Damage by baboons to pine plantations in South Africa : with special reference to the ecology of three troops of baboons in the Western Cape

Erasmus, Diane (1993-01)

Thesis (M. Sc.) -- University of Stellenbosch, 1993.

Thesis

ENGLISH ABSTRACT: Baboon density in the study area was lower than in other studies, probably as a result of removal programmes. Troops had seasonal differenccs in home range utilization. Home range inc reased in summer as troops exploited local crops, and permanent water points. All troops showed a preference for plantations, as they provided shelter, food and protection. Data on feeding habits was collected by faecal analysis as baboons' fear had developed a fear of humans. Favoured foods were monocotyledonous and dicotyledonous plants, bulbs, seeds and cones. Xylem, phloem and cambium cells did not constitute a large proportion of the diet, nor was there any seasonal variation in occurrence. Dicots were selected in spring, pine cones in autumn (probably a selection for seeds not cones), insects in summer and bulbs in winter. The five favoured items were found throughout the year. Baboons have a few staple items which they supplement with seasonally available foods. Bark stripping is inhe.rent in baboons, despite the low energetic value of bark tissues. It is not known why all troops in plantations do not strip. Pine seeds and grasses play an important role in the diet, and may attract baboons into the plantations. Some mineral nutrients in the pine tree tissues varied seasonally. Levels in these tissues were comparable with levels in many plants consumed by baboons elsewhere. Zinc levels were higher in trees damaged by baboons than in other trees. Baboons may thus be selecting for zinc. This phenomenon, and the implications for managing baboon damage, needs further research. 37% of plantations in South Africa experienced baboon damage. This was not restricted to any particular area or species of pine. Less than 15% of the compartments on any station showed damage. On average, less than 25% of the trees within a particular compartment were damaged. Increase in damage within a plantation was isolated. No relationship was found between damage and environmental factors. Less than 2% of the total compartments in South Africa and less than 1% of the total area afforested show damage. Baboon damage at Kluitjieskraal State Forest affected 6% of all compartments. Less than 25% of the trees in these compartments were affected. Damage to the trees varied in severity. Patterns of damage were determined and were found to differ between areas within a plantation. A precise estimate of financial losses on a national scale is not possible due to many complicated factors and the considerable lack of available data. An assessment of-the severity of the damage is provided. Authorities must determine whether it is practical and economical to introduce control measures. Indications are that the losses in South Africa amount to less than R5 000 000 on present areas afforested. Information on control programmes in the Western Cape is scarce, although control has been carried out in Forestry areas for many years. The effectiveness of electric fencing to decrease damage levels is discussed. It is imperative to understand the population dynamics of specific baboon populations to exercise effective control.

AFRIKAANSE OPSOMMING: Bobbejaandigthede in die studiearea was laer as in ander studies, moontlik as gevolg van bobbejaanvewyderingsaksies. Troppe se tuisgebiedbenutting het seisonsveranderinge getoon. Tuisgebiede vergroot in die somer omdat troppe naby-gelee oeste en permanente waterbronne benut. Alle troppe het 'n voorkeur getoon vir plantasies omdat dit skuiling, voedsel en beskerming bied. Data oor voedingsgewoontes is versamel deur misontleding omdat die bobbejane vrees teenoor mense geopenbaar het. Monocot, dicot, bolle, sade en dennekeels is as voorkeurvoedsel verkie. Xileem, floeem en kambiumselle was van minder belang in die dieet en het geen seisonsvariasie getoon nie. Tweesaadlobbige plante is in die lente geselekteer, dennekeels in die herfs (moontlik 'n seleksie van sade en nie keels) , insekte in die sommer en bolle in die winter. Die vyf voorkeurvoedselitems het regdeur die jaar in die dieet voorgekom. Bobbejane benut 'n paar voedselitems waarmee hulle seispnsbeskikbare voedsel aanvul. Basstroping is inherent aan bobbejane ten spyte van die lae energievlak van basweefsel. Dit is onbekend waarom net somige troppe bas in plantasies bas afstroop. Dennesade en grasse speel 'n belangrike rol in hul dieet en mag bobbejane na die plantasies lok. Sommige mineralevlakke varieer seisonaal in die denneweefsel. Mineraalvlakke was vergelykbaar met vlakke in plante wat deur bobbejane in ander areas benut word. Bome wat deur bobbejane beskadig is het hoer sinkvlakke getoon as onbeskadigde bome. Bobbejane mag dus vir sink selekteer. Hierdie verskynsel, asook die impliikasies met die bestuur van bobbejaanskade, verlang verlang verdere studie. 37% van die plantatsies in Suid Afrika ondervind bobbejaanskade. Skade is nie beperk tot 'n geografiese gebied of dennespesie nie. Minder as 15% van die plantasiekompartemente by enige stasie het skade getoon. Gemiddeld 25% van die individuele borne in 'n kompartement was beskadig. Groter skade het in geisoleerde gevalle voorgekom. Geen ooreenkoms is gevind tussen skade en omgevingsfaktore nie. Minder as 2% van die aantal plantasiekomprtemente asook minder as 1% van die oppervlakte orider plantasies in Suid Afrika het skade ondervind. Bobbejaanskade het in 6% van die kompartemente by Kluitjieskraal Staatsbos voorgekom. Minder as 25% van die borne was geaffekteer. Die mate van skade aan individuele borne het gevarieer. Die bepaling van skadepatrone het getoon dat skade varieer in die verskillende gebiede van 'n plantasie. Die bepaling van akkurate finanssiele verliese op 'n nasionale skaal is onmoontlik as gevolg van gekompliseerende faktore en die aansienlike gebrek aan beskikbare data. 'n Skatting van die ernstigheidsgraad van skade is egter weergegee. Owerhede moet bepaal of dit prakties en ekonomies regverdigbaar is om beheermatreels toe te pas. Indikasies dui daaop dat skade in kommmersieel beboste areas in Siud Afrika minder as R5 000 000 beloop. Data oor beheerprogramme in die Wes Kaap is skaars, alhoewel beheer reeds vir baie jare in bosbouareas toegepas word. Die effiktiefigheid van elektriesese heining as 'n beheermetode is maatreels bespreek. Dit is gebiedend om die bevolkingsdinamika van spesifike bobbejaanpopulasies te verstaan voordat effektiewe beheer toegepas kan word.

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