Avenant, Nico Loubser (1993)
Thesis (M. Sc.) -- University of Stellenbosch, 1993.
ENGLISH ABSTRACT: Small mammals were sampled in eight different plant communities in the West Coast National Park and on two farms adjacent to the Park, and along various slopes in the Postberg Nature Reserve section. Rhabdomys pumilio was by far the most abundant species at all sites, although its density varied between plant communities and seasons. Species diversity, absolute and relative density, cover preference and breeding activity of some small mammals and density, group size and habitat preference of the main bird prey species are also discussed. A low incidence of larger prey, e.g. antelope, hyrax and hares in caracal scats probably reflects their low densities in the study area. Together with caracal, the diet of four other sympatric carnivore species was also examined by analysis of scats collected over a 14-month period in the West Coast National Park. Dietary patterns of all predators studied correlated with fluctuations in densities of main prey species, as well as group size of certain prey species. Food niche widths accordingly changed seasonally, being widest during spring and then contracting gradually towards winter. A considerable amount of food niche overlap existed between carnivore species pairs. The main prey item of all the carnivores examined were rodents (mainly Rhabdomys pumilio and Otomys unisulcatus), which were utilized heavily throughout the year, despite marked declines in rodent numbers towards winter. Habitat use by five transmitter-equipped caracal (Felis caracal Schreber 1776) indicated that they spent most of their time active in specific areas where highest rodent density and species diversity were found. Males were active for 45-180 min. in a given area (patch) before moving, without stopping, to another patch; females covered their ranges more uniformly in space. The mean home range size (26.97 ± 0.750 km2) of two males inhabiting the same area, but at different times, was 3.6 times larger than that of each of three females (7.39 ± 1.68 km2). Home ranges overlapped both within and between sexes. Caracal were mostly nocturnal, but were also active during daytime in the colder winter. No correlation was found between degree of activity and cloud cover, full or dark moon, wind speed, or rain, but a significant correlation existed between degree of activity and temperatures above 22°c or below 20°c. Mean litter size was 2.25 ± 0.96, with kittens staying ca 120 days with their mother in her territory. This four-month period coincided with the time when most springbok were predated on and when the highest stock losses were reported on farms in the surrounding Swartland Divisional Council. The impact of caracal on introduced springbok at Postberg Nature Reserve section of the West Coast National Park was studied to aid in the decision of whether springbok can be kept in that section of the Park or not. This study contributes to the conservation and control of caracal in the West Coast Strandveld.
AFRIKAANSE OPSOMMING: Getalle van klein soogdiere is gemonster in agt verskillende plantgemeenskappe in die Weskus Nasionale Park, op twee plase aangrensend aan die Park, en teen verskillende hange in die Postberg Natuurreservaat gedeelte van die Park. Rhabdomys pumilio was by verre die volopste spesie by alle vangplekke, alhoewel digthede verskil tussen plantgemeenskappe en oor seisoene. Spesiediversiteit, absolute en relatiewe digthede, voorkeure vir skuiling en voortplantingsaktiwiteit van klein soogdiere, asook digthede, groepgroottes en habitatsvoorkeure van die vernaamste voel-prooispesies word ook bespreek. Lae voorkoms van groter prooi, bv. antilope, dassies en hase in rooikat mis weerspleel hul lae digthede in die studie area. Die dleet van vier ander simpatriese roofdiersoorte is saam met die van die rooikat oor 'n 14-maande periode in die Weskus Nasionale Park bestudeer m.b.v. misontledings. Dieetpatrone van al die roofdiere bestudeer is gekorrelleerd met fluktuasies in digthede van al die hoof prooispesies en met fluktuasies in groepgroottes van sekere prooispesies. Voedselniswydte van hierdie roofdiere verander ook seisoenaal en is die wydste gedurende lente en neem geleidelik af tot en met die winter. 'n Groot mate van voedselnisoorvleueling kom voor tussen die onderskeie roofdierspesiespare. Die hoof . prooi item van al die roofdiere bestudeer, was knaagdiere (hoofsaaklik Rhabdomys pumilio ·en Otomys unisulcatus) wat in groot getalle reg deur die jaar benut is ten spyte van geweldige afname in muisgetalle voor die winter. Vyf rooikatte (Felis caracal Schreber, 1776), met radio-nekbande voorsien, spandeer meeste van die tyd wanneer aktief is in spesifieke gebiede met hoogste knaagdierdigthede en waar hoogste spesies-diversiteit voorkom. Mannetjies bet vir 45-180 minute in so 'n gegewe area (kol) voorgekom voordat hulle feitlik reguit, en sonder om te stop, na die volgende kol beweeg bet; wyfies bet hul hele loopgebied meer eweredig benut, maar nog steeds meer voorgekom in gebiede met hoer knaagdierdigthede. Die gemiddelde loopgebiedgrootte (26.97 ± 0.750 km2) van twee mannetjies gevestig in dieselfde gebied op verskillende tye was 3.6 keer groter as die gemiddelde loopgebiedgrootte van drie wyfies (7.39 ± 1.68 km2). Loopgebiede oorvleuel beide binne en tussen geslagte. Die rooikatte was meestal riaglewend, maar was ook bedags aktief, veral gedurende die kouer winter. Geen korrellasie is gevind tussen die mate van aktiwiteit en wolkbedekking, volmaan of donkermaan, windspoed, of reen nie, maar wel tussen die mate van aktiwiteit en temperature bo of onder 20°c - 22°c. Die gemiddelde werpselgrootte was 2.25 ± 0.96 en jong katjies bly ongeveer 120 dae by hul ma in haar gebied. Hierdie vier-maande periode kom ooreen met die tyd wanneer daar die meeste op springbokke deur rooikatte gevoed word en wanneer die meeste veeverliese gerapporteer is op plase in die omringende Swartland Afdelingsraad. Die invloed van die rooikat op die eksotiese springbokpopulasie in die Postberg Natuurreservaat-gedeelte van die Park is ook bestudeer om te help met die besluitneming of springbokke in die Postberg-gedeelte van die Weskus Nasionale Park aangehou kan word of nie. Hierdie studie lewer 'n bydrae tot besluitnemings aangaande die bewaring en beheer van rooikatte in die Weskus Strandveld.
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