IUCN / SSC Cat Specialist Group - Digital Cat Library |
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| Funston, P.J. | |
| Kalahari Transfrontier Lion Project - Population ecology and long term monitoring of a free-ranging popuation in an arid environment | |
| 2001 Full Book | |
The Kgalagadi Transfrontier Park (KTP), South Africa/Botswana, lion (Panthera leo) population is exposed to fairly frequent persecution when individuals more onto bordering domestic livestock ranching areas. This is particularly so for boundary prides, with resident adults and dispersing sub-adults both being at risk. Population trends of low-density large predators like lions are difficult to monitor, and although the population has been exposed to this threat for several decades, the only initiatives to determine the consequence of this were two population surveys in 1976 and 1996 of a portion of the population. Population size is only one of many socio-ecological variables needed to assess the impact and long-term viability of this lion population. Very little data on other population characteristics were available, a thorough treatment thereof being one of the major objectives of this study. Population-ecology and demographic data showed that KTP lions exhibit similar population characteristics to most other lion populations that have been studied at similar intensities. Some of the major differences include the low population density (1.25 lions/100 kmý) and large home range sizes (1462 ñ 388 kmý), both of which are a response to low medium-sized ungulate densities that are correlated with low average rainfall. As with other populations, although the average pride size was fairly large (11.3 ñ 1.1), the average foraging group size was much smaller (4.2 ñ 0.4). This is likely to be an ecological response to infrequent large kills, but fortuitously this mechanism also seems to considerably negate the effect of intermittent shooting, in that should a pride related group be destroyed for a boundary transgression, a segment of the breeding component of the pride usually remains. Although the population size seems to vary in response to the cumulative effect of rainfall, the adult segment of the population remains relatively stable over time, the number, and survival of the juvenile segment of the population being most variable. Survival rates during droughts seemed to be so low that fairly synchronized production of large cohorts of cubs in response to improved ecological conditions seemed to happen at the population as well as at the pride level. Initial observations suggested that certain population characteristics were more closely aligned with populations exposed to fairly intense trophy hunting, in that there was a preponderance of males cubs (1 ?:0.5?) born in the population, and that in the adult age-class males were more heavily outnumbered by females than normal (1?:3.2?). Analysis of both these trends suggested that they are both likely to be variable in the ecosystem and are natural responses of the population to ecological pressures, and are not a response to unnatural human induced pressures. Another important difference was that there was no difference in the survival rates of cubs in prides defended either by single or coalitions of males. However, in line with current thinking on the reasons for lion sociality, groups containing cubs had significantly larger numbers of adult females than groups without cubs. The population exhibited similar sub-adult dispersal patterns to other lion populations, but males both stayed longer, and tended to acquire territories close to their natal home ranges, both of which seem to be more prevalent in certain Southern African lion populations. Lions and other large carnivores have declined dramatically during the last 50 years. Today, lions are restricted to protected areas where problems occur with their management due to conflicts with bordering pastoralists and a lack of biological data on lion population ecology. A study of the ecology and dynamics of free-ranging lions in the Kgalagadi Transfrontier Park (KTP) will provide much needed baseline data on limiting factors and population dynamics in a harsh, semi-arid environment. The study will conclude with the implementation of strategic management guidelines for the KTP and lion populations in other restricted conservation areas. |
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