A functional analysis of scent marking and mating behaviour in the aardwolf , Proteles cristatus (Sparrman, 1783) by Alexander Sliwa Submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy in the Faculty of Biological and Agricultural Sciences University of Pretoria May 1996 ii A functional analysis of scent marking and mating behaviour in the aardwolf, Proteles cristatus (Sparrman 1783) by Alexander Sliwa Supervisor: Dr. Philip R.K. Richardson Department of Zoology and Entomology University of Pretoria ABSTRACT This study attempted to answer how scent marks function in terms of aardwolf Proteles cristatus year- round territory maintenance and mating success. A functional analysis of scent marking in the aardwolf was conducted in a two and a half year field study whilst recording 42 000 paste marks. The anatomy and histology of the anal pouch revealed an efficient organ for producing copious amounts of long- lasting fatty pasting secretion, and the apparatus for applying it onto grass stalks. The histology of the penile pad of aardwolf males was similarly geared to production and application of secretion, though its exact function is still not clear. Aardwolves started practising scent marking motor patterns early in life, but physiological maturation of secretion was complete with eight months and independence from their parents only. Cubs practised paste marking by overmarking scent marks of their parents, adjusting their mark-rate to that of the adult followed. After physical and behavioural maturation of paste marking subadults ceased to mark, coinciding with parental aggression, and some remained in their parent’s territories for another year. They started to paste again only when attempting to establish their own territory. Aardwolves scent marked almost exclusively by pasting with their anal pouch. Uncovered faeces away from established middens and urine deposited on middens, predominately by males during the mating season, were however likely to act as additional scent marking agents. iii During the non-mating season scent marking patterns suggested that scent marks functioned as a representation of an aardwolf’s claim to a territory area and its readiness to resort to physical escalation. Female and male motivation for territorial marking might differ slightly. There was a great deal of variation in marking activity due to territory size, individual effort, and territory establishment. Aardwolves responded to greater perceived intruder pressure by increasing their marking activity. Midden and den marking and general usage was adapted as well. Borders where intrusions were most likely were marked selectively more than others. Variation in scent marking activity was even stronger during the mating season. Both sexes increased their rate of marking ouside of their territories in order to advertise to neighbouring mating partners in the weeks around the females’ oestrus. Females only increased their mark-rates when not in attendance by males. Males with high mark-rates scouted in territories of females in pro-oestrus indicating their determination to mate to both their neighbouring males and females. After the mating season when resources, mating partners and food, were scarce scent marking activity was low to increase again when re-establishing territorial borders. At least 62% of observed copulations were extra-pair copulations (EPCs). Males either tried to mate at the critical point for female fertilisation by aggressive intervention or by sneaking copulations avoiding physical escalation. Female encouraged EPCs but still were eager to copulate longer with their partners. They were able to influence the course of the copulation considerably. By defending an exceptionally large territory, as well as having two females, weakened one male’s ability to guard his female partners efficiently from EPCs. In 43 experiment nights the response of aardwolves was monitored when finding 164 translocated scent marks collected from known aardwolves. An increase of scent marking activity at relevant borders and the demonstration that intimidation was transmitted without physical presence of the marker provided support for the intimidation hypothesis. Aardwolves changed their occupied den in response to it being scent marked by a same-sex intruder. Translocated scent marks of a female in pro-oestrus were able to elicit a visitation of her territory by the neighbouring male suggesting sex attractants in female scent marks. Seasonally the messages transmitted by scent marking changed coinciding with a shift in principally defended resource, food or mating opportunity. The study contributes to the understanding of the function of scent marking in the solitary aardwolf, by exposing their capability to transmit messages efficiently and their ability of interpretation to secure their food resources and mating opportunities. iv “Anyone who has spent days and nights watching another animal in the wild will realise that each species perceives a world of its own - totally unlike any other” David Day 1981 v ACKNOWLEDGEMENTS It is a great pleasure that I write these acknowledgements, giving me the opportunity to thank the many people who helped me in all aspects of this thesis. First I would like to thank my parents for introducing me to the magic of travelling and nurturing my deep love and interest for nature. Their ever-present spiritual and financial assistance has enabled me to see many places and transform my early dreams into a professional career. Despite living in Germany they spent many nights out in the field with me, always enthusiastic to learn about the complicated family affairs of the aardwolves. De Beer's Consolidated Mines provided me with unlimited access to the study area on Benfontein farm. I am most grateful to have been allowed to stay in their spacious house at Joint Shaft, close to the study area. Financial support was provided by the Deutscher Akademischer Austausch Dienst (DAAD) for two years, and a University of Pretoria research assistant bursary for two and a half years. The Gibbs family on Benfontein farm, Peter, Jennifer, Gregory, and Nicola provided me with much help, from the first basic needs of comfortable life, to constant help with my highly stressed vehicle as well as the many Sunday lunch invitations. I am most grateful to the staff of the McGregor Museum for providing me with computer access and unlimited use of their equipment, notably Corne Anderson, Tania Anderson who drew the Figure 3.2, Mr. Stockwell and Ivan Swart. Everybody was most helpful in providing assistance when problems arose. I also enjoyed our conversations during my day visits which were very important for my mental health, which was otherwise restricted to the aardwolves out in the veld. If I have to single out one person who helped me more than any other both in the veld and at the Museum, that person must certainly be Beryl Wilson. Despite the dust, mosquitoes, heat and cold, and incredibly heavy spotlamps, she cheerfully braved many nights, going through the agony of watching me miss many of my first shots trying to dart aardwolves. Any problem or issue which asked for a quick, reliable and intelligent solution by discussion and action she handled sovereignly. She probably knows more about aardwolf-researchers’ fads than anyone else. I thank Mark and Tania Anderson for their friendship, always ready to give advice, help at any time of the day or night, especially in the early days of frustration, and tried to relax my single minded aardwolf and cat thoughts with enjoyable birding excursions and tennis games. My supervisor, Philip Richardson introduced me to the aardwolves of Benfontein, and watched anxiously my first ‘hands on’ attempts at collecting scent marks and steering my vehicle clear of termite mounds. Later on for sharing many nights of darting aardwolves and deciphering the first drafts of my thesis and going through them again and again. I profited greatly from his ideas and discussions on aardwolf behaviour and data analysis. vi In Pretoria I was introduced to the subtleties of gas-chromatography by Peter Apps. I am most appreciative of the friendship and enthusiasm of Mike van der Linde at the University's Research Support Department. Particularly for his many months of tireless enthusiasm and help to get the SAS programs working on the vast amounts of data I had amassed as well as writing new programs and translating my summary into afrikaans. Without his help the analysis of my data would have been so much poorer. During the numerous visits to Pretoria I would like to thank Debbie Morris and Uli Rosendahl, and later Philip and Lynne Richardson, Rob Davies, and Tim Jackson for their generous hospitality and ever-present help and support. My sister Karen and her husband Uli Hähnle provided the delicacy-starved temporary bachelor with many delicious meals and a nice place to stay. Stan Harvey of the Kimberley Hospital provided medical supplies ad libitum and always had an ear open to listen to the aardwolves’ story. Without his help my histological analysis would have been impossible. I also would like to thank Andreas Popp from the Bayer’s Toxicology Lab in Wuppertal, Germany for professional help with the histology. Among the many people who joined me in the field and shared my enthusiasm for the aardwolves I mention here Arne Lawrenz, Angus and Ian Burns, Shawn Truscott, and Kathrine Voigt who helped with the darting of aardwolves. Gus van Dyk and Martin Haupt went out of their way to construct some excellent radio-collars. The people from C&B Communications often helped in fixing bent cables and soldering loose connections. For the recording of aardwolf vocalisations Laura Frehsen from the Transvaal Museum provided a generous supply of tapes and the ‘Rolls Royce of sound recorders’, the Nagra IV with microphones. Gustav Peters from the Zoologisches Forschungsinstitut und Museum Alexander Koenig in Bonn, Germany, guided me into the subtleties of recording and analysing sounds.