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A Study of the Diets of Feral Goat Populations in the Snowdonia National Park

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A Study of the Diets of Feral Goat Populations in the Snowdonia National Park A Study of the diets of Feral Goat Populations in The Snowdonia National Park. Bryan Glenville Dickinson BSc HONS (Wales) A thesis submitted in candidature for the Degree of Magister in Philosphiae in the University of Wales. School of Agriculture and Forest Sciences University of North Wales February 1994 SUMMARY A study of the botanical composition of feral goat (Capra hircus) diets was carried out using faecal analysis. Two groups of goats in the northern part of the Snowdonia National Park were selected, one using mainly lowland deciduous woodland, the other restricted to upland heath at over 400 m altitude. Diets of male and female goats were analysed separately on a monthly basis and related to information on range, group structure and habitat utilisation. At the upland site little segregation of the sexes took place and overall diets between the sexes were similar. Thirty plant species were identified in the faeces, and the overall diet consisted of approximately 50 % monocotyledonous plants (mainly grasses and sedges), 40 % ericaceous shrubs, and 10 % ferns, herbs and bryophytes. Dwarf shrubs were important throughout the year. Grasses, especially Nardus stricta, were consumed in late winter and spring but were replaced by sedges in late spring and early summer. At the lowland site the group was much larger, and a greater degree of dispersal and sexual segregation occurred. Over fifty plant species were identified and overall faecal composition differed between the sexes. Male diet consisted of approximately 15 % monocotyledonous species (mainly grasses), 67 % tree browse (leaves) and dwarf shrubs, 10 % ferns and 8 % herbs and bryophytes. Overall, female diet contained a higher proportion of monocotyledons (21 %), less browse (62 %) and similar proportions of other material. Monthly differences in diet composition between the sexes were often large. A variety of woody shrubs were eaten throughout the year, grasses were replaced by tree browse over the summer months and ferns formed up to 30 % of the diet in late autumn. At both sites, similarity in diet composition between the sexes was lowest in late winter when females separated prior to kidding. 1 ACKNOWLEDGEMENTS Thanks are due to all those who have provided assistance in the preparation of this thesis. I am grateful to my supervisor, Dr. Mike Alcock for his advice and encouragement, to Dr. David Bullock for providing access to his literature and plant reference collections, and to the various staff at CCW and Gwynedd County Council for providing maps and practical help. Special thanks are also due to my wife Dr. Jenny Wong, for her general perseverance and help with GIS and computing problems. Finally, much appreciation is due for all the support and company provided in the later stages by Ms. Sattie. 2 List of Contents SUMMARY.........................................................................................................................1 ACKNOWLEDGEMENTS...............................................................................................2 LIST OF ABBREVIATIONS USED IN TEXT.............................................................10 CHAPTER 1. INTRODUCTION AND OBJECTIVES ...............................................11 CHAPTER 2. BACKGROUND......................................................................................13 2.1 Location and description of sites. 13 2.1.1 Location. 13 2.1.2 Topography. 14 2.1.3 Climate. 17 2.1.4 Geology & Soils. 19 2.1.5 Vegetation. 20 2.1.6 Land Use and Conservation Status 22 2.2 Details of Goat groups. 23 2.2.1 Description Goat groups, pelage patterns, history 23 2.2.2 Present numbers, sex & age groups 27 CHAPTER 3. METHODS...............................................................................................29 3.1 Dietary Analysis. 29 3.1.1 Techniques available for the study of ungulate diet composition 29 3.2 The faecal analysis technique. 30 3.2.1 Assumptions. 31 3.2.2 Methodology. 33 3.3 Faecal analysis methods used in this study. 35 3.4 Preparation of Plant cuticle reference material 37 3.5 Fieldwork 40 3.5.1 Initial observations 40 3.5.2 Identification of individuals 40 3.5.3 Field visits 43 3.6 Faecal Collections 43 3.7 Mapping of goat movements 44 3.7.1 Ranges of male and female goats at the two sites. 44 3.7.2 Estimation of vegetation/habitat utilisation and selection. 45 3.8 Social Organisation 45 3.9 Other field observations 46 CHAPTER 4. ASPECTS OF THE FAECAL ANALYSIS TECHNIQUE .................47 4.1 A comparison of composition estimation methods using hand compounded mixtures. 47 4.1.1 Methods 47 4.1.2 Calculation Methods: 49 4.1.3 Analysis of results 53 4.1.4 Results and Discussion: 53 4.1.5 Prediction Equations 56 4.2 Sample size and attendant confidence limits. 58 4.3 Keys to aid identification of plant cuticle fragments. 62 4.4 Identification of plant cuticle material. 62 CHAPTER 5. RESULTS .................................................................................................66 3 5.1 Cwm Ffynnon Field observations 66 5.1.1 Ranges 66 5.1.2 Group Structure 70 5.1.3 Vegetation class utilisation and selectivity 71 5.1.4 Other factors that may affect habitat selection and diet. 74 5.2 Faecal Analysis 75 5.2.1 Overall faecal composition for the year. 78 5.3 Variations in faecal composition by plant category. 80 5.3.1 Monthly variations in faecal composition 81 5.3.2 Differences in faecal composition between the sexes. 87 5.3.3 Variation in diet composition between individual goats. 89 5.4 Field Observations in the Padarn area. 92 5.4.1 Ranges. 92 5.4.2 Group Structure. 92 5.4.3 Vegetation class utilisation and selectivity. 96 5.4.4 Other factors affecting habitat selection and diet. 100 5.5 Faecal analysis of goats in the Padarn area. 101 5.5.1 Overall faecal composition for the year. 102 5.6 Variations in faecal composition by plant category 106 5.6.1 Monthly variations in faecal composition 110 5.6.2 Differences in faecal composition between the sexes. 113 CHAPTER 6. DISCUSSION AND SUMMARY.........................................................116 6.1 Faecal Analysis. 116 6.2 Group structure, seasonal and 12-month ranges. 118 6.3 Habitat utilisation. 120 6.4 Faecal composition. 124 6.5 Management implications. 131 CHAPTER 7. SUMMARY AND CONCLUSIONS....................................................134 7.1 Background 134 7.2 Use of faecal analysis. 134 7.3 Fieldwork 135 7.4 Habitat utilisation 135 7.5 Diet analysis 136 APPENDIX 1. .................................................................................................................139 1.1 Keys to assist in identification of plant cuticle fragments found in faeces. 139 1.2 Key to Epidermal Fragments of common plant taxa found in Cwm Ffynnon. 143 1.3 Key to epidermal fragments from common plant taxa found in the Padarn area 147 1.4 References used in development of keys to plant cuticle / epidermal material. 157 APPENDIX 2. FIELD DATA........................................................................................160 2.1 Cwm Ffynnon 160 2.2 Padarn area. 171 APPENDIX 3. SUMMARY OF FAECAL COMPOSITION DATA. .......................180 3.1 Faecal composition data for individual goats in Cwm Ffynnon 180 3.1.1 Monthly summaries of faecal composition data for Cwm Ffynnon. 183 4 3.2. Summary of faecal composition data for goats in the Padarn area 1991-92. 184 APPENDIX 4. NOTES ON STATISTICAL ANALYSIS...........................................185 4.1 Multivariate Test Statistics 186 4.1.1 Cwm Ffynnon (All data) 186 4.1.2 Cwm Ffynnon (Selected Individuals) 186 4.1.3 Padarn (All data) 186 4.2 Univariate Tests 187 4.2.1 Cwm Ffynnon Data 187 4.3 Cwm Ffynnon Data - Individual Goats 188 4.4 Padarn Data 190 REFERENCES...............................................................................................................192 5 List of Figures Figure 2.1 Location of study sites in N.Wales ................................................................14 Figure 2.2 Extract from O.S. 1:25 000map (sheet SH) showing the Padarn study area. The outermost observations of all goats in the main group are linked to form the 12-month range.........................................................................................15 Figure 2.3 Extract from O.S. 1:25 000 map (sheet SH) showing the Cwm Ffynnon study area. The outermost observations of all goats in the main group are linked to form the 12-month range..........................................................................16 Figure 2.4 Climatic data for Dinorwic Meteorological Station March 1991- February 1992 .........................................................................................................18 Figure 2.5 Goats in the Cwm Ffynnon area: Male (top) and female (bottom). ..............25 Figure 2.6 Goats in the Padarn area: Males (top) and young female (bottom)...............26 Figure 3.1 Fieldsheet notes for identification of goats (top) and photograph of male “M10”, an adult male from the Padarn group. ...............................................42 Figure 4.1 Relationship of estimated composition (using Quadrat Number (QN) method) and dry weight composition for (a) Dicotyledons and b) Monocotyledons......................................................................................................57 Figure 4.2 Estimated percentage composition of two components (a, 40 % and b, 10 % approximately) versus number of fragments identified. Dotted lines show the estimated 95 % confidence limits and the shaded area shows the theoretical 95 %
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