UNIVERSITY OF CAPE TOWN
Rondebosch, South Africa
Overpopulation and Inbreeding inSmall Game Reserves:
the Lion Panthera leo as a Case Study
by
SOPHIE VARTAN
Submitted in partial fulfillment of the requirements for the degree
Master of Science
in
Conservation Biology
Faculty of Science
University of Cape Town
Rondebosch
February 2002
Supervisors: Dr M. Du Plessis (University of Cape Town)
and
Dr R. Siotow (University of Natal)
w
n
To
e
ap
U
ni
ve
rs
ity
of
C
The copyright of this thesis rests with the University of Cape Town. No
quotation from it or information derived from it is to be published
without full acknowledgement of the source. The thesis is to be used
for private study or non-commercial research purposes only.
Acknowledgements
I would like to thank all reserve contacts who provided me with the information
necessary to carry out this study, with special thanks to Hanno Killian, Angus and
Tracey Sholto-Douglas and John O'Brien for their kind hospitality. These persons are
in no way responsible for the opinions expressed herein.
Thanks also to Morne Du Plessis from the University of Cape Town and Rob Siotow
from the University of Natal, for their time invested in me and their helpful advice on
all aspects of my research project. This project was funded by MGM Grand (donation
to C. Packer), the National Research Foundation (donation to R. Siotow) and the
Percy FitzPatrick Institute, University of Cape Town.
And finally but not least, thank-you to Gavin, and the rest of my family and friends
who have provided me with unending support and the constant reminder that there
was an end in sight!
Overpopulation and Inbreeding in SmalJ Game Reserves: the Lion
Panthera leo as a Case Study
SOPHIE VARTAN
Percy FitzPatrick Institute, Department of Zoology
University of Cape Town, Rondebosch 7700 Cape Town, South Africa
Abstract:
Due to habitat loss and fragmentation, many large mammals with historically large ranges
now exist as small, isolated populations. In fenced reserves, limited dispersal options for
individuals have led to problems of inbreeding depression and high rates of population
increase especially where prey species are abundant and competition is low. In this study, I
use the reintroduction of small populations of free-ranging lions (Panthera leo) into game
reserves in South Africa to demonstrate high rates of population increase and levels of
relatedness for large mammals. For a sample of 20 small game reserves (area <100km 2) , I
have compiled information about the translocations of lions, current lion population numbers,
levels of relatedness between individuals and management strategies in place to deal with
potential lion overpopulation and inbreeding problems.
Firstly, with respect to investigating overpopulation within these small reserves, rates of
population increase for reintroduced lions are shown to be relatively high, ranging from 1.18
to 1.71. Conservative and optimistic carrying capacities have already been reached by six of
the sample reserves. The remainder of the reserves will reach their stated carrying
capacities within one to four years' time. Management strategies for controlling lion numbers
in these reserves are presently based translocation and only six reserves have implemented
other methods of population control such as hunting, sterilisation and contraception
techniques. No reserves are planning on using culling as a control method. Secondly, lions
in this study are shown to have high levels of relatedness and the effects of inbreeding are
already apparent in some of these small lion populations.
The results of this study suggest that lion population control in small reserves is necessary
to keep numbers at a sustainable level and that inevitably, with such small founder
populations, inbreeding effects will occur. Three sub-populations of lions in South Africa are
identified, based on the origin of their founder lion populations (Kruger, Etosha and Kalahari
stock), and are used to form the basis of a metapopulation management approach.
Introduction
Small, fenced reserves can contribute towards the conservation of biodiversity (Schafer
1995; Turner and Corlett 1996) but must be rigorously protected and may require intensive
management (Terborqh 1976; Soule and Simberloff 1986). Population numbers of large
predators have the potential to expand until they reach the local carrying capacity (Hunter
1999) and in some cases their numbers have had to be regulated to avoid overpopulation
occurring (Bertram 1973, Owens and Owens 1980; Orford et al. 1988). Population control in
mammals has typically employed methods of removal or contraception (Bertram 1973;
Anderson 1981; Smuts 1982; Bertschinger 2001). In reserves where populations have been
allowed to increase without human intervention, the result has been a reduction in prey
species biomass (Smuts 1982; Orford et al. 1988; Mills et al. 1992; Mills and Shenk 1992;
Hunter 1999) and increased intra-specific competition, which has led to breakouts from the
reserve in search of new territories (Steele 1970; Anderson 1981). Reserve managers are
unfortunately often faced with conflicting management choices since the combination of
capped numbers and limited dispersal of species can lead to effects of inbreeding inbreeding depression, increased homozygosity, the concentration of lethal genes, and the
loss of adaptability to changing environmental conditions (Lande and Barrowclough 1987;
Hedrick and Miller 1992; Rowley et al. 1993; Caughley 1994; Newmark 1996). Examples of
large carnivores existing as small isolated populations and consequently suffering from
inbreeding depression include the Florida Panther (Felis concolor coryi - O'Brien et al. 1990;
Beier 1993; Belden and Hagedorn 1993), the Grizzly bear (Ursus arctos horribilis - Maguir
and Servheen 1992), the wolf (Canis lupus - Laikre and Ryman 1991) and the lion (Panthera
leo - Grubbich 2001). Population numbers should not be less than 50 for any species to
stem inbreeding depression (Soule 1980; Ewens et al. 1987; Goodman 1987) but little is
known about the minimum viable population of large mammal species (Schaffer and
Samson 1985; Ewens et al. 1987; Schaffer 1987).
There is a need for a combined approach involving demography and genetics (Lande
1988). The demographic concept of minimum viable population size is concerned with the
probability of extinction of a population through stochastic demographic forces whilst a
genetic concept is based on the rate at which genetic variation in a population is lost
(Rowley et al. 1993). Small, fragmented populations are increasingly being managed using
metapopulation strategies (Hedrick 1995; Grubbich 2001) whereby each population is
treated as a sub-olvtsrorrof'trre entire population (Hanski and Simberloff 1997; Hanski 1998).
This provides a basis from which genetic and demographic exchange can be mediated
'artificially' by human management. If this species is to persist as viable populations on small
isolated reserves, then constant reintroduction from artificially maintained populations should
2
be used (Hooper 1971). Translocations of individuals between populations (Conant 1988;
Dodd and Siegel 1991; Novellie and Knight 1994; Cunningham 1996) have been used to a)
re-establish previously extirpated P?pulations (Griffith et al. 1989), b) balance ecological
processes (IUCN 1987; Wolf et al. 1996) and c) overcome genetic problems for a wide range
of species (Laikre and Ryman 1991; Maguir and Servheen 1992; Hedrick 1995).
Lions have undergone a significant decrease in range and, whilst once widespread over
Europe, Asia and Africa (Hunter 1999; Grubbich 2001), conflict with humans has led to their
increased eradication outside of protected areas (Frank 1998). Additionally, current
populations are showing the effects of inbreeding depression. The highly inbred Asiatic lion
populations in the Gir Forest, India, reveal degrees of genetic uniformity combined with
structurally abnormal spermatozoa (Wildtet al. 1987; Saberwal et al. 1994). Evidence
suggests that the reproductive performance of the naturally isolated lion population in the
Ngorongoro Crater, Tanzania has decreased as a result of decreasing heterozygosity
(Packer et al. 1991). Today the only relatively large populations of lions left in South Africa
exist in the Kruger National Park (KNP) with population numbers of over 2,000 individuals
(Grubbich 2001). Lion prides at Hluhluwe-Umfolozi Park (HUP) show very little genetic
variation when compared to populations from KNP and cub mortality in HUP is significantly
higher than elsewhere in the wild (Stein 1998). Records of abscesses, generally poor
condition and post-mortem evidence of immuno-incompetence are all thought to be
associated with inbreeding depression in HUP lions (Stein 1997, 1998).
The trend in South Africa over the last thirty years has been for small areas of land
(typically less than 100 km2 in area) to be privately and nationally declared as game
reserves for the purposes of both eco-tourism and biodiversity conservation. Since natural
migration and recolonisation is not often a viable option for lions, due to potential conflict with
humans and well-fenced boundaries, the establishment of new populations within reserves
has had to rely on human intervention. Consequently, a number of free-ranging lions have
been translocated and are now persisting as isolated populations in these small, fragmented
nature reserves. Despite the fact that carnivore translocations are usually risky and
expensive (Miller et al. 1998), the survival and breeding success of translocated lions is very
high (Smuts 1982; Linnell et al. 1997; Hunter 1999). So far, attempts to control the density of
lion populations in national parks have not been particularly successful (Smuts 1978;
Anderson 1981; Smuts 1982; Orford et al. 1988).
The aim of this study is to highlight the potential for overpopulation and inbreeding
problems in reintroduced populations of lions on small reserves. This study can be used as a
model for other species when considering the potential for small populations to be managed
using a metapopulation approach combining both demographics and genetics. My objectives
were twofold: Firstly, to determine to what extent small reserves are facing an
3
overpopulation problem of lions and what management strategies are in place to deal with
this. To achieve this objective, I sought to answer the following questions:
•
What is the rate of lion population increase for each small reserve and, if
populations are left unchecked, what can be the lion population numbers that can
be expected over the next ten years?
•
What are the adult lion carrying capacities for small reserves and how many years
will it take before they are reached given the current rates of increase?
•
What strategies have been implemented to control lion numbers on each small
reserve to address the rate of increase adequately?
•
Given that public perception is vital to the tourist industry for small reserves, what
are the tourist perceptions on the use of various population control techniques?
My second objective was to examine the potential level of inbreeding within reintroduced
populations and to investigate how a metapopulation approach can facilitate mitigation. The
following questions form the basis of this objective:
•
Where are the current sources of lions for reintroduction programmes and can
reserves be grouped on this basis to facilitate a lion metapopulation management
strategy?
•
What is the size and relatedness of the founder lion populations that have been
translocated to small reserves?
•
What is the level of breeding taking place between related individuals after
release?
4
Methods
Study Areas and Information Collected
Twenty game reserves in South Africa are included in this study (Figure 1) covering a crosssection of private, provincial and national management styles. These reserves all met the
following criteria:
a) Less than 100,000 hectares (1000 km2 ) in area;
b) Have reintroduced, or are planning to reintroduce, free-ranging lions (lions that
capture their own prey) within the last 10 years;
c) Are completely enclosed with what is considered to be 'lion-proof' electric fencing.
These criteria exclude parks and reserves such as the Kgalagadi Transfrontier National Park
(KTNP), the Kruger National Park (KNP), private reserves that have removed fences along
KNP's western border and any concessions that keep lions in captivity where they do not
hunt and kill their own prey.
It is necessary to state clarification points for several of the reserves included in this study:
•
HUP has reintroduced lions since 1965 (Anderson 1974; Anderson 1981) from both the
Kruger National Park, South Africa and Etosha National Park, Namibia (Maddock et al.
1996). For comparison with other reserves, only those lions that have been recently
translocated to HUP within the last ten years have been used for analyses here and
these comprise of only Etosha stock lions.
•
Tswalu Game Reserve reintroduced Kruger stock lions from Phinda Game Reserve in
1996, but after testing positive for FIV (feline AIDS), these animals were destroyed
(Loots 2000). A new population of Kalahari stock lions was reintroduced into Tswalu
from KTNP and it is these lions that have been included in this study.
•
Shamwari and Madjuma Game Reserves have previously kept lions that were not freeranging. Only their free-ranging lions, reintroduced more recently, have been included
in this study.
•
Both Madjuma and Entabeni re-stock their lion reserves with prey species on an
annual or biannual basis. Consequently, stated carrying capacities relating to prey
density are much more intensively managed in these instances than other reserves.
I visited 11 of the reserves within a six-week period from October to December 2001 and
personally interviewed reserve management staff (Appendix i). Email or telephonic
interviews were conducted for reserves not personally visited. I recorded information specific
to each reserve including lion translocations, population demographics, and lion population
management strategies using a question-prompt sheet for consistency (Appendix ii).
5
Figure 1. Locations within South Africa of fenced, small game reserves that have reintroduced
free-ranging lions.
Analyses
Part 1: Overpopulation
a) Rates of /ion population increase
I estimated individual rates of increase (A) for lion populations that had been translocated
into reserves between 1992 and 1999 (Equation 1). I have assumed that any population
reintroduced into a reserve after 1999 would not have had sufficient time to establish and
reproduce. The basic unit of a lion population is usually the pride (Schaller 1972; Bertram
1975; Van Orsdol et al. 1985) but I have chosen to use individual numbers for population
increase calculations. This is because, firstly, the lion population in many of these reserves
is too small to have easily recognisable and distinct pride groups. Secondly, it is thought that
social behaviour patterns such as the pride structure may be altered in small, managed lion
populations (Grubbich 2001).
I calculate an average A.
tormese
reserves and apply this to reserves that have
reintroduced lions from 2000 onwards. I also use this average for HUP because there is a
lack of data available for population growth since translocations have been carried out over
30 years. I use A to model the exponential population increase for each reserve from the
present population numbers over the next ten years, and graph the results for reserves with
6
comparatively high, medium and 16w rates of increase. I provide an example of population
increase when taking density-dependent constraints into consideration. The purpose of this
is to show that exponential growth is not ecologically realistic (Boyce 1992) and that
population predictions here are simplified for illustrative purposes. The assumption is made
that no human intervention will purposefully remove individual lions from the system by
translocation or elimination.
Equation 1:
A = (current population + number of individuals removed)
(t/numter of years since release)
number of lions initially reintroduced
b) Reserve carrying capacities
Managers were asked to identify prey species density and catchability, suitable habitat and
density of competitors, before providing an estimate of adult lion carrying capacity (K).
Carrying capacity is defined here as the maximum number of lions that can be ecologically
supported on a reserve without permanently impairing the productivity of the habitat or
reducing prey species. In most cases, a range was given for K, with a lower or conservative
estimate (K1 ) and an upper or optimistic estimate (K2 ) . Where a range was not given, the
assumption is made that the single figure provided represents both K 1 and K2 • Using the
population increase models, I estimate the time in which each reserve will reach K 1 and K2 •
c) Population Control Techniques
Removal of an individual is achieved either by translocation (typically of sub-adults before
they reach two-years old) or through elimination by hunting or culling. The implementation of
contraceptive drugs or performing vasectomy operations can also reduce the rate of
population increase. Managers were asked to state, firstly, whether their lion management
strategy included plans to sell and translocate lions and, secondly, if they had implemented
or were considering implementation of any of the following four techniques:
1) Selective hunting - a hunting licence is sold and the most appropriate animals,
usually older males that have lost dominance of a pride, are shot. Revenue can be
used for reserve management (Creel and Creel 1997; Whitman and Packer 1997).
2)
Culling - excess lions are removed as necessary, usually by shooting or anaesthetic
drug (Smuts 1978; Anderson 1981; Smuts 1982; Funston 2001).
3)
Vasectomy or epididyectomy - operations can be performed to ensure sterility in
males but they will usually continue to mate (Barlow et al. 1997).
7
4) Contraceptive implant - female lions are injected and will not come into oestrus
(Orford et al. 1988). The choice of reversible and irreversible implants is available
depending on requirements (Bertschinger et al. 2001).
d) Tourist Perceptions
Since eco-tourism relies heavily upon reputation, I surveyed tourists visiting game reserves
between November and December 2001 to explore public perception of the above control
techniques (Appendix iii). Tourists were surveyed between game-viewing drives typically
between 1100h-1300h and 1500h-1700h at Welgevonden Game Reserve, Phinda Resource
Reserve, Shamwari and Kwandwe Game Reserve. These reserves were chosen on the
basis of permission given by lodge managers and with the aim of minimising disruption to
tourist activities. The four management techniques outlined above were consistently
explained to tourists and they were asked to rank them in order of preference. The origin of
each tourist was recorded to highlight any significant preferences based on nationality.
Part 2 - Inbreeding:
Founder Populations and relatedness
Using translocation information provided by the reserves, I investigate which reserves have
acted as source and sink populations. I consider a lion 'source' population as any that has
provided founders for establishing a population from a stock of free-ranging, disease-free
lions maintained with known genetic history. 'Sink' populations are those that have only
received lions by translocation and have not, acted as founders to external populations. I
categorise reserves into sub-population groups on the basis of their lion population founder
stock and translocation interaction.
I examine relatedness between individual lions where data is available. Through the use
of a 'studbook' detailing information on individual lions (e.g. date of birth, sire and dam, origin
of founders, deaths and translocation destinations - held by the University of Natal), I
investigate the number and relatedness of population founders. Information on subsequent
mating pairs is analysed and instances of inbreeding recorded. Only those lion pairings that
have produced offspring have been included and pairings that have taken place between
first and second order relatives have been highlighted. Pairings between first-order relatives
(mother-son; father-daughter, brother-sister) have a relatedness of
r = 0.5
(Rowley et al.
1993), whilst second-order pairings (between grandfather-granddaughter, grandmothergrandson, cousin-cousin, aunt-nephew; uncle-niece) are assigned a relatedness of r = 0.25.
8
Results
All private reserves in this study (Table 1) stated that lions were originally reintroduced to
enhance the tourist game-viewing experience and to reach 'Big Five' status. In the provincial
and National Parks, eco-tourism is stated as being a secondary reason for reintroduction,
the primary reason being to restore a natural ecological process to the reserve. The
regulating body for each reserve usually determines the criteria for reintroducing lions,
including such factors as lion-proof fencing, but the level of regulation varies between
provinces.
Table 1. Private, provincial and national reserves included in this study, reserve sizes and the
regulating authority.
Ownership and Reserve Name
Area (hectares)
Regulated by:
Private Reserves
Tswalu Game Reserve*
20 000
Northern Cape Nature Conservation
Welgevonden Game Reserve*
33 000
Northern Province Nature Conservation
1 523
Northern Province Nature Conservation
Shambala Game Reserve*
11 000
Northern Province Nature Conservation
Karongwe Game Reserve
8500
Northern Province Nature Conservation
Makalali Game Reserve
14500
Northern Province Nature Conservation
Entabeni Game Reserve
2 000
Northern Province Nature Conservation
Mthethomusha Game Reserve
8 000
Mpumalanga Nature Conservation
Lowhills Game Reserve
4 000
Mpumalanga Nature Conservation
Tembe Elephant Reserve
30 000
KwaZulu Natal Wildlife Department
Phinda Resource Reserve*
14222
KwaZulu Natal Wildlife Department
Royal-Zulu Game Reserve
4 000
KwaZulu Natal Wildlife Department
Kwandwe Game Reserve
16 000
Eastern Cape Nature Conservation
Shamwari Game Reserve*
18 000
Eastern Cape Nature Conservation
Madikwe National Park*
62 000
North-West Parks and Tourism Board
Pilanesberg National Park*
50 000
North-West Parks and Tourism Board
Hluhluwe - Umfolozi Park*
96 000
KwaZulu-Natal Wildlife
Marakele National Park
65 000
National Parks Board
Addo Elephant National Park*
96 000
National Parks Board
Karoo National Park
70 000
National Parks Board
Madjuma Lion Reserve*
Provincially Managed
South African National Parks
*Reserves that I personally visited between October and December 2001.
9
Part 1. - Overpopulation
a) Rate of population increase, carrying capacity and lion density
The rate of population increase (A) for each reserve that had reintroduced lions prior to 2000
varies between ,1.18 and 1.71 (Table 2). Average.A of these reserves is 1.37 and is used as
the rate of increase for reserves that had reintroduced lions between 2000 and 2001
including HUP.
Table 2.
Lion reintroduction and current demographic data, removals through translocation
or elimination, and predicted population numbers given the rate of population increase (A)for
small reserves
Reserve
Year of
Number
Number
Population
release
released
removed
Predicted
Predicted
(n) end
n in 5
n in 10
2001
years
years
A
Phinda
1992
13
43
15
1.18
34
79
Pilanesberg
1993
19
33
61
1.22
165
446
Makalali
1994
5
20
9
1.29
32
115
Madjuma
1997
4
2
7
1.23
20
55
Madikwe
1997
13
19
45
1.49
330
2427
Welgevonden
1998
5
0
25
1.71
366
5344
Lowhills
1998
6
12
12
1.59
122
1239
Entabeni
1998
4
0
8
1.26
25
81
HUP
1999 - 2001
16
0
120**
1.37*
579
2795
Karongwe
1999
4
0
8
1.41
45
256
Shambala
2000
5
0
5
1.37*
24
116
Mthethomusha
2000
4
0
4
1.37*
19
93
Shamwari
2000
6
0
8
1.37*
39
186
Tswalu
2001
4
0
8
1.37*
39
186
Kwandwe
2001
4
0
6
1.37*
29
140
Royal Zulu
Planned 2002
2/3
0
Tembe
Planned 2002
6
0
Marakele
Planned 2002
2
0
Karoo
Planned 2002
4/5
0
Addo
Planned 2002
11
0
*Rate of increase cannot be estimated given existing data so an average A of 1.37 is used.
**The current population for HUPof120is a result of lions being present since 1965. It is unknown
what contribution lions released between 1999 and 2001 have had to increase population size.
10
Phinda's relatively low rate of increase is probably due to the number of translocations out of
the reserve (Table 2). Pilanesberg's low rate can be attributed to a combination of factors:
lions reaching reproductive age have usually been translocated from the reserve; population
control techniques are practised; and similar to Madikwe, there are higher levels of
competitors present than in most of the other reserves. Nevertheless, high population
numbers are still predicted within ten years due to the current number of lions on these
reserves. Welgevonden's high rate of increase can in part be attributed to an abundance of
suitable habitat and prey species and virtually no competition for food or space from other
predators. Predictions of population increase over the next ten years for all reserves are
shown (Figure 2) and density-dependence for Phinda is shown to slow the rate of increase
(Figure 3).
500
/
400
,/
en
---Phinda
c
.Q
'+-
300
,/
- - - - Pilanesberg
/
0
•
L-
a>
E 200
- - -6- -
:::l
o
Z
.. --
100
.
Makalali
................
.......
... - - - -
0
2001
Madjuma
- Entabeni
2003
2007
2005
2009
2011
Year
a). Reserves that have a comparatively low population increase rate (A) ranging from 1.18 and 1.29.
11
500
l
---Shambala
400
CJ)
c
*
Mthethom usha
a
Shamwari and
Tswalu
.2 300
"I0
lo...
(])
..Q
/
E 200
:::J
Z
- - -te- -
'Kwandwe
100
- - - - Karongwe
0
2001
2003
2005
2007
2009
2011
Year
b). Reserves that have a medium population increase rate (A) of 1.37.
4000
I
I
I
J
3000
/
CJ)
c
/
.2
0
lo...
(])
--HUP
- - (J- - 'Madikwe
tC
Lowhills
- - - - Welgevonden
/
"I-
2000
.0
E
:::J
Z
1000
2001
2003
2005
2007
2009
2011
Year
c). Reserves that have a comparatively high population increase rate (A) ranging from 1.37 to 1.71.
Figure 2. Predicted lion population growth over the next 10 years for small game reserves,
grouped into a) high, b) medium and c) low rates of increase.
12
80
uncontrolled population grovvth
70
60
density dependent
contraints
50
__ x __ • - - • -x
x •• _ • • •
40
_)I •
30
20
curre nt carryin9 capacity
10
O+-----.,...-----..,.-----..,.-----..,.------r--2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
Figure 3. Population increase for Phinda (J=J.18) showing uncontrolled growth, densitydependent constraints and current carrying capacity.
Six reserves (Pilanesberg, Welgevonden, Madjuma, Phinda Makalali and Entabeni) have
already exceeded K1 and are equal to or have exceeded K2 (Table 3). All the other reserves
will have reached their K2 within 4 years. There are a total of 342 free-ranging lions within
the 15 reserves of this sample that have already reintroduced lions. The combined
conservative capacities (K1) of the reserves is 307, whilst the combined optimistic capacities
(K2 ) of the reserves amounts to 435 (Table 3). Hluhluwe-Umfolozi Park, Phinda and
Mthethomusha are the only reserves within this study sample to have experienced lion
breakouts from the reserves.
Densities of lions in these reserves (Table 3) are comparable with other areas of African
savanna. Woodroffe and Ginsberg (1998) found lions in East Africa to have a population
density of 0.16 adults/krn" and the critical reserve size there to be a minimum of 30,000 ha.
In this study, reserves less than 50,000 hectares in area have an average lion density of
0.13 per km2 and for those with areas greater than 50,000 ha have an average density of
0.11. East (1981) found that the average population density of lions in areas of less than
50,000 hectares is 0.29 per km2 and for those in areas greater than 50,000 ha is 0.06.
13
Table 3. Lion population numbers, reserve estimates of adult lion carrying capacity and the
time taken to reach these carrying capacities given current growth rates. Current lion densities
are also shown including the densities at estimated carrying capacities.
Metapopulation
Groups
. Current
population
Time
Time
1
2
to K
to K
Current
Densitylkm
2
120
120
150
o
1
0.13
0.13
0.16
Pilanesberg
61
20
60
o
0.12
0.04
0.12
Madikwe
45
40
60
1
0.07
0.06
0.10
Welgevonden
25
20
25
o
o
o
0.08
0.06
0.08
Madjuma
7
4
7
o
o
o
0.47
0.27
0.47
Shambala
5
10
12
3
3
0.05
0.09
0.11
Entabeni
8
6
6
o
o
0.40
0.30
0.30
Kwandwe
6
15
20
3
4
0.04
0.09
0.13
Shamwari
8
8
10
o
1
0.04
0.04
0.06
8
10
10
1
1
0.04
0.05
0.05
Phinda
15
15
15
o
0.11
0.11
0.11
Makalali
9
6
6
o
o
o
0.06
0.04
0.04
Lowhills
12
15
20
1
1
0.09
0.11
0.14
Mthethomusha
4
10
10
3
3
0.05
0.13
0.13
Karongwe
8
8
24
o
4
0.09
0.09
0.28
HUP
Etosha Stock:
Kalahari Stock:
Tswalu
Kruger Stock:
Total
342
307
435
* K1 and K2 are the conservative and optimistic carrying capacities estimated by the reserve
managers.
b) Management strategies for controlling population numbers
None of the reserves had a long-term management plan for their lion populations. All
reserves in this sample plan to sell and translocate any excess individuals. Only
Pilanesberg, Madikwe, Madjuma, Phinda and Makalali have as yet translocated lions to
other reserves. Marakele, Addo, Karoo, Royal Zulu and Tembe are planning to reintroduce
lions in 2002 and the total number of lions required for establishment of these populations is
approximately 27 lions (Table 2). Four of these reserves are already considering options for
lion population control. No reserves are culling their lion populations at present, but four
reserves stated that they would consider culling as a last resort for control (Table 4). Seven
reserves stressed that they would not consider elimination options because it was against
reserve policy.
14
Table 4. Lion population control measures currently implemented or considered by small
reserves.
Reserve
Would consider
Implemented
. Hunting
Culling
Contra-
Vasec-
ception
tomy
. Hunting
No*
Tswalu
Culling
No*
Madikwe
Yes
Yes
Yes
Pilanesberg
Yes
Yes
Yes
Contra-
Vasec-
ception
tomy
Yes
Yes
Yes
Welgevonden
No*
Marakele
Yes
Madjuma
Yes
Yes
Yes
No*
No*
Yes
Yes
Yes
Shambala
Karongwe
Yes
Yes
Makalali
Lowhills
Yes
Yes
Yes
Mthethomusha
No*
Entabeni
No*
Yes
Tembe
Phinda
Yes
Yes
Yes
Yes
Yes
Yes
HUP
Royal Zulu
Yes
Kwandwe
Shamwari
Yes
No*
No*
Yes
Addo
No*
Yes
Yes
Karoo
No*
Yes
Yes
* 'No' implies that the reserve does not wish to consider an option whilst it is against reserve
management policy.
( - ) indicates where the reserve had not implemented or considered an option but it is not against
reserve policy to do so.
The reserves that consider hunting lions on their property stressed that this would only
occur if they could be confident that it would be carried out professionally and not attract
negative public reputation. Contraceptive techniques were the preferred choices of reserve
managers for controlling lion population numbers. The reserves using contraceptive implants
are still experiencing high growth rates, but this is likely to be due to the fact that only one
lioness in each case has been treated. Three reserves stated that they were not yet in a
position to consider population reduction techniques but would monitor the population as
necessary.
15
c) Public Opinion of Population Control Tectinique
Tourists surveyed originated from Europe, the United States and South Africa. A chi-square
analysis of the survey results shows. that there is no significant difference for preference of
method based on the nationality of the tourist (p =0.576, X2
=4.756, N = 160). The majority
of tourists chose hunting as the least preferred technique (Figure 4a) whilst the most
preferred technique was contraceptive implants (Figure 4b).
o Hunting
~
Culling
Ed Vasectomy
o Contraception
Figure 48. Percentage of tourists ranking population control
methods as their least preferred choice .
Figure 4b. Percentage of tourists ranking population control
methods as tI~eir most preferred choice
16
Part 2. - Inbreeding
a) Founder Populations
Areas that have provided the primary. source of lions for establishing small populations within
South Africa include Etosha National Park, Kruger National Park and the Kgalagadi
Transfrontier National Park. As a result, the free-ranging lion populations can be divided into
three sub-populations: 1) Etosha stock; 2) Kalahari stock and; 3) Kruger Stock (Table 5).
HUP is not included within a sub-population since it has both Etosha and KNP stock lions.
Table 5.
Lion sub-population groups in South Africa, based on the primary origin of the
founder population.
Sub-population Groups
Hluhluwe - Umfolozi Park (HUP)
Source of lions
KNP, Pilanesberg and Madikwe
Sub-population 1: Etosha Stock
Pilanesberg
All from Etosha National Park, Namibia
Madikwe
Etosha and Pilanesberg
Madjuma
Pilanesberg
Shambala
Pilanesberg, Madikwe and Madjuma
Entabeni, Kwandwe, Shamwari, Welgevonden
Pilanesberg and Madikwe
Tembe*, Royal Zulu*, Marakele*
Planning on Madikwe and/or Pilanesberg
Sub-population 2: Kalahari Stock
Tswalu
All from KTNP
Addo*, Karoo*
Planning: KTNP
Sub-population 3: Kruger Stock
Phinda
Tshukudu and Londolozi (not in this study)
Makalali
KNP
Lowhills
KNP, Thornybush and Phinda
Mthethomusha
Phinda
Karongwe
Makalali and Kapama (not in this study)
*Reserves that are planning on reintroducing lions in 2002.
The Etosha population is estimated at 300 individuals (Stander 1991) and has so far
provided a maximum of 21 founder individuals (19 to Pilanesberg and 3 to Madikwe). More
than half of the reserves in this sample have used Etosha stock lions for re-introducing lions.
Reserves that have acted as secondary sources of Etosha stock lions are Pilanesberg,
Madikwe and Madjuma. Pilanesberg and Madikwe have stocked eight other game reserves
within South Africa (Table 6) and will probably provide lions as founder populations for
17
Tembe, Marakele and Royal Zulu game reserves in 2002. Madjuma translocated two
siblings (offspring of lions originally received from Pilanesberg) to Shambala.
Table 6.
Numbers of lions translocated from Pilanesberg and Madikwe.
Receiving Reserves
Lions Translocated
Lions Translocated
From Pilanesberg
From Madikwe
1997-2001
1997-2001
Entabeni
3
1
4
Kwandwe
2
2
4
Madikwe
10
Madjuma
4
0
4
HUP*
9
7
16
Shambala
1
2
5 (2 from Madjuma)
Shamwari
2
3
5
Welgevonden
3
2
5
Outside S.A.
6
4
10
Total translocated in
34
17
51
40
21
61
Total reintroduced
13 (3 direct from Etosha)
S.A.
Total translocated
*HUP is not grouped as part of the Etosha sub-population, but is included here for completeness of
translocations.
The Kgalagadi Transfrontier National Park population is thought to comprise of between 113
and 132 individuals (Funston and Herrmann 2001) and as yet, only Tswalu has reintroduced
Kalahari stock lions. It is plausible that Tswalu may act as a secondary source for this stock
in the future. The Kruger National Park population is by far the largest at 2000 individuals
(Grubbich 2001) and has provided lions for a number of reserves - all of them not included
in this study. Within this study, Phinda and Makalali have acted as secondary source
populations for this stock.
All reserves in this sample have established lion populations with founder groups of less
than 20. Twelve reserves introduced a founder population of between 1 and 5 individuals
and only 2 reserves introduced founders of between 16 and 20 individuals. The number of
founders released was in most cases determined by the availability of funds and lions
accessible in the 'market-place', rather than concerns over future levels of inbreeding.
18
b) Relatedness
t.
Within populations
Data was not available on the
g~nealogy
of founder stocks for lions that had been
translocated from primary source population's i.e., Etosha, Kruger and Kalahari. The
relatedness could be traced for a number of founder stocks from available data in the
studbook (Table 7).
Table 7.
Relatedness of founder stock
Reserve
Total
Average
number of
relatedness
founders
(r)
Welgevonden
2 siblings; 1 half siblings; 2 unrelated
5
0.25
Entabeni
3 half siblings; 1 unrelated
4
0.19
Madjuma
2 sets of siblings
4
0.5
Shambala
1 set of siblings and 2 half-cousins; 2 unrelated
6
0.25
Shamwari
2 sets of siblings; 2 unrelated
6
0.33
HUP
3 sets of siblings and 2 half-siblings; 1 unrelated
9
0.39
Pairings between related individuals that resulted in offspring could be determined for five
lion populations (Table 8). Phinda and HUP are the only reserves to state that their lions
may already suffer from inbreeding effects but as yet results are inconclusive. HUP has
recorded instances of severe joint swellings, high immuno-incompetence, elevated juvenile
mortality, and poor quality of spermatozoa (Stein 1998) thought to be associated with
inbreeding.
Table 8. Number of lion pairings between 1st and 2
Reserve
st
1 Order pairing
N (r
=0.5)
nd
Order relatives.
~a Order pairing
N (r
=0.25)
Number of related pairings out of
total pairings since release
Phinda
2
1
3 out of 20
Makalali
1
1
3 out of 7
Madikwe
1
2
3 out of 18
Welgevonden
1
1 out of 7
Pilanesberg
2
2 out of 30
Total
4
8
li. Between sub-populations
a) Etosha stock/sub-population 1: Of the original founder population of 21 lions from
Etosha, only 11 females and a maximum of 8 males reproduced. These founders
19
have subsequently produced 51 offspring that have been translocated to other
reserves and have now increased to a total of 165 (total number of lions in
Pilanesberg, Madikwe, Entabeni, Kwandwe, Madjuma, Shambala, Shamwari and
Welgevonden).
b) Kalahari stock/subpopulation 2: Two of the four founder lions at Tswalu have already
produced four offspring, but no previous data on genetics of the founder lions before
their release is currently available.
c) Kruger stock/subpopulation 3: Phinda has translocated four lions to Mthethomusha
(all with a relatedness of r
=0.5) and four lions to Lowhills (three siblings, r =0.5, and
their cousin, r = 0.25).
These results show that there is a relatively high instance of relatedness within and between
populations. However, conclusive genetic studies would first need to be conducted to
determine the level of inbreeding in these populations.
20
Discussion
1. Overpopulation and population control
The possible value of small reserves for the conservation of individual species of large
mammals is enhanced by the tendency for population density to be higher than in larger
areas. High densities in small reserves may reflect such factors as more favourable habitat,
the prevention of dispersal by boundary fences and the absence of competitors and/or
predators (East 1981). However population densities will vary according to both prey
biomass and the available suitable habitat of each reserve (Van Orsdol et al. 1985; Hunter
1999). Lions naturally have low adult mortality and high birth rates (Packer et al. 1988;
Smuts 1982) and cub mortality is considerably influenced by food supply and infanticide
following pride takeovers (Bertram 1975; Packer 1983a and 1983b). In all reserves included
in this study, lion reintroductions were mainly into habitats that did not have an existing lion
population with generally low levels of other natural competitors and an abundance of prey
species. Additionally, in a number of the smaller private reserves within this study, a wildlifevetinerary surgeon was available for treatment of injured lions without which, in a natural
environment, the animal probably would have died.
Reserve managers face the dilemma of having to keep lion numbers low enough to be
ecologically sustainable versus maintaining high levels to almost guarantee tourists a Iionviewing opportunity. None of the reserves included in this study as yet have a long-term
management plan for their lion populations, including accurate predictions of adult lion
carrying capacity reinforced by scientific research. Over half of the reserves that have
already reintroduced lions have not implemented any form of population control - yet results
in this study suggest that all of these reserves will, if not already, reach their upper estimate
for carrying capacities within one to four years.
Translocation has been a favourable method for reducing local lion population sizes for
many reserves. However, it is impossible to imagine a sufficient market in new reserves for
the numbers of lions predicted in five to ten years' time. A small market may exist for lions to
be translocated to institutions such as zoos or lion-hunting operations, but most reserves
may wish to avoid the public reputation associated with these. Unfortunately, population
control invokes an emotional response from the general public, especially when associated
with large mammals and this is an important consideration for reserve managers. For
instance, the problem of 'excess elephants' encountered by reserve managers in East Africa
(Myers 1973) demonstrates the level to which public emotions can affect management
decisions. Both hunting and culling of lions has resulted in management and moral
complexities (Funston 2001) and in some cases has damaged public reputation for the
reserve involved (Smuts 1982). Lions are highly souqht after by sport hunters and hunting
21
can generate considerable revenue for conservation activities (Hosking 1996). For example,
in the Selous Game Reserve lions consistently generated 120/0-130/0 of hunting revenue from
1988 to 1992 (Creel and Creel 1997; Whitman and Packer 1997). Some published details on
examples of culling lions are given for Hluhluwe-Umfolozi Park (Anderson 1981) and the
Kruger National Park (Smuts 1978), while Barlowet al. (1997) compare the effects of
continuous control by culling and male sterilisation. Carnivore contraception has become a
useful tool in population management of carnivores in zoos and sanctuaries and has been
used in southern Africa to slow down the rate of breeding in lions, African wild dogs and
cheetahs (Bertschinger et al. 2001). However, experiments with lion contraception in Etosha
National Park (Orford et al. 1988) have to date produced few tangible results and remain
inconclusive for wild felids.
It is extremely unlikely that the very high population numbers predicted here over ten years
will be realised due to factors such as density-dependence (Boyce 1992), population
crashes of predator and prey species (Bascompte and Sole 1998), and increased
competition between lions leading to breakouts (Anderson 1981; Stander 1990). Diminished
reproductive performance has been linked with inbreeding in some lion populations (Packer
et al. 1991) and this may have an impact on slowing the rate of population increase. The
predictions merely serve to illustrate the extent to which management intervention is
necessary. In a more natural scenario the population might fluctuate around carrying
capacity equilibrium but not far exceed it. However, for the reserves in this study, carrying
capacities are being reached and even exceeded, breakouts are occurring and prey species
have to be re-stocked on some reserves. Although translocating lions to establish
populations in other reserves may go some way towards delaying the problem in the very
short-term, it is evident that overpopulation is already a factor in many of these small
reserves and reduction strategies need to be put in place.
2. Inbreeding and metapopulation management
The results of population densities and growth rates collected from these small reserves
cannot predict minimum viable population numbers for lion populations in small reserves.
Whilst considering that the usefulness of minimum viable population numbers (MVP) has
been queried in many texts (Lande 1988; Simberloff 1988; Bullock and Hodder 1997), the
most frequently cited MVP for large carnivores is above 25 animals (East 1981). Fuerst and
Maruyama (1986) propose the following guidelines to prevent the loss of variation in small
populations: establishing populations with no fewer than 20 individuals, supplementing
populations that already exhibit loss of variation and exchanging individuals from compatible
populations thereby maintaining a higher effective population size. All reserves in this study
have established lion populations with fewer than 20 individuals and population numbers are
22
capped at relatively small numbers. The ultimate outcome of a population bottleneck, or
founder effects, depends upon the duration that the population remains small (Grubbich
2001). The ecological isolation of many reserves may allow local adaptation and coadaptation to take place (Franklin 1980) which may even increase overall genetic variation
by increasing variation between populations (Boecklen 1987). Pilanesberg and Madikwe
have been shown to suffer from reduced genetic variation compared to outbred populations
of lions in large reserves (Grubbich2001) but already have acted as significant sources for
many reserves in this study. It is highly likely that all lions translocated from these reserves
to establish small populations elsewhere will in time, if not already, suffer from similar traits
of founder effects and low levels of heterozygosity. Inbreeding effects are apparent in the
HUP (Stein 1997 and 1998) and Phinda populations, and Madikwe and Lowhills may already
be exhibiting founder effects on genetic diversity (Grubbich 2001). Additionally, low densities
of lions may increase the length of pride tenure in small reserves (Orford et al. 1988) and
ultimately result in lower levels of genetic variation (Grubbich 2001).
However, instead of managing these small reserves as 'islands' (MacArthur and Wilson
1967; Goeden 1979; Terborgh 1976), facilitating artificial dispersal within sub-populations
could increase the effective founder population and stem inbreeding depression. It has been
suggested that genetic erosion in small isolated populations of mammals can be reduced
through metapopulation management (Maguir and Servheen 1992; Grubbich 2001). The
idea of a metapopulation is that populations with independent dynamics are spatially
structured into assemblages of local breeding populations with small amounts of immigration
taking place (Hanski and Simberloff 1997; Hanski 1998). In the case of small populations of
free-ranging lions in South Africa, it can be argued that the human-fragmented reserves
represent a transient, non-equilibrium situation in which the previously more continuous
population has become divided into smaller units, representing a 'sample effect' (Wilcox
1980). Simberloff (1988) and other models of metapopulations (Hooper 1971; Richter-Dyn
and Goel 1972; Schaffer 1987) suggest that modest rates of immigration can vitiate
inbreeding depression, loss of diversity by drift, and demographic and environmental
stochasticity. Beier (1993) found that immigration levels as low as between one and four
animals per decade could decrease the risk of inbreeding depression in cougars in areas
below 220,000 ha.
Given the social organisation and historically highly mobile nature of lions, it is highly
unlikely that there is much genetic difference. between sub-populations of lions in South
Africa. Despite general agreement on this it is an accepted management policy by these
reserves that the principle of conserving the genetic integrity of different populations should
be observed. This principle suggests that an animal has genetically adapted to the
environment in which it has evolved over time. Therefore, for the most past, practice has
23
shown that lions are reintroduced from stock most. closely related to those previously
occurring in the area and that there should generally be no genetic mixing of these subpopulations. Mixing sub-populations could arguably be an option to increase genetic
variation but, at this stage, the lion as a species is in no immediate danger of extinction. It's
protection status falls under CITES Appendix II (The Convention on International Trade in
Endangered Species of Wild Fauna and Flora) and while there is no legal protection of the
lion in South Africa, it is ranked as Category 2 of a regional ranking scale for sub-Saharan
Africa (Nowell and Jackson 1996) due to hunting pressure. The previous mixing of subpopulations in some reserves and the presence of disease (e.g. T8 or FIV) may preclude
some populations, such as HUP (Stein 1997 and 1998), from acting as sources in a
metapopulation management strategy (Viggers et al. 1993; Cunningham 1996; Grubbich
2001). If the aim is to continue to keep the sub-populations described in this study distinct,
then clearly new bloodlines must be brought into the populations from the original subpopulation founders of Etosha, Kruger and Kalahari to reduce the risk of inbreeding effects.
My intention is not to advocate the increased and unnecessary movement of lions
between reserves. Lions have highly complex social behaviour (Packer and Pusey 1983a
and 1983b; Van Orsdol et al. 1985; Packer et al. 1988; Funston and Mills 1997; Packer and
Caro 1997) and to date no studies have conclusively examined long-term maladaptive
behaviour or social dysfunction as a result of translocations (8oecklen 1987). Social
behaviour patterns may be altered in small, managed lion populations that have been
reintroduced through translocation (Grubbich 2001). There is potential for small lion
populations to be managed as three sub-populations within a metapopulation but reserve
managers face a difficult task of managing the conflicts between ecology and tourism.
Intervention to normal ecological processes within a small reserve is an absolute necessity if
small populations are to persist without inbreeding depression and overpopulation problems.
However, if a planned metapopulation approach were to be implemented, a combined
demographic and genetic approach should be considered such that the population control
can be coupled with removing highly related lions from the system. The judicious
interchange of individuals via translocation and the maintenance of an accurate studbook for
small reserves involved in exchanging lions could make it possible to beat the genetic
constraints of effective population size and minimum viable population.
24
Suggestions for reserve managers to consider
The following points are suggestions and recommendations for reserve managers to
consider in order to address the problems of overpopulation and inbreeding:
a) Overpopulation
•
Calculate as accurately as possible the reserve carrying capacity based on prey
densities, potential for reserve expansion, density of competitors, size and suitability
of habitats, rather than using estimates.
•
Model the lion population increase specific to each reserve, using the above
parameters and including density-dependence to predict the excess lion numbers
that will occur over time.
•
Model different scenarios of population control (Starfield et al. 1981; Venter and
Hopkins 1988) and realistically low levels of translocation, to assess the most
affective combination of methods.
•
Implement short and long-term plans for managing lion populations on a proactive
rather than a reactive basis, taking into consideration tourist perceptions.
b) Inbreeding
•
Record all pairings and offspring produced and, where possible, re-trace the genetics
of the founder population. Population control could possibly be aimed at taking
related breeding individuals out of the system.
•
Exchange individual lions with primary source populations to increase genetic
variation and freshen bloodlines.
•
Establish
a
metapopulation
management
system
between
small
reserves
encompassing the three sub-populations, and use exchanges of indiviuals to
increase effective population sizes
•
Reserves that are planning on reintroducing lions in 2002 could consider acquiring
larger founder populations and ensure that individuals reintroduced are not related.
25
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31
Appendix i: Contact details of personnel who provided information for this study.
Reserve
Contact providing
Position
Telephone Number
information
Entabeni
Dolf Blignant
Reserve Manager
(014) 743 6054/1
HUP
Owen Howison
Regional Ecologist
(082) 926 4521 or
(035) 562 0255
Dave Balfour
Regional Ecologist
(082) 905 8660
Kwandwe
Angus Sholto-Douglas Reserve Manager
(083) 406 0147
Karongwe
Cailey Ermer
Ecologist
(083) 593 8237
Lowhills
Johan Moller
Reserve Manager
(082) 455 2790
Joanna Swaye
Researcher
(083) 672 4068
Madjuma
Danie de Bruin
Lion Reserve Manager (014) 734 0014
Madikwe
Steven Dell
Ecologist
(082) 801 1180 or
(018) 3672 ext: 2411
Mthethomusha
Conrad Rosner
Reserve Manager
(013) 764 1114
Makalali
Dave Druce
Chief Ecologist
(015) 793 1720 or
(082) 876 8512
Phinda
Kevin Pretorius
Reserve Manager
(035) 562 0271 or
(082) 788 0085
Pilanesberg
Gus Van Dyk
Royal Zulu
Brendon
Ecologist
082-496-3970
Whittingdon- Reserve Manager
Jones
(082) 379 2401 or
(035) 792 8322
Shambala
Andre Pretorius
Reserve Manager
Shamwari
John O'Brien
Chief Ecologist
(042) 203 1111
Tembe
Wayne Mathews
Reserve Manager
(035) 592 0032
Tswalu
Jaco Loots
Predator
Welgevonden
Marakele,
Addo
Hanno Killian
and Dr. Mike Knight
Reserve (083) 669 1374 or
Manager
(053) 7511244
Field Ecologist
(082) 607 0282
SANP
(083) 4489061
Karoo
32
Appendix ii: Questionnaire survey used for reserve staff.
•
What is the area of the reserve (km sq or hectares) and what areas border the
reserve e.g. livestock farms, communal lands etc?
•
What is the main reason that the reserve was set aside and when?
•
Where did the lion come from that have been reintroduced and what were the main
reasons for reintroducing lion onto the reserve?
•
When were the lion reintroduced into the reserve? Has their birth and survival rate
been high, medium or low?
•
Please provide details of age/sex structure of lion that have been reintroduced and
details of whether they have been translocated out, whether they are still alive on the
reserve and all birth and death events.
•
What is the current estimate of your lion population number and what is your
perceived carrying capacity for lion in the reserve?
•
Have you had problems of lion breakouts from the reserve or inbreeding in the lion
population?
•
Please give details of any future plans for expanding the reserve - e.g. if it is hoped
that fences will be dropped, with whom, what area, when etc.
•
What is the official management policy or objective for managing the free-ranging lion
on the property? E.g. to maximise lion numbers for tourist sightings/to manage to
carrying
capacity
through
selective
hunting
and/or
culling
and/or
vasectomy/contraception etc. Please give as much detail as possible. How do you
plan to control the numbers of lion on the reserve?
•
How do you see the reserves lion populatlon fitting into the greater South African lion
metapopulation? What role does the reserves lion population play in terms of future
lion conservation?
33
Appendix iii: Questionnaire used to gain tourist perceptions.
•
I'm from the University of Cape Town and I'm conducting research on lion
management strategies in South Africa. Would it be possible to ask you some short
questions to aid the research?
•
Due to high lion reproduction rates, unless control measures are taken it is thought
that small reserves will face a problem of unsustainable numbers of lion.
•
Some options that are currently used in game reserves are shown in the following
table. The aim of this short questionnaire is for you to rank these options in order of
your preferred technique for controlling lion numbers (1= your most preferred option;
4= your least preferred option). Please use a range of all numbers 1 through to 4.
Management Option Available:
Rank
1- 4
A. SELECTIVE HUNTING - a hunting licence is sold to hunt surplus adult lion, the
field ecologist selecting the most appropriate animals and accompanying the hunter
for control. The revenue raised from the hunt is can be used for continued
management of the reserve and its wildlife.
B. CULLING - the field ecologist determines how many excess lion are in the
reserve on an annual basis and has them put down as necessary, usually either by
shooting or anaesthetic.
C. VASECTOMY - a number of male lions (determined by the field ecologist) will be
operated on to ensure sterility. They will usually continue to mate but unsuccessfully.
D. CONTRACEPTION - a number of female lions (determined by the field ecologist)
will be injected with a contraceptive drug. The lioness will not mate whilst on the
contraceptive but once worn off, typically after 18 months, she is able to mate and
conceive unless injected again.
Which country do you come from?
.
This is an. independent study and these options are in no way meant to reflect the
management plans of this game reserve. Thankyou for your time.
34