A questionnaire-based evaluation of the veterinary cordon fence separating wildlife and livestock along the boundary of the Kruger National Park, South Africa

Abstract

Veterinary cordon fences are used in Southern Africa to separate wildlife from domestic animals in order to prevent transmission of infectious diseases. Such fences are a control method recognized by the World Organization for Animal Health (OIE) for establishing disease-free zones in beef exporting countries. However, few studies have evaluated the ecological impact of these physical barriers or their effectiveness at a multispecies level. We examined the permeability of one such barrier, along 357 km of the western and southern boundary of the Kruger National Park (KNP) during 2007. Information was gathered using a semi-structured questionnaire implemented among 32 teams of fence maintenance workers. Data were analyzed to identify (a) the main causes of fence damage, (b) the seasonality, location and duration of fence repairs, (c) high permeability areas for elephant (Loxodonta africana), kudu (Tragelaphus strepsiceros), impala (Aepyceros melampus), buffalo (Syncerus caffer) and warthog (Phacochoerus africanus), and (d) the influence of fence electrification, rivers and elephant damage on the frequency of observation of wildlife species outside the KNP estimated during the year. Human and elephant damage were the most common reasons for fence repairs. Elephant and buffalo were the most and least common large mammal species reported observed outside the KNP (1076 and 162 reports/year), respectively. Cattle incursions into the KNP were also reported in 44% of the fence sections. Electrification of the fence was an important factor explaining differences in estimated wildlife species observations outside the KNP during the year. Correlations between estimations of observed species suggested that fence gaps created by elephants might be used by the other wildlife species. Estimated annual counts of kudu, impala and buffalo, but not warthog, were found to correlate with elephant observations. Negative binomial regression models were developed to explore the relationships between observed estimations of different wildlife species outside the KNP the fence, electrification of fence sections and the presence of watercourses, suggesting that kudu, impala and buffalo could use elephant induced fence damage to leave the KNP. The questionnaire was able to evaluate fence integrity and identify sections where integrity was sub-optimal for separating wildlife from domestic livestock species. If combined with more quantitative methods and applied on a routine basis, it could provide an efficient and cost-effective method for monitoring the effectiveness of physical barriers to contain wildlife within protected areas such as is the case with veterinary cordon fences in Southern Africa. (Résumé d'auteur

Transmission of foot and mouth disease at the wildlife/livestock interface of the Kruger National Park, South Africa: Can the risk be mitigated?

“…However, a fundamental assumption in the model was that FMD transmission between cattle and buffalo could occur if they shared the same environment within a specific space and for a certain amount of time. The maximum space frame considered for a contact to occur in the different questionnaires implemented (Abu Samra et al, 2012;Jori et al, 2011) being the size of a local soccer field (approximately 0.7 ha) and the time window considered for a contact ranging between 30 min and 1 day were considered plausible scenarios.…”

“…Veterinary fences were specifically developed to prevent those contacts and their success in mitigating FMD transmission during the last two decades has promoted their spread across other countries in southern Africa, despite a highly controversial impact on wildlife populations (Woodroffe et al, 2014). In addition, although not integrated directly in the model, the increase of elephant populations in the KNP (Figure 3), considered as one of the major causes of fence damage in the KNP (Jori et al, 2011;Jori et al, 2009).…”

“…the number of days per year that farmers declared driving their cattle into the KNP for drinking and "n" represented the total number of days that this event could have occurred in one year (Vose 2004). The probability of cattle and buffalo becoming in contact in the KNP was gathered by a questionnaire implemented among fence workers to assess the permeability of the 70% of the KNP Western boundary veterinary fence (Jori et al, 2011). This data set allowed us to quantify the number of days that every fence worker reported the observation of contacts during the previous year (r), and the number of possible days that this event could have been observed by the totality of persons interviewed (n).…”

“…We then used a Beta distribution, as described above, to model this parameter. The mean time of contact between buffalo and cattle inside the KNP as reported by KNP fence workers (Jori et al, 2011), was modelled as a discrete distribution of each observed time interval. To take into account the occurrence of contacts between several individuals of each herd (buffalo and cattle) at water sources in the KNP, we calculated the probability for an individual from a cattle herd to come into contact with at least one individual of the buffalo herd when they would come across each other, P coi , using the following formula:…”

Climate change, cattle, and the challenge of sustainability in a telecoupled system in Africa

“…The sheer extent of fencing throughout the region has altered the landscape and fragmented habitat for migratory wildlife (Gadd 2012). If the same strategy is utilized in Mozambique, fencing could close corridors between protected areas and alter the movement patterns of already at-risk migratory species, such as elephants, which have been trapped by veterinary fences spanning southern Africa (Chase and Griffin 2009, Cushman et al 2010, Ferguson and Chase 2010, Jori et al 2011, Gadd 2012. Additionally, veterinary fencing could hinder the movement of pastoralists in favor of intensive cattle production systems, which are less likely to be environmentally sustainable (Herrero et al 2013).…”