Research Papers

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Demographic Side Effects of Selective Hunting in Ungulates and Carnivores

Selective harvesting regimes are often implemented because age and sex classes contribute differently to population dynamics and hunters show preferences associated with body size and trophy value. We reviewed the literature on how such cropping regimes affect the demography of the remaining population (here termed demographic side effects ). First, we examined the implications of removing a large proportion of a specific age or sex class. Such harvesting strategies often bias the population sex ratio toward females and reduce the mean age of males, which may consequently delay birth dates, reduce birth synchrony, delay body mass development, and alter offspring sex ratios. Second, we reviewed the side effects associated with the selective removal of relatively few specific individuals, often large trophy males. Such selective harvesting can destabilize social structures and the dominance hierarchy and may cause loss of social knowledge, sexually selected infanticide, habitat changes among reproductive females, and changes in offspring sex ratio. A common feature of many of the reported mechanisms is that they ultimately depress recruitment and in some extreme cases even cause total reproductive collapse. These effects could act additively and destabilize the dynamics of populations, thus having a stronger effect on population growth rate than first anticipated. Although more experimental than observational studies reported demographic side effects, we argue that this may reflect the quite subtle mechanisms involved, which are unlikely to be detected in observational studies without rigorous monitoring regimes. We call for more detailed studies of hunted populations with marked individuals that address how the expression of these effects varies across mating systems, habitats, and with population density. Theoretical models investigating how strongly these effects influence population growth rates are also required.

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A Framework for the Ex Situ Reintroduction of the African Lion (Panthera leo)

Ex situ reintroduction remains controversial in conservation scientific debate and practice, and is regarded as a last resort method. It has been argued that this conservational strategy should now be considered, alongside existing in situ practices, for the African lion (Panthera leo). The rapid decline of this culturally important species is symptomatic of the impact a burgeoning human population and their related activities have upon the lion. Published evaluations of reintroductions for all animal groups show relatively poor survival rates per se, particularly when the released animal is captive-bred. In this paper we consider contributing factors to failed and successful captive-bred reintroductions and revisit previous ex situ efforts to release the African lion into the wild. Whilst past attempts to release captive lions into the wild are largely undocumented in the scientific literature, they have valuable lessons to offer future undertakings. We propose a framework for the ex situ reintroduction of the lion based on scientific guidance and previous endeavours. - See more at:

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Conserving large populations of lions – the argument for fences has holes

Packer et al. reported that fenced lion populations attain densities closer to carrying capacity than unfenced populations. However, fenced populations are often maintained above carrying capacity, and most are small. Many more lions are conserved per dollar invested in unfenced ecosystems, which avoid the ecological and economic costs of fencing

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