Abstract
Annual trends in numbers of ungulate species on a 15 km² reserve from 1993 to 1998, were evaluated in the context of lion Panthera leo reintroduction during 1996, and subsequent predation by them. The ungulate prey base was enumerated annually by aerial counts and a road count that took place during 1998. The lion prey record was obtained from direct observations of a radio-located pride of eight lions and daily reserve management records. All ungulate species that underwent precipituous declines were also the most important prey to lions, comprising over 80 % of their prey, and they were preyed upon according to their availability. Lion predation was causal for the declines in wildebeest Connochaetes taurinus, Blesbok Damaliscus pygargus phillipsi and Warthog Phacochoerus africana, while the decline in Kudu Tragelaphus strepsiceros was only partly ascribed to lions, as other non-lion related mortality sources were identified. The only ungulate species to increase subsequent to lion reintroduction was the Impala Aepyceros melampus, which was furthermore under-selected by lions. The uncontrolled population growth of Impala could have elicited ecological degradation, and it was advised to either not stock Impala, or otherwise control their numbers if lions are unable to do so. Lion hunting success and kill rate, were 21 % (n = 63) and 1 kill/4.4 days, respectively. Three bushpigs Potamochoerus larvatus were killed but not utilised,and this finding is corroborated by an intensive study in Kwazulu-Natal, and this aversion is discussed. Predators can cause unprecedented declines of their prey where the prey are confined to small reserves that have no refuge from predation. On an annual basis, prey may need to be augmented to sustain predators on small reserves
Highlights
Predators are unable to regulate their prey where their prey populations undergo seasonal migrations of varying degrees (Sinclair et al 1985; Mills & Retief 1984; Mills & Shenk 1992)
The impala Aepyceros melampus numbers increased, while the warthog Phacochoerus africana numbers remained relatively stable with minor fluctuations (Fig. 1)
It was imminent that some ungulate populations could have become extinct within a year (Fig. 1), which remains to be seen on a small reserve, as Hunter (1998) pointed out
Summary
Predators are unable to regulate their prey where their prey populations undergo seasonal migrations of varying degrees (Sinclair et al 1985; Mills & Retief 1984; Mills & Shenk 1992). Analogous to this, enclosed reserves become islands in which the prey are compelled to be resident, and depending on the number of predators, the prey can be regulated in the same way. On a managed reserve of this nature, with lions Panthera leo, the impact that predation can have on the prey base is an important consideration (Mills 1991; Van Schalkwyk 1994; Viljoen 1996; Van Dyk 1997; Hunter 1998). One requires annual prey numbers at least, and a record of what the lions prey upon (Mills 1991; Van Schalkwyk 1994; Hunter 1998). To accurately and unequivocally demonstrate that a predator has had an impact on the prey; one requires additional information on the Koedoe 45/2 (2002)
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