The concern expressed by John Forrest in a recent article in the journal Oxpecker that mortality among white rhino in South Africa due to present drought conditions could exceed numbers poached, made me consider the early 1980s drought in Hluhluwe iMfolozi Park and additional factors that might now influence mortality.
Drought conditions particularly affecting white rhino in HiP is certainly serious cause for concern, especially when compared with a drought in the early 1980s. Additional factors that are considered to increase the impact of the present drought and have far reaching effect are:
- a reduction in grazing lawns
- large numbers of buffalo
- an increase in large carnivores
- and siltation of rivers.
- Grazing lawns
Until the mid-1970s well utilised grazing lawns in HiP were interpreted by managers as ‘overgrazed’ areas. The response was to remove large numbers of short grass grazers such as white rhino, wildebeest, warthog and impala. Although widespread seedlings of woody species, such as Dichrostachys cinerea and Acacia karroo were also present in these areas of short grass where fire was absent, they were much slower to become established beyond seedling leaf stage due to them being constantly included in grazing pressure. With a consequent reduction in grazers these woody species often became successful as ‘bush encroachment’ while still being protected from fire. Over the past 40 years, bush encroachment has gradually and dramatically reduced optimum white rhino habitat in HiP and in many areas been replaced by woodland and in the north of the park, even forest.
Bush encroachment is likely to continue in HiP due to lack of fire and its frequency as a result of drought, further reducing grassland habitat while continuing to change historic savannah landscapes.
In 1972 there were an estimated 2,229 white rhino in HiP and in 1976 1,629. I have no accurate figures for 1980, although, high mortality during this drought took place despite 616 white rhino being removed during 1979 and 1980, which amounted to about a third of the total population. At present there are about 1,700 white rhino in HiP. This equates to a similar population size of that in 1976 when 40 years ago grazing lawns were far more widespread and annual rainfall was above average during the years 1973-1977.
In 1972 there were an estimated 2,195 buffalo in HiP with the first removals taking place in 1974. These early removals were aimed at providing increased fuel in the form of tall grass, which, when burnt, was hoped to arrest unwanted woody growth (bush encroachment) as it was beginning to be realised to be a major problem. However, during 1979-1981, 961 buffalo were removed primarily because of drought conditions. Although I have no population estimates of buffalo for 1979 in 1976 there were an estimated 2,428 in HiP which emphasises the high percentage considered wise to remove prior to and during the drought.
At present, (January 2016), I understand no buffalo have been removed. Despite a severe drought and wise lessons of past management, about 6,000 buffalo exist. With an additional 700 elephant they will both compete with white rhino for diminishing forage and particularly water, especially in the case of elephant. (Young elephants were only re-established in 1982).
Regarding elephant numbers in HiP and their re-establishment in 1982, a figure of a maximum of 500 was calculated based on elephant densities and rainfall figures in other parts of Southern Africa at the time. With a super abundance of forage in HiP this figure has already been exceeded.
There will be many Zulu who remember the early 1980s drought when thousands of their cattle died surrounding HiP, and when large numbers of animals were culled in HiP and exported with no benefit to them at all, while simultaneously the South African Red Cross organised food for them.
If, or when, any buffalo are removed from HiP I would hope that this time, providing TB is not a stumbling block, some meat could be distributed to hungry Zulu neighbours.
Large carnivores benefit from the present drought conditions in HiP due to an abundance of easily available food. This will in time further contribute to a decline in many herbivore species as carnivore numbers increase. Over the past 20 years many herbivores have already declined in numbers due to a combination of loss of suitable habitat (mainly savannah grassland) and predation, while drought conditions will now only exacerbate their plight. This clearly is a classic example of HiP being a ‘predator pit’ and many large carnivores need to be removed. (Wild dog were only re-established in 1980 as juveniles, and played no part in the early 1980s drought. While lions numbered about 100 at the time).
- Siltation of rivers
Continued siltation and reduced flow in all the large rivers in HiP is yet another problem during low rainfall years. This is because deforested catchments outside of the park can no longer easily retain water while being prone to heavy grazing and soil erosion. Although the term ‘perennial’ was used to describe some of these water courses 40 years ago, ‘seasonal’ is now a more applicable description. The loss of riverine forest in the south of the park during cyclone Demonia in 1984 has created wide shallow water courses where riverine forest is unlikely to become re-established due to seasonal flash flooding and unstable banks.
While accepting that tourism plays an essential role in the continued survival of HiP, drought conditions certainly accentuate the limited size of this island-like park. It reveals the need to reduce popular game viewing species such as white rhino, buffalo elephant and lion.
Anthony Whateley ex Natal Parks Board.