Environmental Engineering Reference
In-Depth Information
century killing of whales in the next section) and the drastic reduction of the once
large and wide-ranging African elephant herds. The bison's demise has been described
and documented in detail (McHugh 1972; Branch 1997; Isenberg 2000). Less appre-
ciated is a remarkable comeback of the species. About half a million animals now
live in the United States and Canada, mostly in private enclosures or national parks,
and bison meat is a small part of the commercial food supply (the nineteenth-century
killings were primarily for hides, not for meat).
The retreat of African elephants has been brought about by a combination of
intensii ed traditional hunting (whose effectiveness was greatly potentiated by the
use of ril es), an expanding ivory trade (with, once again, China and Japan being
traditionally the largest importers, both for various ornamental carvings and for
such mundane objects as hank¯ , personal seals ubiquitous in Japan), and the loss
of habitat owing to the expansion of cultivated land. The best historical evidence,
based on the ivory exports from the continent, indicates substantial pre-1914 l uc-
tuations and a period of recent high losses starting during the 1970s. The best
approximations put the twentieth-century elephant slaughter at roughly twice the
level of the nineteenth-century bison killings when compared in terms of fresh-
weight zoomass (box 7.3).
Compared to the slaughter of bison and elephants, tiger killings have involved
much smaller zoomass totals: their target is a top carnivore, whose abundance is
inherently much lower than that of large herbivores. Common densities are around
1 elephant and up to 10 bison/km 2 (Gates et al. 2005), compared to as few as 1-2
tigers/100 km 2 (Kawanishi and Sunquist 2004). India's tiger numbers were sharply
reduced by frivolous hunting (by the European colonial rulers or members of India's
many princely families) that was one of the hallmarks of the British rule. A con-
servative estimate is that 65,000 Indian tigers were hunted down between 1875
and 1925, with the peak of some 17,000 killed during the 1880s (Rangarajan
1998).
Even before the nineteenth century the surviving Chinese tigers were relegated to
the fringes of the country's territory, and now China's large illegal trade in tiger
products is blamed for a rapid post-1990 decline in India's tiger numbers: some of
the country's famous national parks now do not have a single tiger, or none can be
found even after extensive night camera searches (Bhardwaj 2006; Datta, Anand,
and Naniwadekar 2008). This afl uence-driven destruction may be the end. At the
beginning of the twenty-i rst century the country had fewer than 4,000 tigers, a
tenth of the total count in 1900 (Bhardwaj 2006). Commonly weak enforcement
and the existence of global illegal trade networks that are well i nanced and often
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