THE FEEDING ECOLOGY AND HABITAT USE OF THE AARDVARK Orycteropus aler Submitted in partial fulfillment of the requirements for the degree of Master of Science Wildlife Unit Faculty of Veterinary Science University of Pretoria Onderstepoort © University of Pretoria The Feeding Ecology and Habitat Use of the Aardvark (Orycteropus afer) J.D Skinner Wildlife Unit Private Bag X04 Faculty of Veterinary Science Onderstepoort 0110 The seasonal diet, feeding patterns, feeding selection and habitat selectivity of the aardvark were determined during summer and winter at Tussen die Riviere Nature Reserve in the southern Free State. Pitfall trapping, dig sampling and quadrat sampling were used to determine the resource base of three habitats in the summer and winter of 1998. A total of 44 ant species of 5 sub families and 17 genera, and two termite species of two sub families were recorded. Pitfall trapping was the most successful technique, followed by quadrat sampling (51.1%) and finally, dig sampling (48.8%). Abundance and diversity was higher during summer than winter. Monomorium albopilosum was the most abundant species in all habitats in winter, whilst Anoplolepis custodiens was the most abundant in summer. The grassland habitat yielded the highest abundance and diversity, followed by the steep slope and riverine areas. Seasonal diet and foraging patterns were determined through faecal analysis and observation of four habituated aardvarks. The Formicidae were more important than the Isoptera in both seasons. The feeding of the aardvark was highly selective, only 28.8% of the available species having been utilised. Prey selection was found to be most highly correlated with prey size, prey abundance, prey mobility, and prey calorific value. Aardvarks were highly selective in their habitat utilisation. The vast majority of feeds were made in the grassland areas where prey abundance was greatest, compared to negligible numbers of prey in the rocky steep slopes and no prey in the riverine areas due to periodic flooding. ACKNOWLEDGEMENTS I would like to thank Professor Skinner for giving me the opportunity to study aardvark at Tussen die Riviere and for his financial and intellectual support. To Free State National Parks, and Savvas Vrahimis in particular, I am very grateful for the opportunity to work at TdR, and for the provision of the aardvarks! Martin Haupt did a great job in helping getting the project started and in organising equipment. Mark & Tracy Roods provided endless help, both with practical aspects of the project and in the provision of a social life! I would like to thank Paul Henning and Bill Townley for their help with the fieldwork and their company on the long aardvark following nights! Paul Henning and Gael La Roc also did some great work habituating aardvark and managed to increase the sample size from 2 to 4 remarkably 'tame' animals. I would like to thank Dr Hamish Robertson for the many hours spent identifying ants from my pit fall trapping, dig sampling and quadrats. Ryan Johnson was of great help during the analysis stages and for this I am very grateful. I would also like to thank Dr Hector Dott whom provided highly professional and invaluable input into analysis stages. Dominic Moss and Mike Hoffinan were very helpful throughout the project, not least for their entertainment value. I am very grateful to Pretoria University for their provision of a foreign students bursary for the duration of my study. Most of all, I would like to thank Andrew Taylor for getting the whole project started. He put in the long hours of habituation and developed a situation which enabled me to walk in and start research. He helped me during the protocol stages of my work and put in many hours of brain work into helping me work out analysis problems. Contents Abstract Acknowledgements List of Figures List of Tables General Introduction Chapter One: Introduction Chapter One Results Chapter One Discussion Chapter Two Introduction Behavioural observations Faecal analysis Prey selection Chapter 2 Results 51 Chapter 2 Discussion 88 Chapter 3 Introduction 102 Habitat Utilisation Chapter 3 Results 105 Chapter Discussion 111 Summary 113 References 115 List of Figures Figure 1. The number of species caught in each habitat and season in the pitfall trap samples. Figure 2. The abundance of each of the species caught in the pitfall traps in each season and habitat. Figure 3. A dendrogram of the pitfall trap results in summer and winter. Figure 4. An MDS plot of the pitfall trap results in summer and winter. Figure 5. The number of species recorded in each habitat and season in the dig samples. Figure 6. A dendrogram of the dig sample results in summer and winter. Figure 7. An MDS plot of the dig sample results in summer and winter. Figure 8. The number of species recorded in the three home ranges in the quadrats during the day and at night. Figure 9. A dendrogram of the quadrat results from each home range. Figure 10. The number of species recorded when using each of the sampling methods. Figure 11. The relative importance of the various species in the diet of the aardvark in terms of the time % spent feeding. Figure 12. A dendrogram of the time spent feeding on the various species by each study animal in summer and winter. Figure 13. An MDS plot of the time spent feeding on the various species by each study animal in summer and winter. Figure 14. The relative importance of the various species in the diet of the aardvark in terms of the number % of feeds. Figure 15. A comparison of the winter diet of the aardvark in terms of time % and number % of feeds. Figure 16. A comparison of the summer diet of the aardvark in terms oftime % and number % offeeds. Figure 17. The average lengths of the feed on the various species in summer and winter. Figure 18. The content % of the various species in the faeces in summer and winter. Figure 21. The occurrence % of the various species in the faeces in winter and summer. Figure 22. The percentage content and occurrence of the various species in the faeces in winter. Figure 23. The percentage content and occurrence of the various species in the faeces in summer. Figure 24. The relative importance of the various species in the faeces and in terms of the time spent feeding in winter. Figure 25. The relative importance of the various species in the faeces and in terms of the time spent feeding in summer. Figure 26. The number of consecutive feeds made upon the various species in summer and winter. Figure 27. The average distance walked between feeds on the same and different species in winter. Figure 28. The average distance walked between feeds on the same and different species in summer. Figure 29. The average depths of digs made upon the various species in winter and summer. Figure 33. The proportion of T. trinervoides mounds affected by aardvark activity in the three habitats. List of Tables Table 1. The adjusted abundance of each of the species caught in pitfall traps in summer and winter. Table 2. The results ofa two-way Anosim of the adjusted abundances of the various prey species in the pitfall traps in the two seasons and three habitats. Table 3. The results ofa two-way Anosim of the adjusted abundances of the species utilised by the aardvark in the pitfall traps in the two seasons and three habitats. Table 4. The relative importance of the species utilised by the aardvark in the pitfall trap catches. Table 5. The occurrence % of all the species caught in each habitat in the dig samples. Table 6. A two-way on the occurrence % of the various species caught in the dig samples, between habitat and season. Table 7. The average occurrence % of each of the species recorded in the quadrats at night and during the day. Table 8. The results of a two way Anosim done on the quadrat results from the different home ranges, during the day and at night Table 9. The number, number per Ha, size and proportion of mounds alive a determined from transects during summer and winter. Table 10. The species caught in all of the sampling methods and those specific to one sampling method. Table 11. The two most important species in each habitat when using each of the methods in winter. Table 12. The two most important species in each habitat when using each of the methods in summer. Table 13. A two way Anosim comparing the occurrence % of the various species in the pitfall trap and dig samples in winter. Table 14. A two way Anosim comparing the occurrence % of the various species in the pitfall trap and dig samples in summer. Table 15. The average time % spent feeding on the various species in winter, summer and overall. Table 16. The results of a one way Anosim comparing summer and winter diets of the aardvark in terms of the time % spent feeding Table 17. The time % spent feeding on the various prey species by each of the study animals in winter. Table 18. The time % spent feeding on the various prey species by each of the study animals in summer. Table 19. The percentage number of feeds made upon each of the species in winter, summer and overall. Table 20. The results of a one-way Anosim comparing the diets in terms of the number of feeds on the various species, between season. Table 21. The average feed lengths on the major prey species by the study animals in summer. Table 22. The relative importance of the various species in the faeces of the aardvark in summer and winter.