Document Sample

C. S van Rooyen and J.A. Ledger

1       Introduction
There are no records of interactions between wildlife and electricity structures in southern Africa
documented in biological literature prior to 1972. In that year a note on mortality of Cape Griffons
Gyps coprotheres on 88 kV distribution lines in the former Transvaal was published in the journal
Nature (Markus 1972). Later Ledger and Annegarn (1981) revealed a serious problem for vultures
on 88 kV lines where the so-called kite structure was used. In response to this problem, the South
African national supplier of electricity, Eskom (then known as the South African Electricity Supply
Commission), established the Bird Research Committee in 1978, which later developed into the
Eskom Wildlife Impacts Advisory Committee (EWIAC). One of us (JAL), current director of the
Endangered Wildlife Trust (EWT), acted as consultant on wildlife matters to EWIAC from 1978 to
1996. Membership of EWIAC was (and still is) voluntary.

EWIAC has done a considerable amount of work on wildlife interactions with electricity structures,
largely by way of recommendations to Eskom on how to deal with specific problems that came to
its attention. Considerable progress was made in terms of finding solutions for problems ranging
from electrocution of large birds to woodpeckers drilling holes in wood poles. This resulted in the
publication of the Eskom Bird Identification Guide in 1988 that summarised the knowledge and
experience gained to date, while offering practical advice on how to deal with bird related problems
(Ledger 1988).

Despite valiant efforts by members of EWIAC to communicate recommendations throughout the
organisation, implementation of solutions did not always take place in a satisfactory manner. In
1995 a serious incident involving the electrocution of vultures on 88 kV structures in the North-
West Province of South Africa prompted Eskom to look afresh at the problem of bird interactions
with its electricity structures (Verdoorn 1996).1 A subsequent investigation into the matter revealed
that the following factors had, (and to some extent still have) a major impact on the effective
management of the bird interactions issue:

• Discontinuity due to staff turnover.
• Ad hoc approach to problems.
• Lack of ornithological expertise among Eskom technical staff.

 The remains of many electrocuted Cape Griffons and African Whitebacked Vultures were found under an
88 kV line after farm labourers alerted the landowner, who then contacted Eskom.

• Little integration/coordination of efforts
• Ineffective communication resulting in duplication of efforts and/or application of ineffective
    solutions to specific problems
• Very little monitoring of implemented mitigation measures
• Lack of systematic data collection

The problem of negative interactions between wildlife and electricity structures is an international
one, and the subject has been studied intensively in southern Africa (Ledger 1983; Hobbs & Ledger
1986a; Hobbs & Ledger 1986b; Brown & Lawson 1989; Ledger et. al. 1992; Verdoorn 1996).
Existing studies deal largely with the biological perspective i.e. the impact of interactions on
species that may be biologically significantly affected. These studies often take the form of a pre- or
post-construction study with regard to specific structures2. Attention is also given to the engineering
and economical perspectives of the problem3.

A critical perspective, which has largely been overlooked, is the one of management. Electricity
structures cover vast tracts of land and traverse diverse habitats. In 1996, Eskom’s network of
powerlines amounted to 255 745 km (Eskom Environmental Report 1996). The amount of potential
interactions with these lines is almost overwhelming. Without a proper, integrated management
system, incorporating all three perspectives mentioned earlier, any large- scale effort to reduce or
eliminate negative interactions between wildlife and electricity structures is bound to run into
difficulties sooner or later (Van Rooyen 1996).

Evidence that problems previously thought to have been solved were still regularly encountered, led
to the formation of an Eskom/Endangered Wildlife Trust Strategic Partnership (the Partnership) in

One of the aims of the Partnership is to solve bird interactions problems by following a new,
integrated approach to the issue of wildlife interactions with electricity structures.

3       Methods

 See in this regard Longridge 1986.
 Ledger 1984; Olendorff; Brown; Olendorff et al. 1996.

The Partnership operates on principles of project management. Sparrius (1994) defines a project as
a unique and complex effort consisting of interrelated tasks performed by various contributors to
create a specific result within a well-defined schedule and a limited budget.

A project has four core functions - the management of goal, cost, schedule and work. No project
can be executed in isolation. Stakeholders, i.e. parties who have a vested interest in the outcome of
the project, influence the situation throughout the life cycle of the project (Sparrius 1996).

The goal of the Partnership is the establishment of an integrated management system to manage
negative interactions between wildlife and electricity infrastructures, with the ultimate goal of
containing them within acceptable levels4. Eskom provided funding for five years towards the
administration of the project, including funding for a full-time project manager based at the EWT.
Major stakeholders are Eskom, the EWT, the broader conservation community, municipal
electricity utilities and the public (especially the agricultural community).

The following objectives towards the realisation of the goal and aims were defined as part of a
comprehensive project plan:

1        The development and implementation of an effective reporting network to identify negative
         interactions i.e.

•        Collisions with electricity structures
•        Electrocutions on electricity structures
•        Roosting and nesting birds excreting on insulators resulting in interruptions to the
         electricity supply
•        Nesting activities of birds on electricity structures resulting in interruptions to the electricity

2        The development of a national network of volunteer field investigators to investigate the
         causes of negative interactions and monitor the effectiveness of mitigation measures

  It goes without saying that any attempt to completely eliminate negative interactions between birds and
electricity structures would inevitably fail due to the sheer number of interactions, as well as the enormous
size of the electricity grid. For the same reasons detailed bird impact assessment studies for each incident fall
outside the scope of the Partnership. The focus is on the provision of hands-on, practical advice to Eskom
staff to deal with problems encountered in the course of their everyday duties. However, the identification of
opportunities for dedicated research and the facilitation of such research falls well within the scope of the

3        The establishment of a database on negative interactions between birds and electricity
         structures to facilitate the future design and placing of electricity structures

4        The implementation of an effective, ongoing awareness campaign to familiarise Eskom
         staff, field investigators and the general public with the project.

5        The implementation of mitigation measures to minimize negative interactions between
         wildlife and electricity structures.

6        The development of an Internet facility to facilitate communication between researchers
         and conservation managers active in the field of birds and electricity structures.

All these objectives were further broken down into individual tasks. Each task was linked to a
responsible person or persons for execution.

Major mileposts5 in the 15-month period between 1 April 1996 to 31 July 1997 were:

• A project plan and budget, finalised in 1996.

• A reporting network within Eskom and the general public, especially rural landowners with
    electricity structures on their property. A toll-free line was installed at the EWT on 1 August
    1996 for the reporting of bird interactions with electricity structures. The existence of the line
    was widely advertised in the national media, (both printed and electronic), and within Eskom
    itself through its internal communication channels. A special effort was directed at the
    agricultural community to get them to report negative interactions between birds and electricity
    structures on their property. Between 1 August 1996 and 31 July 1997, 393 incidents of
    medium-sized to large birds interacting negatively with electricity structures (excluding
    roosting, perching and nesting) were reported mostly by the agricultural community, but also by
    Eskom staff.

• A national network of field investigators involving full-time EWT project executants, volunteers
    from EWT working groups, staff from provincial nature conservation bodies and members of the
    public. The network currently consists of 103 individuals, and is still expanding.

• A database on negative interactions between birds and electricity. Data capturing sheets were
    developed for use by the field investigators to capture data on each reported incident. Incidents
    were categorised into four categories i.e. collision, electrocution, nesting and perching/ roosting.

The following pertinent data was captured (when available) and stored in a central database:

Species and age

Type of structure
Eskom pole identification number(s)
Approximate date of incident
Weather conditions at time of incident
Prevailing wind conditions
Habitat and land use
Visibility of earthwire against background
Length and width of line inspected
Visible injuries
Affected species behaviour during approximate time when incident occurred
Time when greatest number of flights across line take place
History of collisions
Source of historical data

Species and age

Type of structure
Eskom pole identification number(s)
Approximate date of incident

 Important events that must occur during the project in order to achieve the overall project goal (Sparrius

Weather conditions at time of incident
Habitat and land use
Length and width of line inspected
Visible injuries
Availability of alternative roosts/perches
Affected species behaviour during approximate time when incident occurred
History of electrocutions
Source of historical data
Factors possibly contributing to the incident (e.g. proximity of food)

Species that built the nest

Species currently using the nest

Availability of alternative potential nesting substrate

Condition of nest

Direct cause of electrical fault (e.g. stick dropped across two conductors)

Type of structure
Eskom pole identification number(s)
Approximate date of electrical fault(s)
Weather conditions at time of electrical fault(s)
Habitat and land use
History of breeding on pylon
Source of historical data



Type of structure
Eskom pole identification number(s)
Approximate date of electrical fault
Weather conditions at time of electrical fault
Habitat and land use
Availability of alternative roosts/perches
History of perching/roosting
Source of historical data
Factors possibly contributing to the roosting /perching (e.g. proximity of food)

Every incident was registered on a central incident register for easy reference.

• A standard working procedure for the investigation of incidents. This involved a field
    investigation by the field investigator and Eskom technical staff, resulting in a set of detailed
    recommendations from the EWT on how the problem must be dealt with. This included, where
    necessary, the retrofitting of the structure or marking of the line with devices to make it safe for
    birds. To date (September 1997), Eskom has attended to approximately 32% of the structures
    earmarked by the Partnership for retrofitting.

•   Awareness within Eskom staff, field investigators and the general public about the activities of
    the Partnership. The media (both electronic and printed) has been covering the project
    extensively to date. Presentations to selected audiences within Eskom and in the agricultural
    community were made. A basic information sheet with information on problems associated with
    birds and electricity structures was compiled and distributed to all field investigators. A colour
    poster depicting birds that interact negatively with electricity structures was developed for
    distribution to Eskom technical staff.

Major constraints which the Partnership have had to deal with were:

•   Low stocks of mitigating devices. This problem will hopefully be overcome in the near future.
•   Organisational red-tape within Eskom. This is seriously hampering mitigation efforts, since
    obtaining the necessary funding for mitigation measures is often a protracted process.
•   Lack of suitable field investigators in outlying areas. This remains a problem, and leads to
    delays in the investigation of incidents.

•      Apathy from Eskom staff. This was not a general problem, but it was found that awareness and
       attitude varied greatly within Eskom from region to region.
•      Organisational restructuring within Eskom. This led to tasks sometimes not being completed.
These problems were (and still are) dealt with on a continuous basis.

4          Results

The following data was collected in the 12-month period from1 August 1996 to 31 July 1997.

4.1.       Collisions

Species                                               Number
White Stork Ciconia ciconia                           66
Blue Crane Anthropoides paradisea                     57
Ludwig’s Bustard Neotis ludwigii                      47
Lesser Flamingo Phoenicopterus minor                  28
Grey Crowned Crane Balearica regulorum                14
Kori Bustard Ardeotis kori                            11
Greater Flamingo Phoenicopterus ruber                 8
Sacred Ibis Threskiornis aethiopicus                  8
Cape Griffon Gyps coprotheres                         8
White Pelican Pelecanus onocrotalus                   4
Egyptian Goose Alopochen aegyptiacus                  4
Secretary Bird Sagittarius serpentarius               3
Cattle Egret Bubulcus ibis                            3
Wattled Crane Grus carunculatus                       2
Bald Ibis Geronticus calvus                           1
African Hawk Eagle Hieraaetus fasciatus               1
Tawny Eagle Aquila rapax                              1
Martial Eagle Polemaetus bellicosus                   1
Blackbreasted Snake Eagle Circaetus gallicus          1
Goliath Heron Ardea goliath                           1
Whitebreasted Cormorant Phalacrocorax carbo           1
Yellowbilled Duck Anas undulata                       1

Spurwinged Goose Plectropterus gambensis           1
Total                                              271

4.2       Electrocutions

Species                                            Number
Cape Griffon Gyps coprotheres                      32
Black Crow Corvus capensis                         16
Hadeda Bostrychia hagedash                         11
Barn Owl Tyto alba                                 9
African     Whitebacked    Vulture    Pseudogyps 8
White Stork Ciconia ciconia                        6
Helmeted Guineafowl Numida meleagris               5
Egyptian Goose Alopochen aegyptiacus               4
Spotted Eagle Owl Bubo africanus                   4
“Owl”?                                             4
Pied Crow Corvus albus                             4
Martial Eagle Polemaetus bellicosus                3
Jackal Buzzard Buteo rufofuscus                    3
Black Eagle Aquila verrauxi                        3
Grey Crowned Crane Balearica regulorum             2
Blackshouldered Kite Elanus caeruleus              2
Blackbreasted Snake Eagle Circaetus gallicus       1
Tawny Eagle Aquila rapax                           1
Brown Snake Eagle Circeatus cinereus               1
Greater Kestrel Falco rupicoloides                 1
Grey Heron Ardea cinerea                           1
Blackheaded Heron Ardea menalocephala              1
Gymnogene Polyboroides typus                       1
Steppe Buzzard Buteo buteo                         1
Total                                              122

4.3       Perching and/or roosting causing electrical faults

Species                                               Structure                Number of incidents

Cape Griffon Gyps coprotheres                         132     kV       Delta 4
Helmeted Guineafowl Numida meleagris                  88 kV Kite               3

4.4       Nesting causing electrical faults

Species                               Structure                        Number of incidents
Black Crow Corvus capensis            11 kV                            2

Pied Crow Corvus albus                11 kV                            Could not be established

5.        Discussion
In the discussion that follows, an attempt will be made to sketch an historical overview of problems
recorded in southern Africa, as well as the significance of the data collected in the first year of the
Partnership. It must however be kept in mind that detailed analysis of the results has not been done
at this stage, as the project is still in progress.

5.1       Collisions

It seems clear that some birds will always collide with overhead wires - it is the species involved,
and the overall effects of their collision related deaths that must be understood before rational action
can be taken to address the issue. It is interesting that in southern Africa, avian collisions with
overhead transmission lines have not received as much attention as electrocutions, yet it is a major

issue with North American utilities. There is no legislation in Africa that is comparable to the acts
referring to endangered species and migratory birds in the United States of America.6

The only detailed study of bird collisions with electricity structures ever undertaken in Africa prior
to the inception of the Partnership, is that by Mark Longridge (1986). He found that flamingos
(both Greater and Lesser, Phoenicopterus ruber and P. minor), Spurwinged Geese Plectropterus
gambensis and Yellowbilled Ducks Anas undulata were particularly susceptible to being killed or
crippled by colliding with powerlines in his study area (the Blesbokspruit Conservation Area, a
narrow wetland on the eastern edge of the Witwatersrand urban area).

In the current study, flamingos collectively constituted 13% of reported collision related deaths.
According to the latest information available (Simmons 1996), flamingo numbers have declined by
40% in the last 15 years due to breeding failure (only three major breeding events in 40 years in
Southern Africa ). They have never bred successfully in South Africa. The southern African
population of Lesser Flamingos is estimated to be about 25 000, and Greater Flamingos about 47
000. Lesser and Greater Flamingos are classified as vulnerable in the Namibian Red Data Book
(Namibia holds 93% of the Southern African population of Lesser Flamingos and 84% of the
Greater Flamingo population). The situation needs careful monitoring.

In southern Africa we are at the end of the long migration route of birds from Europe, and the
results show that, contrary to what was previously thought, we do have evidence of significant
mortality of migrant White Storks Ciconia ciconia on utility structures. Twenty four percent of
collision related deaths reported to the Partnership involved this species. The White Stork is not
currently regarded as a globally threatened species, but it has undergone a decline in its breeding
ground in Western Europe (Allan 1997a). Some of the biggest concentrations of White Storks occur
in the sparsely populated areas such as the Karoo and the northern part of the Eastern Cape
province where it is unlikely that deaths would be recorded and reported. It is therefore likely that
only a fraction of the actual number of collision related deaths of White Storks are reported.
Another fact is that farm labourers may not report it to the landowner, as they often prefer to harvest
the carcasses. Scavengers such as stray dogs and Blackbacked Jackal also regularly remove

  An Endangered Species Protection Act for South Africa is currently being drafted. South Africa is also a
signatory of the Bonn Convention on the Conservation of Migratory Species of Wild Animals.

The species’s association with agricultural activities (Allan 1997a) is confirmed by the Partnership
data. It seems that irrigated lucerne fields attract large numbers of these birds. This should be taken
into account should any pro-active marking of powerlines be attempted in future.

Collisions with electricity structures have been identified as the single biggest cause of unnatural
mortality of the South African population of Wattled Cranes Grus carunculatus (McCann &
Wilkins 1995). The current South African breeding population of Wattled Cranes is estimated to be
c 250 individuals. The species is regarded as endangered in South Africa (Brooke 1984), and
vulnerable globally (Collar et al. 1994). Although the two incidents reported to the Partnership
constitute only 0.8% of the population, the death of even a single bird has serious implications for
the species in South Africa.

Following the results of an Eskom-funded study, a new 400 kV transmission line in KwaZulu/Natal
has been routed in such a way that Wattled Crane breeding and foraging sites are avoided as far as
possible7. Steps are also currently taken by Eskom to pro-actively mark all powerlines in the
vicinity of breeding pairs of this species in KwaZulu/Natal, its last remaining stronghold in South

South Africa’s national bird, the Blue Crane Anthropoides paradiseus, is also threatened through
collisions with powerlines. Twenty one percent of collision related deaths recorded by the
partnership constitute this species. The Blue Crane is a southern African endemic with the
population concentrated in the south-west Cape, Karoo and the eastern grasslands (Allan 1997b).
The global population of Blue Cranes is estimated at c 20 800 birds (Allan 1997), and it is listed as
vulnerable in the Threatened Birds of Africa and Related Islands Red Data book (Collar et al.
1994). Collision related deaths constitute an important cause of mortality in the Karoo, where an
estimated 5800 of these birds occur (Allan 1997b)8. In one instance, 31 Blue Cranes were killed
through collisions with a 10km stretch of powerline in a period of 5 months. As with the White
Stork Ciconia ciconia, and for the same reasons, it is likely that only a fraction of the actual number
of collision related deaths of Blue Cranes are reported. Blue Cranes use farm dams and natural pans
for roosting purposes, and they are particularly vulnerable to collisions with adjacent powerlines,
especially at dusk when coming in to roost.

Grey Crowned Cranes Balearica regulorum constituted 5% of reported collisions. Although the
Grey Crowned Crane is neither listed globally as threatened (Collar et al. 1994), nor included in the

    See McCann and Wilkins 1995.
    Deliberate and accidental poisoning with agricultural chemicals by crop farmers also takes place.

South African Red Data book (Brooke 1984), recent evidence of large scale decreases suggest that
this is not an accurate reflection of the status of the species (Allan 1997c). The total population of
Grey Crowned Cranes in South Africa is estimated to be only c. 2500 birds, concentrated in the
eastern grassland biome (Allan.1997c). Although collisions with powerlines have not been regarded
as a major threat in the past (Allan 1997c), the situation must be closely monitored, as reports of
powerline related deaths are slowly adding up. Unlike the other two crane species, the Grey
Crowned Crane is also susceptible to electrocution through its habit of roosting on electricity

Collectively, Ludwig’s Bustard Neotis ludwigii and Kori Bustard Ardeotis kori accounted for 21%
of reported collision related deaths ( Ludwig’s Bustard = 17%, Kori Bustard = 4%). Bustards’
susceptibility to collisions with powerlines has been documented (Allan 1997d, 1997e). The extent
and dynamics of the problem are not well understood as yet, but the concern expressed is justified.
Two inspections of the same 10 km stretch of transmission line in its stronghold, the semi-arid
Karoo, conducted 12 months apart, produced respectively 8 and 10 fresh Ludwig’s Bustard
carcasses. Another 10km stretch of line, monitored monthly for 5 months, killed 22 Kori and
Ludwig’s Bustards in that period. Both the Ludwig’s and Kori Bustard are classified as vulnerable
in the South African Red Data book - birds (Brooke 1984).

Despite high population estimates for Ludwig’s Bustard             ( Allan (1994) estimated the total
population size of the species between 56 000 and 81 000 individuals), its susceptibility to
powerlines remains a cause for concern. Several landowners remarked about the decrease in
numbers of Ludwig’s Bustard, since the construction of powerlines on their farms. The seemingly
erratic movement of the birds is often related, it seems, to the seasonal availability of food in the
semi-arid areas where it occurs, making it difficult to tackle the collision problem pro-actively. It
seems that most collisions occur in late afternoon, when the birds return to favourite roosts, often on
higher ground. Evidence is also emerging that lines running north-south are a much bigger hazard
to these birds than lines running east-west. Human disturbance e.g. vehicle traffic, also causes birds
to flush and fly into powerlines (pers. obs.).

Collisions with powerlines are but one of many threats faced by the much bigger and rarer Kori
Bustard (Allan 1997e). There is general concensus that its range has contracted, and that it is under
severe pressure outside protected areas (Allan 1997e). Research into the problem of bustards
colliding with powerlines has been identified as a priority, and a dedicated research project, funded

Collectively, collisions and electrocutions accounted for 16 Grey Crowned Crane reported deaths in the 12-
month period under discussion.

by Eskom, is to commence soon under the auspices of the Partnership in an attempt to gain further
insight into the problem.

The general trend in southern Africa has been to mark powerlines that have been proved to be a
hazard to birds. A wide variety of devices of all shapes, sizes and colours have been used to mark
powerlines to make them visible for birds.10 The trend lately has been to use the well-known Bird
Flight Diverter (BFD), locally produced by Preformed Line Products. BFD’s has been proven to
reduce collisions by up to 89% ( Brown et al 1994).

Eskom is currently testing a new product, the Bird Flapper, which was developed locally by an
Eskom employee concerned about bird collisions, and the high cost of mitigating devices. The Bird
Flapper can be fitted under live-line conditions with a link stick, thereby eliminating the need for an
expensive live-line vehicle, or the inconvenience and loss of revenue incurred when the line has to
be switched off for marking. After initial structural failure, the latest version seems to have
overcome its problems and the product is currently being tested under field conditions at several
sites. The Bird Flapper is available from Preformed Line Products in either black or white.11

5.2      Electrocution

The electrocution of Cape Griffons Gyps coprotheres on 88 kV transmission towers in what is now
the North-West Province of South Africa, first drew attention to the problem that electricity posed
to especially raptors in the region. This happened due to the incompatibility of a large bird with a
dangerous design, the so-called “Kite“ structure. Vultures were killed when landing on the cross-
arm of the tower and contacting a conductor with their extended wings. A three-year study
identified the specific problem areas, and perches were fitted to several hundred towers. This was
thought to have largely solved the problem; where it persisted, due to high densities of roosting
vultures, PVC spirals were fixed to the middle conductor around the insulator clamp to create a
barrier to the wing-tips touching the conductor at the moment of landing. After the problems with
“Kite” structures came to light, Eskom stopped building them12.

   For an historical overview of marking devices used in southern Africa, see Ledger 1994.
   Recent research into bird vision (Kreithen 1996) proved that bird vision peaks in the ultra violet range, and
that contrasting black and white patterns are best seen by birds. The possibility of producing an ultra-violet
reflective flapper is currently being pursued.
   Unfortunately, independent contractors are reportedly still erecting these structures.

As can be seen from the data collected by the Partnership, the problem of vulture electrocutions is
still very much with us, with 26% of all electrocutions reported being Cape Griffons. Collectively,
Cape Griffons and their close relatives, African Whitebacked Vultures Pseudogyps africanus
constituted 32% of reported electrocutions13. Investigations into vultures dying on “Kite” structures
thought to be safe after being fitted with PVC spirals in the manner described above, revealed that
the problem had not been solved14. A new approach was tried i.e. to stretch two inter-linked spirals
directly above the bottom cross-arm, effectively preventing the vultures from landing. This seems to
have reduced the rate of electrocutions, but the problem has not been entirely solved15.

Another structure that is emerging as a vulture killer, is the so-called 88 or 132 kV Delta
Suspension structure. Both Cape Griffons and Whitebacked Vultures have been electrocuted on
these steel structures, presumably when they take off from or land on the lowest cross-arm. The
vultures prefer to perch on the extreme end of the cross-arm, right above the string insulator
(pers.obs.). Another possibility (believed widely by Eskom field staff) is that the birds often excrete
before taking off, thus bridging the critical gap between conductor and cross-arm, and causing a
phase to earth fault16.

Various bird guards have been proposed to prevent the birds from perching above the insulator, but
we have always maintained that by preventing the bird from perching on the structure, the problem
is simply transferred to the next structure. An attempt was made to accommodate the birds by fixing
PVC spirals to the conductor around the insulator clamp to create a barrier to the wing-tips touching
the conductor at the moment of landing (as was done with the 88 kV Kite constructions). Although
this method initially rendered positive results, electrocutions were again reported from poles
modified in this manner. A possible explanation might be that the spirals themselves become
energised after a couple of years, and/or the fact the Cape Sparrows have taken to nesting inside the
spirals (, thereby seriously reducing their insulating effect.

Field tests are currently being conducted on a sleeve manufactured from preformed, heat shrinking,
insulating material that is fitted to the insulator, effectively insulating the conductor for 1 metre on
either side of the insulator. This sleeve could be fitted to the top and bottom insulators on the Delta
Suspension structure, and on the middle phase in the Kite structure. This will accommodate the bird

   The danger that electricity structures pose for vultures was clearly illustrated when the highest cause of
mortality recorded for a reintroduced population of Eurasian Griffons Gyps fulvus fulvus in France, was
electrocution, despite the modification of 300 structures prior to the release the birds (Sarrazin et al.1994) .
   Eskom field staff reported between three to five vultures per month dying on a 5km stretch of line modified
in the manner described above.
   On a 10km stretch of line modified in this manner, electrocutions have dropped to two to three a year.
   See also the discussion under 5.3.

and simultaneously solve both the problem of electrocution and the frequent flashovers caused by
the excreting birds17. The cost of manufacturing this relatively expensive product and fitting it to
selected structures must be weighed against the labour cost involved in fitting an entire line with
cheaper bird guards.

A more insidious problem has been the electrocution of raptors (and to a lesser extent Grey Cowned
Cranes and White Storks) on 11 and 22 kV lines. An estimated 160 000 km of these lines cross
rural terrain within South Africa, while Botswana, Lesotho, Namibia, Swaziland and Zimbabwe
also have extensive networks of similar design. The majority of these lines are constructed on
wooden poles with a horizontal cross-arm bearing the conductors on pin or post insulators above
the cross-arm (usually referred to as the T-structure). In many cases, an earthwire for lightning
protection runs up the pole and terminates in a spike between the middle and an outer insulator. The
potential for phase to phase, or phase to earth electrocutions on such structures is clearly high, yet
very little information on raptor mortality was accumulated over the years that EWIAC has been

A questionnaire survey conducted in the Colesberg district in the Eastern Cape Province, (before
the inception of the Partnership) elicited the following raptor electrocution figures from 55

Martial Eagle - 21
Black Eagle - 20
Vultures - 20 (of which 4 were named as Cape Griffons)
“Eagles” - 15
“Hawks” - 6
“Owls” - 6
Jackal Buzzard - 2

An unexpected finding from the survey was the extent to which raptors are being electrocuted on
terminal structures in rural areas. On many farms there may be a number of such structures where
the overhead line terminates at a transformer to supply a water pump or other equipment. The
terminal structure is usually a twin-pole design, with a horizontal cross-arm bearing three strain
insulators for the incoming conductors. Jumper leads from these three conductors go downward to
connect to the transformer, while another three jumper leads go above the cross-arm to connect to

     See 5.3.

the lightning arrestors. The cross-arm is bonded and earthed, and any bird that perches on the cross-
arm and touches one of the jumpers is electrocuted.

The lethal nature of these terminal structures was confirmed by the data collected by the
Partnership. Approximately 50% of reported electrocutions happened on terminal structures. Owls
and Hadeda Ibis Bostrychia hagedash seem to be particularly susceptible to electrocutions on
terminal structures, as the 17 owls and 11 Hadeda Ibis reported all died in that manner.

The high incidence of electrocutions on terminal structures seems to be brought about by a
combination of factors. Firstly, the design is inherently dangerous for large and medium-sized birds.
Secondly, terminal structures are usually associated with water reservoirs for live stock, especially
in arid and semi-arid areas. Often these reservoirs constitute the only accessible surface water for a
large area, which act as a magnet to raptors such as Martial Eagles Polemaetus bellicosus, Black
Eagles Aquila verreauxii and other birds who use the water for drinking and bathing purposes. The
terminal structure then serves as a convenient perch, with fatal consequences. Fourthly, virtually
every farm yard has one or two terminal structures. Barn Owls Tyto alba and Spotted Eagle Owls
Bubo africanus often frequent farm yards, presumably for the nesting opportunities in barns, and
the large rodent populations often associated with farm yards. They use the terminal structures as
convenient hunting perches with fatal consequences. Neither the Barn Owl nor the Spotted Eagle
Owl is presently regarded as threatened in southern Africa, but the situation needs careful
monitoring. The last factor that must be mentioned is that birds electrocuted on a terminal structure
is more likely to be noticed and reported than those on other structures, since terminal structures are
frequently visited by landowners, or Eskom staff (for maintenance purposes).

The solution to these hazards to raptors is relatively simple, but time-consuming and labour
intensive. Intermediate structures can be rendered safe by cutting a 500 mm gap in the earth wire
(or removing the earth spike completely and terminating the earthwire just below the cross-arm
braces), in conjunction with insulation of the middle phase conductor. This is done by fitting the
locally developed RP 3 Raptor Protector (Ledger 1992), or by fitting a length of split XLPE (cross-
linked polyethylene) tubing to the middle phase conductor.

To render the terminal structures safe for raptors and other birds, split XLPE insulation is fitted to
all the jumper leads above the crossarm, and to the jumpers running to the transformer. Lightning
arrestors are now fitted on the transformer rather than the crossarm, elimnating the need for jumper
leads on the top cross-arm.

Eskom field staff is modifying dangerous structures as they are identified by the Partnership, and in
certain regions, the systematic gapping of earthwires and modification of terminal points have
progressed far. Steps are currently being taken to get the gapping of earthwires on existing poles
accepted as a standard throughout Eskom. Eskom management agreed in 1991 to direct that only
bird-friendly designs should be used in rural areas in future. The design of choice is the single pole
with staggered insulators, as described by Hobbs et al. (1990), although an equally good design is
one where the outer conductors hang below the cross-arm on suspension insulators. Of great
concern is the ongoing construction of bird-unfriendly powerlines throughout Africa.

5.3     Perching and roosting

We define perching as the use of electricity structures as daytime resting sites, or as vantage points
for hunting by raptors, while roosting is defined as the overnight use of a structure for birds to sleep
on. In both cases the problem is primarily one of the birds' excreta falling onto the insulators below,
causing the breakdown of insulation and flashovers to the earthed steelwork of the towers. A
number of different birds have been involved, and a number of different solutions tried.

One particular trouble-spot has been the Warmbad-Witkop 132 kV line in the Northern province of
South Africa. The route was surveyed during the dry season, and at the time those involved in this
task were not aware that periodic flooding of the Nyl River basin results in many towers standing in
a metre of water. During such flood years, the area attracts an estimated 80 000 birds which arrive
to breed. Many herons, egrets and ibises roost on the towers, and very many outages have been
experienced at such times. The fitting of deterrent "bird guards" to prevent perching proved
ineffective, and shields of fibreglass and wood were subsequently fitted to the towers, to prevent
excreta from falling onto the insulators. To date the Partnership has not received any reports of
bird-related problems on that line.

The Bald Ibis Geronticus calvus is endemic to South Africa and was listed as endangered in an
earlier edition of the South African Red Data book - Birds. However, it was omitted from the 1984
revision of that book, as its status is now better known. This species forms flocks during the non-
breeding period (April to August), and these groups have caused outages on 275 kV lines in the
former Transvaal. "Bird guards" made from stiff brushes of galvanised wire proved ineffective, as
the Bald Ibises bent the wires and forced their way back into the cross-arm. Eventually wooden
shields were fitted to prevent excreta from falling onto insulator strings, with some success. The
main problem here is the changing of roosts according to the local availability of food.

Cape Griffons (sometimes with a few Whitebacked Vultures Pseudogyps africanus) establish quite
large roosts on 132, 275 and 400 kV lines, especially in the semi-arid north-western parts of South
Africa. Pollution of insulators with excreta is an ongoing problem, and shields have been fitted to
many towers. The birds move their roosts to areas where livestock or wildlife is dying, and
ornithological expertise is unable to predict where this might happen next. The problem thus
remains rather exasperating for maintenance staff, who in some cases have resorted to insulator
washing by helicopter.

The most recent case relates to an 80 km stretch of 132 kV Delta Suspension line in
KwaZulu/Natal. Since February 1991,when record keeping started, the line experienced 131 bird
related faults. Insulating sleeves (see 5.2) were fitted on problem structures as part of a field test in
1996, and initial results are looking promising.

A rather unexpected impact of Crowned Guineafowls Numida meleagris roosting in the guyed
towers of the Alpha-Beta 765 kV line was the threat of corrosion to the base of the structure,
resulting from the blocking of drain holes by the droppings from the birds (5).

Helmeted Guineafowl Numida meleagris roost in large numbers on electricity structures (pers.ob.).
In the incidents reported to the Partnership, up to 80 of these birds roosted on several Kite structures
(with V-string insulators for the middle conductor), and even on the earthwire on either side of the
structures. Pollution with excreta did not seem to be a problem, yet persistent, unexplained faults
occurred. It seemed that the only plausible explanation was that birds, on their way to the top cross-
arm, settled momentarily in the base of the V, where the two insulator strings meet. In doing so,
they presumably bridged the critical gap between the steel frame and the live conductor, causing a
flashover. After consultation with us, Eskom staff resorted to stretching PVC spirals across the V to
prevent them from landing there. No further faults have been reported, but the situation is closely

5.4     Nesting

The systematic collection of data on raptors nesting on electricity structures does not fall within the
scope of the Partnership, unless the nesting activities are causing electrical faults. However, there
have been attempts at systematic data collection in the past, and is still continuing in some

The first reference to a Martial Eagle Polemaetus bellicosus nesting in a transmission tower dates
back to 1975 (Dean 1975). At one time it was standard practice for Eskom maintenance crews to
remove all nests built in transmission towers, in the belief that they would sooner or later cause
problems. These actions were of concern to conservationists, particularly when such nests were
those of raptors in general, and threatened large eagle species in particular. By bringing biological
expertise to the fore through the medium of EWIAC, it was pointed out that most problems
occurred during the nest-building phase, when large sticks brought by the birds could bridge the
insulator strings and cause flashovers. Removal of nests merely resulted in more nest-building
activity. By trimming long sticks from below the nests, and encouraging the establishment of stable
eagle pairs that would defend their territories, a considerable saving in effort and maintenance costs
was achieved.

Although nesting platforms have been used successfully in the USA, we have found that raptors do
not readily use them in southern Africa, and seem to have very definite preferences for making their
own decisions about which towers they will select.

Today it is Eskom policy that no raptor nest may be removed at any time, unless it is actually a
threat to the supply. As a result of this policy, a wide variety of raptors are now regularly nesting on
towers, as indicated by the following 1988 list by Allan (1988):

Tawny Eagle Aquila rapax
Black Eagle Aquila verreauxii (see also Boshoff & Fabricius 1986 and Ledger et al. 1987)
Martial Eagle Polemaetus bellicosus
African Hawk Eagle Hieraaetus fasciatus
Whitebacked Vulture Pseudogyps africanus (see also Ledger and Hobbs 1985)
Lanner Falcon Falco biarmicus
Greater Kestrel Falco rupicoloides
Rock Kestrel Falco tinnunculus

The first five construct their own nests, while the three Falco species use nests originally built by
eagles or crows.

Recently, African Fish Eagles Haliaeetus vocifer have been added to this list (De Goede

The value of electricity transmission towers as nesting sites for raptors, is highlighted in a recent
paper by Boshoff (1993). He monitored 7-18 pairs of Martial Eagles breeding in Eskom

transmission towers in the Nama-Karoo, over a period of 5-10 years. This was done by flying an
annual series of flights in fixed-wing aircraft along 420 km of power line. Mean linear density was
1 pair/19 km and mean minimum territory size 284 A lack of marked variation in annual
breeding effort indicated that the population was stable. Breeding success was 0.70 (eggs to
nestlings) and 0.62 (breeding attempts to nestlings). Overall minimum reproduction rate was 0.52
young\pair\year. Boshoff concludes that Martial Eagles enjoy enhanced breeding success on
electricity transmission towers. He suggests that persecution of birds on towers may be less than for
birds nesting in low trees or the large boulders and low cliffs found in the Nama Karoo. Safety from
predators is also a factor, as towers provide a nesting substrate inaccessible to mammalian
predators, including man. Boshoff also recounts the case of a pair of Martial Eagles that nested in a
highly vulnerable position in a tree on a low cliff. They built a new nest on an Eskom tower within
one year of the construction of the powerline.

Two species of crows nest on electricity structures in southern Africa, notably the Pied Crow
Corvus albus and the Black Crow Corvus capensis. Both species often use lengths of wire
discarded from farm fences to build their nests, causing electrical problems, as described by Lawson
and Wyndham (1992). The incidents reported to the Partnership seem to fall into this category.
Once constructed, however, such wire nests are usually stable and long-lasting.

The Social Weaver Philetairus socius occurs in the arid western parts of southern Africa. It
constructs an enormous communal nest, which may often be placed on the cross-arm of a wood
pole structure. Considerable damage may result from fires caused by these nests, and entire wood
pole-structures are frequently burned down. To date this problem has not been resolved, and the
birds have resisted nesting in poles erected alongside the energised line. However, no reports of
problems with these nests were received in the study period.

The Redbilled Buffalo Weaver Bubalornis niger builds a large communal nest from thorny twigs,
and may place this in the cross-arm of a transmission tower. Efforts to remove these nests and to
deter the birds have failed, and the only solution appears to be to exclude them totally by enclosing
the cross-arm in netting. This is a hindrance to live-line maintenance, and in most areas the weaver
nests are now left in place

Cape Sparrows Passer capensis cause occasional problems in substations, such as those at Hydra
substation in the Karoo where the birds incorporated wire into their nests build into capacitor banks,
causing flashovers and expensive damage to capacitors. Regular removal of nests and nesting

material has been found to be the only effective counter to sparrows and other passerines which
may attempt to build in substation equipment at times.

6        Conclusion

The EWT/Eskom Strategic Partnership has gone some way towards addressing the problems set out
in the beginning of this paper.

By consistently applying project management techniques, the Partnership is managed in an
integrated manner. Once the project goal has been achieved, the system can be maintained for as
long as the problem continues, provided adequate funding is available. A further advantage of such
a system is that, once established, it can be used for other purposes e.g. reporting incidents of illegal
poisoning of wildlife.

Critical success factors for sustainable, long-term functioning of the Partnership are:

• Continued high levels of awareness and enthusiasm among stakeholders, specifically Eskom
    field staff, EWT field investigators and the public.
• Visible commitment to the initiative from Eskom’s top management through environmental
    policy and commitment of resources.

Unfortunately, little attention has been given thus far to the issue of birds and utility structures in
the rest of Africa. We have ourselves seen rural woodpole contructions of similar design to the
dangerous Eskom structures in several African countries. These include Botswana, Kenya, Lesotho,
Malawi, Mozambique, Swaziland and Zimbabwe. No doubt most African countries use similar
bird-unfriendly structures. Most African utilities are primarily concerned with providing electricity
to promote development and economic growth, whilst alleviating the health and environmental
problems associated with meeting energy needs from other sources. We suspect that avian mortality
on rural powerlines in most parts of developing Africa is not accorded a high priority. The
provision of affordable electricity is much more important on a continent with serious social,
environmental and economic deficiencies that demand urgent attention.

Given this scenario, we believe that funding agencies and consulting engineers from developed
countries have an important role to play in influencing African utilities to build bird-friendly
electricity structures. A good example of this is the Lesotho Highlands Water Project (LHWP),

where the influence of the World Bank has played a major role in ensuring that bird friendly
structures for the construction powerlines have been installed and the best line routes followed.

Unfortunately, however, this has not affected the local electricity supplier, and World Bank-funded,
bird-friendly powerlines in Lesotho often run parallel to existing structures which are bird-
unfriendly. A new dimension to the problem is required - notably that existing structures also be
rendered bird-safe as part of the overall aid package to the recipient country. This could be quite
cost-effective if carried out as part of the new contract.

Likewise, all financial and technical aid packages for powerline construction in African countries
from First World donors should specify that all the structures must conform to bird-friendly
designs. Without such a policy, the number of bird-unfriendly structures in Africa will proliferate,
creating an environment in which few large birds, and in particular vulnerable and endangered
raptors, will be able to survive in the future.

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Authors’ details and addresses

Chris S. van Rooyen
Co-ordinator: Eskom/EWT Strategic Partnership
Private Bag X11
South Africa

Dr John A. Ledger
Director: Endangered Wildlife Trust
Private Bag X11
South Africa