Spatial and feeding ecology of elephant (Loxodonta africana) on Sanbona Wildlife Reserve, Little Karoo, South Africa.

Swanepoel, Pascale (2019-04)

Thesis (MScConEcol)--Stellenbosch University, 2019.

Thesis

ENGLISH ABSTRACT: African elephants (Loxodonta africana) are megaherbivore mixed feeders. They are an important keystone species, influencing a variety of factors within an ecosystem. Historically elephants migrated throughout large parts of South Africa, including the valleys of the Little Karoo. However, these seasonal migration routes have long since disappeared and most of these large herbivores now only occur in South Africa within fenced reserves. This containment of populations can have a negative impact on landscapes as areas are utilised across seasons, thus not allowing vegetation a recovery period. In a sensitive semi-arid environment such as the Little Karoo, this has been a concern with the reintroduction of such large herbivores, as their spatial use and feeding ecology are largely unknown in this area. Sanbona Wildlife Reserve is a 57 600-ha reserve in the Little Karoo which has reintroduced various animals since its creation in 2002. Since the introduction of elephants in 2003 and 2009 the population has increased to 17 individuals between two herds. Habitat heterogeneity, local rainfall, and spatio-temporal distribution of food and water are some of the key elements determining the size and structure of elephants’ home ranges. GPS satellite collars were used to determine the areas utilised by both elephant herds on the reserve. An individual from each elephant herd was fitted with a GPS satellite collar which recorded their hourly movements over an 18-month period. The data collected were utilised to determine home ranges and core zones using the Kernel Density Estimate and Grid Square Methods. Weather patterns were also recorded throughout the study period through the use of weather stations and observations. This information was used to determine the influence of weather on seasonal spatial usage as well as the impact of water points on their movement on the reserve. Results indicated the importance of river lines within both elephant herds’ core zones, however mountain slopes and open valleys were also utilised within their home ranges. The Northern herd’s home range spanned over 25% of the available area (60.4 km2) whereas the Southern herd had a home range of 73.9 km2, 31% of the available area. Furthermore, results show that rainfall, temperature, seasonal vegetation growth and water availability influence seasonal spatial usage.The preferred space utilised correlates with the elephants’ diet preferences. Previous studies of elephant diet in semi-arid to arid environments recorded the utilisation of a combination of graze (C4), woody browse (C3) and succulent browse (CAM), with season and habitat determining the percentage present in the diet. A combination of scan sampling and isotopic analysis of faeces samples was used to better understand the diet of elephants on Sanbona Wildlife Reserve. Results from the scan sampling show that a variety of plant species (at least 94) were recorded to constitute the elephants’ diet. Through the combination of both methods over a 16-month period seasonal differences in diet and between herds was recorded. The Northern herd's diet consisted of 62% browse species, 28% graze and 10% succulents, compared to 79% browse, 2% graze and 19% succulent species in the Southern herd's diet. The results of this study will help Sanbona Wildlife Reserve to better understand the ecological requirements of elephants within this area, as well as their impact on sensitive, slow growing plant species on the reserve. This information will allow wildlife management to make informed decisions with regards to population management strategies.

AFRIKAANSE OPSOMMING: Afrika-olifante (Loxodonta africana) is mega-herbivore, gemengde vreters. Hulle is ‘n belangrike hoeksteen-spesie wat ‘n verskeidenheid faktore binne ‘n ekosisteem beïnvloed. Geskiedkundig het olifante deur groot dele van Suid-Afrika, insluitende die valleie van die Klein Karoo, gemigreer. Daardie seisoenale migrasieroetes het egter lank reeds verdwyn en die meeste van hierdie groot herbivore kom nou slegs binne omheinde reservate in Suid-Afrika voor. Hierdie inperking van bevolkings kan ‘n negatiewe impak op landskappe meebring, aangesien gebiede oor seisoene heen benut word en die plantegroei dus nie ‘n hersteltydperk gegun word nie. In ‘n sensitiewe halfdorre omgewing soos die Klein Karoo was dit ‘n rede tot kommer met die hervestiging van sulke groot herbivore, aangesien hulle gebiedsbenutting en voedingsekologie grootliks onbekend is in hierdie gebied. Sanbona Wildreservaat is ‘n 57 600-ha reservaat in die Klein Karoo wat sedert sy oprigting in 2002 verskeie diere hervestig het. Sedert die vestiging van olifante in 2003 en 2009 het die bevolking aangewas tot 17 individue tussen twee kuddes. Habitat-heterogeniteit, plaaslike reënval en tydruimtelike verspreiding van kos en water is party van die sleutel-elemente wat die omvang en struktuur van olifante se tuisgebiede bepaal. GPS-satellietkrae is gebruik om vas te stel watter gebiede deur albei olifantkuddes in die reservaat benut word. ‘n Individu uit elke olifantkudde is met ‘n GPS-satellietkraag toegerus, wat hul bewegings uurliks oor ‘n tydperk van 18 maande opgeneem het. Die data wat versamel is, is gebruik om met behulp van die Kerndigtheidsberaming- en Vierkantrooster-metodes tuisgebiede en kernsones te bepaal. Weerpatrone is ook deurgaans tydens die studie aangeteken met behulp van weerstasies en deur waarnemings. Hierdie inligting is gebruik om die invloed van weer op seisoenale gebiedsbenutting te bepaal, sowel as die impak van waterpunte op hul beweging binne die reservaat. Resultate het op die belangrikheid van rivierlyne binne albei olifantkuddes se kernsones gedui, alhoewel berghange en oop valleie ook binne hul tuisgebiede benut is. Die Noordelike kudde se tuisgebied het meer as 25% van hul beskikbare area (60.4 km2) beslaan, waarteenoor die Suidelike kudde ‘n tuisgebied van 73.9 km2 gehad het, 31% van die beskikbare area. Verdermeer toon resultate dat reënval, temperatuur, seisoenale plantegroei en beskikbaarheid van water seisoenale gebiedsbenutting beïnvloed. Die gebiede wat by voorkeur benut is, stem ooreen met die olifante se dieetvoorkeure. In vorige studies van olifante se dieet in halfdorre tot dorre omgewings is aangeteken dat ‘n kombinasie van gras (C4), houtagtige takvoer (C3) en vetplant-beweiding (CAM) benut word, waar seisoen en habitat bepaal watter persentasie in die dieet teenwoordig is. ‘n Kombinasie van visuele observasie steekproefneming en isotopiese ontleding van ontlastingsmonsters is gebruik om die dieet van olifante in die Sanbona Wildreservaat beter te begryp. Die resultate van die visuele observasie steekproefneming toon aan dat die olifante se dieet uit ‘n verskeidenheid van plantspesies bestaan (ten minste 94 is aangeteken). Met behulp van die kombinasie van albei metodes oor ‘n tydperk van 16 maande is seisoenale verskille in dieet en tussen kuddes aangeteken. Die Noordelike kudde se dieet het bestaan uit 62% takvoer-spesies, 28% grasspesies en 10% vetplante, vergeleke met 79% takvoer-, 2% gras- en 19% vetplantspesies in die Suidelike kudde se dieet. Die resultate van hierdie studie sal die Sanbona Wildreservaat help om die ekologiese vereistes van olifante binne hierdie gebied beter te verstaan, sowel as hul impak op sensitiewe, stadig groeiende plantspesies in die reservaat. Hierdie inligting sal die wildbestuurspan in staat stel om ingeligte besluite omtrent bevolkingsbestuur strategieë te neem.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/106140
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