). This is a very beneficial practice as conservation areas comprise of not more than 3% of the Free State Province (SAEO, 2012b). Sasol Ltd. being landowners, did not declare Leeuspruit Private Nature Reserve as a formally protected area in terms of the National Environmental Management: Protected Areas Act (Act No. 57 of 2003) or the National Environmental Management: Biodiversity Act (Act No. 10 of 2004) but the land is protected from the public and managed in terms of its rehabilitation plan.
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Figure 4.1: Predation chart of snakes and their eggs (Patterson & Meakin, 1986).
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4.2.1.1. Tortoises and Terrapins
The only species of tortoise which may potentially occur within the geographical range of the Leeuspruit Private Nature Reserve is Stigmochelys pardalis (Leopard tortoise). Tortoises are diurnal reptiles and hence most commonly found during daylight hours (Branch, 1998; Branch, 2008). Stigmochelys pardalis feeds on a variety of plant matter; which is abundantly available in the Leeuspruit Private Nature Reserve. Stigmochelys pardalis requires plenty of vegetative cover (especially juveniles) and this species is prone to hibernate in abandoned animal burrows or deep in vegetation together with other reptile species (Boycott & Bourquin, 2000).
Conservation protection is offered to this species as in some areas local populations have been declining due to the pet trade and introduction of electric fencing (Branch, 2008).
One species of terrapin falls within the geographical range of the Leeuspruit Private Nature Reserve. Pelomedusa subrufa (Marsh terrapin) has a vast distribution range all over Africa and is a very common species in suitable habitats (Branch, 2008; Vargas-Ramirez et al., 2010). This species is omnivorous, consuming almost anything edible and generally hibernates in burrows excavated in soft soil (Boycott & Bourquin, 2000; Marais, 2004; Alexander & Marais, 2007; Branch, 2008).
This species is extensively poached for the pet trade and is occasionally consumed by humans (Branch, 2008; Vargas-Ramirez et al., 2010). However, due to its pungent smell very few people eat them (Branch, 2008).
4.2.1.2. Snakes
Whereas reptiles and arachnid species have important ecological roles to play, many of them are also useful to humans. Boaedon capensis (Brown house snake), given its rodent diet can be considered a human commensal. Patterson (1987) and Jacobsen (2005) state that this species is one of South Africa’s most useful reptiles. Pseudaspis cana (Mole snake) is similarly as useful at controlling bulkier rodents due to its larger size, and it is regarded as completely harmless and an inveterate rodent catcher (Jacobsen, 2005). Both P. cana and B. capensis can be found in a range of
26 habitats, P. cana spending most of its time underground and B. capensis can be found under any type of cover, be it natural or man-made (Marais, 2004; Alexander & Marais, 2007).
Aparallactus capensis (Black-headed centipede-eater) and D. lutrix lutrix (South African slug-eater) are extremely useful due to their specialised diets (FitzSimons, 1974). Aparallactus capensis feeds exclusively on centipedes and termite lava, and D. lutrix lutrix feeds exclusively on slugs and snails (FitzSimons, 1974; Jacobsen & Haacke, 1980; Patterson & Meakin, 1986; Patterson, 1987; Branch, 1998; Alexander & Marais, 2007). Duberria lutrix lutrix favours damp locations where its source of food is abundant and A. capensis generally spends its life in moribund termitaria and under suitable natural cover (Branch, 1998; Marais, 2004).
Other specialised diets are seen in Dasypeltis scabra (Rhombic egg-eater), Causus rhombeatus (Rhombic night adder), Lycodonomorphus rufulus (Brown water snake), Crotaphopeltis hotamboeia (Red-lipped snake), Prosymna sundevallii (Sundevall’s shovel-snout) and Lycophidion capense capense (Cape wolf snake) (Marais, 2007; Marais, 2011). Dasypeltis scabra feeds exclusively on bird’s eggs (Branch, 1998; Jacobsen, 2005; Marais, 2007; Alexander & Marais, 2007; Marais, 2011). Causus rhombeatus, L. rufulus and C. hotamboeia feed primarily but not exclusively on amphibians (Branch, 1998; Alexander & Marais, 2007). Prosymna sundevallii feeds on small invertebrates, and L. capense capense feeds on skinks and other snakes (FitzSimons, 1974; Jacobsen & Haacke, 1980; Patterson & Meakin, 1986; Patterson, 1987; Branch, 1998; Jacobsen, 2005; Alexander & Marais, 2007). These species are generally found under rock, logs or any other form of suitable cover.
The five fossorial species potentially found within the geographical range of the Leeuspruit Private Nature Reserve are important for specialised diets in their own right. These species include Rhinotyphlops lalandei (Delalande’s beaked blind snake), Afrotyphlops bibronii (Bibron’s blind snake), Leptotyphlops scutifrons scutifrons (Peters’ thread snake), Leptotyphlops incognitus (Incognito Thread snake) and Leptotyphlops scutifrons conjunctus (Eastern Cape thread snake). All of these species of fossorial blind and thread (worm) snakes spend their lives underground and are therefore rarely seen (Jacobsen & Haacke, 1980; Patterson & Meakin, 1986; Marais, 1999; Jacobsen, 2005; Marais, 2007). These snakes are very well adapted
27 to a fossorial existence and little is known about their habits, biology and breeding (Jacobsen, 2005). These snakes play a significant role in invertebrate (especially ants and termites) population control as these invertebrates form the staple diet of the aforementioned snake species (Branch, 1998; Jacobsen, 2005; Alexander & Marais, 2007). These fossorial species are also largely reliant on specific soil type and texture to facilitate their burrowing existence (Branch, 1998).
These specialised diets in the aforementioned species of the genera Duberria, Aparallactus, Rhinotyphlops, Afrotyphlops and Leptotyphlops maintain vertebrate and invertebrate populations that are seldom preyed upon by other species.
A total of five grass and sand snakes potentially occur within the geographical range of the Leeuspruit Private Nature Reserve (Patterson and Meakin, 1986; Branch, 1998; Jacobsen, 2005; Alexander & Marais, 2007). These include Psammophis brevirostris (Short-snouted grass snake), Psammophis trinasalis (Fork-marked sand snake), Psammophis crucifer (Cross-marked grass snake), Psammophylax rhombeatus rhombeatus (Spotted grass snake) and Psammophylax tritaeniatus (Striped grass snake). These snake species eat a variety of rodents, amphibians, lizards and birds as well as other snakes (FitzSimons, 1974; Jacobsen & Haacke, 1980; Patterson & Meakin, 1986; Patterson, 1987; Branch, 1998; Jacobsen, 2005; Alexander & Marais, 2007; Marais, 2011). These species are all diurnal and extremely active, seeking refuge under rocks, in holes, under logs, etc. Psammophylax rhombeatus rhombeatus is especially interesting as this species lays well-developed eggs that hatch after a brief incubation period and it is one of two snake species in southern Africa that is known to guard its eggs until they hatch. This adaptation may well indicate a shift from being oviparous to viviparous (Marais, 2004).
Bitis arietans arietans (Puff adder) and Hemachatus haemachatus (Rinkhals) are the only two medically important snakes that potentially occur in the Leeuspruit Private Nature Reserve. This is not to say that these species are the only snakes with venom potentially occurring in the research site, but their envenomation may be life threatening. Bitis arietans arietans is a hinged front fanged species with cytotoxic venom that attacks cells and tissue, especially blood and vessels (Blaylock, 2005). Hemachatus haemachatus is a front fixed fanged species with dangerous neurotoxic
28 venom that also has cytotoxic properties which attacks the muscles and central nervous system (Blaylock, 2005). These species have a varied diet which includes amphibians, rodents, lizards, other snakes, birds and their eggs, and other vertebrates (FitzSimons, 1974; Jacobsen & Haacke, 1980; Patterson & Meakin, 1986; Patterson, 1987; Branch, 1998; Marais, 1999; Jacobsen, 2005; Alexander & Marais, 2007; Marais, 2011). These species are generally diurnal and favour almost any form of retreat available. Both these species are viviparous.
Lamprophis aurora (Aurora house snake) and the Lycodonomorphus inornatus (Olive ground snake) are interesting and relatively rare species. L. aurora is currently under conservation evaluation (Alexander & Marais, 2007). These species mainly eat rodents and lizards and on occasion amphibians and other snakes (Jacobsen & Haacke, 1980; Marais, 2008). Lamprophis aurora and L. inornatus are generally found under rocks and in moribund termitaria. Philothamnus semivariegatus (Spotted bush snake) and Philothamnus hoplogaster (South eastern green snake) feed on lizards, amphibians and the occasional invertebrate (Marais, 2004; Alexander & Marais, 2007). Elapsoidea sundevallii media (Highveld garter snake) is a venomous species that feeds on a variety of rodents, amphibians, other snakes and lizards and is mainly found under rocks, logs and in moribund termitaria (FitzSimons, 1974; Marais, 2004; Alexander & Marais, 2007).
A species of whose survival is of great concern is Homosorelaps dorsalis (Striped harlequin snake). This species has been classified as ‘rare’ in the South African Red Data Book: Reptiles and Amphibians since 1988 (Branch, 1988) and as ‘near threatened’ by the IUCN. The reason as to why this species is of interest; is due to its rare status as well as its geographical distribution (potentially including the Leeuspruit Private Nature Reserve). This species has been recorded in Suikerbosrand Nature Reserve (Branch, 1988) and the possibility of it occurring in the Leeuspruit Private Nature Reserve is very high. Homoroselaps dorsalis is an extremely secretive and rare species (Branch, 1998) and chances of finding this species in the Leeuspruit Private Nature Reserve are very slim; although it may well occur in the region.
A species of the same genus as H. dorsalis, Homosorelaps lacteus (Spotted harlequin snake) also occurs in the geographical region. Both H. dorsalis and H.
29 lacteus feed primarily on blind snakes (Typlopidae) and thread snakes (Leptotyphlopidae) (Branch, 1998; Jacobsen, 2005; Alexander & Marais, 2007) and spend most of their time in moribund termitaria.
The Leeuspruit Private Nature Reserve can be seen as an interesting biodiversity spot in terms of snake species richness. These species coexist due to a number of suitable micro-habitats favoured by individual species and the availability of adequate food sources. For example, snakes that feed mainly on amphibians (C. rhombeatus, C. hotamboeia and L. rufulus) need proximity to a permanent water source. The terrestrial snakes (B. capensis, L. aurora, Psammophis spp., Psammophylax spp., H. haemachatus, B. arietans arietans, etc.) prefer the flat grasslands and retreat under stones, in holes, in moribund termitaria or any other means of cover (Branch, 1998; Alexander & Marais, 2007). The fossorial species of the genera Homoroselaps, Rhinotyphlops, Afrotyphlops and Leptotyphlops spend most of their lives underground and prefer a binding moist soil or leaf litter as retreats and hunting grounds (Branch, 1998). Moribund termitaria are commonly used as a retreat by A. capensis, L. aurora, B. capensis, D. scabra, Psammophylax spp., Psammophis spp., L. capense capense, Homoroselaps spp., C. hotamboeia, R. lalandei, A. bibronii and Leptotyphlops spp. (Branch, 1998; Jacobsen, 2005; Alexander & Marais, 2007).
4.2.1.3. Lizards
Skinks are the most diverse group of lizards in southern Africa (Branch, 1998) and a total of five species potentially occur in the geographical location of the Leeuspruit Private Nature Reserve. These five species include Acontias gracilicauda (Thin- tailed legless skink), Trachylepis capensis (Cape skink), Trachylepis punctatissima (Speckled rock skink), Trachylepis varia (Variable skink) and Afroablepharus wahlbergii (Wahlberg’s snake-eyed skink).
Acontias gracilicauda is a legless skink species that prefers moist soils and feeds on invertebrates (Branch, 1998; Alexander & Marais, 2007).
Trachylepis capensis, T. punctatissima, T. varia and A. wahlbergii are common skinks that have a very good chance at inhabiting the Leeuspruit Private Nature
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Reserve. These skinks are diurnal and feed on a variety of invertebrates (Branch, 1998; Alexander & Marais, 2007; Marais, 2011). Finding these species basking in the sun shine is rather straight-forward and more so in terms of identification as these skink species are very distinctive from one another. These skinks shelter under rocks, in vegetation litter, under logs and any other form of cover.
Four typical lizards (Lacerta) may be found which include Nucras lalandii (Delalande’s sandveld lizard), Pedioplanis lineoocellata lineoocellata (Spotted sand lizard), Ichnotropis squamulosa (Common rough-scaled lizard) and Gerrhosaurus flavigularis (Yellow-throated plated lizard). These are all diurnal lizards and feed on a variety of invertebrates (Branch, 1998; Alexander & Marais, 2007). All of these species burrow in soil to some extent and may also be found under rocks, logs and on rock outcrops (Branch, 1998; Alexander & Marais, 2007; Marais, 2011).
Cordylus vittifer (Common girdled lizard) and Smaug giganteus (Giant girdled lizard) are invertebrate feeders, with S. giganteus occasionally feeding on small vertebrates and only lives in self-constructed burrows. Smaug giganteus is of key concern as the species is given ‘vulnerable’ status by the IUCN (Alexander & Marais, 2007). This species may not be as threatened in the Leeuspruit Private Nature Reserve if it is found there but there is concern that the population may be too small to sustain itself. Cordylus vittifer on the other hand, only occupies fissures in rock outcrops as a retreat. Both species are oviparous. Many of these are habitat specific species such as Cordylus vittifer which occupy rock outcrops and use cracks and fissures as retreats, N. lalandii commonly digs holes under rocks and P. lineoocellata lineoocellata prefers flat rocky grassveld (Branch, 1998; Alexander & Marais, 2007).
The only two monitor lizard (varanidae) species found in southern Africa may potentially occur in the geographical range of the Leeuspruit Private Nature Reserve. These two species are namely Varanus albigularis albigularis (Rock monitor) and Varanus niloticus (Water monitor). These species are the two largest lizards in southern Africa and feed on anything from invertebrates to vertebrates and more specifically anything they can overpower and swallow. Both species of varanidae are protected by CITES International Legislation under Appendix 2 (Alexander & Marais, 2007) and both species have appeared in the South African Red Data Book (McLachlan, 1978) although this status was recently downgraded due to their wide
31 spread distribution. The two Varanus spp. make use of active termitaria for egg deposition and generally retreat in any crevice, hole or cover available.
Agama aculeata distanti (Distant’s ground agama) and Agama atra (Southern rock agama) are both diurnal and terrestrial, although A. atra is commonly found around rock outcrops (Alexander & Marais, 2007). These are lizards that are common in suitable habitats and one can stalk these species to only a few meters for identification (Alexander & Marais, 2007). These agamid species are very energetic during the day and actively prey on invertebrates. Due to the undulating landscape of the Leeuspruit Private Nature Reserve these agamid species are in prime habitat as they prefer rocky and elevated terrains.
Two gecko species have the potential of occurring in the Leeuspruit Private Nature Reserve (Branch, 1998; Alexander & Marais, 2007). These include Lygodactylus capensis capensis (Common dwarf gecko) and Pachydactylus capensis (Cape gecko). Lygodactylus capensis capensis is a diurnal species that feeds on invertebrates and may use any form of crevice or cover as a retreat. Pachydactylus capensis is a nocturnal species that feeds on invertebrates and is commonly found under rocks and in moribund termitaria.
Chamaeleo dilepis dilepis (Common flap-necked chameleon) is the only chameleon species that falls within the geographical range of the Leeuspruit Private Nature Reserve (Alexander & Marais, 2007; Tolley & Burger, 2007). This species appears to survive well during the winter months in the Highveld and feeds on a variety of insects with strictly diurnal habits (Branch, 1998; Alexander & Marais, 2007). Chamaeleo dilepis dilepis favours a variety of shrubs and trees, both exotic and indigenous (Branch, 1998; Alexander & Marais, 2007).
4.2.2. Large Arachnids
The ecological value and function of large arachnids in South Africa often goes unnoticed, but these species are an important component of interdependent food webs in the Highveld grasslands (Dippenaar-Schoeman, 2002; Leeming, 2008).
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According to the National Environmental Management: Biodiversity Act (Act No. 10 of 2004), protection status is provided to Harpactira hamiltoni (Golden starbust baboon spider) as well as Opistophthalmus pugnax (Pugnacious burrowing scorpion), as these species are facing a high risk of extinction in the medium-term future (Leeming, 2008). Both of these species potentially occur in the Leeuspruit Private Nature Reserve (Dippenaar-Schoeman, 2002; Leeming, 2003).
Baboon spiders of the family Theraphosidae, including H. hamiltoni (Golden starbust baboon spider) are in great demand in the pet trade and are consequently regarded as commercially threatened by the International Union for the Conservation of Nature (IUCN). Scorpions are also commonly captured and kept as novel pets, which leads to population decline and fragmentation. In 1987, three Theraphosidae genera including Harpactira were added to Schedule VII of the Transvaal Provincial Nature Conservation Ordinance of 1983 as Protected Invertebrate Animals (Dippenaar- Schoeman, 2002).
Large arachnids in southern Africa are undergoing extensive taxonomic revision at present and many species are in genera that are currently under taxonomic review (Gallon, 2002).
4.2.2.1. Baboon Spiders
Baboon spiders have generally been poorly assessed in South Africa with no conclusive distribution maps. Even more problematic is that a number of distinct species have not been described yet and there is a lack in taxonomic assessment. According to Dippenaar-Schoeman (2002), current knowledge of species distributions indicates that Harpactira hamiltoni (Golden starbust baboon spider) is the only baboon spider species that potentially occurs in the Leeuspruit Private Nature Reserve.
An important note is that H. hamiltoni is a soil specific species as they are regarded as burrowers and soils need to be of a composition that can facilitate excavation (Dippenaar-Schoeman, 2002; Gildenhuys, 2009). Burrows are lined with silk and are constructed in the open, under a tuft of grass or a rock and the entrance is covered with a thin layer of silk when not active (Dippenaar-Schoeman, 2002). Males can
33 frequently be found temporarily sheltering under any form of cover due to their constant movements in search of a mate (Dippenaar-Schoeman, 2002; Gildenhuys, 2009). Baboon spiders generally sit at the entrance of their burrows and prey on invertebrates, arachnids, and small vertebrates that venture close-by; this is especially true for Theraphosidae (Dippenaar-Schoeman, 2002).
4.2.2.2. Scorpions
Scorpion identification is less problematic than baboon spiders but none the less a significant number of species have not fully been described yet and distribution maps generalise species localities.
According to Leeming (2003), three species of scorpion may potentially occur in the Leeuspruit Private Nature Reserve. These include Pseudolychas ochraceus, Uroplectes triangulifer triangulifer and Opistophthalmus pugnax (Leeming, 2003). Other species may occur in the research site and in this case, new distribution ranges will be acknowledged.
A very important aspect needs mentioning; previously the species Pseudolychas ochraceus was mistakenly identified as Pseudolychas pegleri and therefore P. pegleri would have been mistakenly added to the list of species potentially found in the study area. Prendini (2004) clarified this mistake by noting the confusion surrounding the distribution of both P. pegleri and P. ochraceus and concluded that P. ochraceus occupies the distribution range that was previously thought to be that of P. pegleri. This mistaken identification was overlooked to an extent that Leeming (2003) published this wrong information in ‘Scorpions of southern Africa’. It is therefore concluded that P. ochraceus may potentially occur in the study area and not P. pegleri, as some distribution maps and literature mistakenly states.
Pseudolychas ochraceus and U. triangulifer triangulifer are terrestrial species that generally make a scrape under rocks, logs, vegetation litter and bark as a retreat, although U. triangulifer triangulifer prefers rocks (Leeming, 2003). These two species feed on invertebrates and avoid moist locations. Uroplectes triangulifer triangulifer is a very common species in the Highveld (Leeming, 2003).
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Opistophthalmus pugnax is a burrowing species that relies on specific soils to construct a horizontal burrow under rocks and other surface debris (Leeming, 2003). This species is relatively large (up to 70mm long) and feeds primarily on invertebrates (Leeming, 2003).
It is interesting to note that three different species of scorpion potentially occur in the Leeuspruit Private Nature Reserve that are divided into three genera.
4.3. REPTILE AND LARGE ARACHNID BIOLOGY
Reptiles and large arachnids generally brumate or at least remain inactive (torpor) during unfavourable weather conditions such as the winter months, between prolonged drought cycles, and when conditions exceed a specimen’s capacity for homeostasis (Marais, 2004). Individuals then feed voraciously when conditions improve and food is abundant. Hibernation and dormancy is therefore the direct result of cold temperatures and/or changes in resource availability. Reptiles and large arachnids have developed a number of biological tools to benefit energetically from these adaptive responses which conserve energy during their months of dormancy and inactivity (Shanas et al., 2006).
Species richness is most clearly observed during spring and summer when feeding and mating behaviour are at their peak following seasonal inactivity (Buys & Buys, 1983; Branch, 1998; Shanas et al., 2006; Alexander & Marais, 2007). Reptile and arachnid activity peaks on the arrival of the rainy season (Marais, 2004; Shanas et al., 2006). I have observed this phenomenon numerous times after heavy rain when it seems that the veld comes to life as reptiles and large arachnids are seen in abundance. Another peak in activity is noted towards the end of the summer months when reptiles and large arachnids are actively seeking out food to ensure adequate fat reserves and shelter for the approaching cold season (Marais, 2004).
Reptiles may either be oviparous or viviparous depending on the genus and sometimes the species or geographical location of a species. Viviparous species possess a placenta that has a similar function to the mammalian uterus (Fitzsimons, 1974). These species simply find a secluded site and give live birth to their offspring. Oviparous species lay eggs in suitably secluded and moist sites that generally
35 uphold a constant temperature gradient; such as under a rock, in rotting vegetation or in a burrow (Branch, 1998). Viviparous species increase the likelihood of their offspring surviving as some parental care is offered until juveniles are fully developed but oviparous species simply lay partially developed eggs, leaving a higher probability of fatalities occurring. On the contrary, viviparous species spend more energy in reproduction as offspring is developed inside females over the entire gestation period and oviparous species require less energy input as eggs are deposited partially developed (Branch, 1998).
There are two main methods employed as hunting techniques by reptile and large arachnid species. The one being active pursuit of prey and the other being ambush predators (Shanas et al., 2006). Active pursuit of prey requires more energy consumption as the species is in constant activity in search of prey while ambush predator species lie and wait for prey to cross within range of capture. The benefit of ambush predation is that energy usage is at a minimum and by down-regulating intestinal function and morphology with the completion of digestion, energy expenditure between meals is reduced (Shanas et al., 2006). To a certain extent, all large arachnids (primarily females) (Dippenaar-Schoeman, 2002) and snakes such as Bitis arietans arietans (Puff adder) are typical ambush predators. Active foraging requires more energy but the succession of catching prey is much higher and therefore energy spent is energy received. Typical active foragers are species of the families: Elapidae (mambas, cobras and their relatives), Atractaspididae (African burrowing snakes), Lamprophiidae (African nocturnal snakes) Colubridae (typical snakes), Psammophiidae (sand snakes and allies), Typhlopidae (blind snakes), Leptotyphlopidae (thread snakes), Scincidae (skinks), Lacertidae (lacertids), Gerrhosauridae (plated lizards), Cordylidae (girdled lizards), Varanidae (monitors), Agamidae (agamas), Chamaeleonidae (chameleons), Gekkonidae (geckos), Buthidae (thick-tailed and bark scorpions), Scorpionidae (burrowing scorpions) and Theraphosidae (baboon spiders).
Baboon spiders are regarded as more primitive amongst the large arachnids and little information is available on their behaviour and biology in southern Africa (Dippenaar-Schoeman, 2002). Male Harpactira hamiltoni (Golden starbust baboon spider) are more likely to be found than females. This is because naturally their females are outnumbered by males that are scattered in the vicinity around a single
36 female; a typical matriarchal colony (Gildenhuys, 2009). Harpactira hamiltoni females seldom venture outside of their burrows while males wander around in search of females (Gildenhuys, 2009). All baboon spiders dig burrows to some or other degree. These silk-lined burrows are very important for a well-balanced microclimate and protection (Dippenaar-Schoeman, 2002). Eggs are deposited in a silk constructed egg sac which the females guard in their burrows (Dippenaar- Schoeman, 2002).
4.4. ALIEN INVADER RISKS
The threat of alien invader species needs to be emphasised as alien reptiles and large arachnids that are exotic to the region may potentially occur in the Leeuspruit Private Nature Reserve. According to Van Wilgen et al. (2010), 275 alien reptile species from 30 families have been introduced into South Africa by means of the exotic pet trade. Some exotic reptile and arachnid species escape from captivity into the wild or are released by their owners due to the animals becoming too big to manage or too aggressive (Van Wilgen et al., 2010). Alien reptiles and large arachnids pose many serious bio-ecological problems such as food and habitat competition with native species, the introduction of new diseases, predation on indigenous species, hybridization with indigenous species and attacks on humans, livestock and wild animals (Van Wilgen et al., 2008). United Nations Environmental Programme (UNEP) (2002) and World Resources Institute (WRI) (2000) as cited in State of the Environment Report (SOER): Mangaung (2003), state that the introduction of alien species is one of the major threats to indigenous biodiversity. There is a possibility that an exotic reptile or arachnid species has been introduced into the Leeuspruit Private Nature Reserve and if such a species is located it should be removed immediately.
Trachemys scripta elegans (Red-eared slider) (Figure 4.2) is renowned as an alien invader and this species has become established around the country after owners released them. This species is listed as a prohibited alien invader in South Africa and if encountered, needs to be destroyed (Bruton & Merron, 1985; Branch, 1998). A number of these exotic Red-eared sliders have been released around Pretoria, Johannesburg and Durban (Branch, 1998). Trachemys scripta elegans could
37 potentially occur in the study area as well as other invasive and exotic reptile and large arachnid species.
Figure 4.2: Trachemys scripta elegans (Red-eared slider) are known to be persistent alien invaders.
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CHAPTER 5
RESEARCH METHODOLOGY
5.1 INTRODUCTION
The following chapter deals with the various methods utilised in the research conducted. Firstly, the development of species inventories is discussed in order to acknowledge how species potentially found in the study area were listed. The methodology behind field work and data capture is discussed, explaining and detailing the primary method (physically searching for, identifying and listing species and ecological variables) as well as the use of pitfall traps and funnel trap arrays. The analysis of ecological requirements entails a detailed discussion of the identification of suitable and necessary ecological variables utilised by the various species. The basis of the model developed to analyse the dependency of species based on their occurrence and suitability of habitat is further discussed with an emphasis on how such a scoring system combined with ecological requirements is utilised to shed light on species survival requirements. Tables and various graphs are included to support the literature and methodology discussion that follows.
5.2 DEVELOPMENT OF SPECIES INVENTORIES
Since this research is the first ecological study on the reptiles and large arachnids of the Leeuspruit Private Nature Reserve there was no data available from past studies. An inventory was created on all the reptiles and large arachnids that could potentially be found at the study area. The inventory was created from the known species distribution ranges based on the works of FitzSimons (1974); De Waal (1978); Jacobsen & Haacke (1980); Patterson & Meakin (1986); Branch (1998); Marais (1999); Boycott & Bourquin (2000); Dippenaar-Schoeman (2002); Leeming (2003); Leroy & Leroy (2003); Marais (2004); Tolley & Burger (2007); Alexander & Marais (2007); Branch (2008); Holm & Dippenaar-Schoeman (2010); as well as on databases (ReptileMAP, ScorpionMAP, SpiderMAP; Animal Demography Unit: UCT)
39 and the researchers own knowledge of species distributions. All these sources were consulted to determine the geographical distributions of all reptiles and large arachnids found in southern Africa that may potentially occur in the Leeuspruit Private Nature Reserve or within a reasonable range of the study area. The species that potentially occur within the geographical location of the Leeuspruit Private Nature Reserve were then compiled in a species potential inventory.
The species potential inventory compiled does not mean that the species listed are the only species potentially found in the Leeuspruit Nature Private Reserve nor does it mean that all these species will occur in the study area. On numerous occasions, reptile and large arachnid species that are well out of their distribution ranges based on current literature have been identified in regions where there are no previous records of such species. Such new distribution ranges are an important contribution to a better understanding of species requirements, thus the data collected and analysed have the potential to be useful in similar studies in the future.
Various databases were consulted to determine the conservation status of species potentially found in the study area which include the ReptileMAP (formerly known as the South African Reptile Conservation Assessment; SARCA), ScorpionMAP, SpiderMAP, South African National Survey of Arachnida (SANSA), South African National Biodiversity Institute (SANBI), Convention on International Trade in Endangered Species (CITES), South African Red Data Books, International Union for Conservation of Nature (IUCN) and Alexander & Marais (2007).
The probability of a species of reptile or large arachnid occurring in the Leeuspruit Private Nature Reserve was based firstly on the geographical distribution of each species and secondly on the availability of suitable on-site habitat. These two methods are only probability determinants and in order to determine which species actually occur in the Leeuspruit Private Nature Reserve the species need to be physically found, identified and photographed.
The following criteria discussion on occurrence probabilities has been adapted from Kalibbala (2011) and minor changes have been made based on adjustments suited to the species concerned in this research: 40
A high probability of a species occurring would be applicable to a species which geographical distribution overlies the study area as well as the presence of suitable ecological variables (food and habitat requirements). A high probability will also be considered for species that are regarded as common, or species that are normally considered to occur at high densities (Boaedon capensis, Dasypeltis scabra, Hemachatus haemachatus, Crotaphopeltis hotamboeia and Uroplectes triangulifer triangulifer).
Consequently, a medium probability of occurrence would be applicable to a species which geographical distribution peripherally (just enters or just misses) overlies the study area but the ecological requirements are sub-suitable, with the exception of species known for advanced adaptation capabilities. The medium probability species occurrence criteria work similarly and vice versa. If a species geographical distribution peripherally overlies the study site but there is favourable ecological conditions for the species to survive it will receive medium occurrence status. The species listed as medium probability of occurrence are species that usually do not occur at high densities (Lamprophis aurora, Elapsoidea sundevallii media, Varanus albigularis albigularis, Pseudolychas ochraceus and Harpactira hamiltoni).
A status of low probability of occurrence of a species is given if a species geographical distribution is peripheral to or does not overlie the study area and if the ecological requirements of that species are very limited or non-existent. A low probability of occurrence also applies to species that are known to be very rare (Lycodonomorphus inornatus and Homoroselaps dorsalis).
The inventory of all the species that could potentially occur in the study area includes each species’ scientific name, common name, endemism and the probability of a species occurring based on the outcome of extensive literature review and analysing the habitat and dietary variables present in the study area (Table 5.1 and Table 5.2). The arrangement of snake families in the inventory was based on recent molecular phylogeny as proposed by Kelly et al. (2008).
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Table 5.1: Species potentially occurring in the Leeuspruit Private Nature Reserve with key notes. Taxonomic Break Common Name Endemism Probability of Down and occurrence Scientific Name CLASS: REPTILES REPTILIA Order: SCALED REPTILES SQUAMATA Suborder: Snakes Serpentes Family: Viperidae Adders and vipers Causus rhombeatus Rhombic night adder Medium
Bitis arietans arietans Puff adder Medium Family: Elapidae Mambas, cobras and their relatives Hemachatus Rinkhals Endemic – High haemachatus southern Africa Elapsoidea sundevallii Highveld garter snake Endemic – Low media southern Africa Family: African burrowing snakes Atractaspididae Homoroselaps lacteus Spotted harlequin snake Endemic – Medium South Africa Homoroselaps dorsalis Striped harlequin snake Endemic – Low South Africa Aparallactus capensis Black-headed centipede- High eater Family: Sand snakes and allies Psammophiidae Psammophis Short-snouted grass snake Medium brevirostris Psammophis trinasalis Fork-marked sand snake Low Psammophis crucifer Cross-marked grass snake Endemic – High southern Africa Psammophylax Spotted grass snake High rhombeatus rhombeatus Psammophylax Striped grass snake Medium tritaeniatus Family: Colubridae Typical snakes Crotaphopeltis Red-lipped snake High hotamboeia
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Philothamnus Spotted bush snake Low semivariegatus Philothamnus South eastern green snake Low hoplogaster Dasypeltis scabra Rhombic egg-eater High Family: African nocturnal snakes Lamprophiidae Boaedon capensis Brown house snake High Lycodonomorphus Olive ground snake Endemic – Low inornatus South Africa Lycodonomorphus Brown water snake Endemic – High rufulus southern Africa Lamprophis aurora Aurora house snake Endemic – Medium South Africa Lycophidion capense Cape wolf snake Medium capense Family: Mole and keeled snakes Pseudaspididae Pseudaspis cana Mole snake High Family: Prosymnidae Shovel-snouted snakes Prosymna sundevallii Sundevall’s shovel-snout Endemic – Low southern Africa Family: Afro-malagasy snakes Pseudoxyrhophiidae Duberria lutrix lutrix South African slug-eater Medium Family: Typhlopidae Blind snakes Rhinotyphlops lalandei Delalande’s beaked blind Endemic – Medium snake southern Africa Afrotyphlops bibronii Bibron’s blind snake Endemic – High southern Africa Family: Thread snakes Leptotyphlopidae Leptotyphlops Peters’ thread snake High scutifrons scutifrons Leptotyphlops Eastern Cape thread snake High scutifrons conjunctus Leptotyphlops Incognito thread snake Medium incognitus Suborder: Sauria Lizards Family: Scincidae Skinks Acontias gracilicauda Thin-tailed legless skink Endemic – Medium South Africa Trachylepis capensis Cape skink High Trachylepis Speckled rock skink High punctatissima
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Trachylepis varia Variable skink High Afroablepharus Wahlberg’s snake-eyed High wahlbergii skink Family: Lacertidae Old world lizards or lacertids Ichnotropis Common rough-scaled Low squamulosa lizard Nucras lalandii Delalande’s sandveld lizard Endemic – Low South Africa Pedioplanis Spotted sand lizard Endemic – Low lineoocellata southern lineoocellata Africa Family: Plated lizards and Gerrhosauridae relatives Gerrhosaurus Yellow-throated plated Low flavigularis lizard Family: Cordylidae Girdled lizards and relatives Smaug giganteus Giant girdled lizard Endemic – Low South Africa Cordylus vittifer Common girdled lizard Medium Family: Varanidae Monitors Varanus albigularis Rock monitor Low albigularis Varanus niloticus Nile monitor Medium Family: Agamidae Agamas Agama aculeata Distant’s ground agama High distanti Agama atra Southern rock agama Endemic – High southern Africa Family: Chameleons Chamaeleonidae Chamaeleo dilepis Common flap-neck Medium dilepis chameleon Family: Gekkonidae Geckos Lygodactylus capensis Common dwarf gecko High capensis Pachydactylus capensis Cape gecko Endemic – High southern Africa Suborder: Modern tortoises Cryptodira Family: Testudinidae Land tortoises Stigmochelys pardalis Leopard tortoise Medium Suborder: Side-necked terrapins Pleurodira Family: Side-necked terrapins
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Pelomedusidae Pelomedusa subrufa Marsh terrapin High CLASS: ARACHNIDS ARACHNIDA Order: SCORPIONS SCORPIONES Suborder: African scorpions Neoscorpionina Family: Buthidae Thick-tailed and bark scorpions Pseudolychas Plain pygmy-thicktail Endemic – Medium ochraceus South Africa Uroplectes triangulifer Highveld lesser-thicktail Endemic – High triangulifer South Africa Family: Scorpionidae Burrowing scorpions Opistophthalmus Pugnacious burrowing Endemic – High pugnax scorpion South Africa Order: ARANEAE SPIDERS Suborder: Trapdoor and Baboon Mygalomorphae spiders Family: Baboon spiders Theraphosidae Harpactira hamiltoni Golden starbust baboon Endemic – Medium spider South Africa
The inventory that was created includes the following species which potentially could occur in the Leeuspruit Private Nature Reserve; 29 species of the Serpentes suborder which are represented by eleven families and 21 genera; 18 species of the Sauria suborder which are represented by eight families and 14 genera; one species of the Cryptodira suborder; one species of the Pleurodira suborder, three species of the Neoscorpionina suborder which are represented by two families and three genera and one species of the Mygalomorphae suborder.
5.3. FIELD WORK AND DATA CAPTURE
Two main methods of field work and data capture were employed in this study, namely; the primary method (active searching for reptiles and large arachnids) and the secondary method of the utilisation of pitfall trap and funnel trap arrays. The
45 estimated field time that the researcher took over the one year period whilst conducting this research is estimated to be in the order of 500 hours.
5.3.1. Primary method
It must be borne in mind that reptiles and large arachnids are generally very secretive animals that avoid detection (Branch, 1998; Marais, 2004). The majority of reptiles and large arachnids are nocturnal and often only seasonally active which adds to their cryptic behaviour.
Reptiles and large arachnids are seldom observed in abundance and therefore some searching was necessary to provide the primary data required. The identification of as many species as possible in the study area is a major contribution to current literature given that there is no knowledge on which species actually occur in the Leeuspruit Private Nature Reserve. By having a good understanding of the natural history of reptiles and large arachnids, one can limit searches to specific conditions to obtain the most successful outcomes. For example, during the field work it became clear that a number of more common species are located frequently. Species specific searches were also done, based on the researcher’s past knowledge of different retreats commonly used by a specific species as well as diurnal and seasonal activity patterns based on the more ‘uncommon’ species.
The primary method for finding reptiles and large arachnids is to search under boulders and rock flakes, in moribund termitaria, trees, under vegetation litter and in holes or any other naturally occurring crevice (Branch, 1998; Marais, 2004; Alexander & Marais, 2007). Here again it is important to understand the preferred retreats utilised by different species (Table 5.2). As a result, regular site visits were undertaken in an attempt to find and identify as many reptiles and large arachnids as possible over the research period. Interestingly, in a pilot study conducted by the researcher in the Leeuspruit Private Nature Reserve, six species of snake, three species of lizard, one species of terrapin and three species of large arachnid, all of which pertained to this study, were found in just three days.
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The study area was visited on a weekly basis (Monday to Friday) during warm weather conditions and visits were limited to fortnight intervals during the cold winter months as species enter a state of torpor and become generally inactive. Figure 5.1 portrays the protective gear and equipment that was needed to conduct the primary method of searching for reptiles and large arachnids. Each species of reptile and large arachnid identified was recorded in the inventory and photos were taken, as well as the number of individuals of each species found.
Figure 5.1: Protective gear and equipment utilised in the capture of reptiles and large arachnids.
The primary method and the utilisation of pitfall trap and funnel trap arrays (discussed next) in locating reptiles and large arachnids were utilised concurrently, as pitfall traps generally capture species that tend to move around actively and primary methods are therefore needed to capture species that are prone to reside in one niche habitat and generally are not wanderers.
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5.3.2. Pitfall trap and funnel trap arrays
Pitfall trapping and funnel trapping are one of the most widely used methods in studies pertaining to species occurrence (Fisher et al., 2008; Richter & Freegard, 2009). One can also determine the abundance of a particular species, diurnal rhythms of species and compare activity in different niche habitats (Richter & Freegard, 2009), although this study was only concerned with species occurrence.
There are a number of advantages in utilising the pitfall trapping and funnel trapping techniques; they are simple, cheap and cost effective; have no moving parts; do not kill the animals; collect large numbers of animals; are easy and safe to operate; and are usually the only practical alternative to analyse species (Department of Environment and Resource Management (DERM), 2009; Richter & Freegard, 2009).
The pitfall traps and funnel traps that were constructed in the Leeuspruit Private Nature Reserve consisted of buckets (9 litre), shade netting (30cm width), cardboard tubes (840mm length x 83mm width), steel mesh and wooden support beams (Figure 5.5). The basic construction involves the sinking of four buckets into the earth so that the mouth of the bucket is level with the natural ground level. These buckets are arranged in a typical ‘Y’ shape and are seven meters apart (Figure 5.2 and Figure 5.3). A length of shade netting is then lined out to cross the middle of each bucket while still maintaining the ‘Y’ shape of the construction to create a drift fence. A drift fence was utilised to offer a greater catchment area and direct specimens to the buckets and funnel traps. This shade netting is kept in an upright position and supported by a number of wooden support beams that are sunken into the ground. Finally, wooden beams are sunk around each bucket on which the lid of each bucket was placed and weighed down with heavy objects (e.g. bricks or stones). Funnel traps were constructed from cardboard tubes that are closed off on both sides by a mesh cone with a central hole cut out (Figure 5.4). The idea is that specimens will be guided by the drift fence and enter the funnel trap through the cone opening with difficulty in finding their way out (Figure 5.3 and Figure 5.4).
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Figure 5.2: Overview array of pitfall traps and funnel traps.
The purpose of the pitfall traps and funnel traps is to trap reptile and large arachnid species that are difficult to find using primary methodology (physical searching). Since reptiles and large arachnids will generally follow an elevated feature (for instance, wall and drift fence) the idea is that species will follow the drift fence until they fall into one of the pitfall traps or enter a funnel trap. The length of each drift fence strip is seven meters, so as to increase the catchment area of reptiles and large arachnids that are passing the general location of the pitfall trap and funnel trap array.
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Figure 5.3: Cross-section view of pitfall trap and funnel trap array.
Figure 5.4: Basic design of a funnel trap.
In whichever direction a species approach the pitfall trap array, the drift fence will guide the species to encounter a pitfall trap or funnel trap, either the central trap or traps located at each arm of the ‘Y’ shape trap array. The lids of all the buckets were suspended and weighted down slightly above the bucket itself so as to only allow reptiles and large arachnids to be captured and limit the access of carnivores and direct rain from entering.
Diurnal and nocturnal patterns of species are also important as pitfall traps and funnel traps can be opened and set during the day to trap diurnal species, cleared in the afternoon and then set again to trap nocturnal species overnight.
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Important considerations when utilising pitfall traps and funnel traps were:
To keep the bucket lids closed and remove funnel traps when traps were not in use.
To place pitfall traps and funnel traps away from slopes where water could collect and therefore drown occupants.
To place pitfall traps and funnel traps in shaded area to reduce the risk of occupants overheating.
To offer cover in the buckets for species (e.g. egg cartons, leaf litter).
To check active pitfall trap and funnel trap arrays early in the morning.
To safely release all occupants as quickly as possible after identification.
To keep all pitfall traps and funnel traps hygienic and in proper working order.
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Figure 5.5: Equipment needed to construct pitfall trap and funnel trap arrays.
A manhole that is used for water and ash pipeline management occurs in the study area (Figure 5.6). This manhole has proven to be a permanent ‘pitfall trap’ to the reptiles and other animals occurring in the Leeuspruit Private Nature Reserve. This permanent ‘pitfall trap’ is in no way deliberate and merely a human structure used to control pipeline flow. None the less, a number of reptiles and other animals have been recovered frequently from the manhole and thus this structure can be regarded as a permanent ‘pitfall trap’ that must be constantly surveyed.
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Figure 5.6: The manhole that serves as a permanent ‘pitfall trap’.
A concern is that once the researcher has completed this research, the manhole will remain and continue trapping reptiles. This structure cannot be closed or removed such as the pitfall traps and funnel traps constructed by the researcher.
An important limitation to be mentioned is that the trapping methods discussed in this research only prove species occurrence and not absence. None the less, the utilisation of trapping methods is highly recommended as a vast number of species can be trapped that would have previously been too elusive or secretive to generally observe or identify in the field.
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5.4. ECOLOGICAL REQUIREMENTS
Reptiles and large arachnids, like all animals, rely on two basic ecological requirements, namely; the availability of food and the availability of suitable habitat that can support their existence. The next step was therefore to analyse all the different types of habitat features and dietary items at the study area. The study area was extensively analysed to identify as many habitat and dietary requirements as possible that are of essence to the survival of the various reptile and large arachnid species potentially occurring in the Leeuspruit Private Nature Reserve. Dietary items that were identified in the study area are depicted in Plates 11 and 12 of Appendix 2, and habitat features present in the study area are depicted in Plates 13, 14 and 15 of Appendix 2.
The dietary and habitat requirements of each species potentially occurring in the Leeuspruit Private Nature Reserve were tabulated (Table 5.2). The sources of dietary requirements were from the researcher’s own knowledge as well as from FitzSimons (1974); De Waal (1978); Jacobsen & Haacke (1980); Buys & Buys (1983); Patterson & Meakin (1986); Branch (1998); Marais (1999); Boycott & Bourquin (2000); Branch (2000); Leeming (2003); Leroy & Leroy (2003); Marais (2004); Branch (2005); Jacobsen (2005); Marais (2007); Tolley & Burger (2007); Alexander & Marais (2007); Branch (2008); Marais (2011) and Broadley & Blaylock (2013).
Dietary requirements were based on all records of what each species predominantly feeds on as well food items that are occasionally consumed if the opportunity arises. The study area was extensively analysed to detect and identify all the dietary requirements available to reptiles and large arachnids. Species of dietary items were also classified as some species or reptile and large arachnid will only eat species specific items.
Habitat requirements were considered on three main aspects; requirements for peak seasonal activity, requirements for the deposition of eggs and requirements for hibernacula or during periods of dormancy. The study area was extensively analysed in this regards and all habitat requirements were taken into consideration. 54
The habitat and dietary requirements identified at the study area are therefore the variables proposed in the scoring model.
Table 5.2: Species potentially occurring in the Leeuspruit Private Nature Reserve with dietary and habitat requirements. Taxonomic Break Common Name Dietary and Habitat Down and Requirements Scientific Name (Diurnal/Nocturnal – Oviparous/Viviparous) CLASS: REPTILES REPTILIA Order: SCALED SQUAMATA REPTILES Suborder: Snakes Serpentes Family: Viperidae Adders and vipers Causus rhombeatus Rhombic night adder Dietary: Amphibians, occasionally rodents. Habitat: Damp localities, moribund termitaria, logs, rocks, building rubble. (Diurnal/Nocturnal – Oviparous) Bitis arietans arietans Puff adder Dietary: Rodents, amphibians, small mammals, birds, lizards, occasionally snakes and tortoises. Habitat: Vegetation, rocks, rock outcrops, disused burrows, logs, building rubble, vegetation litter. (Diurnal/Nocturnal –Viviparous) Family: Elapidae Mambas, cobras and their relatives Hemachatus Rinkhals Dietary: Amphibians, rodents, lizards, haemachatus snakes, birds, bird’s eggs Habitat: Rocks, rock outcrops, vegetation litter, moribund termitaria, disused burrows, building rubble, usually near water sources. (Diurnal/Nocturnal –Viviparous) Elapsoidea sundvallii Highveld garter snake Dietary: Snakes, lizards, reptile eggs, media amphibians, rodents Habitat: Moribund termitaria, rocks, logs, vegetation litter, soil specific. (Nocturnal – Oviparous) Family: African burrowing Atractaspididae snakes Homoroselaps lacteus Spotted harlequin snake Dietary: Lizards (Skinks), blind snakes
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(Typhlops spp.) and thread snakes (Leptotyphlops spp.) Habitat: Moribund termitaria, rocks, soil specific. (Diurnal/Nocturnal – Oviparous) Homoroselaps dorsalis Striped harlequin snake Dietary: Thread snakes (Leptotyphlops spp.) Habitat: Moribund termitaria, rocks. (Diurnal/Nocturnal – Oviparous) Aparallactus capensis Black-headed Dietary: Centipedes (invertebrates) centipede-eater Habitat: Moribund termitaria, vegetation litter, rocks, logs, vegetation. (Nocturnal – Oviparous) Family: Sand snakes and allies Psammophiidae Psammophis Short-snouted grass Dietary: Snake, lizards (skinks and brevirostris snake geckos), rodents, birds Habitat: Moribund termitaria, rocks, disused burrows, logs, vegetation litter. (Diurnal– Oviparous) Psammophis trinasalis Fork-marked sand Dietary: Lizards, rodents, snakes snake Habitat: Rocks, moribund termitaria, disused burrows, logs, vegetation litter. (Diurnal– Oviparous) Psammophis crucifer Cross-marked grass Dietary: : Lizards, amphibians snake Habitat: Rocks, moribund termitaria, disused burrows, vegetation litter, vegetation. (Diurnal– Oviparous) Psammophylax Spotted grass snake Dietary: Lizards, amphibians, rodents, rhombeatus birds, snakes rhombeatus Habitat: Moribund termitaria, rocks, vegetation, vegetation litter, disused burrows, building rubble. (Diurnal– Oviparous) Psammophylax Striped grass snake Dietary: Lizards (skinks), amphibians, tritaeniatus rodents, birds Habitat: Moribund termitaria, rocks, vegetation, vegetation litter, disused burrows, building rubble. (Diurnal– Oviparous) Family: Colubridae Typical snakes Crotaphopeltis Red-lipped snake Dietary: Amphibians, lizards (skinks hotamboeia and geckos) Habitat: Damp localities, moribund termitaria, rocks, building rubble, vegetation litter, disused burrows. (Nocturnal – Oviparous) Philothamnus Spotted bush snake Dietary: Lizards (geckos and semivariegatus chameleons) and frogs
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Habitat: Arboreal, rock outcrops. (Diurnal– Oviparous) Philothamnus South eastern green Dietary: Amphibians, invertebrates, hoplogaster snake lizards, fish Habitat: Permanent water, arboreal, damp localities, vegetation litter. (Diurnal– Oviparous) Dasypeltis scabra Rhombic egg-eater Dietary: Bird’s eggs Habitat: Moribund termitaria, rocks, logs, vegetation litter, arboreal. (Nocturnal – Oviparous) Family: African nocturnal Lamprophiidae snakes Boaedon capensis Brown house snake Dietary: Lizards, rodents, occasionally bats, birds, amphibians Habitat: Moribund termitaria, building rubble, vegetation litter, rocks, disused burrows, logs. (Nocturnal – Oviparous) Lycodonomorphus Olive ground snake Dietary: Lizards, rodents, snakes inornatus Habitat: Damp localities, moribund termitaria, building rubble, rocks, logs, vegetation litter. (Nocturnal – Oviparous) Lycodonomorphus Brown water snake Dietary: Amphibians and fish, rufulus occasionally rodents and birds. Habitat: Permanent water, rocks, logs, vegetation litter, building rubble. (Diurnal/Nocturnal – Oviparous) Lamprophis aurora Aurora house snake Dietary: Lizards, rodents, amphibians, snakes Habitat: Moribund termitaria, damp localities, rocks, building rubble, logs, vegetation litter. (Nocturnal – Oviparous) Lycophidion capense Cape wolf snake Dietary: Lizards (skinks and geckos) capense and snakes Habitat: Moribund termitaria, rocks, logs, vegetation litter, damp localities, building rubble, disused burrows. (Nocturnal – Oviparous) Family: Mole and keeled Pseudaspididae snakes Pseudaspis cana Mole snake Dietary: Rodents and lizards, occasionally birds and bird’s eggs Habitat: Soil specific, disused burrows, rocks. (Diurnal–Viviparous) Family: Prosymnidae Shovel-snouted snakes Prosymna sundevallii Sundevall’s shovel- Dietary: Reptile eggs, lizards and
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snout occasionally invertebrates Habitat: Moribund termitaria, rocks, soil specific, logs. (Nocturnal – Oviparous) Family: Afro-malagasy snakes Pseudoxyrhophiidae Duberria lutrix lutrix South African slug- Dietary: Slugs and snails (invertebrates) eater Habitat: Damp localities, rocks, logs, vegetation litter, moribund termitaria. (Diurnal/Nocturnal –Viviparous) Family: Typhlopidae Blind snakes Rhinotyphlops lalandei Delalande’s beaked Dietary: Invertebrates (termite and ant blind snake larvae) Habitat: Soil specific, rocks, logs, moribund termitaria, active termitaria. (Diurnal/Nocturnal – Oviparous) Afrotyphlops bibronii Bibron’s blind snake Dietary: Invertebrates (termite and ant larvae). Habitat: Soil specific, rocks, logs, moribund termitaria, active termitaria. (Diurnal/Nocturnal – Oviparous) Family: Thread snakes Leptotyphlopidae Leptotyphlops Peters’ thread snake Dietary: Invertebrates (termites) scutifrons scutifrons Habitat: Moribund termitaria, vegetation litter, logs, rocks, vegetation, active termitaria, soil specific. (Diurnal/Nocturnal – Oviparous) Leptotyphlops Eastern Cape thread Dietary: Invertebrates (termites) scutifrons conjunctus snake Habitat: Moribund termitaria, vegetation litter, logs, rocks, vegetation, active termitaria, soil specific. (Diurnal/Nocturnal – Oviparous) Leptotyphlops Incognito thread snake Dietary: Invertebrates (termites) incognitus Habitat: Moribund termitaria, rocks, logs, vegetation litter, vegetation, active termitaria. (Diurnal/Nocturnal – Oviparous) Suborder: Sauria Lizards Family: Scincidae Skinks Acontias gracilicauda Thin-tailed legless Dietary: Invertebrates skink Habitat: Soil specific, logs, rocks, moribund termitaria. (Diurnal/Nocturnal –Viviparous) Trachylepis capensis Cape skink Dietary: Invertebrates Habitat: Soil specific, logs, rocks, moribund termitaria, disused burrows, vegetation litter, vegetation. (Diurnal–Viviparous)
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Trachylepis Speckled rock skink Dietary: Invertebrates punctatissima Habitat: Arboreal, rocks, logs, building rubble. (Diurnal–Viviparous) Trachylepis varia Variable skink Dietary: Invertebrates, occasionally other lizards Habitat: Rocks, arboreal, logs, vegetation. (Diurnal–Viviparous) Afroablepharus Wahlberg’s snake-eyed Dietary: Invertebrates wahlbergii skink Habitat: Logs, rocks, vegetation, moribund termitaria, vegetation litter. (Diurnal– Oviparous) Family: Lacertidae Old world lizards or lacertids Ichnotropis Common rough-scaled Dietary: Invertebrates squamulosa lizard Habitat: Soil specific, vegetation, rocks. (Diurnal– Oviparous) Nucras lalandii Delalande’s sandveld Dietary: Invertebrates lizard Habitat: Stones, logs, soil specific, vegetation. (Diurnal– Oviparous) Pedioplanis Spotted sand lizard Dietary: Invertebrates lineoocellata Habitat: Rocks, soil specific, rock lineoocellata outcrops. (Diurnal– Oviparous) Family: Plated lizards and Gerrhosauridae relatives Gerrhosaurus Yellow-throated plated Dietary: Invertebrates flavigularis lizard Habitat: Soil specific, rocks, logs, building rubble, vegetation, vegetation litter. (Diurnal– Oviparous) Family: Cordylidae Girdled lizards and relatives Smaug giganteus Giant girdled lizard Dietary: Invertebrates and small vertebrates Habitat: Soil specific, vegetation. (Diurnal–Viviparous) Cordylus vittifer Common girdled lizard Dietary: Invertebrates Habitat: Rocks, rock crevices, rock outcrops. (Diurnal–Viviparous) Family: Varanidae Monitors Varanus albigularis Rock monitor Dietary: Any invertebrate and vertebrate albigularis that can be overpowered and swallowed Habitat: Disused burrows, rocks, logs, arboreal, rock outcrops, rock cracks, moribund termitaria. (Diurnal– Oviparous) 59
Varanus niloticus Nile monitor Dietary: Any invertebrate and vertebrate that can be overpowered and swallowed Habitat: Permanent water, rock outcrops, rock cracks, disused burrows, moribund termitaria, active termitaria. (Diurnal– Oviparous) Family: Agamidae Agamas Agama aculeata Distant’s ground agama Dietary: Invertebrates (Termites and distanti ants) Habitat: Soil specific, vegetation, rocks logs, holes. (Diurnal– Oviparous) Agama atra Southern rock agama Dietary: Invertebrates and vegetation Habitat: Rocks, logs, rock outcrops, rock cracks. (Diurnal– Oviparous) Family: Chameleons Chamaeleonidae Chamaeleo dilepis Common flap-neck Dietary: Invertebrates dilepis chameleon Habitat: Arboreal, vegetation. (Diurnal– Oviparous) Family: Gekkonidae Geckos Lygodactylus capensis Common dwarf gecko Dietary: Invertebrates (Ants and capensis termites) Habitat: Logs, vegetation, rock cracks, rock outcrops, arboreal. (Diurnal– Oviparous) Pachydactylus capensis Cape gecko Dietary: Invertebrates Habitat: Logs, moribund termitaria, rock cracks, rocks, building rubble. (Nocturnal – Oviparous) Suborder: Modern tortoises Cryptodira Family: Testudinidae Land tortoises Stigmochelys pardalis Leopard tortoise Dietary: Vegetation Habitat: Vegetation, disused burrows, rock outcrops, rock cracks. (Diurnal– Oviparous) Suborder: Side-necked Pleurodira terrapins Family: Side-necked terrapins Pelomedusidae Pelomedusa subrufa Marsh terrapin Dietary: Aquatic vegetation, amphibians, fish, invertebrates, crustaceans, birds. Habitat: Permanent/semi-permanent water, logs, disused burrows, vegetation, soil specific. (Diurnal– Oviparous)
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CLASS: ARACHNIDS ARACHNIDA Order: SCORPIONS SCORPIONES Suborder: African scorpions Neoscorpionina Family: Buthidae Thick-tailed and bark scorpions Pseudolychas Plain pygmy-thicktail Dietary: Invertebrates ochraceus Habitat: Rocks, logs, vegetation litter. Uroplectes triangulifer Highveld lesser- Dietary: Invertebrates triangulifer thicktail Habitat: Rocks, logs, vegetation litter. Family: Scorpionidae Burrowing scorpions Opistophthalmus Pugnacious burrowing Dietary: Invertebrates pugnax scorpion Habitat: Soil specific, rocks, building rubble. Order: ARANEAE SPIDERS Suborder: Trapdoor and Mygalomorphae baboon spiders Family: Baboon spiders Theraphosidae Harpactira hamiltoni Golden starbust baboon Dietary: Invertebrates spider Habitat: Soil specific, rocks, logs, disused burrows.
5.5. THE SCORING MODEL
The aim then was to assess to what extent the ecological conditions of the study area match the basic ecological requirements of a particular species of reptile or large arachnid found in the Leeuspruit Private Nature Reserve. Therefore, a scoring model will be developed and is briefly discussed below:
Reptiles and large arachnids occur in areas that offer two basic ecological needs (requirements), namely; the availability of food and the availability of suitable habitat (Pienaar, 1966; Branch, 1998; Alexander & Marais, 2007). Food and habitat variables were categorised to include all the possible basic ecological requirements that any one of the potential species needs to survive in the study area. For example, food categories included rodents, bird’s eggs, amphibians and
61 invertebrates, while the habitat categories will include moribund termitaria, rocks, permanent/semi-permanent water availability and vegetation litter (these variables are indicated in Figure 5.7).
The food and habitat categories cover all the major ecological needs of any given reptile or large arachnid potentially found in the study area. It was then important to identify which of these ecological requirements occur in the Leeuspruit Private Nature Reserve. The ecological variables that make up the model are all variables that can be managed, preserved and conserved and do not include ecological aspects that cannot be controlled such as rainfall and temperature. The ecological requirements present at the study area are provided in Figure 5.7.
Each time a reptile or large arachnid is found and identified in the study area, that species will be compared against the categories in the model and score one point for each positive ecological requirement. For example, Aparallactus capensis (Black- headed centipede-eater) will receive a point for the (1) availability of centipedes (exclusive prey species) as prey as well as the (2) availability of termitaria, (3) boulders and (4) shrubs for habitat requirements. Therefore, this species will receive four points. Similarly, these criteria will be assessed and scored for all species that are identified in the study area.
The output of such a model can also be used to explain the absence of a species. For example, although there is the (1) availability of termitaria, (2) boulders and (3) shrubs for habitat requirements but there are no (4) bird’s eggs at the study area it is impossible for Dasypeltis scabra (Rhombic egg-eater) to occur. This is because D. scabra is a specialised feeder that exclusively feeds on bird eggs and although habitat requirements are ideal its existence is impossible because of the lack of its only food source.
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DIET REQUIREMENTS Rodents Bird’s eggs Lizards Snakes (other species) Invertebrates (species specific) Invertebrates (general) Amphibians Small terrestrial mammals Birds Vegetation Fish HABITAT REQUIREMENTS Vegetation (shrubs, grassland) Species of Damp localities Points Allocated Reptile or Large to Species Arachnid Moribund termitaria Active termitaria Logs Rocks/flat stones Building rubble Permanent/semi-permanent water Disused burrows Rock crevices/outcrops Soil specific (composition) Arboreal (trees) Vegetation litter Bark
Figure 5.7: The proposed model based on dietary and habitat requirements.
As briefly alluded to earlier, Kalibbala (2011) conducted a study on the probability of occurrence of reptiles at a site where each ecological variable was weighed against the species. For example, each species that is probable to occur in the geographical range of the study area was awarded 100% and the species was marked down if ecological needs were not present at the site to give a percentage of the species probability of occurring. The main problem with such a system is that species can be marked down for ecological variables that are not applicable to the particular species. Another limitation associated with the research conducted by Kalibbala
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(2011) is that the ecological variables are not provided upfront and therefore, the credibility of these variables is not verifiable. The model that is proposed in this research will minimise these shortcomings by only allowing species to receive points for suitable ecological requirements.
Alternatively, Haacke (2009) determined the probability of occurrences of herpetofauna species based on their respective geographical distributions and the suitability of on-site habitat. A high probability was applicable to a species with a distributional range overlying the study site as well as the presence of prime habitat conditions in the study site. However, this research was not adequate to suggest feasible and detailed methodology for research work. Therefore the model utilised in the proposed research is not statistical but rather a model based on a scoring system that is dependent on a number of on-site ecological variables
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CHAPTER 6 RESULTS
6.1. INTRODUCTION
The analyses of the methodological approaches utilized in this study are discussed in terms of the success of each approach. The allocation of points awarded to all the species that occur in the study area based on the scoring model is evaluated. The discussion proceeds with the ecological requirements that were identified as being most significant to ensure the survival of reptiles and large arachnid species. A comprehensive description on the comparisons made between all the species that potentially could have occurred and the species that were identified to occur in the study area in relation to their key ecological requirements is conferred. The dominant ecological requirements are analysed and supporting reasons are specified as to the significance of ecological requirement availability as a deciding factor in species occurrence.
6.2. METHODOLOGICAL APPROACHES
The primary method (active searching for reptiles and large arachnids in their retreats and in the open) turned out to be the best and most practical method when compared to the utilisation of pit fall traps and funnel trap arrays. No reptile or large arachnid species were captured with the use of these traps during field work in the study area. Many traps were disturbed by large game and the utilisation of traps was limited to suitable climatic conditions.
The traps did have some benefit none the less, as different species of invertebrates were inadvertently trapped and these findings contributed to a better understanding of the potential food species available in the study area.
The model served as an indicator into the ecological requirements that reptiles and large arachnids need in order to survive. The model also had the benefit of utilising ecological variables that can be environmentally managed and preserved by Sasol
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Ltd. in an effort to conserve the species that occur in the Leeuspruit Private Nature Reserve.
6.3. SPECIES CONFIRMED TO OCCUR IN THE LEEUSPRUIT PRIVATE NATURE RESERVE
A total of twenty eight species (sixteen snakes, six lizards, one terrapin, four scorpions and one baboon spider) have been found and identified in the Leeuspruit Private Nature Reserve. These species were; one member of the family Viperidae, one Elapidae, two Atractaspididae, two Psammophiidae, two Colubridae, four Lamprophiidae, one Pseudaspididae, one Typhlopidae, two Leptotyphlopidae, three Scincidae, one Agamidae, two Gekkonidae, one Pelomedusidae, two Buthidae, two Scoprionidae and one Theraphosidae. The species are listed in Tables 6.1 and 6.2.
The species that were recorded to occur in the Leeuspruit Private Nature Reserve as well as the Plate and Figure number in Appendix 1 are listed in Table 6.1. With regards to Table 6.1, the insert ‘previously recorded’ pertains to species that have previously been recorded as occurring in the quarter degree grid cell (2627DD) of the study area based on De Waal (1978); Bates (1992), ReptileMAP (2013), ScorpionMAP (2013) and SpiderMAP (2013). Species with the insert ‘new record’ are species that have, from the outcome of this study, been recorded in quarter degree grid cell 2627DD for the first time. A very positive result of this study is that of the 23 species of reptile that have been identified to occur in the study area, 14 (61%) of these species are completely new records for the quarter degree grid cell 2627DD. The four species of scorpion that have been found to occur in the study area (quarter degree grid cell 2627DD) are all new records which have never previously been recorded.
With regards to the large arachnids in the study area (Table 6.1), there is no literature on what baboon spider species have been formally recorded in the quarter degree grid cell 2627DD and therefore it is not certain whether to indicate a species of baboon spider as previously recorded or as a new record. None the less, it is for certain that Harpactira hamiltoni is a new record for the quarter degree grid cell
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2627DD as there is no literature that reports this species occurring within the geographical range of the Leeuspruit Private Nature Reserve. Furthermore, Opistophthalmus pugnax was the only species of burrowing scorpion expected to occur in the study area, yet the field work and primary data collection exposed another Opistophthalmus sp. which was identified as Opistophthalmus glabrifrons. A number of lesser-thicktailed scorpions, Uroplectes triangulifer marshalli, which is a subspecies of Uroplectes triangulifer triangulifer were found in the study area which constitutes another unexpected find. Both the unexpected finds of the Opistophthalmus glabrifrons and Uroplectes triangulifer marshalli are discussed in Chapter 7.
Table 6.2 provides a list of the species identified that occur in the study area as well as the individual counts of the number of individuals of the species that were found, captured or seen. Table 6.2 also depicts the points that each species received based on the scoring model. Each point is a reflection of a species’ favourable ecological variable that occurs in the study area.
The results of this study, new recorded species occurrence in quarter degree grid cell 2627DD as well as the extended geographical distributions of Opistophthalmus glabrifons and Uroplectes triangulifer marshalli, will be supplied to ReptileMAP, ScorpionMAP and SpiderMAP to increase their databases and give further insight into the distribution of our indigenous fauna.
A total of 207 snakes, 77 lizards, 8 terrapins, 101 scorpions and 32 baboon spiders were found, captured or seen, setting a grand total of 425 records for the entire duration of this study. These individual specimens were found, captured or seen over a duration of twelve months (March 2012 to March 2013), which is roughly estimated at 500 hours of field work.
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Table 6.1: Species occurring in the Leeuspruit Private Nature Reserve and figure reference.
SCIENTIFIC NAME COMMON NAME FIGURE RECORD REFERENCE Bitis arietans arietans Puff adder Plate 1, Figure 1; New Record Plate 8, Figures 39,40 Hemachatus Rinkhals Plate 1, Figure 2 Previously Recorded haemachatus Homoroselaps Spotted harlequin Plate 1, Figure 3 New Record lacteus snake Aparallactus Black-headed Plate 1, Figure 4 New Record capensis centipede-eater Psammophis crucifer Cross-marked grass Plate1, Figure 5; New Record snake Plate 7, Figure 37; Plate 10, Figure 53 Psammophylax Spotted grass snake Plate 1, Figure 6; Previously Recorded rhombeatus Plate 7, Figures 37, rhombeatus 38; Plate 9, Figures 45,47,50; Plate 10, Figure 52 Crotaphopeltis Red-lipped snake Plate 2, Figure 7; New Record hotamboeia Plate 7, Figure 36; Plate 9, Figure 49 Boaedon capensis Brown house snake Plate 2, Figure 8 New Record Lamprophis aurora Aurora house snake Plate 2, Figure 9 Previously Recorded Lycodonomorphus Brown water snake Plate 2, Figure 10 Previously Recorded rufulus Pseudaspis cana Mole snake Plate 2, Figure 11 New Record Lycophidion capense Cape wolf snake Plate 2, Figure 12 New Record capense Dasypeltis scabra Rhombic egg-eater Plate 3, Figures Previously Recorded 13,14,15,16 Afrotyphlops bibronii Bibron’s blind snake Plate 3, Figures New Record 17,18
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Leptotyphlops Peters’ thread snake Plate 4, Figure 19 New Record scutifrons scutifrons Leptotyphlops Eastern Cape thread Plate 4, Figure 20 New Record scutifrons conjunctus snake Acontias gracilicauda Thin-tailed legless Plate 4, Figure 21 Previously Recorded skink Trachylepis capensis Cape skink Plate 4, Figures Previously Recorded 22,23 Trachylepis Speckled rock skink Plate 4, Figure 24 Previously Recorded punctatissima Agama atra Southern rock Plate 5, Figure 25 New Record agama Lygodactylus Common dwarf Plate 5, Figure 26 New Record capensis capensis gecko Pachydactylus Cape gecko Plate 5, Figure 27; Previously Recorded capensis Plate 8, Figure 42; Plate 9, Figure 48 Pelomedusa subrufa Marsh terrapin Plate 5, Figure 28 New Record Uroplectes Highveld lesser- Plate 5, Figures New Record triangulifer thicktail 29,30; Plate 8, triangulifer Figure 44 Uroplectes Marshall’s lesser- Plate 8, Figure 44 New Record triangulifer marshalli thicktail Opistophthalmus Pugnacious Plate 6, Figures New Record pugnax burrowing scorpion 31,32 Opistophthalmus Rough burrowing Plate 6, Figure 33 New Record glabrifrons scorpion Harpactira hamiltoni Golden starbust Plate 6, Figures Unknown baboon spider 34,35; Plate 8, Figures 41,43
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Table 6.2: Species occurring in the Leeuspruit Private Nature Reserve with points allocated on ecological requirements.
SCIENTIFIC NAME COMMON NAME INDIVIDUALS POINTS FOUND ALLOCATED Bitis arietans arietans Puff adder 2 13 Hemachatus haemachatus Rinkhals 7 13 Homoroselaps lacteus Spotted harlequin 1 6 snake Aparallactus capensis Black-headed 4 6 centipede-eater Psammophis crucifer Cross-marked grass 1 7 snake Psammophylax Spotted grass snake 38 11 rhombeatus rhombeatus Crotaphopeltis hotamboeia Red-lipped snake 27 8 Boaedon capensis Brown house snake 1 11 Lamprophis aurora Aurora house snake 2 9 Lycodonomorphus rufulus Brown water snake 24 9 Pseudaspis cana Mole snake 1 7 Lycophidion capense Cape wolf snake 1 9 capense Dasypeltis scabra Rhombic egg-eater 27 6 Afrotyphlops bibronii Bibron’s blind snake 19 6 Leptotyphlops scutifrons Peters’ thread snake 34 9 scutifrons Leptotyphlops scutifrons Eastern Cape thread 18 9 conjunctus snake Acontias gracilicauda Thin-tailed legless skink 21 5 Trachylepis capensis Cape skink 8 8 Trachylepis punctatissima Speckled rock skink 34 5 Agama atra Southern rock agama 2 6 Lygodactylus capensis Common dwarf gecko 9 6 capensis Pachydactylus capensis Cape gecko 3 6
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Pelomedusa subrufa Marsh terrapin 8 11 Uroplectes triangulifer Highveld lesser-thicktail 74 4 triangulifer Uroplectes triangulifer Marshall’s lesser- 13 4 marshalli thicktail Opistophthalmus pugnax Pugnacious burrowing 12 4 scorpion Opistophthalmus Rough burrowing 2 4 glabrifrons scorpion Harpactira hamiltoni Golden starbust 32 5 baboon spider
The following conclusions can be drawn from the points allocated to species occurring in the study area:
There is no definitive score as to how many points a species minimally requires to occur in the study area, although in this study the lowest points allocated is four (4) and the three species with the lowest scores are all scorpions (Uroplectes spp. and Opistophthalmus spp.).
Some species could probably occur with the satisfaction of one dietary (not including exclusive feeders such as Dasypeltis scabra (Rhombic egg-eater) item and one habitat feature, but although all habitat features are present in the study area, all species receive points for all favourable ecological requirements.
The lower a species score, the less adaptable that species may be to environmental change. Species with low scores could therefore be significant environmental indicators.
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6.4. COMPARISON OF SPECIES ECOLOGICAL REQUIREMENTS
In order to determine how significant a particular dietary or habitat requirement (ecological requirements) is to reptiles and large arachnids in the Leeuspruit Private Nature Reserve; these ecological requirements need to be represented in an order of magnitude of importance. These representations were done for both the species that could potentially occur in the study area as well as for the species that were confirmed to occur in the study area. Hence, the following graphs (Figures 6.1 – 6.4) represent the total number of species dependant or in favour of a particular dietary or habitat requirement. It is valuable to conclude the close relationship and definite association between species potentially occurring and species confirmed to occur in the study and the dietary and habitat features present.
6.4.1. Species dietary requirements comparison
The graphs pertaining to dietary requirements (Figures 6.1 and 6.2) include all the dietary requirements that any species potentially occurring or occurring in the Leeuspruit Private Nature Reserve relies on as a food source. Therefore Figure 6.1 depicts the most commonly consumed dietary items by all the species that could potentially occur in the study area, and Figure 6.2 depicts the most commonly consumed dietary items by all the species that were identified and are found in the study area. The keys to these graphs are explained as follows:
Exclusive – pertains to species that exclusively feed on the dietary source in question. For example, Scincidae and Leptotyphlopidae that only feed on invertebrates and no other food category.
Occasional - pertains to species that may occasionally accept the food source in question if other, more preferred, food sources are not available. For example, L. aurora (Aurora house snake) occasionally feeds on snakes if the more favourable diet of rodents, lizards and amphibians is not immediately available.
Variable – pertains to species that are unselective feeders and will feed on the food source in question but also accept a number of other food sources
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without discrimination. For example, Hemachatus haemachatus (Rinkhals) will whenever the opportunity arises; feed on rodents, amphibians, birds, lizards, snakes and bird’s eggs.
There are a number of significant correlations that can be concluded based on the abundance of certain dietary items and the occurrence of species that feed on such diets. When representing the dietary requirements based on all species potentially found in the study area it is important to note that invertebrates are listed as the most common source of food; followed by lizards, amphibians, rodents and then snakes (Figure 6.1). This means that the more abundant a dietary source is, for example amphibians, the potential for species that include amphibians in their diet would have an increased probability of occurring in the study area and at higher densities than species that do not include amphibians as part of their dietary intake. Therefore based on the dietary total (Figure 6.1), species that include invertebrates in their diets should be most abundant followed by lizards, amphibian, rodents and then snakes. Yet this notion is also dependant on the abundance of the dietary source, for example, invertebrates may be the most common dietary source as indicated by all the species potentially found in the Leeuspruit Private Nature Reserve but in reality this may not be true if invertebrates are not abundant.
Similarly when the dietary requirements of all species that were identified to occur in the study area are represented (Figure 6.2), there are some very significant changes in dietary item dominance. Species occurring in the Leeuspruit Private Nature Reserve indicate that their occurrence is largely based on the abundance of certain food sources. The dominating dietary items based on species occurring in the study area are firstly invertebrates, followed by amphibians, lizards, birds and then rodents. This comparison between species potentially occurring and species that do occur in the study area indicates that amphibians and birds as a dietary source are more significant than lizards and rodents.
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Dietary requirements of all species potentially found in the study area 40 35
30 25 20 1 25 2 15 2 1 Number of Species of Number 10 1 20 1 3 Exclusive 13 15 5 1 10 8 8 Occassional 1 1 5 4 0 3 1 3 2 Variable
Dietary Variables
Figure 6.1: Dietary requirements of all potential species found in the Leeuspruit Private Nature Reserve.
A significant deduction can be made here, as the Leeuspruit Private Nature Reserve is a seasonal wetland it holds a wealth of amphibian and bird life. It is therefore interesting to see that because such dietary items (amphibians and birds, including their eggs) are more accessible and abundant, species that feed on these dietary items occur in high densities in the study area. Similarly, species that do not feed on such dietary items (amphibians and birds) were not recorded as occurring in the study area or occur at low densities.
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Dietary requirements of all species found in the study area 16 14 12 10 2 8 13
6 1 2 9 1 9 Number of Species of Number 4 Exclusive 2 5 4 5 1 2 2 Occassional 0 1 1 1 1 Variable
Dietary Variables
Figure 6.2: Dietary requirements of species found to occur in the Leeuspruit Private Nature Reserve.
It is also important to note that the most occasional dietary items taken are amphibians and birds. Amphibians are also the most important variable dietary item and birds are the second most variable dietary item. Both these indications correlate with the wealth of amphibians and birds present in the seasonal wetlands of the Leeuspruit Private Nature Reserve. Amphibians and birds are of such a significant level as a dietary source that it is important to list a number of commonly found species in the study area. The following species of amphibians are commonly found; Amietophyrnus gutturalis (Guttural toad), Amietophrynus poweri (Western olive toad), Amietophrynus rangeri (Raucous toad), Xenopus laevis (Common platanna), Cacosternum boettgeri (Boettger’s caco), Amietia angolensis (Common river frog) and Amietia fuscigula (Cape river frog) (Du Preez & Caruthers, 2009). The following bird species are commonly seen; Vanetlus coronatus (Crowned plover), Streptopelia capicola (Cape turtle dove), Ploceus cucullatus (Spotted-backed weaver), Ploceus velatus (Masked weaver), Passer domesticus (House sparrow), Passer melanurus
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(Cape sparrow), Motacilla capensis (Cape wagtail), Numida meleagris (Helmeted guinea fowl), Burhinus capensis (Spotted thick-knee) and Pycnonotus barbatus (Common bulbul).
Another noteworthy finding is that there is an apparent scarcity of lizards and rodents in the study area. The scarcity of rodents has also been remarked upon by De Wet (2012b) who conducted research in the Leeuspruit Private Nature Reserve. Since there is a scarcity of both lizards and rodents, snake species that have a varied diet or do not exclusively feed on lizards and rodents are more likely to occur in the study area because amphibians and birds form part of a varied or occasional diet. This conclusion is supported by the fact that amphibian and/or bird feeding species such as Crotaphopeltis hotamboeia (Red-lipped snake), Hemachatus haemachatus (Rinkhals), Lycodonomorphus rufulus (Brown water snake) and Psammophylax rhombeatus rhombeatus (Spotted grass snake) are found in abundance and at very high densities. Similarly species that do not feed on/or infrequently feed on amphibians and birds but rather rodents and lizards are of a much lower abundance and many of these species have only been recorded a few times during the conducted research such as Lycophidion capense capense (Common wolf snake), Boaedon capensis (Brown house snake), Pseudaspis cana (Mole snake) and Homoroselaps lacteus (Spotted harlequin snake). The abundance of birds also serves as a direct relationship with the large numbers of Dasypeltis scabra (Rhombic egg-eater) as this species exclusively feeds on bird’s eggs.
These deductions are highly significant and are a clear indication of how analysing the ecological requirements of reptiles can bring to light the species that may without a doubt occur in an area.
6.4.2. Species habitat requirements comparison
The graphs pertaining to habitat requirements (Figures 6.3 and 6.4) include all the habitat requirements that any species potentially occurring in the Leeuspruit Private Nature Reserve relies on. Once again, two separate graphs were created to indicate a comparison between the habitat requirements of all the species potentially found in
76 the study area (Figure 6.3) and all the species identified in the study area (Figure 6.4). The keys to these graphs are explained as follows:
Hibernacula – pertains to species that utilise the habitat source in question as a retreat during periods of dormancy or inactivity as geared by the onset of unfavourable conditions. For example, a number of species are known as generally utilising moribund termitaria as a retreat during the cold inactive winter months such as Dasypeltis scabra (Rhombic egg-eater), Aparallactus capensis (Black-headed centipede-eater), Lycophidion capense capense (Cape wolf snake) and Boaedon capensis (Brown house snake).
Egg sites – pertains to species that are known to favour a certain or number of certain habitat phenomena as an egg deposition site. For example, Psammophylax rhombeatus rhombeatus (Spotted grass snake) shows a preference in utilising flat rock slabs as an egg deposition site.
Favourable – pertains to species that generally favour the habitat phenomena during periods of activity. For example, Crotaphopeltis hotamboeia (Red- lipped snake) may equally be found under rocks, logs, in holes, etc. during the warmer active months.
There are a number of significant correlations that can be deducted based on the availability of certain habitat phenomena that are utilised by species as either hibernacula, egg deposition site or regarded as favourable features. When representing the habitat requirements based on all species potentially found in the study area it is important to note that moribund termitaria are the most utilised habitat feature followed by vegetation litter, rocks and flat stones, disused burrows and lastly logs (Figure 6.3).
Similarly when the habitat requirements of all species that were identified to occur in the study area are represented (Figure 6.4), there are some very significant changes in habitat requirement dominance. Species that occur in the Leeuspruit Private Nature Reserve indicate that their occurrence is largely based on the abundance of certain habitat features. The dominating habitat features based on species occurring
77 in the study area are firstly rocks and flat stones, followed by moribund termitaria and vegetation litter and lastly disused burrows and logs.
Habitat requirements of all species potentially found in the study area 90 80 70 60 30 4 16 50 10 40 22 11 18 30 10 22 11
Number of Species of Number 42 10 20 34 7 8 26 5 10 20 18 2 4 21 2 14 10 16 9 Hibernacula 0 7 6 4 Egg Sites Favourable
Habitat Variables
Figure 6.3: Habitat requirements of all potential species found in the Leeuspruit Private Nature Reserve.
This means that the more available a habitat feature is, for example moribund termitaria, the potential for species that utilise these features would have an increased probability of occurring in the study area and at higher densities than species that do not utilise these habitat features as part of their daily or seasonal cycles. Therefore based on the habitat total (Figure 6.3), species that utilise moribund termitaria should hypothetically be most abundant followed by vegetation litter, rocks and flat stones, disused burrows and lastly logs. Yet this notion is also dependant on the abundance of the habitat feature, for example, moribund termitaria may be the most utilised habitat features as indicated by all the species potentially found in the Leeuspruit Private Nature Reserve but in reality this may not be true if
78 moribund termitaria are not abundant and therefore species may need to utilise a secondary or tertiary habitat feature depending on favourability.
Habitat requirements of all species found in the study area 45 40
35 9 11 11 30 25 8 10 1 11 20 4 11 15 8 10 22 4 5 2 Number of Species of Number 17 18 16 12 4 11 5 10 8 Hibernacula 0 3 3 2 4 4 Egg Sites Favourable
Habitat Variables
Figure 6.4: Habitat requirements of species found to occur in the Leeuspruit Private Nature Reserve.
A significant deduction can be made here, as the Leeuspruit Private Nature Reserve is an area that is largely covered by dolerite outcrops and therefore rocks and flat stones are found throughout the study area. It is therefore interesting to see that because such habitat features (rocks and flat stones) are more accessible and widespread, species that utilise these features occur at high densities in the study area. Similarly there is a severe scarcity of moribund termitaria and therefore rocks and flat stones have become the most commonly used retreats, which are positively reflected in the species that occur in the study area.
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Favourable habitat features by species occurring in the study site include rocks and flat stones, logs, moribund termitaria and vegetation litter. The finding of rocks and flat stones as a key habitat feature is supported by the fact that numerous outcrops occur in the study area and the majority of species have been found under rocks and flat stones.
The most commonly utilised hibernacula by species identified in the Leeuspruit Private Nature Reserve are moribund termitaria, vegetation litter and disused burrows which are secondly followed by rocks and flat stones. Since there is a lack of moribund termitaria, these habitat features are probably communally utilised by various species such as Lamprophis aurora (Aurora house snake), Lycophidion capense capense (Common wolf snake), Boaedon capensis (Brown house snake), Dasypeltis scabra (Rhombic egg-eater), Aparallactus capensis (Black-headed centipede-eater), Leptotyphlops spp. (thread snakes), Crotaphopeltis hotamboeia (Red-lipped snake), Trachylepis spp. (skinks), Homoroselaps lacteus (Spotted harlequin snake), Pachydactylus capensis (Cape gecko) and Uroplectes spp (lesser- thicktailed scorpions). The notion of communal hibernacula is supported by Branch (1998) and Marais (2004). Rocks and flat stones are mainly utilised by Uroplectes spp. and Opistophthalmus spp. as hibernacula which was evident whilst conducting this study. Whilst vegetation litter was frequently utilised by diurnal species that still emerged during warm winter days to bask and forage.
Egg deposition sites which are favoured by species that were confirmed to occur in the study area include firstly vegetation litter, followed by moribund termitaria and lastly rocks and flat stones. Due to the lack of moribund termitaria, species are presumed to deposit eggs in other favourable sites. Psammophylax rhombeatus rhombeatus (Spotted grass snake) supports the findings with regards to the utilisation of rocks and flat stones as egg deposition sites. Numerous batches of eggs have been found throughout the study area where P. rhombeatus rhombeatus females remain coiled around their eggs. Other eggs that were found under rocks and flat stones include the following species based on the diameters and count of the egg shells; Dasypeltis scabra (Rhombic egg-eater), Psammophis crucifer (Cross- marked grass snake), Crotaphopeltis hotamboeia (Red-lipped snake) and Lycodonomorphus rufulus (Brown water snake). Vegetation litter such as the heaps of mowed grass offer ideal egg deposition sites due to a rather constant level of
80 moisture and temperature that facilitate egg development. A number of hatched egg batches have been found in the mowed grass heaps which strongly supports this conclusion.
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CHAPTER 7
DISCUSSION OF RESULTS
7.1. INTRODUCTION
This chapter deals with a discussion on the results and some of the observations made during the current research. Firstly, an explanation is provided as to why certain species were not identified as occurring in the study area. Secondly, the question of extended geographical distributions for species belonging to the Opistophthalmus genus (Opistophthalmus glabrifrons) and Uroplectes genus (Uroplectes triangulifer marshalli) is discussed as a key outcome of the current research. Lastly, some recommendations are offered based on the results emanating from the research. These recommendations are associated with ecological requirements of each positively identified species.
7.2. SPECIES ABSENCE AND UNCERTAINTY
The occurrence of a number of species could not be confirmed by the current research in the study area. Listed below are the species whose occurrence is questionable and key notes on reasons for possible individual species absence is provided.
Causus rhombeatus (Rhombic night adder) – the occurrence of this species in the study area could not be confirmed although it may well occur based on species distribution range and the fact that prevailing habitat and dietary variables suit this species. There are no reasons evident as to why this species may be absent from the study area. The occurrence of C. rhombeatus could also not be confirmed by De Waal (1978) within the quarter degree grid cell 2627DD. However, C. rhombeatus has been previously recorded from neighbouring quarter degree grid cells 2627DB and 2628CA (ReptileMAP, 2013).
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Elapsoidea sundevallii media (Highveld garter snake) – Occurrence not confirmed although it is likely that this species may well occur in the study area. A possible reason for not finding this species is that due to its fossorial existence it is difficult to come across. E. s. media has been recorded from neighbouring quarter degree grid cells 2627DB and 2627DC (ReptileMAP, 2013).
Homoroselaps dorsalis (Striped harlequin snake) – Occurrence not confirmed. This species is listed as ‘vulnerable’ by the IUCN and as ‘rare’ by the South African Red Data Book: Reptiles and Amphibians (Branch, 1988). H. dorsalis may well occur in the study area but because of its secretive and rare nature no specimens have been found. H. dorsalis has been recorded from neighbouring quarter degree grid cells 2627DB and 2628CA (ReptileMAP, 2013).
Psammophis brevirostris (Short-snouted whip snake) – Occurrence not confirmed, possibly due to an exaggeration in this species distribution range. Psammophis brevirostris has been recorded from neighbouring quarter degree grid cell 2628CA (ReptileMAP, 2013).
Lycodonomorphus inornatus (Olive ground snake) – Occurrence not confirmed, this species is relatively rare in the Highveld and therefore the chances of this species occurring in the study area are very unlikely. Lycodonomorphus inornatus has been recorded from neighbouring quarter degree grid cell 2628CA (ReptileMAP, 2013).
Prosymna sundevallii (Sundevall’s shovel-snout) – Occurrence not confirmed, possibly due to the limited availability of sandy soils although this species has been found at a neighbouring quarter degree grid cell (Uitkomst 2628CA) some five kilometres away as well as neighbouring quarter degree grid cells 2627DA, 2628CA and 2628CC (ReptileMAP, 2013).
Philothamnus semivariegatus (Spotted bush snake) and Chamaeleo dilepis dilepis (Common flap-neck chameleon) – Occurrence not confirmed, possibly because of a severe lack of trees and bushes in the study area and where trees and bushes do occur, these are never densely grouped but rather
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scattered. Philothamnus semivariegatus has been recorded from neighbouring quarter degree grid cell 2627DB and C. dilepis dilepis has been recorded in neighbouring quarter degree grid cells 2627DB and 2628CA (ReptileMAP, 2013). Although C. dilepis dilepis has not been found in the study area during the duration of this research, many years ago this species was found by the author in Sasolburg and the preserved specimen is available at the laboratories of the Department of Zoology at the University of Johannesburg.
Duberria lutrix lutrix (South African slug-eater) – Occurrence not confirmed, the reasons for possible absence are not evident as suitable habitat is evidently present. This species may well occur in the study area but through extensive field work no specimens were found. Duberria lutrix lutrix has been catalogued as a species of rare occurrence in the Free State Province since the first analysis of Free State Province Reptilia (Bates, 1992; De Waal, 1978). Duberria lutrix lutrix has been recorded from neighbouring quarter degree grid cells 2628CA and 2628CC (ReptileMAP, 2013).
Trachylepis varia (Variable skink) – Occurrence not confirmed, the reasons for this species absence is unknown due to the abundance and distribution of this species in other quarter degree grid cells. Trachylepis varia has been recorded from neighbouring quarter degree grid cells 2627DA, 2627DB, 2628CA, 2628CC and 2627DC (ReptileMAP, 2013).
Afroablepharus wahlbergii (Walberg’s snake-eyed skink) – Occurrence not confirmed, reasons for this are unknown due to this species being significantly common and widespread. Afroablepharus wahlbergii has been recorded from neighbouring quarter degree grid cells 2627DA, 2627DB, 2628CA, 2628CC and 2627DC (ReptileMAP, 2013).
Nucras lalandii (Delalande’s sandveld lizard) – Occurance not confirmed, the possible absence of this species may be due to a lack of a sand substrate which is required for the survival of this burrowing species. Nucras lalandii has been recorded from quarter degree grid cells 2627DA, 2627DB, 2628CA and 2628CC (ReptileMAP, 2013).
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Gerrhosaurus flavigularis (Yellow throated-plated lizard) – Occurrence not confirmed, possibly absent due to a lack of burrowing substrate such as in the case of N. lalandii. Gerrhosaurus flavigularis has been recorded from neighbouring quarter degree grid cells 2627DB, 2628CA and 2628CC (ReptileMAP, 2013).
Cordylus vittifer (Transvaal girdled lizard) – Occurrence not confirmed, possibly because of the lack of sufficient dolerite outcrops in the study area that are heavily utilised by this species and the lack of surrounding outcrops in the regional vicinity, therefore creating no joining bridges for this species to migrate into the study area. Cordylus vittifer has been recorded from neighbouring quarter degree grid cells 2627DA, 2627DB, 2628CA, 2628CC and 2627DC (ReptileMAP, 2013).
Smaug giganteus (Giant girdled lizard) – Occurrence not confirmed, this species is listed as ‘vulnerable’ by the IUCN and the South African Red Data Books: Reptiles and Amphibians (McLachlan, 1978; Branch, 1988). It is doubtful that this species occurs in the study area due to the large scale habitat destruction within the surrounding areas as well as historic disruption in the study area. Smaug giganteus has been recorded from neighbouring quarter degree grid cells 2728AA and 2727BB (ReptileMAP, 2013).
Varanus albigularis albigularis (Rock monitor) and Varanus niloticus (Nile monitor) both do not occur in the Leeuspruit Private Nature Reserve as there is insufficient permanent water supply for V. niloticus as well as insufficient foraging grounds and the study area is historically too disturbed to support both Varanus spp. However, V. niloticus does occur three kilometres away from the study area in man-made industrially utilised dams (Strydom, 2012). V. niloticus has been recorded from neighbouring quarter degree grid cell 2627DA and V. albigularis albigularis has never been previously recorded at any neighbouring quarter degree grid cells (ReptileMAP, 2013).
Agama aculeata distanti (Distant’s ground agama) – Occurrence not confirmed, for unknown reasons and it is doubtful that the species occurs in the study area as this species is easily seen and identified. Agama aculeata
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distanti has been recorded from the quarter degree grid cell in question (2627DD) as well as from neighbouring quarter degree grid cells 2627DA, 2727DB, 2628CA, 2628CC, 2728AA and 2627DC. (ReptileMAP, 2013).
Stigmochelys pardalis (Leopard tortoise) seems to be absent from the study area. Possible reasons for this may be the historical disturbance of the site and the large number of carnivores (especially mongoose). If this species is present at the study area, it is known that tortoises take a long time for populations to re-establish themselves (Branch, 2008).
Pseudolychas ochraceus (Plain pygmy-thicktail) seems to be absent from the study area. There is no indication of why this species is absent but a possible reason may be because its distribution range has been exaggerated (Leemimg, 2008).
The following species have not been found in the study area nor recorded from neighbouring quarter degree grid cells and therefore their occurrence is very doubtful; Psammophis trinasalis (Kalahari sand snake), Psammophylax tritaeniatus (Striped grass snake), Philothamnus hoplogaster (Green water snake), Leptotyphlops incognitus (Incognito thread snake), Ichnotropis squamulosa (Common rough-scaled lizard), Pedioplanis lineoocellata lineoocellata (Spotted sand lizard) and Stigmochelys pardalis (Leopard tortoise) (ReptileMAP, 2013). Possible reasons as to why these species have not been found in the study area nor recorded from neighbouring quarter degree grid cells is that either; species distribution maps have been largely generalised or exaggerated or these species have been seen in neighbouring quarter degree grid cells or in the vicinity of the study area but these sightings have never been recorded.
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7.3. EXTENSION OF SPECIES DISTRIBUTION RANGES
7.3.1. Thread snake (Leptotyphlops sp.)
Three species of the Leptotyphlops genus potentially occur within the geographical range of the Leeuspruit Private Nature Reserve. These species are Leptotyphlops scutifrons scutifrons (Peters’ thread snake), Leptotyphlops scutifrons conjunctus (Eastern Cape thread snake) and Leptotyphlops incognitus (Incognito thread snake), based on current taxonomy and distribution data as appose to the recent taxonomy proposed by Adalsteinsson et al. (2009). Both L. scutifrons scutifrons and L. scutifrons conjunctus have a very high probability of occurring in the study area, while L. incognitus has a low probability of occurrence due to this species peripherally entering the geographical range of the study area.
The distinguishing physical features between L. scutifrons scutifrons and L. scutifrons conjunctus are very minimal and essentially rely on the rostral size, yet this distinction is unreliable. De Waal (1978) emphasises that in the Free State Province, there is no constant correlation between the two species and the distinguishing features between L. scutifrons scutifrons and L. scutifrons conjunctus is extremely difficult. Marais (2004) states that L. scutifrons scutifrons has 225-309 ventrals and 19-30 subcaudals, while L. scutifrons conjunctus has 192-258 ventrals and 18-28 subcaudals. Although these morphological differences can distinguish the two species from one another, it is not practical for this research as the specimens would need to be killed in order for ventrals and subcaudals to be counted. In terms of best ethical practice, this method is not viable. Three dead specimens have been found and ventrals and subcaudals were counted to the best of the researches ability. One of these dead specimens had 18 subcaudals and the other two had 29 subcaudals.
Therefore, for the purpose of this research and due to the large number of Leptotyphlops sp. found as well as the subcaudal counts on dead specimens, it will be concluded that both L. scutifrons scutifrons and L. scutifrons conjunctus are present in the Leeuspruit Private Nature Reserve. A supporting argument is that both Leptotyphlops spp. have been previously recorded from neighbouring quarter degree
87 grid cells which proves that both species occur within the general region. Leptotyphlops scutifrons scutifrons has been recorded in neighbouring quarter degree grid cells 2628CA and 2728AA, whilst L. scutifrons conjunctus has been recorded from neighbouring quarter degree grid cell 2627DB (ReptileMAP, 2013).
7.3.2. Scorpions (Opistophthalmus sp. and Uroplectes sp.)
Opistophthalmus pugnax, according to Leeming (2003) is the only species of Scorpioidae that occurs within the geographical range of the Leeuspruit Private Nature Reserve. Three scorpion species are listed as potentially occurring in the study area (two from the Buthidae family and one from the Scorpionidae family). Opistophthalmus pugnax has very distinctive physical characteristics and has been identified in the study area during this project.
The problem arises with the appearance of a Scorpionid (Plate 5, Figure 26) that is not listed in any literature as occurring within the geographical range of the study area. This species of Scorpionid does not resemble O. pugnax, neither physically nor morphologically but is definitely of the Opistophthalmus genus.
Since the Leeuspruit Private Nature Reserve is in the northern Free State Province and boarders Gauteng Province, species occurring in Gauteng Province need to be considered as possible candidates for this species of questionable identity. This species is too physically distinct from O. pugnax to be the same species and therefore a literature review was necessary.
The second species of Opistophthalmus found in the Leeuspruit Private Nature Reserve is not O. pugnax based on the morphological and physical appearance of the species. It was very difficult to determine the exact species in question as specimens had to be extensively photographed and analysed to verify its identity. I came to the conclusion that the second Opistophthalmus sp. is indeed Opistophthalmus glabrifrons (and confirmed by the expert panel from ScorpionMAP) and therefore this species has an extended distribution range in the extreme northern Free State Province that has not previously been recorded (Engelbrecht, 2013). Thus, the finding contributes new knowledge in an extended species distribution range. The nearest known locality of O. glabrifrons is at Lanseria Airport
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(Gauteng) and Fourways (Gauteng) (Engelbrecht, 2013), some 100 kilometres away from the Leeuspruit Private Nature Reserve which makes this finding very significant as this species was never considered to potentially occur in the study area.
Furthermore, a species of Uroplectes was found in the study area that physically does not resemble the well-known U. triangulifer triangulifer. Engelbrecht (2013) identified this species as Uroplectes triangulifer marshalli a subspecies of U. triangulifer triangulifer. Uroplectes triangulifer marshalli has recently been found to occur in eastern Gauteng Province (Engelbrecht, 2013) and the outcome of this current research proves that this species occurs in the study area (Sasolburg) as well.
Both these findings of Opistophthalmus glabrifrons and Uroplectes triangulifer marshalli in the study area are unexpected due to the fact that both species, as an outcome of this research, are now found considerably further away from their previously known distribution ranges.
7.4. BEHAVIOUR, ECOLOGY AND FIELD OBSERVATIONS.
The vast majority of species were found, identified or seen after moderate to heavy rains. Reptiles and large arachnids were very active after heavy rains, especially the first rainfalls directly after winter and in the beginning of spring. Marais (2013) supports this notion as rainfall triggers biological responses in many species including foraging, hunting and breeding. Many fossorial species were also seen in abundance during this time as many are flushed out of their retreats and hibernacula.
There seems to be pronounced success in the reproduction of reptiles and large arachnids in the study area as can be seen in:
The large number of hatched egg batches that have been found over autumn and spring from the previous breeding season.
The abundance of juvenile reptiles and large arachnids that were found.
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The abundance of gravid females that were frequently found during the spring and summer breeding season.
The abundance of live egg batches that were found during the spring and summer months.
Marais (2013) states that depending on species and location, the number of reptile and large arachnid individuals found and observed may be as little as 5% of the individuals what occurs in the area. Therefore, if such an abundance of individual species was found during the duration of this research it can be said that many more individuals have gone unnoticed.
It has been observed that in communal egg deposition sites there are always a few eggs that have not hatched and consequently only skeletons remain in desiccated egg shells. It is therefore possible that there may be some disruption of clutches of eggs in communal egg laying sites, such as under loose dolerite rock slabs, when gravid females disturb other eggs inadvertently in search of a site to lay their own eggs, consequently moving or destroying some of the existing eggs. This is a significant possibility with regards to embryo mortality. Where a single batch of eggs is found under an individual rock slab, all eggs show evidence of slits in the eggs shells and successful development and hatching, which indicates that single egg batches are less disturbed than communal egg deposition sites.
Pelomedusa subrufa (Marsh terrapin) is the first species observed that enters dormancy/hibernation with the onset of cooler temperatures at the start of winter. Research indicates that P. subrufa is inactive when water temperature drops below 17°C (Branch, 2008), and consequently seek out shelter in self-excavated burrows.
It has been noted that only certain species are seen active and found in early spring with the onset of warmer temperatures. During the end of August, certain species have left their shelters and appear to be active. The majority of these species are fossorial (Acontias gracilicauda, Afrotyphlops bibronii and Leptotyphlops spp.). Fossorial species are mainly found under stones and this is a strange phenomenon as temperatures under stones were still relatively cold and individuals were rather inactive due to such temperature drops. It is known that these individual species did not utilise the stones as retreats during the cooler winter months as extensive field
90 work in the winter months did not indicate any fossorial species. The only explanation that may be furnished for such behaviour in fossorial species is that due to the diet of these species (termites, ants and their lava) they are far less dependent on rainfall as a source of moisture as their diet satisfies all their moisture requirements.
An interesting observation is that Crotaphopeltis hotamboeia (Red-lipped snake) is the only species of snake seen active during the beginning of spring when temperatures were below 10°C at night. This behaviour is even more perplexing due to that fact that this is a nocturnal species and temperatures below 10°C do not seem comfortable for such species (FitzSimons, 1974). A possible reason for such early activity may be for breeding purposes or because this species generally inhabit moist areas and are therefore more resilient to low temperatures than other species. Marais (2013) commented that the reason for such activity in cold weather by C. hotamboeia is not clear and there is no evidence for this behaviour as of yet. There is a wide range of patterning and colour variation amongst individuals of Dasypeltis scabra (Rhombic egg-eater). Normally the colour ranges from bright yellow to dull brown and patterning varies from deep rhombic markings to completely plain. Jacobsen and Haacke (1980) state that the plain patternless variety is rather common in the Sasolburg region. Furthermore, Bates et al. (2012) state that Dasypeltis scabra consists of three clades in southern Africa, with two possible new species. For this reason, it is important to conserve this population with its particular colour variation and further studies on this genetic variation are highly recommended.
There is an important distinction to be made between the nocturnal and diurnal habits of reptiles that occur in the Leeuspruit Private Nature Reserve. Of the 23 species of reptile occurring in the study area; eight species (35%) are diurnal, seven species (30%) are nocturnal and eight species (35%) are active both nocturnally and diurnally. From this ratio of diurnal versus nocturnal habit preference, a deduction can be made. Climatically the study area is warm enough in the summer months to allow a temperature higher than the required minimal activity temperature for reptiles which are ectothermic. This means that reptiles are capable of foraging, hunting and breeding at night because temperatures do not drop below a state of minimal activity for ectothermic species. The fact that eight species are both nocturnal and diurnal in
91 habits, would suggest that nocturnal temperatures in summer are mild enough to allow these animals to be active around the clock instead of limiting their activities to daytime only. This is however not true for the winter months when temperatures may fall well below freezing and all reptiles undergo prolonged periods of torpor. All large arachnids are nocturnal and are able to be active regardless of the temperature.
The reproductive strategies of reptiles are similarly influenced by the higher temperatures during summer. Of the 23 reptile species in the Leeuspruit Private Nature Reserve, 17 species (74%) are oviparous (egg-laying) and six species (26%) are viviparous (live bearing). This ratio would once again suggest favourable weather conditions during the spring and summer months which are warm enough to promote oviparity. Oviparity increases with increasing temperatures and viviparity increases with decreasing temperatures because eggs need a certain amount of external heat to incubate successfully. An advantage of oviparity is that females do not need to be gravid for long periods and several batches of eggs can be laid per season. This correlation between reproductive strategies and ambient temperature is challenged however by the reproductive strategies of Trachylepis capensis (Cape skink). Trachylepis capensis is known to be both oviparous and viviparous depending on its geographical location (Branch, 1998; Jacobsen, 2005; Alexander & Marais, 2007). In the study area (Highveld), this species is viviparous (Jacobsen, 2005). Nonetheless, from this research it is evident that many oviparous species benefit from the warm climatic conditions in the study area. Baboon spiders are all oviparous and scorpions are all viviparous so they have been excluded from this discussion.
It has been observed that locations in the Leeuspruit Private Nature Reserve where grass has been mowed there is an absence of reptile species. Masterson et al. (2008) concluded the same observation and state that vegetation structure appears to be the key factor affecting the structure of herpetofaunal assemblages, furthermore, Masterson et al. (2009) state that reptile species richness is higher in pristine habitats as appose to previously modified areas.. The mowed landscape offers little security in terms of protective cover and therefore species tend to move out of the region to more favourable areas. A striking observation is that previously utilised egg deposition sites are therefore not utilised on mowed land and these previously ideal egg deposition sites are rendered unfit. This aspect is of some
92 concern as potential egg deposition sites are therefore left unused until the following breeding season or when grass growth returns.
Ecological impacts from mining activities include the loss of habitats and the impaired quality and functionality of the ecosystem (SAEO, 2012b). These impacts include alterations in the water table, decline in ecosystem efficacy, influx of pollutants in the region, disruption of land forms and a general disturbance to local fauna and flora (SAEO, 2012b). Wetlands are especially susceptible to such anthropogenic impacts but no such impacts were identified in the study area.
Reptiles and large arachnids in their natural setting serve as prey for a number of other animals (Figure 4.1). In the Leeuspruit Private Nature Reserve, a number of small terrestrial carnivorous mammals have been identified that prey on reptiles and large arachnids. These small terrestrial mammals include Cynictis penicillata (Yellow mongoose)), Atilax paludinosusis (Water mongoose), Galerella sanguinea (Slender mongoose) and Suricata suricatta (Meerkat). It is said that mongoose species include reptiles as a large proportion of their dietary intake but this notion is largely overrated according to Jacobsen & Haacke (1980). Predatory birds such as Tyto capensis (African grass owl) have been periodically seen in the study site and Marais (2004) states that the Boaedon capensis (Brown house snake) is largely preyed upon by owl species. Snakes are considered high profile enemies to reptiles (including other snakes) and since five snakes are present that include other snake species in their diet, this ratio is rather high in the study area. Man of course is the worst enemy, whether it is the killing of snakes and large arachnids out of fear, destroying suitable habitats or poaching for the illegal trade in indigenous species. Despite all these predators and enemies, it seems that the abundance of reptiles and large arachnids in the study area is only slightly threatened and a homeostatic environment and ecological balance is achieved.
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7.5. RECOMMENDATIONS
7.5.1. Vegetation litter
Vegetation litter has proven to be an essential requirement for species both in the winter and summer months as an egg deposition site, hibernacula and as a temperature regulated retreat. The mowing of grass is encouraged to control potential wild fires from spreading and the mowed grass should be left on site for species to occupy this suitable habitat. De Wet (2012a) emphasises that the mowing of indigenous grass in the Leeuspruit Private Nature Reserve should be practiced. For this reason, it is important that mowed grass be continuously placed in piles throughout the study area as is currently the practice (Plate 14, Figure 72).
Species however, tend to retreat from areas that have been mowed due to the decrease in vegetation cover and therefore the secure concealment of both nocturnal and especially diurnal species. However, these mowed areas are relatively narrow and cover a small percentage of the study area.
7.5.2. Fires
Fires are a major threat to the reptiles and large arachnids in the Leeuspruit Private Nature Reserve (De Wet, 2012b), and anywhere else for that matter (Branch, 1998; Marais, 2004; Alexander & Marais, 2007). Although no fires have been experienced during the research period, the impact of fire on the environment is an aspect of environmental management concern and therefore warrants further studies. During the current research it was observed that fields that were burned extensively (such as the fire breaks along the boundary of the study area) acted as a push factor that drives away reptiles and other animal species and which renders the environment relatively ecologically inactive. Another important point is that species that migrate from burned fields to the surrounding urban areas may lead to an increased need for the removal of undesirable reptiles. Burned fields therefore create a severe decrease in vertebrate activity. De Wet (2012a) has noted that fire has severe impacts on reptiles. None the less narrow fires breaks should continue to be burned annually as is the case in the study area (Figure 7.1). 94
Figure 7.1: A fire break on the boundary of the study area.
7.5.3. Moribund termitaria
It is proven that the utilisation of moribund termitaria by reptiles is paramount to their survival (Marais, 2013). Many species utilise moribund termitaria as egg deposition sites, hibernacula, hunting grounds and as general retreats (Plate 14, Figure 75). There is a scarcity of moribund termitaria at the study area and considering the importance of these features it is of upmost priority to conserve the currently existing moribund termitaria. Marais (2013) states that it may take up to a century to replace these habitat features (from a termite colony establishing itself, to building a termiteria, the colony dying off and providing a moribund termitaria to be utilised by other species) naturally if they were to be destroyed.
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7.5.4. Amphibians and water quality
Since amphibians are without a doubt the most important and primary dietary source to Viperidae, Lamprophiidae and Colubridae it is imperative that amphibians, and therefore their conditions for survival, be managed appropriately. The pH of the Leeuspruit as well as the seasonal wetlands and pans was taken to determine the suitability of aquatic conditions for the survival and reproduction of amphibians. The pH readings of the water sources were between the values of 6.5 – 8, which is adequate to support amphibian life and there is no need for concern, as long as water quality does not deteriorate. The water quality is also of upmost importance to species that rely on permanent water sources such as Lycodonomorphus rufulus (Brown water snake) and Pelomedusa subrufa (Marsh terrapin).
7.5.5. Rocks, stones and building rubble
Since rocks, stones and building rubble are commonly utilised retreats, hibernacula and egg deposition sites, these habitat features should be preserved (Plate 13, Figures 66 and 70). Existing building rubble should rather be left in the study area and not removed as this rubble offers a habitat that fulfils various seasonal-biological activities.
7.5.6. Manhole
The manhole that houses the flow tap for the transportation of water and ash (Figure 5.6) can be regarded as a permanent pitfall trap. It has been observed that a large number of snakes (as well as other vertebrates) venture into this manhole in an attempt to find a suitable retreat. The problem arises when snakes fall into this feature and find it impossible to get out. Interestingly, only nocturnal species of snake have been found to enter the manhole, namely; Crotaphopeltis hotamboeia (Red-lipped snake), Dasypeltis scabra (Rhombic egg-eater) and Lamprophis aurora (Aurora house snake). Snakes have periodically been found in an emaciated state due to the lack of food and water once trapped. This manhole does have a secure cover but the agility and slim build of snakes still allows them to venture into this
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‘trap’. It is therefore recommended that this manhole be checked for occupants on a periodic basis to release such trapped snakes, and other vertebrates, from possible death.
7.5.7. Human impacts
The Leeuspruit Private Nature Reserve, as the name suggests, is a private nature reserve. Humans are potentially the greatest threat to reptiles and large arachnids (FitzSimons, 1974) in the study area with regard to aspects such as ecological degradation, poaching of indigenous fauna and the unnecessary killing of indigenous reptiles and large arachnids. The author has witnessed on numerous occasions people catching baboon spiders, scorpions and reptiles illegally in the wild to be kept as pets. For these reasons the Leeuspruit Private Nature Reserve should remain private and continue to restrict entrance to the public.
7.5.8. Environmental legislation
Measures that can be put in place to protect the environment and faunal ecology is to register the study area as a nature reserve in terms of the National Environmental Management: Protected Areas Act 2003 (Act 57 of 2003) to obtain environmental protection status. This can be achieved by referring to chapter 2 – Systems of protected areas in South Africa and chapter 3 – Declaration of protected areas, part 3 – nature reserves in the NEMPAA (Act 57 of 2003). The National Environmental Management: Biodiversity Act (Act 10 of 2004) offers further protection over indigenous fauna as a national heritage. Species of red data status are automatically offered legal protection. It is strongly suggested that such legal protection and registration be employed.
7.5.9. Further research
Research is without a doubt the imperative first step in any attempt at conserving and managing the environment. Research needs to be the input for a systems
97 approach after which strategies and methodologies can be put in place to maintain any environment. It is therefore recommended that Sasol Ltd. continue to encourage research activities in their nature reserves and employ consultants for monitoring aspects within the various disciplines of the natural sciences. By conducting research in various natural science fields of study, a holistic view of the aspects pertaining to the environment can be achieved and implemented.
7.5.10. Push factors
Based on this research it is evident what ecological requirements reptiles and large arachnids need in order to successfully survive and reproduce. If any primary or favourable ecological requirements are lost or destroyed, this may render the environment unfit for certain species. Push factors pertain to environments that no longer offer satisfactory ecological requirements to species and species may tend to migrate in search of more suitable conditions or even become locally extinct. A few species are known to be wanderers and migrate in order to find more suitable environmental conditions, for example Pelomedusa subrufa (Marsh terrapin), Boaedon capensis (Brown house snake), Hemachatus haemachatus (Rinkhals) and Crotaphopeltis hotamboeia (Red-lipped snake). The author is a member of the West Rand Herpetological Association and it is not uncommon to hear of ‘problem snake removal’ callouts by the public. These ‘problem snake removals’ are due to species venturing away from their natural habitat and into urbanised areas due to ecological push factors. The recommendation based on this statement is therefore to maintain favourable ecological conditions within the study area based on the outcomes of this research so that species do not have a need to migrate from internal push factors.
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CHAPTER 8
CONCLUSION
Since reptiles are one of the least studied taxa worldwide when compared to all other fauna and even less is known about the large arachnids, the environmental management of reptile and large arachnid species has received relatively less attention. This problem is further exacerbated due to a considerable lack of knowledge on the ecological requirements (dietary and habitat requirements) that are species specific.
The fact that one cannot manage reptiles and large arachnids environmentally without determining which of these species occur in the study area was an on-going focus throughout this study. A model based approach was utilised to study the diversity of reptiles and large arachnids that occur in the Leeuspruit Private Nature Reserve in an effort to analyse the interrelationships between species and ecological requirements. This aim was achieved and the results indicated a direct relationship between the abundance and availability of dietary and habitat resources and the occurrence and abundance of various species.
This research provided the first list of the Reptilia and Arachnida (Neoscorpionina and Mygalomorphae) of the Leeuspruit Private Nature Reserve in the northern Free State Province. Additional information such as favourable ecological requirements, species’ conservation status and levels of endemism was also provided. It was found that reptile and large arachnid species occurrence is invariably determined not only by the availability of ecological requirements but also the abundance of those ecological requirements. Amphibians and birds are significant dietary sources for snakes in the study area. For example, there is a significant correlation between the abundance of amphibians and birdlife in the study area due to the fact that the Leeuspruit Private Nature Reserve is a seasonal wetland. Fossorial species have proven to be both diverse and abundant due to suitably textured soils that facilitate burrowing.
A total of 28 species have been recorded of which 23 are reptiles and five are large arachnids, proving a significant level of biodiversity within a relatively small area (423 hectares). Significant field work findings include unexpected extension of the
99 geographical distribution of a species of burrowing scorpion (Opistophthalmus glabrifrons) and lesser-thicktailed scorpion (Uroplectes triangulifer marshalli) and 14 new records of reptile species not previously recorded as occurring in quarter degree grid cell 2627DD. This finding pertaining to the newly recorded reptile species depicts a 61% increase in the knowledge of reptiles that geographically occur in the study area and all large arachnids found in the study area are new records. All new records have been submitted to ReptileMAP, ScorpionMAP and SpiderMAP to improve the national database on indigenous herpetofauna and scorpions.
Based on the findings emanating from the current research, useful guidelines are available to the landowners of the Leeuspruit Private Nature Reserve regarding strategies to enhance environmental management in this study area. It is hoped that these guidelines will help to preserve the biodiversity and abundance of indigenous reptile and large arachnid fauna. It is hoped that the research conducted in the Leeuspruit Private Nature Reserve will shed some light in the study field of reptile and large arachnid ecology.
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CHAPTER 9
REFERENCES
Acocks, J.P.H., 1988. Veldtypes of South Africa. (3rd Ed.). Memoirs of the Botanical Survey of South Africa. Botanical Research Institute: Pretoria.
Acocks, J.P.H., 2000. Acock’s veld types of South Africa: Environmental potential atlas for Free State: Vegetation. Department of Environmental Affairs: Pretoria.
Adalsteinsson, S.A., Branch, W.R., Trape, S., Vitt, L.J. & Hedges, S.B. 2009. Molecular phylogeny, classification, and biogeography of snakes of the family Leptotyphlopidae (Squamata, Scolecophidia). Zootaxa, 2244, 1-50.
Alexander, G. & Marais, J., 2007. A guide to the reptiles of southern Africa. Struik: Cape Town.
Bach, L.A., Pedersen, R.B.F., Hayward, M., Stagegaard, J., Loeschcke, V. & Pertoldi, C., 2010. Assessing re-introductions of the African wild dog (Lycaon pictus) in the Limpopo Valley Conservancy, South Africa, using the stochastic simulation program VORTEX. Journal of Nature Conservation, 18, 237-46.
Bates, M.F., 1992. The herpetofauna of the Orange Free State – with special emphasis on biogeographical patterning. Unpublished MSc thesis. University of Natal: Department of Biology.
Bates, M.F., Broadley, D.G., Barlow, A., Wuster, W. & Tollet, K.A. 2012. Taxonomy and distribution of the African egg-eating snakes of the genus Dasypeltis. Seventh World Congress of Herpetology, Vancouver, Canada.
Blanc, J.J., Barnes, R.F.W., Craig, G.C., Dublin, H., Thouless, C.R., Douglas- Hamilton, I. & Hart, J.A., 2007. African elephant status report 2007: An update from the African elephant database. IUCN/SSC African elephant specialist group report No. 33. Gland: Switzerland. http://www.iucn.org/dbtw.../SSC-OP- 033.pdf. Accessed 27 June 2012.
101
Blaylock, R.S., 2005. The identification and syndromic management of snakebite in South Africa. South African Farming Practice, 47 (9), 48-53.
Bonardi, A., Dimopoulo, P., Ficetola, F., Kallimanis, A.S., Labadessa, R., Mairota, P. & Padoa-Schioppa, E., 2011. BIO_SOS biodiversity multisource monitoring system: from space to species. Deliverable No: D6.6 – Selected Bio- indicators. http://www.globallandproject.org/arquivos/news9/Feature_article4.pdf. Accessed 21 August 2012.
Boycott, R.C. & Bourquin, O., 2000. The southern African tortoise book – A guide to southern African tortoises, terrapins and turtles. Interpak: Pietermaritzburg.
Branch, B., 1998. Field guide to snakes and other reptiles of southern Africa. Struik: Cape Town.
Branch, B., 2000. Everyone’s guide to snakes, other reptiles and amphibians of southern Africa. Struik: Cape Town.
Branch, B., 2005. Snakes, other reptiles and amphibians of east Africa. Struik: Cape Town.
Branch, B., 2008. Tortoises, terrapins and turtles of Africa. Struik: Cape Town.
Branch, W.R., 1988. South African red data book: Reptiles and amphibians. South African National Scientific Programmes Report No 151. Council for Scientific and Industrial Research (CSIR): Pretoria.
Broadley, D.G. & Blaylock, R., 2013. The snakes of Zimbabwe and Botswana. Edition Chimaira: Frankfurt am Main.
Bruton, M.N. & Merron, S.V., 1985. Alien and translocated aquatic animals in southern Africa: A general introduction, checklist and bibliography. South African National Scientific Programmes Report no. 113. Council for Scientific and Industrial Research (CSIR): Pretoria.
Buys, P.J. & Buys, P.J.C., 1983. Snakes of south west Africa. Star Binders & Printers: Windhoek.
102
Council for Geoscience, 2000a. Environmental potential atlas for the Free State: Dominant Geology. Department of Environmental Affairs: Pretoria.
Council for Geoscience, 2000b. Geology of South Africa. Department of Environmental Affairs: Pretoria.
Council for Geoscience, 2000c. Environmental potential atlas for the South Africa: Geological Association. Department of Environmental Affairs: Pretoria.
Craigie, I.D., Baillie, E.M., Balmford, A., Carbone, C., Collen, B., Green, R.E. & Hutton, J.M., 2010. Large mammal population declines in Africa’s protected areas. Biological Conservation, 143, 2221-8.
De Waal, S.W.P., 1978. The Squamata (Reptilia) of the Orange Free State, South Africa. Memoirs of the National Museum, Volume 11. National Museum Press: Bloemfontein.
De Wet, K., 2012a. Soils, vegetation, landuse and management: Sasolburg grassland and savanna areas. Specialist report: Sasol Ltd.
De Wet, K., 2012b. Report on the study of the terrestrial vertebrate assemblage at the Sasol properties near Sasolburg, Free State Province. Specialist report: Sasol Ltd.
Department of Environment and Resource Management (DERM), 2009. Use of pitfall traps – standard operating procedure. Animal Ethics Committee. http://www.uq.edu.au/research/rid/files/...DERM%20-%20Pitfall%20Traps.pdf. Accessed 21 April 2012.
Dippenaar-Schoeman, A., 2002. Baboon and trapdoor spiders of southern Africa: an identification manual. Plant Protection Research Institute handbook No. 13. Agricultural Research Council: Pretoria.
Du Preez, L. & Caruthers, V., 2009. A complete guide to the frogs of southern Africa. Struik: Cape Town.
Egoh, B.N., Reyers, B., Rouget, M. & Richardson, D.M., 2011. Identifying priority areas for ecosystem service management in South African grasslands. Journal of Environmental Management, 92, 1642-50.
103
Engelbrecht, I., 2013. Gauteng Nature Conservation: Conservation biologist (ScorpionMAP: Expert panel): Personal communication.
Fabricius, C., Burger, M. & Hockey, P.A.R., 2003. Comparing biodiversity between protected areas and adjacent rangeland in xeric succulent thickets, South Africa: arthropods and reptiles. Journal of Applied Ecology 40 (2): 392-403.
FitzSimons, V.F.M., 1974. A field guide to the snakes of southern Africa. Collins: London.
Fisher, R., Stokes, D., Rochester, C., Brehme, C. & Hathaway, S., 2008. Herpetological monitoring using a pitfall trapping design in southern California. U.S. Geological Survey. Reston: Virginia. http://www.pubs.usgs.gov/tm/tm2a5/pdf/tm2a5.pdf. Accessed 9 January 2013.
Gallon, R.C., 2002. Revision of the african genera Pterinochilus and Eucratoscelus (Araneae, Theraphosidae, Harpactirinae) with description of two new genera. Bulletin of the British Arachnology Society, 12, 201-32.
Gauteng Department of Agriculture, Conservation and Environment (GDACE), 2009. GDACE requirements for biodiversity assessment, Version 2. http://www.iaia.co.za/File.../GDACErequirementsforbiodiversityassessment_1. pdf. Accessed 4 June 2012.
Gildenhuys, P., 2009. A pictoral guide to the baboon spiders of Southern Africa. Cadiz Street Publishing: Cape Town.
Google Earth, 2012. Google Earth maps. http://www.googleearth.com. Accessed 13 April 2012.
Haacke, W.D., 2009. Herpetofauna habitat assessment of Mokolo – Crocodile River water pipeline phase 1. Galago Environmental: fauna and flora specialists. http://www.dwa.gov.za/.../Mokolo%20phase%201%20- %20App%20d%20Herpetofauna%20Final2.pdf. Accessed 4 April 2012.
Holm, E. & Dippenaar-Schoeman, A.S., 2010. Goggo guide: The arthropods of southern Africa. LAPA: Cape Town.
104
Institute for Soil, Climate and Water, 2000a. Environmental potential atlas for the Free State: Generalised soil description. Department of Environmental Affairs: Pretoria.
Institute for Soil, Climate and Water, 2000b. Environmental potential atlas for the Free State: Soil depth classes. Department of Environmental Affairs: Pretoria.
Institute for Soil, Climate and Water, 2000c. Environmental potential atlas for the Free State: Soil leaching status classes. Department of Environmental Affairs: Pretoria.
Institute for Soil, Climate and Water, 2000d. Environmental potential atlas for the Free State: Clay classes of the topsoil. Department of Environmental Affairs: Pretoria.
Institute for Soil, Climate and Water, 2000e. Environmental potential atlas for the Free State: Terrain morphological units. Department of Environmental Affairs: Pretoria.
Jacobsen, N.H.G., 2005. Remarkable reptiles of southern Africa. Briza Publications: Pretoria.
Jacobsen, N.H.G. & Haacke, W.D., 1980. Harmless snakes of the Transvaal. Transvaal Nature Conservation Division: Information Series 2. Tritone Litho: Pretoria.
Jansen, C., 2009. Sasol Sasolburg stakeholder SH&E Brief 2009. http://www.sasolsdr.investoreports.com/...2009/.../Sasolburg%20SHE%20Brie f%202009.pdf. Accessed 7 July 2012.
Kalibbala, F., 2011. West Rand strengthening project – 400kV double circuit power line from Westgate substation to Hera substation and Westgate substation extension, Gauteng: Biodiversity Assessment. SiVest Environmental Division: Gauteng. http://www.sevest.co.za/.../10983%20west%20Rand%20Strengthening%20pr oject/.../20111213%20WEST%20RAND%20DM.pdf. Accessed 13 May 2012.
105
Kearney, M. & Porter, W., 2009. Mechanistic niche modelling: Combining physiological and spatial data to predict species’ ranges. Ecological Letters, 12, 1-17.
Kelly, C.M.R., Barker, N.P., Villet, M.H. & Broadley, D.G., 2008. Phylogeny, biogeography and classification of the snake superfamily Elapoidea: a rapid radiation in the late Eocene. Cladistics, 24, 1-26.
Leeming, J., 2003. Scorpions of southern Africa. Struik: Cape Town.
Leeming, J., 2008. Protected arachnids in South Africa. http://www.scorpions.co.za/index.php?option=com_docman&task=catview&Ite mid=57&gid=57. Accessed 28 February 2012.
Leroy, J. & Leroy, A., 2003. Spiders of southern Africa. Struik: Cape Town.
Lindsey, P.A., Alexander, R.R., du Toit, J.T. & Mills, M.G.L., 2005. The potential contribution of ecotourism to African wild dog Lycaon pictus conservation in South Africa. Biological Conservation, 123, 339-348.
Low, A.B. & Rebelo, A.G., 1996. Vegetation of South Africa, Lesotho and Swaziland. National Botanical Institute: Pretoria.
Marais, J., 1999. Snakes and snake bite in southern Africa. Struik: Cape Town.
Marais, J., 2004. A complete guide to the snakes of southern Africa. Struik: Cape Town.
Marais, J., 2007. What’s that snake? – A starter’s guide to snakes of southern Africa. Struik: Cape Town.
Marais, J., 2011. What’s that reptile? – A starter’s guide to reptiles of southern Africa. Struik: Cape Town.
Marais, J., 2013. African Snake Bite Institute: Herpetologist: Personal communication.
Masterson, G.P.R., Maritz, B. & Alexander, G.J. 2008. Effects of fire history and habitat structure on herpetofauna in a South African grassland. Applied Herpetology, 5, 129-143.
106
Masterson, G.P.R., Maritz, B., Mackay, D. & Alexander, G.J. 2009. The impacts of past cultivation on the reptiles in a South African grassland. African Journal of Herpetology, 58, 71-84.
McLachlan, G.R., 1978. South African red data book: Reptiles and amphibians. South African National Scientific Programmes Report No 23. Council for Scientific and Industrial Research (CSIR): Pretoria.
Mucina, L. & Rutherford, M.C., 2006. The vegetation of South Africa, Lesotho and Swaziland. Sterlitzia 19. South African National Biodiversity Institute (SANBI): Pretoria.
Patterson, R., 1987. Reptiles of southern Africa. Struik: Cape Town.
Patterson, R. & Meakin, P., 1986. Snakes. Struik: Cape Town.
Pienaar, U. de V., 1966. The reptiles of the Kruger National Park. National Parks Board of Trustees: Pretoria. Published as a supplement to Koedoe.
Porteous, A., 2000. Dictionary of environmental science and technology. (3rd Ed.) Wiley: New York.
Prendini, L., 2004. Systematics of the genus Pseudolychas Kraepelin (Scorpiones: Buthidae). Annuals of the Entomological Society of America, 97, 37-63.
ReptileMAP, 2013. Virtual museum database. Animal Demography Unit: University of Cape Town. http://www.sarca.adu.org.za.
Richter, V. & Freegard, C., 2009. Dry pitfall trapping for vertebrates and invertebrates: standard operating procedure – No. 9.3. Department of Environment and Conservation: DEC Nature Conservation Service. http://www.dec.wa.gov.au/.../3652-sop-9-3-dry-pitfall-trapping-for-vertebrates- and-invertebrates.html?... Accessed 21 April 2012.
Scholtz, C., 2006. Sasol Sasolburg SH&E Brief. http://www.sasoldr.investoreports.com/sasol_sr_2006/.../sasol_sr_2006_39.p df. Accessed 26 April 2012.
107
ScorpionMAP, 2013. Virtual museum database. Animal Demography Unit: University of Cape Town. http://www.vmus.adu.org.za.
Shanas, U., Galyun, Y.A., Alshamlih, M., Cnaani, J., Guscio, D., Khoury, F., Mittler, S., Nassar, K., Shapira, I., Simon, D., Sultan, H., Topel, E. & Ziv, Y., 2006. Reptile diversity and rodent community structure across a political border. Biological Conservation, 132, 292-9.
Smart, R., Whiting, M.J. & Twine, W., 2005. Lizards and landscapes: integrating field surveys and interviews to assess the impact of human disturbance on lizard assemblages and selected reptiles in a Savanna in South Africa. Biological Conservation, 122, 23-31.
Souter, N.J., Bull, C.M., Lethbridge, M.R. & Hutchinson, M.N., 2007. Habitat requirements of the endangered Pygmy bluetongue lizard, Tiliqua adelaidensis. Biological Conservation, 135, 33-45.
South African Environmental Outlook (SAEO), 2012a. Chapter 1: Land – Draft 2. Department of Environmental Affairs: Republic of South Africa. http://www.environment.gov.za/environmental...south-africa/state-of- environment-portal-site-goes-live.html. Accessed 14 May 2012.
South African Environmental Outlook (SAEO), 2012b. Chapter 2: Biodiversity and ecosystem health – Draft 2. Department of Environmental Affairs: Republic of South Africa. http://www.environment.gov.za/environmental...south- africa/state-of-environment-portal-site-goes-live.html. Accessed 14 May 2012.
South African Weather Services (SAWS), 2012. Climatological data for Sasolburg. http://www.saws.com. Accessed 26 May 2012.
Sparling, D.W., Linder, G. & Bishop, C.A., 2000. Ecotoxicology of amphibians and reptiles. Setac Press: Brussels.
SpiderMAP, 2013. Virtual museum database. Animal Demography Unit: University of Cape Town. http://www.vmus.adu.org.za.
State of the Environment Report (SOER): Mangaung, 2003. Mangaung state of the environment report.
108
http://www.mangaung.co.za/.../Environmental.../State%20of%20the%20enviro nment%20report%202003/. Accessed 2 June 2012.
Steyn, J.N., Steyn, T.M. & Crafford, J.E., 2007. Proposed power line between Etna and Glockner substations – ecological assessment report. Naledzi Environmental Consultants CC. Department of Economic Development, Environment and Tourism: Pretoria.
Strangeways, I., 2003. Measuring the natural environment. Cambridge University Press: Cambridge.
Strydom, J., 2012. Leeuspruit Private Nature Reserve: Game Ranger: Personal communication.
Surface Resources of South Africa, 2000a. Environmental potential atlas for Free State: Primary catchment runoff. Department of Environmental Affairs: Pretoria.
Surface Resources of South Africa, 2000b. Environmental potential atlas for Free State: Quaternary catchment runoff. Department of Environmental Affairs: Pretoria.
Surface Resources of South Africa, 2000c. Environmental potential atlas for Free State: Secondary catchment runoff. Department of Environmental Affairs: Pretoria.
Surface Resources of South Africa, 2000d. Environmental potential atlas for Free State: Tertiary catchment runoff. Department of Environmental Affairs: Pretoria.
Tolley, K. & Burger, M., 2007. Chameleons of southern Africa. Struik: Cape Town.
Tucker, C.S. & D’Abramo, L.R., 2008. Managing high pH in freshwater ponds. Southern Regional Aquaculture Center: Publication No. 4604. http://srac.tamu.edu/index.cfm/event/getFactSheet/.../205/. Accessed 7August 2012.
109
Van Wilgen, N.J., Richardson, D.M. & Baard, E.H.W., 2008. Alien reptiles and amphibians in South Africa: towards a pragmatic management strategy. South African Journal of Science, 104, 13-20.
Van Wilgen, N.J., Wilson, J.R.U., Elith, J., Wintle, B.A. & Richardson, D.M., 2010. Alien invaders and reptile traders: what drives the live animal trade in South Africa? Animal Conservation, 13, 24-32.
Van Wyk, J., 2012a. Environmental Scientist: Sasol Ltd.: Personal communication.
Van Wyk, M., 2012b. Botanist: Unemployed: Personal communication.
Vargas-Ramirez, M., Vences, M., Branch, W.R., Daniels, S.R., Glaw, F., Hofmeyr, M.D., Kuchling, G., Maran, J., Papenfuss, T.J., Siroky, P., Vieites, D.R. & Fritz, U., 2010. Deep genealogical lineages in the widely distributed African helmeted terrapin: evidence from mitochondrial and nuclear DNA (Testudines: Pelomedusidae: Pelomedusa subrufa). Molecular Phylogenetics and Evolution, 56, 428-40.
Watson, L.H., Odendaal, H.E., Barry, T.J. & Pietersen, J., 2005. Population viability of Cape mountain zebra in Gamka Mountain Nature Reserve, South Africa: the influence of habitat and fire. Biological Conservation, 122, 173-180.
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APPENDIX 1:
Plates 1 – 15
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PLATE 1
Figure 1: Bitis arietans arietans (Puff adder). Figure 2: Hemachatus haemachatus (Rinkhals).
Figure 3: Homoroselaps lacteus (Spotted harlequin snake). Figure 4: Aparallactus capensis (Black-headed centipede- eater).
Figure 6: Psammophylax rhombeatus rhombeatus (Spotted Figure 5: Psammophis crucifer (Cross-marked grass snake). grass snake).
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PLATE 2
Figure 7: Crotaphopeltis hotamboeia (Red-lipped snake). Figure 8: Boaedon capensis (Brown house snake).
Figure 9: Lamprophis aurora (Aurora house snake). Figure 10: Lycodonomorphus rufulus (Brown water snake).
Figure 11: Pseudaspis cana (Mole snake). Figure 12: Lycophidion capense capense (Cape wolf snake).
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PLATE 3
Figure 13: Dasypeltis scabra (Rhombic egg-eater) - Colour Figure 14: Dasypeltis scabra (Rhombic egg-eater) - Rare and pattern variations. patternless variety.
Figure 15: Dasypeltis scabra (Rhombic egg-eater) - Plain Figure 16: Dasypeltis scabra (Rhombic egg-eater) – phase. Uncommon striped variety lacking most characteristic rhombic markings.
Figure 17: Afrotyphlops bibronii (Bibron's blind snake). Figure 18: Afrotyphlops bibronii (Bibron's blind snake) – Xanthic phase due to a genetic pigment anomaly.
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PLATE 4
Figure 19: Leptotyphlops scutifrons scutifrons (Peters’ thread Figure 20: Leptotyphlops scutifrons conjunctus (Eastern Cape snake). thread snake).
Figure 21: Acontias gracilicauda (Thin-tailed legless skink). Figure 22: Trachylepis capensis (Cape skink).
Figure 23: Trachylepis capensis (Cape skink) –Specimen Figure 24: Trachylepis punctatissima (Speckled rock skink). lacking characteristic markings.
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PLATE 5
Figure 25: Agama atra (Southern rock agama). Figure 26: Lygodactylus capensis capensis (Common dwarf gecko).
Figure 27: Pachydactylus capensis (Cape gecko). Figure 28: Pelomedusa subrufa (Marsh terrapin).
Figure 29: Uroplectes triangulifer (Bark scorpion). Figure 30: Uroplectes triangulifer (Bark scorpion) with brood on back.
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PLATE 6
Figure 31: Opistophthalmus pugnax (Burrowing scorpion). Figure 32: Opistophthalmus pugnax (Burrowing scorpion) - Heavily gravid female.
Figure 33: Opistophthalmus glabrifrons (Burrowing Figure 34: Harpactira hamiltoni (Common baboon spider). scorpion).
Figure 35: Harpactira hamiltoni (Common baboon spider) – Juvenile.
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PLATE 7
Figure 36: Crotaphopeltis hotamboeia (Red-lipped snake) - Figure 37: Communal egg deposition site under a flat rock – In threat pose. presumably of Psammophylax rhombeatus rhombeatus (Spotted grass snake) or Psammophis crucifer (Cross-marked grass snake).
Figure 38: Psammophylax rhombeatus rhombeatus (Spotted grass snake) - A good example of egg deposition sites being utilised communally by members of the same species. Two Psammophylax rhombeatus rhombeatus utilise the same concrete slab, one female with her batch of eight eggs and the other female heavily gravid.
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PLATE 8
Figure 39: Bitis arietans arietans (Puff adder) - Skin shedding Figure 40: Bitis arietans arietans (Puff adder) - Head of a of Bitis arietans arietans evident from markings. deceased specimen.
Figure 41: Entrance to a burrow of Harpactira Hamiltoni Figure 42: Eggs of a Gekkonidae species, presumably (Common baboon spider). Pachydactylus capensis (Cape gecko).
Figure 43: Egg-sack of Harpactira hamiltoni (Common Figure 44: Parasite infestation in Uroplectes triangulifer baboon spider). marshali (Bark scorpion).
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PLATE 9
Figure 45: Communal egg deposition - The batch on the left Figure 46: Close-up of egg batch of unknown species. is of Psammophylax rhombeatus rhombeatus (Spotted grass snake) evident from the female remaining with the eggs, the batch on the right is of an unknown species.
Figure 47: Close-up of Psammophylax rhombeatus Figure 48: A pair of Pachydactylus capensis (Cape gecko) rhombeatus (Spotted grass snake) eye. Note the large pupil found under the same rock. due to a diurnal existence
Figure 49: All three of these Crotaphopeltis hotamboeia Figure 50: Close-up of Psammophylax rhombeatus (Red-lipped snake) where found under the same rock, rhombeatus (Spotted grass snake) eggs - Decalcified egg although not of breeding size. This poses the question of shells reveal visible embryonic development. communalism.
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PLATE 10
Figure 51: Archive of collected hatched eggs, snake sheddings, reptile remains and regurgitated bird's eggs from Dasypeltis scabra (Rhombic egg-eater).
Figure 52: Psammophylax rhombeatus rhombeatus (Spotted Figure 53: Psammophis crucifer (Cross-marked grass snake) - grass snake) - Aggressively biting leather glove. Hatchling mortality.
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PLATE 11
Figure 54: Amietophrynus gutturlis (Guttural toad) - One of Figure 55: Xerus inauris (Cape ground squirrel) - Small many amphibian species available as a dietary source. terrestrial mammal available as a dietary source.
Figure 56: Streptopelia capicola (Cape turtle dove) - One of Figure 57: Ploceus velatus (Masked weaver bird) nests - many bird dietary sources. Bird's eggs as a dietary source.
Figure 58: Centipede as a specialised dietary source for Figure 59: Ants with their eggs and lava as a dietary source. Aparallactus capensis (Black-headed centipede-eater).
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PLATE 12
Figure 60: Slugs as a specialised dietary source for Duberria Figure 61: Evidence of moles that serve as a dietary source lutrix lutrix (South African slug-eater). for many snake species.
Figure 62: Vegetation as a dietary source for herbivorous Figure 63: Grasshoppers are common invertebrate dietary and omnivorous reptile species. items.
Figure 64: Rodent nest - Rodents and nestlings are taken by many species as a varied dietary source.
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PLATE 13
Figure 65: Fissures in exposed dolerite provide excellent Figure 66: Building rubble (bricks and concrete) utilised as retreats for scorpions and reptiles. retreats by reptiles and arachnids.
Figure 67: Trees and bushes utilised by arboreal and semi- Figure 68: Soft soil utilised by species that require specific arboreal species. soils for burrowing. A heavily gravid Afrotyphlops bibronii (Bibron’s blind snake) was found in this soil with a very complex array of burrows.
Figure 69: Exfoliating bark is a commonly utilised retreat for Figure 70: Dolerite boulders from exposed outcrops occur in arboreal and semi-arboreal species. large numbers all over the study area.
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PLATE 14
Figure 71: Logs from fallen trees offer a cool and humid Figure 72: Vegetation litter from mowed grass fire breaks habitat. are scattered all over the study area and offer ideal egg deposition sites due to moisture and heat retention.
Figure 73: Disused mammal burrows accommodate large Figure 74: Active termitaria. snake species such as Hemachatus haemachatus (Rinkhals).
Figure 75: Moribund termitaria with access holes exposed. Figure 76: Exposed dolerite outcrops over the winter months.
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PLATE 15
Figure 77: Seasonal wetlands appear after heavy rainfall Figure 78: Winter landscape. over the summer months.
Figure 79: Summer landscape. Figure 80: Vegetation available as cover for diurnal species.
Figure 81: The Leeuspruit flowing through the study area.
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APPENDIX 2:
Agreement letter from Sasol Ltd. to conduct research in the Leeuspruit Private Nature Reserve.
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APPENDIX 3:
Field Guide Association of Southern Africa (FGASA) approved snake identification, snake bite first aid and venomous snake handling course certificate.
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