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Pigs, Peccaries and
Hippos Status Survey and Action Plan (1993) Chapter
3.4 Review
of Priorities for Conservation Action and Future Research on Hippopotamuses. S. Keith
Eltringham Introduction This chapter reviews the recommendations made in
Chapters 3.2 and 3.3 concerning the research and conservation priorities for
the two species of hippopotamus. The species are not very similar as the
pygmy hippopotamus is essentially a forest animal that occurs singly or in
small groups, in contrast to its larger, gregarious, grassland relative. It
is also less aquatic. There are marked differences in diet. Whereas the large
hippopotamus is almost entirely a grazer, the pygmy species is more catholic
in its tastes, taking browse, roots and fallen fruit. They are, however,
similar in feeding mainly at night. The common hippopotamus is widely
distributed throughout much of sub-Saharan Africa, but the pygmy is more or
less confined to Liberia with only remnant populations in a few neighboring
countries. The common hippopotamus has been intensively studied in recent
years but there is still much to learn about the behavioral ecology of the
pygmy species. The principal threat to the survival of both species is loss
of habitat. In the case of the pygmy hippopotamus it is the potential loss of
the forest itself that is the problem. Two types of habitat are involved in
the case of the common hippopotamus. It is unlikely to experience shortage of
water in which to spend the day but it is vulnerable to the loss of grazing land,
particularly to rice plantations in West Africa and to cereals in East
Africa. The conservation status of the pygmy hippopotamus is notably worse
than that of the larger species. Its numbers are much lower and although the
precise population size is unknown, it probably numbers no more than a few
thousand. Objectives 1. To establish
the distribution of the two species particularly in those range states for
which information is sketchy or non-existent at present. 2. To identify
populations that are at risk. 3. To maintain
viable populations of both species within their present ranges. 4. To
disseminate information about the conservation status of hippopotamus. 5. To
investigate ways in which to exploit the commercial value of the common
hippopotamus. 6. To encourage
zoos to co-operate in building up and maintaining viable breeding groups in
captivity. Conservation
Action Priorities A.
Conserve Populations at Risk An essential prerequisite to conserving the species
is to identify those populations, which are most at risk. This problem
requires a knowledge of the numbers and distribution of each species. The
recent questionnaire survey has provided useful data to this end but there is
obviously much more to be discovered about the ranges of the two
hippopotamuses. As the pygmy hippopotamus is largely confined to Liberia, it
is in that country that most conservation effort should be concentrated. At
the same time, the status of the species in the other range countries needs
to be investigated and their conservation encouraged in order to maintain the
maximum genetic diversity. Conservation measures are urgent in the case of the
pygmy hippopotamus, which is classed as vulnerable in the IUCN Red List of
Threatened Animals. The status of the common hippopotamus is more
satisfactory and there is no immediate risk of extinction. Nevertheless there
are countries where the hippopotamus is of particular conservation
significance, either on account of its rarity or of its status as an
ecological keystone species. For both species the highest priority should be
given to projects that fill gaps in the information acquired in the present
survey about their numbers and distribution. Action is required as follows: 1. Establish
the status of the species in those countries from which no information was
acquired in the recent survey. In the case of the common
hippopotamus, these are Angola, Chad and Rwanda, all of which once contained
large populations of the species. 2. Extend the
observations in those countries, which were only partially covered in the
recent survey. These include all range states in
the case of the pygmy hippopotamus. No information on its status was received
from Guinea Bissau, where a population of the pygmy hippopotamus is said to
occur, though most authorities doubt that it ever existed and consider that
the original record was of a calf of the larger species. It does not seem
worth the time and effort that would be required to disprove its existence
there. On the other hand, the continued presence of a population of pygmy
hippopotamus in Nigeria should be investigated especially as the original
specimens that were collected were placed in a separate subspecies. The
existence of this population was assumed, but not confirmed, by a correspondent
in the recent questionnaire survey. Countries poorly covered in the case of
the common hippopotamus included Cameroon, Ethiopia, Malawi, southern Sudan
and Zambia. 3. Monitor
those populations, which the survey found to be dangerously small and giving
cause for concern. The status of the pygmy
hippopotamus in Liberia is unclear but the most seriously threatened
population elsewhere is probably that in Sierra Leone. Of the countries
containing the larger species, those with threatened populations include
Central African Republic, Equatorial Guinea, The Gambia, Ghana, Ivory Coast,
Mali, Nigeria, Niger and Sierra Leone. 4. Monitor
populations in those countries in which the common hippopotamus is abundant
and doing well in order to ensure that they continue to be secure. Countries with large populations
include Ethiopia, Kenya, South Africa, Sudan, Tanzania, Uganda, Zambia and
Zimbabwe. The degree of political stability in these countries varies
considerably and will influence the quality of the protection afforded to
these populations as well as the feasibility of carrying out further surveys.
Adequate funding is a further prerequisite for effective protection. B.
Conservation Management Hippopotamuses As a large, herbivorous mammal, the common hippopotamus
has a considerable impact on its environment, which does not endear it to
agriculturalists, particularly peasant farmers, for a single animal is
capable of destroying a year's harvest in one night. The hippopotamus can
also be extremely dangerous and numerous cases are known of people being
killed or injured, especially fishermen in their canoes. Consequently,
hippopotamus populations need to be carefully managed in order to avoid
confrontations between them and local people. National parks or equivalent
reserves offer the best opportunities but there are still places outside
national parks where hippopotamus will have to co-exist with people if they
are to survive. Research should be directed towards devising management
techniques based on cases where hippopotamus appear not to conflict with
human interests. The pygmy hippopotamus is less of a problem, partly
because it is too small to be a serious threat to human life and partly
because its smaller size limits the extent of any effects it has on
vegetation, although reports were received of it raiding gardens. The rarity
of the species makes it all the more important that such behaviour is reduced
to a minimum. The security of both species would be enhanced if they could be
shown to have a positive value that could be realized by the local people. Because the main threat to both species is loss of
habitat, conservation measures should be directed towards preserving the
environment. The following are suggestions for some future action in this and
other fields. 1. Identify the best area(s) for conserving both
species. In the case of the pygmy
hippopotamus, criteria for assessing possible regions include suitable
habitat, evidence of recent sightings, isolation from human interference and
assurance that legal protection can be enforced. No one place fulfils all
these requirements but the only realistic choice must be the Sapo National
Park. This is large (1,207 sq. km) by West African standards and contains an
extensive area of mature lowland forest, which according to correspondents,
is well protected. The number of pygmy hippopotamus is unknown but is thought
to be low. There have been two recent sightings. Its conservation in other
areas must also be vigorously pursued as it is a feature of the species in
Liberia that it occurs in small but widely dispersed groups and the
protection of the Sapo National Park alone would certainly not ensure the
survival of the pygmy hippopotamus. The choice of suitable conservation areas
for the common hippopotamus is wider but in selecting such regions, attention
should be given to ensuring adequate grazing areas as well as to access to
water. For this it will be necessary to ascertain the grazing area necessary
to support the hippopotamus in its various habitats to ensure that the
animals are maintained within their carrying capacity. 2. Conduct pygmy hippopotamus status survey in
Liberia. Since deforestation is the
greatest threat to the survival of the pygmy hippopotamus in Liberia, a
survey of all the forests in the country should be made to identify those
regions where the destruction of forests is minimal. It is in such places
that the protection of the species is likely to be most successful. 3. Conduct a survey of human-common hippopotamus
relations in places where the two already co-exist. A good example of this is the
township of Lake Katwe in the Queen Elizabeth National Park, Uganda. A key to
the harmonious relations may be that the people do not molest the animals.
Other areas should be identified where hippopotamus are tolerated, either
because the human population is small or because the local residents, usually
wealthy, like to see the animals, e.g. around Lake Naivasha in Kenya. 4. Examine ways of preventing hippopotamus, of both
species, gaining access to cultivated areas. Some progress has been made with
this problem in The Gambia, where electric fences are said to be effective in
keeping the animals away from rice fields. These and other barriers merit
further investigation. 5. Investigate inbreeding and other potential
problems relating the isolation of small, remnant populations. The isolated nature of the small
populations of the pygmy hippopotamus that occur in Liberia raises worries
about the deleterious effects of possible inbreeding that may be taking
place. Nothing seems to be known of the dispersal of young animals from these
groups, which is presumably the natural way by which inbreeding depression is
avoided. The problem could be investigated by examining the relatedness of the
members of these groups through genetic "finger-printing" to see
how genetically heterogeneous they are. This would normally involve the
taking of blood or tissue samples, which would not be an easy task, and the
possibility of using alternative techniques should be investigated. 6. Develop guidelines for the enhanced future
management of captive populations of both species. Both species of hippopotamus breed
well in captivity but this is of greater significance in the case of the much
rarer pygmy hippopotamus, for which captive breeding may become an essential
means of conserving the species. Present efforts to achieve a genetically
diverse population in the world's zoos through selective breeding should be
supported. Further research into the routine husbandry techniques and
demographic management of the species is required in order to improve
reproductive success amongst captive animals. C. Management of Common Hippopotamus for Profit. The pygmy hippopotamus is probably too rare for
trade in its products to be viable, but the common hippopotamus has a
commercial value on account of its meat, hide and teeth. The meat is
palatable and is readily eaten throughout Africa when it is available. The
traditional use of the hide for the manufacture of whips and shields has
declined but new techniques for its use in the manufacture of shoe leather
are being developed. The canine teeth, which resemble small elephant tusks,
have always found a ready market amongst craftsmen for the production of
carvings or for incorporation into ornaments and other wildlife trinkets.
Incisor teeth, although less valuable, may also be used in this way. There is
a fear that the banning of the ivory trade resulting from the recent listing
of the African elephant on Appendix I of CITES will result in an increased
demand for hippopotamus tusks. The evidence that this is happening is slight
but it is certainly a possibility that needs further investigation. The
rational exploitation of the hippopotamus has rarely been attempted and for
its future success, several aspects require investigation. Some of these are
listed below. 1. Establish
the locations of hippopotamus populations that are large enough to sustain
regular cropping. (If it takes place, the proposed cropping scheme at Ifakara
in Tanzania could provide useful information in this context.) 2. Investigate
improved ways of estimating sustainable yields from hippopotamus populations
in terms of meat and ivory. 3. Establish
the best techniques for the harvesting and processing of exploited
hippopotamus populations. 4. Carry out
market research into the sale of hippopotamus products. 5. Investigate
the possibility of cross infection between hippopotamus and domestic
livestock. D.
Regulation of Trade in Hippopotamus Products. If the exploitation of the hippopotamus is extended
along the lines suggested in Section C above, there is a danger that
unscrupulous operators will attempt to extend their profits through illegal
activity such as smuggling or over-cropping. At present, there is no legal
requirement to control the trade as the common hippopotamus is not listed on
any of the CITES appendices except Appendix III by Ghana. This has little
effect other than on exports from Ghana. Actions to improve the monitoring of
the trade in hippopotamus products and to establish a regulatory system
include the following actions. 1. Conduct an investigation into
the extent of the trade in hippopotamus products, particularly the teeth. 2. Promote the listing of the
common hippopotamus on Appendix II of CITES in those regions where they are
being, or are likely to be, over-exploited. 3. Investigate methods whereby
curios carved from hippopotamus teeth can be distinguished by
non-specialists, such as customs officers, from those made of elephant ivory. E.
Development of Education and Training Programmes. It is probable that the great majority of the human
population of Liberia is ignorant of the unique position of the country in
holding most of the world's population of the pygmy hippopotamus. A public
education campaign should therefore be mounted to impress upon the people
that their country is principally responsible for the custody of this rare
and vulnerable species. Given the political turbulence in this country in
recent years, however, it may prove necessary to postpone conservation
education operations until such time as stability is restored. If local
people are to tolerate the presence of the common hippopotamus in their home
areas, with the risks of crop damage and danger to life that this entails, it
is important that they should be aware of the potential benefits that can
ensue from the exploitation of the species. In the case of small populations
unsuitable for exploitation but important for conservation, ways in which the
potential conflict between people and hippopotamus can be minimized must be
explored. The dissemination of the conservation message for both species will
require trained personnel able to discuss management problems realistically
and sympathetically with local residents. Some of the enterprises in this
area that should have priority include: 1. Training of
personnel to communicate conservation and management principles to local
people. Appropriate persons include
biologists, social workers and teachers, though other persons with no formal
qualifications would be suitable for training provided they were suitably
motivated. 2. Development
of conservation education programmes for both schoolchildren and adults in
rural areas where the hippopotamus occurs. 3. Production
of posters, pamphlets and other material to publicize the need to conserve
the hippopotamus. Future
Research Priorities There is much still to be learned about the basic
biology of the pygmy hippopotamus and the effective conservation of the
species depends on these gaps in our knowledge being filled. Future research
on this aspect is probably best carried out in Liberia, where the species is
most numerous, but political considerations may dictate that the smaller
populations elsewhere are studied first. Although the basic biology of the
common hippopotamus is now reasonably well known, certain aspects need to be
clarified. From the conservation perspective, the most urgent requirement is
up-to-date information on the numbers and distribution of the species,
particularly in West Africa, where populations are small and vulnerable. Few
observers in the present enquiry were able to record numbers and some
improvements in survey methods are desirable. The following research projects
should be given priority. A.
Pygmy Hippopotamus 1. The
determination of the home range of the various age and sex classes. 2. A study of
the reproductive biology of the species with particular reference to pair
bonding, breeding rates and reproductive success. 3. A study of
group size and composition, the permanence of social associations and the
dispersal of the young after weaning. 4. An
assessment of the role of the pygmy hippopotamus in the dispersion of the
seeds of forest trees through frugivory. 5. An investigation
the best ways of estimating the numbers of pygmy hippopotamus in its forest
habitat. 6. A study of
the circadian activity of the various age and sex classes. 7. A
continuation of studies of the genetic relationships of captive pygmy
hippopotamus in order to ensure that the captive population remains as
genetically heterogeneous as possible. B.
Common Hippopotamus 1. A study of
the social relationships between hippopotamus of various age/sex classes,
with particular reference to the tenure of territories, the duration of the
mother/calf bond and the dispersal of young animals on reaching maturity. 2. Measure the
activity and time budgets of each class of hippopotamus. 3. Studies of
habitat use and the carrying capacities of various vegetation types. 4. Investigate
means of marking individual hippopotamus for behavioral research purposes. Studies of social relationships
and activity are greatly facilitated by the ability to recognize individual
animals and although this can be done on the basis of scars and other
anatomical features, a reliable method of attaching artificial marks is
urgently required. In radio-tracking studies this is obviously essential. 5. Investigate
the effects of cropping on the social habits and population dynamics of the
species. Such studies are required before
any large-scale exploitation takes place. These can best be carried out at a
cropping station and a suitable opportunity would be provided in the Selous
Game Reserve in Tanzania if the proposed cropping of hippopotamus takes place
there. 6. Conduct
research into improved methods of census. Most studies have depended on
counting the animals by day, when they are in the water. Aerial survey using
photography seems to be the most promising method and ways of refining it,
perhaps by using helicopters, should be investigated. 7. Conduct
survey of hippopotamus diseases and of the parasites and disease organisms
carried by them. This is particularly important in
those regions where the species is likely to come into contact with domestic
livestock. At least one disease of economic importance is now known to affect
hippopotamus for antibodies to rinderpest were found to be widespread in
animals from Uganda. 8.
Re-investigate the taxonomy of the species in order to assess the extent of
geographical variation and, if the currently described subspecies are found
to be valid, to identify their ranges. |
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Afrotropical Suids |