Group Dynamics of Zebra and Wildebeest in a Woodland Savanna: Effects of Predation Risk and Habitat Density

.Using generalized linear models, we examined the relative importance of habitat type (differing in vegetation density), probability of encountering lion (based on utilization distribution of all individual lions in the reserve), and season in predicting group size and composition. We found that only in open scrub habitat, group size for both ungulate species increased with the probability of encountering lion. Group composition differed between the two species and was driven by habitat selection as well as predation risk. For both species, composition of groups was, however, dominated by males in open scrub habitats, irrespective of the probability of encountering lion.Distribution patterns of wildebeest and zebra groups at the landscape level directly support the theoretical and empirical evidence from a range of taxa predicting that grouping is favored in open habitats and when predation risk is high. Group composition reflected species-specific social, physiological and foraging constraints, as well as the importance of predation risk. Avoidance of high resource open scrub habitat by females can lead to loss of foraging opportunities, which can be particularly costly in areas such as KGR, where this resource is limited. Thus, landscape-level grouping dynamics are species specific and particular to the composition of the group, arising from a tradeoff between maximizing resource selection and minimizing predation risk

Home Range Utilisation and Territorial Behaviour of Lions (Panthera leo) on Karongwe Game Reserve, South Africa

Interventionist conservation management of territorial large carnivores has increased in recent years, especially in South Africa. Understanding of spatial ecology is an important component of predator conservation and management. Spatial patterns are influenced by many, often interacting, factors making elucidation of key drivers difficult. We had the opportunity to study a simplified system, a single pride of lions (Panthera leo) after reintroduction onto the 85 km 2 Karongwe Game Reserve, from 1999–2005, using radio-telemetry. In 2002 one male was removed from the paired coalition which had been present for the first three years. A second pride and male were in a fenced reserve adjacent of them to the east. This made it possible to separate social and resource factors in both a coalition and single male scenario, and the driving factors these seem to have on spatial ecology. Male ranging behaviour was not affected by coalition size, being driven more by resource rather than social factors. The females responded to the lions on the adjacent reserve by avoiding the area closest to them, therefore females may be more driven by social factors. Home range size and the resource response to water are important factors to consider when reintroducing lions to a small reserve, and it is hoped that these findings lead to other similar studie

Reproductive biology of a pride of lions on Karongwe Game Reserve, South Africa

The reproductive biology of a pride of lions (Panthera leo) was studied on the 8500 ha Karongwe Game Reserve from 1999 to 2005. Over this period, the pride consisted of between four and 11 lions with a paired coalition of adult males during the first three years and a single adult male for the next three years.We recorded shorter than normal interbirth intervals, high birth rates of 1.3 cubs/lioness/year, very high cub survival rates, and subadults leaving the pride at young ages. This translated into substantially faster growth rates than are typical in large lion  populations in ecologically similar circumstances such as Kruger National Park, but are similar to those of lions in Serengeti National Park. These demographic  characteristics were probably induced initially by a lack of intense intraspecific competition and high prey availability, but population stability was maintained through the removal of young subadults by management. Interestingly, variability in conception rates between lionesses resulted in lower growth rates than have been found in other similar reintroduced lion populations. These demographic traits characterize many of the small reintroduced lion populations, and call for appropriate management to avoid the consequences of high predator densities.Key words: birth rate, inter-birth interval, intraspecific competition, pride size, small enclosed reserves

Home ranges of (A) male coalition, (B) single male, (C) females before male was removed, and (D) females after removal of the male.

<p>Home ranges of (A) male coalition, (B) single male, (C) females before male was removed, and (D) females after removal of the male.</p

The effect of coalition size manipulation (male removal) on territorial behaviour of pride males.

<p>The effect of coalition size manipulation (male removal) on territorial behaviour of pride males.</p

Selected nights showing movement paths travelled by the pride male, illustrating distance and path walked during territorial patrols.

<p>Selected nights showing movement paths travelled by the pride male, illustrating distance and path walked during territorial patrols.</p

Spatial patterns in territorial behaviour indicated by density of behaviours across the reserve.

<p>Locations of (A) scent marks made by the pride males from 1999 to 2002, (B) scent marks by the single male from 2002–2005, (C) roars by the pride males from 1999 to 2002 and (D) roars by the single male from 2002–2005.</p

Location of Karongwe Game Reserve and the neighbouring Makalali Game Reserve in Limpopo Province, South Africa.

<p>Location of Karongwe Game Reserve and the neighbouring Makalali Game Reserve in Limpopo Province, South Africa.</p

Best supported models that predict the group size and group composition of wildebeest (n = 133 groups) and zebra (n = 116 groups) in Karongwe Game Reserve.

<p>Reported are the number of parameters (<i>K</i>, which includes the intercept β₀ and residual variance σ²), Akaike's Information Criterion adjusted for small sample size (AIC_c), distance from the lowest AIC_c (Δ AIC_c), and Akaike's model weight (<i>w_i</i>). Only models with Δ AIC_c <2 are shown for sake of clarity.</p

Occurrence of groups of wildebeest and zebra in the different habitats of Karongwe Game Reserve.

<p>Shown are the proportion occurrence of groups of wildebeest (n = 133, white bars) and zebra (n = 116, gray bars) with 95% confidence intervals. Proportions of available habitat (black bars) are listed in order of decreasing structural density.</p