Horn growth
The average weight of the horn of a white rhinoceros
bull is 5 kg. It is likely, therefore that on the first
harvest an adult male will yield 3.16 kg of horn, and
adult female 2.02 kg of horn, a sub-adult male 2.16
kg and a sub-adult female 1.02 kg of horn (Refer to
Chapter 27). The estimated harvest is 65% of the total
horn available of the animal. The regrowth of the horn
if cut correctly as described above is an average of 2
kg for a cow that can be harvested every two years.
The growth will depend on how active animals will use
their horns to mark their territories.
One of the suggested reasons for the failure of
the Hwange National Park dehorning was that the
rhinoceroses carried at least 18 months of re-growth
when they were poached (Lindsey & Taylor, 2011).
However ranchers dehorn their animals twice per year
to limit the risk of poaching.
Population size that must be dehorned
To prevent poaching the aim must be to dehorn
hundred percent of the population. The dehorning of
animals as a commercial exercise it is recommended
not to dehorn a rhinoceros younger than 4 years.
Depending on the age and sex ratios 50% of a
population must be dehorned at the same time. A
cut can be made in the toe nail that will indicate to
poachers that the rhinoceros is dehorned.
Tourism
Purists feel that tourists want to see a rhinoceros with
a horn. However, dehorning could actually benefit
tourism operations by demonstrating that ranch
owners are actively trying to do something to prevent
poaching. This factor will be determined how active
tourist operators market the dehorning of animals
under their clients.
The question must be asked – is a tourist
happy with this image?
Storage risks
Security is a major risk. Private landowners in South
Africa store their horns in a variety of locations,
typically in vaults located off the property such
as banks. There is a risk that government officials
can leak information of dehorning operations to
syndicates. A case is known where the permit was
issued and followed by an armed robbery the next
day. However, faked robbery can also happen where
the horns are removed legally and afterwards robbed.
The cost to store 10 kg of horn in a private bank safe is
ZAR 120 per annum.
There is risk that insects may cause damage to
the horns during the storage period. In the past
naphthalene moth balls were used, but the poison
can cause harm to humans. Currently diatomite is
recommended as described in Chapter 23.
Horns can dry out if stored for long periods. The Table
17.1 below indicates that 0.6 % per annum is lost over
a period of 17 years.
Table 17.1: Weight loss in rhinoceros horn
RHINOS
No
WEIGHT
(g)
WEIGHT
(g)
WEIGHT
LOSS (g)
WEIGHT
LOSS (%)
24/04/
1995
04/05/
2012
17 years
17 years
3
1325
1218
107
8,00
4
2149
1870
279
12,98
6
1644
1508
136
8,27
TOTAL
5118
4596
AVERAGE/
YEAR
522
10,19
30.7 gram
0,60 %
Ecological
Conservationists feel that a rhinoceros bull needs his
horn to protect its territory and a cow to protect her
calf against predators. There are no scientific studies
based on a control where a certain group of animals
are not dehorned. However, a case is known where
an adult bull was dehorned and soon after dehorning
killed an adult cow. It is not recommended to dehorn
animals in wilderness areas where lions occur.
References
Lindsey, P.A. & Taylor, A. (2011). A study on the dehorning
of African rhinoceroses as a tool to reduce the risk of
poaching. Report Department of Environmental Affairs.
2016
SEPTEMBER
15