"TOWARDS AN INTEGRATED MANAGEMENT SYSTEM FOR INTERACTIONS BETWEEN"
1 BIRDS AND UTILITY STRUCTURES –DEVELOPMENTS IN SOUTHERN AFRICA 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. 1 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. 2 • 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 1996. 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 2 See in this regard Longridge 1986. 3 Ledger 1984; Olendorff et.al.1981; Brown et.al.1994; Olendorff et al. 1996. 3 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 supply 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 4 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 Partnership. 4 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. 5 • 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: Collision Species and age Coordinates 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 Topography 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 Electrocution Species and age Coordinates Type of structure Eskom pole identification number(s) Approximate date of incident 5 Important events that must occur during the project in order to achieve the overall project goal (Sparrius 1994). 6 Weather conditions at time of incident Habitat and land use Topography 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) Nesting 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) Coordinates 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 Topography History of breeding on pylon Source of historical data Perching/roosting Species Coordinates 7 Type of structure Eskom pole identification number(s) Approximate date of electrical fault Weather conditions at time of electrical fault Habitat and land use Topography 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. 8 • 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 9 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 africanus 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 10 Species Structure Number of incidents Cape Griffon Gyps coprotheres 132 kV Delta 4 Suspension 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 Substation 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 11 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 carcasses. 6 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. 12 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 Africa. 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 7 See McCann and Wilkins 1995. 8 Deliberate and accidental poisoning with agricultural chemicals by crop farmers also takes place. 13 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 structures.9 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 9 Collectively, collisions and electrocutions accounted for 16 Grey Crowned Crane reported deaths in the 12- month period under discussion. 14 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. 10 For an historical overview of marking devices used in southern Africa, see Ledger 1994. 11 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. 12 Unfortunately, independent contractors are reportedly still erecting these structures. 15 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 (pers.bo.), 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 13 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) . 14 Eskom field staff reported between three to five vultures per month dying on a 5km stretch of line modified in the manner described above. 15 On a 10km stretch of line modified in this manner, electrocutions have dropped to two to three a year. 16 See also the discussion under 5.3. 16 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 active. 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 respondents: 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 17 See 5.3. 17 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. 18 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. 19 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 monitored. 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 instances. 20 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 pers.com). 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 21 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 sq.km. 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 22 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), 23 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. 6. References Allan, D. G. 1997a. White Stork Ciconia ciconia. In: The Atlas of Southern African Birds. Vol.1: Non-passerines. Harrison, J.A., Allan, D.G., Underhill, L.G., Herremans, M., Tree, A.J., Parker, V. and Brown, C.J. (eds.), pp 82-83. BirdLife South Africa. Allan, D. G. 1997b. Blue Crane Anthropoides paradiseus. In: The Atlas of Southern African Birds. Vol.1: Non-passerines. Harrison, J.A., Allan, D.G., Underhill, L.G., Herremans, M., Tree, A.J., Parker, V. and Brown, C.J. (eds.), pp314-315. BirdLife South Africa. Allan, D. G. 1997c. Crowned Crane Balearica regulorum. In: The Atlas of Southern African Birds. Vol.1: Non-passerines. Harrison, J.A., Allan, D.G., Underhill, L.G., Herremans, M., Tree, A.J., Parker, V. and Brown, C.J. (eds.), pp316-317. BirdLife South Africa. Allan, D. G. 1997d. Kori Bustard Ardeotis kori. In: The Atlas of Southern African Birds. Vol.1: Non-passerines. Harrison, J.A., Allan, D.G., Underhill, L.G., Herremans, M., Tree, A.J., Parker, V. and Brown, C.J. (eds.), pp346-347. BirdLife South Africa. Allan, D. G. 1997e. Ludwig’s Bustard Neotis ludwigii. 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Electricity SA, March/April 1990, Crown Publications, Johannesburg.43-47 Kreithen, M.L. Development of an Optical Painted Pattern Designed to Reduce Avian Collisions with Obstacles. Abstracts of the 2nd International Conference on Raptors. p.12. Raptor Research Foundation/University of Urbino. Lawson, A. B. and M.J. Wyndham. 1993. A System of Monitoring Wildlife Interactions with Electricity Distribution Installations in a Supply Region of the Cape Province in southern Africa. Proceedings: Avian Interactions with Utility Structures: 5-1. Prepared by the Electric Power Research Institute, Palo Alto, California. Ledger, J. 1983. Guidelines for Dealing with Bird Problems of Transmission Lines and Towers. Escom Test and Research Division Technical Note TRR/N83/005. Ledger, J. 1988. Eskom Bird Identification Guide. Eskom, Johannesburg. Ledger, J. 1992. Protecting Eagles and Other Large Birds from Electrocution on Rural Powerlines. South African Eagle Insurance Company Limited. Ledger, J. and J. Hobbs. 1985. First Record of African Whitebacked Vultures Nesting on Man- made Structures. Bokmakierie 37:99-109. Ledger, J., J. Hobbs and D. Van Rensburg. 1987. First Record of Black Eagles Nesting on an Electricity Transmission Tower. African Wildlife 41:60-66. Ledger, J.A. 1984. Engineering Solutions to the Problem of Vulture Electrocutions on Electricity Towers. The Certificated Engineer 57:92-95. Ledger, J.A. 1994. Marking Devices to Prevent Bird Collisions with Overhead Lines. EWIAC. Johannesburg. Ledger, J.A. and H.J.Annegarn. 1981. Electrocution Hazards to the Cape Vulture (Gyps coprotheres) in South Africa. Biological Conservation 20:15-24. 26 Ledger, J.A., J.C.A. Hobbs and T.V. Smith. 1992. Avian Interactions with Utility Structures: Southern African Experiences. Proceedings of the International Workshop on Avian Interactions with Utility Structures, Miami, Florida, 13-15 September 1992. Electric Power Research Institute Longridge, M.W. 1986. The Impacts of Transmission Lines on Bird Flight Behaviour with reference to Collision Mortality and System Reliability. Report to Eskom Bird Research Committee, Johannesburg. Markus, M.B. 1972. Mortality of Vultures Caused by Electrocution. Nature, London 238:228. McCann, K.I. and H.J.Wilkins. 1995. Ariadne-Venus 400kV Transmission Powerline: A study of the annual biology and movement patterns of the three crane species in the KwaZulu/Natal midlands for purposes of aiding in the selection of the route for the Ariadne-Venus 400kV powerline. Eskom and Endangered Wildlife Trust. Unpublished report. Olendorff, R. R., Ansell, A.R., Garrett, M.G., Lehman, R.N. and Miller, A.D. 1996. Suggested Practices for Raptor Protection on Powerlines: The State of the Art in 1996. Avian Power Line Interactions Committee (APPLIC). Edison Electric Institute/Raptor Research Foundation. Washington. D.C. Olendorff, R.R., A.D. Miller, and R.N. Lehman. 1981. Suggested Practices for Raptor Protection on Powerlines: The State of the Art in 1981. Prepared by the Raptor Research Foundation, St. Paul, Minnesota. Prepared for the Edison Electric Institute, Washington, D.C. Sarrazin, F., Bagnoli, C., Pinna, L.P., Danchin, E. and J. Clobert. 1994. High Survival Estimates of Griffon Vultures Gyps fulvus fulvus in a Reintroduced Population. The Auk 111 (4): 853-862. Simmons, R. E., 1996. Population Declines, Viable Breeding Areas and Management Options for Flamingos in Southern Africa. Conservation Biology 10 (2) 504-514. Sparrius, A. 1994. Project Management. Project Management Seminar, Technikon SA. Sparrius, A. 1996. Stakeholder Management. Project Pro 6:2: 41-42. 27 Van Rooyen, C. S. 1996. Towards an Integrated Management System for the Management of Wildlife Interactions with Electricity Structures. Abstracts of the 2nd International Conference on Raptors p.9. Raptor Research Foundation/University of Urbino. Verdoorn, G.H.1996. Mortality of Cape Griffons Gyps coprotheres and African Whitebacked Vultures Pseudogyps africanus on 88 kV and 132 kV powerlines in Western Transvaal, South Africa, and mitigation measures to prevent future problems. Abstracts of the 2nd International Conference on Raptors pp. 7-8. Raptor Research Foundation/University of Urbino. Authors’ details and addresses Chris S. van Rooyen Co-ordinator: Eskom/EWT Strategic Partnership Private Bag X11 Parkview South Africa 2122 Dr John A. Ledger Director: Endangered Wildlife Trust Private Bag X11 Parkview South Africa 2122