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| July 2009 |
Insight/Opinion |
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Moving animals for lucrative game industry impacts diversity in SAEngela Duvenhage
The translocation of game species such as rhinoceros, giraffe and antelope to stock zoos, nature reserves and other wildlife areas has in many cases unintentionally caused the homogenizing of ungulate diversity worldwide and in South Africa. Translocation of similar species to different countries around the world has had a much more significant impact on homogenizing ungulate communities than animal extinctions have had. This is one of the findings of Dr Dian Spear of the DST-NRF Centre of Excellence for Invasion Biology at Stellenbosch University, who received her doctorate in zoology from Stellenbosch University in December 2008. Her promoter is Prof Steven Chown, also of the DST-NRF Centre of Excellence for Invasion Biology. The worldwide movement of biota is of substantial concern for the conservation of biodiversity because of fears for the loss of genetic diversity, competition, hybridization and disease transmission. “Ungulates are big business worldwide and they have been moved around the globe for centuries for food and hunting,” says Prof Chown. “They continue to be moved to satisfy the lucrative game ranching and hunting industries.”
Ungulates are also translocated for conservation purposes such as reintroducing species to places where they have previously gone extinct and to mitigate inbreeding in small, isolated populations. At a grander scale controversial proposals have been developed to re-wild continents with the species similar to those that were found there in recent archaeological history. According to Dr Spear, translocation of similar species to different countries around the world has had a much more significant impact on homogenizing ungulate communities than animal extinctions have had. Nonetheless, in some instances ungulate groups in neighbouring countries have become more different due to the introduction of different ungulate species. She found that countries with the most introduced ungulates also have the most non-indigenous ungulates in their zoos. Over 100 non-indigenous ungulates species have been sold from zoos to non-zoo owners in 32 countries globally since 1970. “The sale of surplus animals to private landowners rather than to other zoos may inadvertently be contributing to conservation problems,” Dr Spear believes. Her study also focussed on South Africa, where she found that local homogenization is increasing at a steady tempo.
“In the past, introductions in South Africa were made to increase the economic viability of marginal areas poor for indigenous species and marginal for livestock, but more recently, non-indigenous ungulates are being introduced to more densely populated, wealthy areas perhaps to take advantage of a growing sport hunting and ecotourism market,” she says. The movement of the country’s many indigenous ungulates outside their natural distribution ranges has changed ungulate biotas more than introductions from outside the country, she found. The former extralimital introductions (the translocation of species outside their natural distribution ranges within geopolitical boundaries) have increased the similarity of spatially disjunct ungulate assemblages, whereas the extraregional (translocation of species outside geopolitical boundaries and their natural distribution ranges) introductions have led to differentiation of assemblages. Sufficient evidence for the impacts of non-indigenous ungulates on biodiversity both in South Africa and globally is lacking despite substantial concern for their impacts. Dr Spear suggests that exclosure and enclosure experiments should be used to demonstrate the impacts of non-indigenous ungulates and to show population declines in indigenous species. Her research, in conjunction with Prof Chown, has been published in the Journal of Biogeography. More information:
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Journal
of Biogeography 35, 1962-1975. see: