THE EFFECT OF ELECTRIC FENCING ON LARGE MAMMAL MOVEMENT IN THE

Kilombero Valley Biological Surveys Frontier Tanzania Savanna Research Programme

Kilombero Valley Teak Company Frontier-Tanzania

THE EFFECT OF ELECTRIC FENCING ON LARGE MAMMAL MOVEMENT IN

THE KILOMBERO VALLEY, TANZANIA

Frontier-Tanzania University of Dar es Salaam

Society for Environmental Exploration

Dar es Salaam 2005





Frontier-Tanzania Savanna/Miombo

Environmental Research Programme

THE EFFECT OF ELECTRIC FENCING ON LARGE MAMMAL MOVEMENT IN

THE KILOMBERO VALLEY, TANZANIA

Grainger M.J., Howell, K.M., Fanning, E., and Wegner, G. (eds)

Frontier-Tanzania University of Dar es Salaam

Society for Environmental Exploration

Dar es Salaam 2005


Kilombero Valley Teak Company Frontier-Tanzania i

FOR MORE INFORMATION:

Department of Zoology & Marine Biology University of Dar es Salaam P.O. Box 35064, Dar es Salaam, Tanzania Tel: 255-22-2410462 E-mail: [email protected] Frontier-Tanzania P.O. Box 9473, Dar es Salaam, Tanzania Tel: 255-22-2780063 E-mail: [email protected]

Society for Environmental Exploration 50-52 Rivington Street, London, U.K. Tel: +44 20 76 13 24 22 Fax: +44 20 76 13 29 92 E-mail: [email protected]

Kilombero Valley Teak Company (KVTC) KVTC was set up in 1992 by the Commonwealth Development Corporation (CDC) with the aim of creating and implementing an ecologically, socially and economically sustainable hardwood reforestation programme, with teak plantations arranged in a mosaic between natural forests and other natural vegetation. An area of 28,159 ha was leased by KVTC for this purpose. The company achieved certification from ISO 14001 in 2004 and is presently undergoing certification from the Forestry Stewardship Council (FSC).

The University of Dar es Salaam (UDSM)

The University of Dar es Salaam was established in July 1970 as a centre for learning and research in the arts and the physical, natural, earth, marine, medical and human sciences. The University is surveying and mapping the flora and fauna of Tanzania, and is conducting research into the maintenance and improvement of the environment and the sustainable exploitation of Tanzania’s natural resources.

The Society for Environmental Exploration (SEE)

The Society for Environmental Exploration was formed in 1989 and is a non-profit making company limited by guarantee. The Society’s objectives are to advance field research into environmental issues, and implement practical projects contributing to the conservation of natural resources. Projects organised by The Society are joint initiatives developed in collaboration with national research agencies in co-operating countries.

Frontier Tanzania Savanna Research Programme (FT SRP)

The Society for Environmental Exploration and the University of Dar es Salaam have been conducting collaborative research into environmental issues since July 1989 under the title of Frontier-Tanzania, one component of which is the Frontier Tanzania Savanna Research Programme (FT SRP). The FT SRP has been working in the Kilombero Valley Since July 1998, undertaking conservation research and development activities that included baseline biological surveys of the Kilombero floodplains and miombo woodland, surveys of river birds and fisheries, studies of the puku antelope, land use planning for Itete Ward, facilitation of the establishment of a Community Based Organisation, and the development of an environmental education programme.

mailto:[email protected]




Kilombero Valley Teak Company Frontier-Tanzania ii

Acknowledgements This report is the culmination of the advice, co-operation, hard work and expertise of many people. In particular acknowledgements are due to the following: WILDLIFE DIVISION Director of Wildlife: Mr. Emmanual Severre Director of Research: Mrs. Miriam Zakariah SOCIETY FOR ENVIRONMENTAL EXPLORATION Managing Director: Ms. Eibleis Fanning Programme Manager, Development: Mr. Paul Rubio Programme Manager, Overseas Operations: Ms. Patricia Davis UDSM FT Co-ordinators: Dr. M. Muruke &

Prof. K. M. Howell. KVTC General Manager: Mr. Chris Bekker Project Manager: Mr. Ryno Martyn Technical Manager: Mr. Roland Freyer FRONTIER-TANZANIA Projects Co-ordinator: Ms. Giulia Wegner Research Co-ordinator: Mr. Matt Grainger Assistant Research Co-ordinators: Mr Colin Bonnington, Mr. Jim Cox,

Mr. Dan Cox, Ms Deborah Leach and Ms. Wendy Murray

FT Driver: Mr. Hamisi Zuberi Research Assistants: All those who participated in field

phase TZS502 ULANGA DISTRICT Game guards: Mr. A. Matitu, Mr. P. Msangameno,

Mr. I Mwaisela and Mr A. Mwangalile


Kilombero Valley Teak Company Frontier-Tanzania iii

Table of contents

Acknowledgements ....................................................................................................... ii

Table of contents ......................................................................................................... iii

Abstract ......................................................................................................................... 1

Aims & Objectives ........................................................................................................ 3

Methods ......................................................................................................................... 4 Transect walks ........................................................................................................... 5 Spoor plots................................................................................................................. 5 Camera Traps ............................................................................................................ 6

Results ........................................................................................................................... 7 Transect walks ........................................................................................................... 7 Spoor plots................................................................................................................. 9 Camera traps ............................................................................................................ 11

Discussions ................................................................................................................. 12

Conclusions ................................................................................................................ 16

Recommendations ...................................................................................................... 17

References ................................................................................................................... 18

Appendices ....................................................................... Error! Bookmark not defined. Appendix 1. Photographs taken at the 1.5m fence in the dry season .............. Error! Bookmark not defined. Appendix 2. Photographs taken at the full fence in the wet season ................. Error! Bookmark not defined.


Kilombero Valley Teak Company Frontier-Tanzania 1

Abstract

Electric fences are commonly used to prevent pest species from raiding and

trampling over crops and plantations. Elephants are known to damage commercially

important trees, and the use of electric fences in limiting elephant movement is

generally accepted. However, ethical considerations about the conservation of wildlife

need to be taken in to account when controlling pest species. Pest species like

elephants may be considered endangered, and other large mammals may suffer from

the erection of electric fences that constitute an indiscriminate barrier regardless of

their potential as pests.

In 2004 the Kilombero Valley Teak Company (KVTC), a timber production

company operating in the Kilombero Valley, Tanzania, converted the full electric

fences surrounding its teak plantation plots into fences with a single electrified strand

1.5m high from the ground level. This was intitiated with the express purpose of

allowing large mammals, other than elephants, free movement into and across KVTC

land. The response of large mammals to the 1.5m high strand fence was assessed

using transects spoor, plots, and camera traps to determine which species walked

across, along or away from the fence. Results from this study indicate that fences with

strands of a minimum height of 1.5m from the ground level allow significantly higher

numbers of large mammals to cross it than the full fence.

Consequently, this novel and unique approach to wildlife management needs

to be highlighted as a viable option for forestry in Africa and Asia. In view of possible

elephant behaviour changes to overcome artificial barriers, management measures that

can react quickly and mitigate for any new behaviours exhibited need to be in place.

Based on the results of this study management recommendations are made to

ensure the effective long-term management of the elephant and other large mammal

species through the use of 1.5m high electrified fences.



Introduction

It is well documented that elephants cause damage to both commercial crops

and subsistence-level agriculture creating conflict between humans and wildlife. For

example, the Asian elephant (Elephas maximus) in Sumatra annually destroys

agricultural crops including date palms and sugarcane (Sterba, 1989). The African

elephant (Loxodonta africana) is increasingly in conflict with humans especially in

draught-prone areas in Sub-saharan Africa where crop-raiding threatens food security

(Osborn and Anstey, 2002).

In the past, elephants were routinely killed in response to crop or livestock

raiding and damaging. In the 1970’s a large number of elephants (Loxodonta

africana) were shot in the forests of Uganda because they fed on valuable timber

species (Laws et al. 1975). Through the increased awareness of wildlife conservation

issues, the wholesale slaughter of the past is now seen as ethically unacceptable,

especially when the pest species is considered endangered, as in the case of the

elephant (Osborn and Anstey, 2002).

The main alternative method of controlling the movement of large mammal

species is the use of barriers. In Africa and Asia, high-tension cable fences have been

erected to exclude elephants from many commercially productive areas. Electric

fences are commonplace in zoos, game farms and National Parks, where they restrict

large mammal movement outside of these protected areas and so prevent them from

disease, being poached and causing damage to neighbouring commercially productive

areas (Osborn and Anstey, 2002).

However, fences are indiscriminate and block the movement of all but the

smallest mammals, including those that are not pest species. By restricting their

movement, and in particular by impairing their long distance migration to areas where

water and forage are freely available, fences can have profound effects on large

mammal populations. In the southern African region the erection of fences has

severely reduced the populations of blue wildebeest (Connochaetes taurinus),

tsessebe (Damaliscus lunatus), sable antelope (Hippotragus niger), and eland

(Taurotragus oryx). The most striking example is the virtual cessation of the

wildebeest migration in the Kalahari region of Botswana (Kruger2Canyons 2000).

The Kilombero Valley Teak Company (KVTC) was established in Tanzania in

1992, by leasing 28,159ha of land located in the Kilombero Valley, between the

Udzungwa Mountains National Park and the Selous Game Reserve, Tanzania. This



land is situated in Miombo woodland that grows along the edge of the floodplain of

the Kilombero Valley. KVTC established a land management plan whereby teak

plantation plots are arranged in a mosaic among miombo woodland and other natural

vegetation plots.

KVTC experienced elephant damage in the Nakafulu plantation plot between

2001 and 2002. The potential loss in timber growth amounted to US$4.2 million. In

2002, to prevent continued damage, KVTC encircled the plantation plots, as well as

other natural vegetation plots, with an electrified wire full game fence with a lower

strand 50cm high from the ground level. Wildlife corridors were left unfenced to

permit animal populations, and more specifically elephant populations, movement and

inter-connectivity among the fenced plots.

However, concerns arose that a full game fence would impair access to and

movement through teak and other vegetation plots to other non-pest species. In order

to re-instate this access while preventing elephants from entering the plantation plots,

KVTC started to remove the lower strands of the game fence in 2004 to leave one

single electrified strand 1.5m high from the ground level.

The same year KVTC requested that Frontier-Tanzania investigate the

effectiveness of the 1.5m high strand fence in allowing large mammals to cross it,

whilst excluding elephant.

Aims & Objectives

This paper aims to evaluate the permeability of electrified wire fences

composed of one single electrified strand 1.5m high from the ground level to large

mammal movement whilst excluding elephant.

To achieve this aim the following objectives were set:

1. Assess the number of species and individuals that cross or fail to cross

the 1.5m high strand electric fence;

2. Assess the number of large mammal species and individuals that cross

or fail to cross the full electric fence;

3. Assess the number of large mammal species that venture close or keep

away from the 1.5m high strand electric fence;

4. Assess the number of large mammal species that venture close or keep

away from the full electric fence.



Methods

The study was carried out in the dry season (October/November) of 2004 and

the wet season (April/May) of 2005. Transects, spoor plots and camera taps were

established at two trap sites in the Namhanga district of the Kilombero Valley,

Tanzania (Table 1).

WORK SITE LOCATION GPS 37L UTM

GPS GRID REFS

Trap site 1 Namhanga district 0231637 9068086

S 08º 25’ 23.3” E 036º 33’ 46.3”

Trap site 2 Namhanga district 0231424 9061057

S 08º 29’ 12.0” E 036º 33’ 37.9”

Table 1. GPS coordinates of trap site 1 and trap site 2.

Transect walks along each type of fence line were carried out in the wet

season only in order to achieve objectives 1 and 2, i.e. to record data on animal

movement across, along or away from each type of fence. The wet condition of the

soil provided clear imprints of spoor. Data from both seasons was combined for

analysis.

Spoor plots were set up at sites along full fence lines (n=4) and the 1.5m fence

lines (n=4) in order to achieve objectives 3 and 4, i.e. to assess whether large

mammals ventured close to or kept away from each type of fence. The data was

collected for a period of ten days at each spoor plot site during both the dry and the

wet season.

Camera traps were set up at each spoor plot site to achieve objectives 1 and 2,

i.e. to gather data on animal movement across, along or away from each type of fence,

and to confirm spoor identifications from the spoor plots.

Large mammals were classified as those with an average weight above 4kg,

thus excluding any mammal smaller than the greater canerat, Thryonomys

swinderianus). Spoor was identified with the help of an Ulanga District trained Game

Scout. As spoor between closely related species is difficult to distinguish some

species were combined when recorded (in accordance with Sutherland, 1996).

Harvey’s red duiker (Cephalophus harveyi) and the grey or bush duiker (Sylvicapra

grimmia) were recorded as ‘duiker’. The Southern reedbuck (Redunca arundinumi)

and the bohor reedbuck (Redunca redunca) were recorded as ‘reedbuck’. Mongoose

(Herpestidae) species were all recorded under the collective term ‘mongoose’.



Transect walks

Transects were carried out at full and 1.5m fences to identify spoor and record

evidence of large mammal movement across, along or away from both type of fence.

Each transect was 200m long and 5m wide from the fence. In total 1.2km of transect

along both full and 1.5m fences was surveyed. Species were categorised according to

their movement within the vicinity of the fence line as follows:

• The “away from” category was defined as evidence of a mammal approaching the

fence and then turning round and moving away.

• The “along” category was defined as evidence of an animal moving in the same

direction as the fence.

• The “across” category was defined as evidence of an animal stepping under the

strands of the electric fence.

A T-test was used to compare the full fence and the 1.5m fence in terms of

their differences in abundance of mammals going across, away from, and along each

fence type. Analysis was carried out using the facilities of SPSS for Windows, version

7.5.1 (1996).

Spoor plots

Spoor plots were constructed by clearing an area of 3m x 5m of vegetation

adjacent to the outside of the fence line (in accordance with Sutherland, 1996). This

area was divided into three strips of 1m x 5m. Strip 1 was the closest one to the fence

and strip 3 the furthest one from the fence. Spoor of large mammals were recorded per

strip. Spoor plots were visited at least once every two days. After each visit the spoor

plot was raked to remove previously recorded spoor.

Two analysis tools were used to analyse data from spoor plots and establish

whether the full fence and the 1.5m fence have an effect on large mammal movement.

A One-way Analysis of Variance (ANOVA) was first used to compare strips 1, 2 and

3 among each other in order to assess if there was a difference in their respective

abundance of spoor. Tukey’s Honestly Significant Difference Test (THSDT) was then

used to determine which strips were similar and fall into a single subset and which

ones were different and fall into a separate subset. A lack of difference in spoor

abundance among strips 1, 2 and 3 would suggest that large mammals venture on all

strips with the same constancy, including strips 1 and 2 that are closer to the fence,

and that therefore such fence has no effect on large mammal movement. On the



contrary, a lower abundance of spoor on strips 1 and/or 2 than on strip 3 would

suggest that large mammals do not venture closer than strip 3 to the fence, and that

therefore such fence has an effect on large mammal movement. Analysis was carried

out using the facilities of SPSS for Windows, version 7.5.1 (1996).

Camera Traps

Camera traps (DeerCam® DC-200) using Olympus Trip 505 cameras were set up

at each spoor plot site to photograph animals walking on the spoor plot. Photographs

were used to gather data on animal movement across, along or away from each type

of fence, and to confirm spoor identifications from the spoor plots.



Results Transect walks

On the transects a total of 14 species of large mammal were identified. On the

1.5m fence spoor of aardvark (n=2), buffalo (Syncerus caffer) (n=1), bushbuck (n=5),

bush pig (n=4), duiker (n=4), elephant (n=2), mongoose (n=2), warthog (n=5),

waterbuck (n=1) and yellow baboon (n=1) were identified. On the full fence spoor of

bushbuck (n=4), bush pig (n=4), civet (Civettictis civetta) (n=1), duiker (C. harveyi

and S. grimmia) (n=5), elephant (n=4), Kirk’s dik dik (n=4), spotted hyena (n=1),

mongoose (n=1), warthog (n=3), and waterbuck (Kobus elliprymnus) (n=3) and

yellow baboon (n=2) were identified. Table 2 shows each species’ abundance of spoor

moving across, along and away from the 1.5m fence. Spoor from all species apart

from elephant (Loxodonta africana) indicate animals crossing the 1.5m fence.

Species

Number of spoors

Across Away Along Total

Aardvark (Orycteropus afer) 1 - 1 2

Buffalo (Syncerus caffer) 1 - - 1

Bushbuck (Tragelaphus scriptus) 3 - 2 5

Bush pig (Potamochoerus porcus) 2 1 1 4

Duiker (C. harveyi and S. grimmia) 2 - 2 4

Elephant (Loxodonta Africana) - 1 1 2

Mongoose (Herpestidae) 1 - 1 2

Warthog (Phacochorerus) 2 1 2 5

Waterbuck (Kobus elliprymnus) 1 - - 1

Yellow baboon (Papio cynocephulus) 1 - - 1

Total 14 3 10 27

Total without Duiker and Dik dik 12 3 8

Table 2. Occurrence of spoor of animals along the transects, indicating movement across, along and away from the 1.5m fence.



Table 3 shows each species’ abundance of spoor moving across, along and

away from the full fence. Only spoor from the bush pig (Tragelaphus scriptus), duiker

(C. harveyi and S. grimmia), Kirk’s dik dik (Madaqua kirki) and yellow baboon

(Papio cynocephulus) indicate movement of these animals across the full fence.

Species

Numberof spoors

Across Away Along Total

Bush buck (Tragelaphus scriptus) - 1 3 4

Bush pig (Potamochoerus porcus) 1 - 3 4

Civet (Civettictis civetta) - - 1 1

Duiker (C. harveyi and S. grimmia) 2 - 3 5

Elephant (Loxodonta africana) - 1 3 4

Kirk’s dik dik (Madaqua kirki) 4 - - 4

Mongoose (Herpestidae) - - 1 1

Spotted hyena (Crouta crouta) - - 1 1

Warthog (Phacochorerus) - 1 2 3

Waterbuck (Kobus elliprymnus) - 1 2 3

Yellow baboon (Papio cynocephulus) 1 - 1 2

Total 8 4 20 32

Total without Duiker and Dik dik 2 4 17

Table 3. Occurrence of spoor of animalsalong the transects, indicating movement across, along and away from the full fence.

Results from the T-test indicated that when duiker and dik dik are removed

from the analysis a significant difference is seen between the full and the 1.5m fences

in terms of abundance of large mammals getting across (T-test, t (df=144)= -0.274,

P<0.01) , with more animals getting across the 1.5m fence (n=12) than the full fence

(n=2). There was no significant difference between the 1.5m and the full fences in

terms of abundance of animals walking along (T-test, t (df=144)= 0.285, P>0.05) or

away (T-test, t (df=144)= 0.359, P>0.05) from the fence, even when duiker and dik dik

were removed from the analysis.

Figure 1 shows the abundance of large mammals crossing, walking away

from, or along the 1.5m and full fences as a percentage of all large mammals recorded

along the transects (duiker and dik dik removed).



58%

19%23%

39%

12%

49%

0

10

20

30

40

50

60

ACROSS AWAY ALONG

Abundance of animals (%)

Full FenceHalf Fence

Figure 1. Abundance of large mammals crossing, walking away from, or along the 1.5m and full

fences as a percentage of all large mammals recorded along the transects. Data analysis shows a

significant difference between the 1.5m and full fences in terms of abundance of large mammals

crossing each fence (T-test, t (df=144)= -0.274, P<0.01). There was still no significant difference

between the full and the 1.5m fences in terms of abundance of animals walking away from (T-test, t

(df=144)= 0.359, P>0.05) or along (T-test, t (df=144)= 0.285, P>0.05) the fence (duiker and dik dik

removed).

Spoor plots

In total 11 species were recorded on the spoor plots. On the full game fence plot bush

pig (Potamochoerus porcus) (n=2), duiker (C. harveyi and S. grimmia) (n=6), Kirk’s

dik dik (Madaqua kirki) (n=1), porcupine (Hystrix africaeaustralis) (n=1), spotted

hyena (Crouta crocuta) (n=10), reedbuck (n=3) and yellow baboon (Papio

cynocephulus) (n=5) were recorded. On the 1.5m fence plot aardvark (Orycteropus

afer) (n=6), bushbuck (Tragelaphus scriptus) (n=1), bush pig (n=2), yellow baboon

(n=1), duiker (C. harveyi and S. grimmia) (n=6) and warthog (Phacochoerus

aethipicus) (n=4) were recorded.

Table 4 shows each species’ abundance of spoor on strips 1, 2 and 3 on spoor

plots at the 1.5m fence. Most species that walked on the spoor plots at the 1.5m fence

left the same or a higher number of spoor on strip 1 and 2 than on strip 3. The total

number of spoor on strip 1 (n=7), 2 (n=6) and 3 (n=7) were found to be similar. When

compared to strips 1 and 2 at the full fence, the abundance of spoor left on strips 1 and

2 at the 1.5m fence is higher.



Species

Numberof spoors

Strip 1 Strip 2 Strip 3 Total

Aardvark (Orycteropus afer) 2 2 2 6

Bushbuck (Tragelaphus scriptus) 1 - - 1

Bush pig (Potamochoerus porcus) 2 - - 2

Duiker (C. harveyi and S. grimmia) 2 2 2 6

Warthog (Phacochorerus) - 2 2 4

Yellow baboon (Papio cynocephulus) - - 1 1

Total 7 6 7 20

Table 4. Occurrence of spoor on strips 1, 2 and 3 recorded at 1.5m fence.

Table 5 shows each species’ abundance of spoor on strips 1, 2 and 3 on spoor

plots at the full fence. Apart from porcupine (Hystrix africaeaustralis), all species that

happened to walk on the spoor plots at the full fence left a higher number of spoor on

strip 3 than on strips 2 and 1. Spoor on strip 1 and 2 were often equal to 0. The total

number of spoor results to be higher on strip 3 (n=23) than on strip 2 (n=3) and 1

(n=2).

Species

Numberof spoors

Strip 1 Strip 2 Strip 3 Total

Bush pig (Potamochoerus porcus) - 1 1 2

Duiker (C. harveyi and S. grimmia) - 1 5 6

Kirk’s dik dik (Madaqua kirki) - - 1 1

Porcupine (Hystrix africaeaustralis) 1 - - 1

Reedbuck (R. arundinumi, R. redunca) 1 1 1 3

Spotted hyena (Crouta crouta) - - 10 10

Yellow baboon (Papio cynocephulus) - - 5 5

Total 2 3 23 28

Table 5. Occurrence of spoor on strips 1, 2 and 3 recorded at full fence.



Results from the ANOVA analysis showed that there was no significant spoor

abundance difference among strips 1, 2 and 3 on the spoor plots at the 1.5m fence

(ANOVA, F2, 298=0.164, P> 0.05). On the contrary, there was a significant difference

between strip 1, 2 and 3 on the spoor plot at the full fence (ANOVA, F2, 298=18.458,

P< 0.01). THSD test then indicated that at the 1.5m fence full fence strips 1, 2 and 3

all fall into a single subset. On the contrary, at the full fence strips 1 and 2 fall into a

single subset, while strip 3 falls in to its own subset, with spoor being more abundant

on strip 3.

Camera traps

During the dry season there were 22 pictures taken at sites along the 1.5m high

fence and 7 at sites along the full fence. Only 3 of the 22 photographs taken at the

1.5m fence contained pictures of animals, which comprised of two pictures of

waterbuck (taken on different days and possibly showing different individuals) and

one picture of bushbuck crossing the fence (Appendix 1). None of the photographs

taken at the full fence showed animals.

During the wet season there were 38 pictures taken along the full fence and 10

at the full fence. Only 5 of the 38 photographs taken at the full fence contained

pictures of animals, which comprised of 1 picture of a female bushbuck and 4 pictures

of baboon (all taken on different days and possibly showing different individuals)

walking along the full fence (Appendix 2). None of the photographs taken at the 1.5m

fence showed animals.



Discussions

This study indicates that the electric fence with one single strand 1.5m high

from the ground level achieves the desired goal of excluding elephant from teak

plantations, whilst allowing other large mammals access into and movement through a

semi-enclosed area. The transects show that all species recorded except elephant are

crossing the 1.5m fence (Table 2). These findings are also confirmed by data from the

spoor plots, which show that all species apart from elephant venture close to the 1.5m

fence (Table 4). Results from the ANOVA and THSD analysis show that at the 1.5m

fence there is no difference in spoor abundance between strips 1, 2 and 3, indicating

that in this instance large mammals venture on all strips with the same constancy,

including strips 1 and 2 that are closer to the fence, and that therefore this fence type

has no effect on large mammal movement.

This study also indicates that the full game electric fence blocks the movement

of most large mammals. In fact, data from transects show that all species (with the

exception of duiker, dik dik, bush pig and yellow baboon) fail to cross the full fence

(Table 3). These findings are also confirmed by data from the spoor plots, which show

that most species do not venture close to the full fence (Table 5). Results from the

ANOVA and THSD analysis show a lower abundance of spoor on strips 1 and 2 than

on strip 3, suggesting that large mammals do not venture beyond strip 3 and closer

than 2m to the full fence, and that therefore the full fence is having an effect on large

mammal movement. The repelling of non-pest large mammals at the full fence is a

source of concerns, especially when the repelled species is categorised with a

conservation status. Of the species recorded in this study only buffalo (Syncerus

caffer), reedbuck (R. rundinumi andR. Redunca), and waterbuck (Kobus elliprymnus)

are listed in the IUCN red list as lower risk/conservation dependant (LR/cd) (Hilton-

Taylor, 2004).

When comparing the 1.5m fence and the full fence, data from the transects

(Table 2 and 3) and results from the T-test show that, when duiker and dik dik are

removed from the analysis, more animals cross the 1.5m fences than the full fence.

Photographs that contained pictures of animals confirmed some of the spoor

identification and supported results obtained from the transects and spoor plots,

indicating that non-pest large mammals such as waterbuck and bushbuck cross the

1.5m fence (Photos 1, 2 and 3), while they fail to cross the full fence (Photos 4 and 5).



Despite 1440 hours of camera trapping only a few photographs showed

pictures of large mammals. This is in due, in part, to the fact that the density of large

mammals is low in miombo woodland (Rodgers et al. 1996) and therefore to capture

photographic evidence of mammals crossing a fence is extremely difficult. The low

number of photos containing pictures of mammals may be also due to the relatively

low number of trap cameras utilised by this study (2 cameras along 130km of fence)

and the nature of the camera trap model utilised (time lapse between detection and

actual image capture). Nevertheless, a large amount of data was collected during

transects, which remain the most effective and rapid tool for detecting large mammals

(Silvera et al., 2003)

The results of this study show that 1.5m from the ground is an effective height

to block elephant and yet allow other large mammals access to and movement through

a semi-enclosed area. A higher strand may prove inefficient to block elephants, while

a lower strand may restrict the movement of relatively taller mammals such as

buffalo, eland and waterbuck. On the basis of data collected from the transects, large

mammals from this study can be divided into four groups according to their average

shoulder height (Kingdon, 1997) and their reaction to the 1.5m and full fences:

1. Mammals with an average shoulder height of <50cm (dik dik and

duiker). Data from the transects and spoor plots indicate that these

small antelopes are able to cross under the 50cm lower strand of the

full fence without danger of electric shock. These antelopes inhabit

areas of dense bush and thick undergrowth (Kingdon, 1997), and this

may be another reason why they do not consider the 50cm lower strand

of a full fence as a barrier.

2. Mammals with an average shoulder height of ≥50cm and ≤ 1.5m

(aardvark, bushbuck, bush pig, civet, mongoose, porcupine, reedbuck,

spotted hyena and warthog,). Data from the transects, spoor plots and

photo no. 3 indicate that these species fail to cross the full fence, while

successfully crossing the 1.5m fence. Where the bush pig and the

yellow baboon were seen crossing the full fence (see table 2) the gap

between the lower strand and the ground level had been increased

because of soil erosion, and signs of digging were also observed at

such sites. Other species that cannot burrow into the soil failed to cross

at such sites.



3. Mammals with an average shoulder height of >1.5m and <2.4m

(buffalo, waterbuck, and eland). Data from the transects, spoor plots

and photos no. 1 and 2 indicate that despite their size these species are

capable of crouching under the 1.5m fence without danger of electric

shock. This was proven by the lack of distress dung and signs of fence

damage at sites where spoors from these animals were identified.

4. Mammals with an average shoulder height of ≥2,4m (elephant). Data

from the transects indicate that elephants cannot cross the full fence

nor the 1.5m fence.

There was no significant difference between the 1.5m and full fences in terms

of number of large mammals that walked along or away from fence (Figure 2 and 3).

The number of large mammals reaching the 1.5m fence and then turning away (less

than 12%) or walking along (39%) is probably due to the fact that animals are yet to

fully learn that the 1.5m fence is no longer a barrier to them. The considerable

abundance of spoor of large mammals that walked along both types of fences may be

due to the fact that vegetation on either side of the electric fence is cleared to allow

access for erection and maintenance. Large mammals find it functional to use cleared

areas as a pathway, and territorial mammals may even perceive it as a convenient

boundary marker. To support this thesis, evidence of hyena pasting, which hyena uses

to mark its territories (Kingdon, 1997), was found along the 1.5m fence.

It is important that the success of the 1.5m high strand electric fence is

monitored and that management is reactive to new behaviours that elephants may

develop. Previous studies have ascertained that elephants are able to overcome fences

despite voltage or design (Osborn & Anstey, 2002). During this study on KVTC land,

evidence at the Nakafulu plantation plot suggested that elephants had pushed a tree

over onto the fence and then crossed into the plantation and damaged teak trees.

In view of the possibility of elephant behaviour changes to overcome artificial

barriers, management should be targeted at instilling the recognition in elephants that

a fence demarcates a no-go area. This can be achieved in a number of ways. In Asia

electric fences have been successfully used in conjunction with trenches. Trenches are

dug wide and deep enough to stop an elephant from crossing (elephants can not jump)

(Osborn and Anstey, 2002). However, other heavy non-jumping species such as

Buffalo (Syncerus caffer) and Zebra (Equs burchelli) may also be impaired by such



trenches; trenches may also increase soil erosion and elephants have been known to

fill them in (Hoare, 1992). Other possible methods include planting barrier crops such

as chillies in front of the fence. Chillies do not constitute a barrier to large mammals

because in order to act as repellent they need to be crushed, and mammals other than

elephant and maybe buffalo are not heavy enough to crush them (Osborn and Anstey,

2002). Negative habituation may be considered, whereby elephants are attracted to the

fence with bait (fruit or fruit essence) on metal plates hanging off the fence. When the

elephant touches the bait they receive a shock. This negative habituation can only

work if the fences are guaranteed to give a high voltage shock every time. To prevent

other mammal species from reaching the metal plates, these plates need to be put at a

height that cannot be reached by them (Osborn and Anstey, 2002).

If elephants break down a fence they need to be quickly moved out of the

enclosed area and actively encouraged to leave the site altogether. If elephants are

scared they are more likely to stay away from a site, but may become highly

aggressive (Osborn and Anstey, 2002).

It is also important to mention that there was no damage recorded by KVTC in

the Kilombero Valley prior to 2001. If the ecological reasons for damage could be

determined and effectively addressed then the use of fencing may not be ultimately

necessary. However, this kind of study is long term and therefore would need to run

in conjunction with the use of fences to limit harm to plantations until the ecological

reasons for such damage are determined.



Conclusions KVTC has established a land management plan whereby teak plantation plots

are arranged in a mosaic among miombo woodland and other natural vegetation plots.

All these plots are now encircled by electric fences that keep elephants outside from

the plantations and the natural vegetation plots. Wildlife corridors permit elephant

movement through KVTC land to compensate for the erection of these electric fences

around plantation and other vegetation plots. The 1.5m high strand electric fence

allow other non-pest large mammals access to and movement through the enclosed

areas.

It is necessary to convert the remaining full fences to 1.5m high strand fences.

It is important that conversion of fences near to water supply areas is considered a

priority to allow large mammals movement through enclosed areas to gain access to

water during the dry season.

The combination of the 1.5m high strand electric fences and wildlife corridors

provide an effective and ecologically viable management system for the joint

management of elephant and other large mammal movement through commercially

productive areas. This management system could act as a model for other forestry

and crop production organisations in Africa and Asia who experience problems with

elephant damage as well as the adverse effects of fences on the movement of other

non-pest large mammals.

The use of 1.5m high strand electric fences represents not only a successful

method to repel elephant whilst allowing other non-pest large mammals access to the

an enclosed area, but also a novel and unique approach to wildlife management. In

fact, most wildlife management systems utilise fence designs that are not selective

and impair the movement of all large mammals indiscriminately. Hoare (1992), for

example, differentiate between a 2.7m high full fence to control large mammals in the

presence of predators, and a 2.1m high full fence to control large mammals in the

absence of predators, yet these fences are not species selective, as they act to restrict

all large mammals movement. Single species exclusion methods instead are not well

documented, and are generally aimed at carnivorous species (Cheetah Conservation

Fund, 2005). This study highlights a successful single species exclusion fence that

allows all large mammals, except elephant, access to enclosed areas.



Recommendations

1. Convert the remaining full fences to 1.5m high strand fences to increase free

movement of non-pest large mammals into fenced plantation and natural

vegetation plots. It is important that conversion of fences near to water supply

areas is considered a priority to allow large mammals movement through

enclosed areas to gain access to water during the dry season.

2. Ensure that management protocols for breaches of the fence by elephant are in

place and they are rapidly executed when needed.

3. Monitor elephant behaviour in response to the fence to ensure that

management can react quickly and mitigate for any new behaviours exhibited.

For example, if elephants were to routinely knock trees on to the fence to gain

access to enclosures, it may be necessary to remove or harvest trees of a

certain height from the vicinity of the fence.

4. Determination of the ecological reasons that cause elephants to damage teak

may ultimately reduce the need for fencing in the future. An understanding of

why elephant damage to teak started after 2001 may be beneficial for future

plantations and for other organisations experiencing similar problems. It may

also be able to aid the understanding of the conservation requirements for

elephants within the Kilombero Valley as a whole.

5. The existing wildlife corridor system needs to be assessed to ensure that it is

adequate in size and design and that large mammals (with particular focus on

elephant) can effectively use them. It is also important to assess if poachers

target wildlife corridors, as animals are concentrated within them. If this is the

case anti-poaching patrols need to be increased within wildlife corridors.



References

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Rodgers, A., Salehe, J. & Howard, G. (1996). The biodiversity of miombo

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Appendices Appendix 1. Photographs taken at the 1.5m fence in the dry season

Photo 1. One waterbuck (Kobus ellipsiprymnus) crossing the 1.5m fence

Photo 2. Two waterbuck crossing the 1.5m fence.



Photo 3. One bushbuck (Tragelaphus scriptus) crossing the 1.5 fence



Appendix 2. Photographs taken at the full fence in the wet season

Photo 4. Bushbuck walking along the full fence

Photo 5. Baboons (Papio cynocephulus) walking along the full fence

Documents

THE EFFECT OF ELECTRIC FENCING ON LARGE MAMMAL MOVEMENT IN THE