Article

Population and Trophy Quality Trends of Three Gregarious Herbivores in an Insulated Semi-Arid Savanna Ecosystem (Cawston Ranch, Zimbabwe), 1997–2014

Authors:
  • Mogale Meat Co South Africa
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Abstract

Long term monitoring of population estimates and trophy size trends is requisite to ensure that trophy hunting is sustainable. We explored the influence of trophy hunting on population size and trophy quality of impala (Aepyceros melampus), greater kudu (Tragelaphus strepsiceros) and sable (Hippotragus niger) antelopes from 1997 to 2014 in Cawston Ranch, Zimbabwe. Population estimates of the three species showed a cyclical declining trend, albeit being statistically insignificant for the three species. Hunting pressure had no significant effect on the population estimates of the three species for the period 1997-2014. Impala population declined (-30 %) between 2003 and 2008 possibly due to increased illegal hunting pressure associated with land invasions during this period. Trophy size of all species declined over time, 2004-2014, (impala (-1.3 %), kudu (-3.9 %), sable (-2.6 %) possibly due diet quality and loss of genetic variability in these populations. However, trophy size for greater kudu and sable were within the minimum score range of the Safari Club International. We recommend research on genetic variability and inbreeding levels of hunted populations in closed ecosystems to inform adaptive management as a way of ensuring sustainability of trophy hunting as a conservation tool in small isolated parks in Africa.

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Trophy hunting in ungulates may favour individuals with smaller horns. A decrease in horn/antler size may jeopardize the conservation potential of hunting areas, which would be a major concern in Africa where hunting zones represent over half of the total area of protected lands. We investigated horn length trends of harvested male impalas Aepyceros melampus, greater kudus Tragelaphus strepsiceros and sable antelopes Hippotragus niger, from 1974 to 2008 in Matetsi Safari Area, Zimbabwe. Horn length declined by 4% in impalas, partly because male harvest age decreased. In greater kudus, surprisingly, horn length increased by 14%, while mean age of harvested male greater kudus increased during the study period. Reduced hunting pressure on this species during the study may have allowed males to live longer and to grow longer horns before being harvested. Horn length declined by 6% in sable antelopes, independent of age, suggesting that trophy hunting selected male sable antelopes with smaller horns through time, provided that horn length is heritable. Hunting pressure and trophy value were higher for sable antelopes than for impalas and greater kudus. Accordingly, the decline of horn length in this species was more pronounced. More valuable trophy species, such as sable antelopes, require special attention because they may be exposed to higher hunting pressure, and are therefore more likely to experience a decrease in horn size.
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Hunting is one of the greatest conservation challenges facing tropical wildlife. Wildlife in Indian tropical forests are vulnerable to hunting, although data on hunting impacts from the region are limited. We use a meta-analysis of 143 hunting studies from India to identify the species and geographic regions most at risk, and to assess their legal protection. We found evidence of hunting in 114 mammal species, with larger-bodied mammals being particularly vulnerable. Although 75% of all studies focused on mammals, few actually quantified hunting impacts. Further, among studies of all terrestrial vertebrates where hunting was mentioned, only 6% focused exclusively on hunting. With further research, we expect that the suite of species known to be exploited by hunters will increase. We conclude that the Eastern Himalaya and Indo-Myanmar biodiversity-hotspot complex is particularly vulnerable to hunting. Quantitative studies of hunting impacts are urgently needed across India, especially in this biodiversity-hotspot complex.
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In Tanzania, where tourist hunting is employed as a conservation tool for habitat protection, information on population sizes and hunting offtake was used to assess the impact of tourist hunting on mammal densities. In general, tourist hunting pressure was unrelated to local population sizes, but for most species, animals were removed at a level of less than 10% of the local population size, suggesting that over-exploitation was unlikely. Eland, however, and perhaps small antelope, bushbuck, kudu and reedbuck were hunted at levels which may be unsustainable in the long term. Analyses also identified areas of Tanzania with high levels of tourist hunting pressure, showed that, in certain areas, species with small population sizes such as eland could be declining as a result of tourist hunting, and suggested that current levels of lion and leopard offtake are too high. These findings, although preliminary, allow recommendations to be put forward for changing hunting quotas for certain species in particular areas of Tanzania.
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Illegal hunting of wildlife, or top-down harvesting, is a major issue in today's society, particularly in tropical ecosystems. There has been widespread concern about increasing illegal hunting of wildlife in most conservation areas in Zimbabwe following the political instability and economic decline the country faced since 2000. In this study, we focused on the northern Gonarezhou National Park (GNP), a large and unfenced protected area, and adjacent communal areas in southern Zimbabwe. We hypothesised that illegal hunting activities would (1) be perceived to have increased due to economic collapse and (2) vary with law enforcement efforts. A total of 236 local residents from eight villages adjacent to the northern GNP were interviewed using semi-structured questionnaires from December 2010 to May 2011, and law enforcement data for northern GNP between 2000 and 2010 were retrieved from the park law enforcement database. A total of 26 animal species were reportedly hunted. Bushmeat consumption and the need for local trade to raise income were reported as the main reasons behind illegal hunting. Contrary to the first hypothesis, the majority of respondents (n = 156, 66%) reported that illegal hunting activities had declined between 2000 and 2010 largely due to increased park protection as also supported by law enforcement data. A total of 22 animal species were recorded as having been illegally hunted in northern GNP. The number of illegal hunters arrested declined with increased law enforcement efforts although the number of wire snares recovered and hunting dogs shot appeared to increase following increased law enforcement efforts. These results partly support the second hypothesis that illegal hunting activities would vary with law enforcement efforts.
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In the Katavi-Rukwa ecosystem of western Tanzania, aerial censuses carried out between 1988 and 2002 show that populations of several large ungulate species had declined. Five competing factors that could be responsible for these changes were investigated. (i) Rainfall increased slightly over 25 years and (ii) no obvious outbreaks of disease were witnessed, suggesting that populations are not suffering food shortages or disease. (iii) Large predators live at low densities and are not increasing, and estimates suggest that that predation is unlikely to impact larger prey species. (iv) Some assessments of illegal hunting indicate little influence on herbivore populations but one measure points to giraffe, hippopotamus, warthog and perhaps other species being adversely affected. (v) Tourist hunting quotas of lions and greater kudu in hunting blocks appear high and there are indications that both may be declining. Preliminary data, approximate calculations and elimination of hypotheses point to anthropogenic factors being partly responsible for changes in this ecosystem and constructive recommendations are made to alter these. More generally, this study highlights the importance of monitoring in conjunction with collecting diverse data when trying to stop population declines before they become too serious.
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In Kenya knowledge of the relative severity of threats to protected areas and the vulnerability of these areas to any threats is lacking. Such information is required, however, for assessment of the effectiveness of management of the country’s protected areas, and to help identify critical management and policy weaknesses and priorities for improving management and allocating resources. We therefore studied the relative severity of threats to Kenya’s 50 protected areas and their relative vulnerability to such threats based on the perceptions of protected area managers. Ten threats were identified by these managers, of which the most severe were illegal bushmeat hunting, poaching of large mammals, human–wildlife conflicts, human encroachment, and loss of migration corridors and dispersal areas. Thirty-two (64%) protected areas were vulnerable to over half of the threats, 54% vulnerable to over six of the threats and 32% vulnerable to over seven of the threats. Protected areas in marine, forested/montane and inland wetland ecosystems were regarded as highly vulnerable to the perceived threats. Protected areas adjacent to urban/industrial and agricultural areas were vulnerable to most of the threats. Our findings demonstrate that protected areas in Kenya are increasingly threatened, that major threats needs to be mitigated, and that prioritization of protected areas for strategic actions is required for effective management.
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Data on densities, biomass and ecological factors governing the distribution of various wild ungulate species in the difFerent management units of Gir forest from 1987 to 1989 were collected. Density of ungulates ranged from 50.8 km−2 to 0.42 km−2, the highest for chital (Axis axis), followed by chinkara (Gazella gazella), sambar (Cervus unicolor), nilgai (Boselaphus tragocamelus) and chowsingha (Tetracerus quadricornis). The density of chital did not vary significantly between different censuses and management units. The wild ungulate biomass ranged from 3290 kg km−2 in the National Park to 1900 kg km−2 in the Sanctuary East. Following the partial removal of people and livestock in the mid-1970s, there was an increase in the population of all wild ungulates except nilgai and wild pig (Sus scrofa). Concurrently, there was an increase in the proportion of wild ungulate prey in the lion's diet. Chital density has shown a 1320% increase. An increase in suitable habitats and a decrease in direct competition with livestock are the most likely factors to have triggered the eruption in chital population. These density estimates are discussed in relation to the prevailing ecological conditions in different management units of Gir.
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Populations of many wild ungulate species in Africa are in decline largely because of land-use changes and other human activities. Analyses that document these declines and advance our understanding of their underlying causes are fundamental to effective management and conservation of wild ungulates. We analyzed temporal trends in wildlife and livestock population abundances in the Mara region of Kenya. We found that wildlife populations in the Mara region declined progressively after 1977, with few exceptions. Populations of almost all wildlife species have declined to a third or less of their former abundance both in the protected Masai Mara National Reserve and in the adjoining pastoral ranches. Human influences appeared to be the fundamental cause. Besides reinforced anti-poaching patrols, the expansion of cultivation, settlements and fences and livestock stocking levels on the pastoral ranches need to be regulated to avoid further declines in the wildlife resource.