Mesopredator abundances, prey interactions and diet of Caracal caracal and Canis mesomelas in the Gamkaberg, Western Cape

Steenkamp, Elani (2018-12)

Thesis (MSc)--Stellenbosch University, 2018.

Thesis

ENGLISH ABSTRACT: Carnivore conservation is considered a priority due to a rise in conflict between involved species and humans. Conservation strategies are thus essential in ensuring the persistence of carnivores in carnivore-human conflict. This conflict affects many livestock farmers, whose main concern is the loss of income due to livestock deaths from predators. Reported incidences of depredations could intensify the human-wildlife conflict in an area, which could potentially result in predators being killed by, for example, trapping and through sport hunting. This measure-for-measure retaliatory response can drive predators to local and regional extirpation, often resulting in an increase of wild herbivore densities. Small stock farmers in South Africa regard leopard, caracal (Caracal caracal) and black-backed jackal (Canis mesomelas) as vermin. In the Gamkaberg region of South Africa’s Western Cape Province, the diet of the Cape leopard has been studied quite extensively, but research on the diets of the black-backed jackal and the caracal in the area is lacking. Consequently, this study focussed on the distribution and diet of caracal and black-backed jackal using camera traps and scat and stomach content analyses. The first part of this thesis focuses on the diets of the two species and compares dietary preferences on farmland and in conservation areas. Results pose a clear contrast to livestock farmers’ view on these predators’ natural diet. Both focal species were found to prey upon predominately smaller prey and were opportunistic. Insects were found in approximately 10% of both the jackal and caracal scats. Other invertebrates were also identified in the scats of both species, including scorpions and Solifugae. The stomachs of 11 black-backed jackal contained Solifugae and egg remnants; the softer nature of such diets makes it difficult to detect them in scats. Stomach content analyses thus indicated more recent and detailed diet results, in particular for the opportunistic black-backed jackal that ingests many soft-tissue prey items, such as carrion and Arthropoda that rarely persist through the digestive tract. Mammals, especially rodents, are a very important food source for mesopredators and were found in most of the samples for both jackal and caracal. In this study, 83.3% and 88.1% of jackal and caracal scat samples, respectively, contained rodent parts. Rodents, therefore, account for a significant part of both mesopredators’ diets in the Little Karoo. The large variation found in both the caracal and black-backed jackal diets confirmed their opportunistic feeding nature in the Gamkaberg. This flexibility in diet, especially for the black-backed jackal, makes it difficult to determine a prey-specific preference pattern. The diets of the focal species in this study are adaptable to time, space and prey availability. The second part of the thesis focuses on estimating population density based on camera trapping. Population size and density estimates are informative to conservation and management planning but are difficult to estimate, especially if the species is rare or elusive. This study used estimators based on relative abundance and presence-absence records to assess the relative abundance of caracal and black-backed jackal in the study area. Camera traps were used for a 10 month period (June 2014-April 2015) in farmlands and conservation areas, whilst also testing different sampling efforts. Graphs were produced to illustrate activity periods of the focal species throughout the year. In particular, caracal and black-backed jackal were found to roam in overlapping areas, preying on similar species and showing similar activity patterns. A significant difference was found between prey diversity of the two land-uses (P=0.001). Significant differences were also found between randomised and intensive sampling (P=0.03) as well as between randomised and extensive sampling (P=0.05). However, there were no significant differences in prey diversity between intensive and extensive sampling. In total, 28 caracal and 115 black-backed jackal occurrences were recorded on camera traps, with less caracal and black-backed jackal detected on farmlands than in conservation areas, indicating their preference for natural prey in reserves over prey on farmlands. This also corroborates the results from the scat samples found on farmlands and in conservation areas for both focal species.

AFRIKAANSE OPSOMMING: Karnivoorbewaring word as 'n prioriteit beskou as gevolg van ‘n styging in konflik tussen mense en die betrokke spesies. Bestuursstrategieë is dus baie belangrik omdat dit die aanhoudende teenwoordigheid van karnivore verseker. Veëboere se grootste bekommernis is die verlies van inkomste weens veë afnames veroorsaak deur roofdiere. Voorbeelde soos hierdie kan ‘n styging in mens-roofdier konflik veroorsaak en kan daartoe lei dat roofdiere doodgemaak word met lokvalle en sportjag. Die nagevolge hiervan is die uitwissing van roofdiere wat die natuurlike herbivoor populasies in toom hou. Veëboere beskou luiperde, rooikatte en rooijakkalse as peste en hierdie roofdiere veroorsaak veral mense-dier konflik in die area van die Gamkaberg in the Wes-Kaap in Suid-Afrika. Hierdie tesis poog daarom om rooikatte en rooijakkalse deeglik te bestudeer omdat daar min oor hulle huidige ruimtelike ekologie verken is. Diëetstudies is al in diepte breedvoerig onderneem vir die Kaapse luiperd, egter is daar `n tekort aan studies wat op die diëet van rooijakkalse en rooikatte in die Gamkaberg area fokus. In hierdie studie gaan rooikatte en rooijakkalse in meer diepte bestudeer word met gebruik van diëetanalise en kamera lokvalle. Die eerste gedeelte van hierdie tesis fokus op die diëte van die rooikat (Caracal caracal) en die rooijakkals (Canis mesomelas). Dit word gedoen om kennis te bekwaam oor die rooikat en rooijakkals se diëetvoorkeure tussen plaaslande en natuurreservate. Hierdie kan vir veëboere ‘n nuwe perspektief bied oor karnivore se natuurlike diëet. Albei fokusspesies het op kleiner prooi gevoer en was veelsydig in hul prooikeuse. Insekte is ook in baie stoelgang monsters vir beide die rooikat en rooijakkals gevind (omtrent 10% vir elk). Ander ongewerweldes soos skerpioene en geleedpotiges is gevind in albei fokusspesies. Dit is merkwaardig dat daar baie sagte prooi gevind is in die 11 rooijakkals maaginhoude wat bestudeer is. Die rooijakkals neem baie sagte voedingstowwe in soos aas en geleedpotiges wat vernietig word binne-in die spysverteringskanaal. Dié sagte materiaal sal glad nie, of baie selde, teenwoordig wees in die harde stoelgang monsters. Dus bied maaginhoudanalise meer volledige resultate, veral vir die veelsydige rooijakkals. Soogdiere, veral knaagdiere, is ‘n baie belangrike voedselbron vir kleiner roofdiere en is in meeste van die monsters vir die rooijakkals en rooikat opgemerk. In hierdie studie het 83.3% en 88.1% van die jakkals en rooikat se stoelgang onderskeidelik knaagdierinhoud bevat. Knaagdiere vorm dus ‘n beduidende deel van albei fokusspesies se diëte in die Klein Karoo. Die wye verskeidenheid in albei fokusspesies se diëte bevestig hulle wye habitat omvang in Suidelike Afrika. Hul diëet verskeidenheid, veral dié van die rooijakkals, maak dit moeilik om ‘n spesifieke prooikeuse-patroon te bepaal. Die jakkals en rooikat toon dat hulle diëte maklik aanpasbaar is tot tyd, ruimte en wat beskikbaar is. Die tweede gedeelte van die tesis handel oor die beraming van bevolkingsdigtheid vir die bogenoemde fokusspesies. Bevolkingsgrootte- en digtheidberamings bied belangrike bewarings- en bestuursplanne. Ongelukkig is dit soms moeilik om dié inligting te verg as die spesies skaars en ontwykend is. Die relatiewe oorvloed en teenwoordig-afwesig beramings word gebruik om die rooikatte en rooijakkalse se getalle te bepaal. Kamera lokvalle is opgestel om vir tien maande (Junie 2014 - April 2015) tussen plaaslande en nattuurreservate inligting te versamel, asook verskillende steekproefpogings te toets. Grafieke is getrek om die fokusspesies se aktiwiteitspatrone deur die loop van die jaar te illustreer, wat hul aktiwiteit sal wys. In hierdie studie is dit gevind dat die rooikatte en rooijakkalse in soortgelyke areas voorgekom het, voedsel gekies het en dat hulle dieselfde tye aktief was. ‘n Beduidende verskil (P=0.001) is gevind tussen prooidiversiteit op plaaslande en in natuurreservate. Beduidende verskille is ook gevind tussen die lukrake- en intensiewe steekproefpogings (P=0.03) asook die lukrake en ekstensiewe steekproefpogings (P=0.05). Daar is egter geen beduidende verskille gevind in prooiverskeidenheid tussen intensiewe en ekstensiewe steekproefpogings nie. ‘n Somtotaal van 28 rooikatte en 115 rooijakkalse is deur al die kamera lokvalle afgeneem. Daar het minder rooikatte en rooijakkalse op plaaslande voorgekom in vergelyking met natuurreservate. Dit kan beteken dat hulle natuurlike prooi verkies in natuurreservate bo veë in plaaslande. Dit korreleer met die aantal stoelgang monsters wat gevind is op plaaslande en op natuurreservate vir beide fokusspesies.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/105098
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