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Conserving Addo's elephants - the past, present and future of the population
Dr Anna Whitehouse
Elephants, the world's largest living land mammal, hold a special
fascination for many people. As much loved, high profile creatures, they have
been the focus of many conservation programmes across Africa and Asia. Dr Anna
Whitehouse will be delivering a lecture detailing aspects of the conservation
biology of the Addo Elephants at the Sasol Scifest 2002.
Addo Elephant National Park, which is situated approximately one hour's drive
inland from Port Elizabeth, in the Eastern Cape Province of South Africa, is
home to a population of more than 340 elephants. These animals are all
descendents of just a handful of individuals who survived an attempt in the
early 1900s to wipe out the entire Eastern Cape elephant population.
In 1900, this elephant population was the largest surviving stronghold of
elephants in South Africa. Elsewhere hunting had decimated populations but, due
to the impenetrable nature of the Addo bush, the elephants of the Eastern Cape
survived this onslaught. However, the development of agriculture in this area
inevitably led to conflicts between the Addo elephants and the farmers, and
before long the farming community decided
their elephant neighbours were unacceptable pests. As a result, a professional
hunter, Major P.J.Pretorius, was hired to exterminate the animals, and between
July 1919 and August 1920 he killed about 120 elephants in the area. Fortunately
this slaughter was halted before the task was completed, and in 1931 Addo
Elephant National Park was created to provide protection for the 11 surviving
elephants.
The recovery of the Addo elephant population from the brink of extinction
appears to have been a great success. But, what does the future hold for the
elephants of Addo, and is their survival really secure? A research programme
looking at the conservation biology of the Addo elephants was initiated in 1996.
Careful examination of the population's history and current status are used to
address questions concerning the population's possible future prospects.
A key component of this project involved getting to know every elephant in
the population. Elephants can be recognised by looking at the notches and holes
in their ears (which are caused by the ears being torn in the bush or during
fights), the size, shape and configuration of their tusks, and the patterns of
wrinkles on their face and blood vessels in their ears.
Photographic identification files of the Addo population have been compiled,
containing photographs of the right and left side of every individual who is
more than six years old (calves can most easily be recognised by their
association with their mother).
The complete history of the elephant population since the creation of the
park was then reconstructed by tracing individual elephants' life histories
using photographic records studied in conjunction with all available written
reports. Individual elephants can be identified in photographs taken throughout
their lives by studying their vein and wrinkle patterns which, like a human
finger-print, are unique for each animal and do not change as the animal grows
older. The dates of birth and death of every elephant in the Addo population
were estimated, and maternal family trees dating from 1931 to the present were
compiled. The result is a unique data set, spanning 70 years, and enabling
in-depth demographic analyses of the population's growth and recovery.
One of the key factors facilitating the population's recovery was the fencing
of the park in 1954. Prior to this, the elephants continued to roam outside
their protected area, resulting in fatal conflicts with local farmers. As a
result, population mortality was high, and the growth rate minimal. The secure
fencing of the park immediately reduced mortality rates, enabling an increase in
population growth. Between 1931 and 1954, the elephant population increased from
11 animals to just 22. Since the fencing of the park, the population has
increased more than 15-fold, to its current size of over 340 elephants.
Although the fencing of the park clearly benefited the population as a whole,
confinement has created new problems. One of these is the unusually high level
of aggression observed between Addo elephant bulls. Since the fencing of the
park, at least 70 % and up to 90 % of male deaths have been caused by fighting.
This appears to be a result of unusually intense mating competition which is
caused by the population's confinement at high density within a relatively small
area. Clearly, elephants do not just need space to provide them with sufficient
food, but space is also needed to enable natural behavioural patterns - and this
should be taken into account when managing small elephant populations such as
Addo's.
Genetic considerations are also vitally important when managing small
populations, especially where these have been through a tight bottleneck. The
reduction of the Addo elephant population to such a small number in 1931, and
the inevitable inbreeding that followed, make it crucial to now consider the
genetic health of the herd. Therefore, genetic analyses were conducted, and the
results revealed considerable loss of genetic variation amongst the Addo
elephants. This is concerning, as it may reduce the future fitness of the
population, by decreasing its adaptability and evolutionary potential.
Management to increase the genetic diversity of the population should,
therefore, be considered.
Due to plans to ambitiously expand Addo Elephant National Park, the future of
the Addo elephants looks bright. The population can continue to grow as the park
is enlarged, and may increase to 100 times its original founder size. However,
both genetic and behavioural considerations need to be taken into account in
management plans, in order to ensure the secure future of this fascinating
elephant population.
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