bird impact assessment study

8/13/2019 Bird Impact Assessment Study

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Bird Impact Assessment Study

The proposed deviation of a portion of the

400kV Duvha-Minerva power line to theeast of Kusile Power Station

March 2011

Prepared by:

Chris van Rooyen Consulting30 Roosevelt StreetRobindaleRandburg2194South AfricaTel. International: +27 824549570Tel. Local: 0824549570Fax: 0866405205

Email: [email protected]
mailto:[email protected]:[email protected]


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EXECUTIVE SUMMARY

Proposed mining operations to the east of the Kusile Power Station necessitates the deviation of the

Duvha-Minerva 400kV transmission line, because it is currently located in the area where proposedmining operations will be undertaken. In order to deviate the 400kV Duvha-Minerva power line, aportion of the existing line must be decommissioned and the deviation (or new portion of the powerline) must be constructed, which requires an EIA to be undertaken. This study deals with the potentialimpacts on avifauna, of the proposed deviation.

Electrocutions

Electrocution refers to the scenario where a bird is perched or attempts to perch on the electricalstructure and causes an electrical short circuit by physically bridging the air gap between livecomponents and/or live and earthed components. Due to the large size of the clearances onoverhead lines of 400kV, electrocutions are ruled out as even the largest birds cannot

physically bridge the gap between energised and/or energised and earthed components.

Collisions

The most likely impact that the proposed line could potentially have on Red Data birds are collisionswith the overhead earth wire. This impact is most likely to occur close to wetlands, where the line skirtsa dam or where it is positioned across a drainage line. Species at risk are water birds of several specieswhere it skirts larger dams, including the Yellow-billed Stork and Black Stork. Another collision hazardexists where the line will cross patches of grassland, as this is the preferred habitat of most of theremaining large terrestrial Red Data species, including the Blue Crane (if it still occurs), Secretarybirdand two species of Korhaan.

Habitat destruction

A limited degree of habitat destruction always takes place when a power line is constructed. In thisinstance some areas of the study area has been intensively transformed through agriculture andmining, which has destroyed some of the original grassland. However, some wetlands have survivedand this could be damaged in the course of construction activities. This could in turn impact on birdsusing in the wetlands. Generally speaking though, habitat destruction is not foreseen as a majorimpact, because of the extensive impacts already evident in the study area.

Disturbance

No significant disturbance of birds is foreseen. Such disturbance as would take place is likely to betemporary and should cease after the dismantling of the existing line and the construction of the

deviation.

Preferred alignment

From the analysis of various risk related factors, alternative 4has emerged as the preferred option

from a bird interaction perspective.

RECOMMENDATIONS

Those sections of line that will require the application of bird flight diverters (BFDs) are indicated on theaccompanying sensitivity map (Appendix C). Sensitive sections will include dams, wetlands, drainage


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crossings and areas of grassland. The proposed BFD is the Double Loop Bird Flight Diverter. BFDsshould be placed on the earthwires, staggered, alternating black and white, 10 metres apart.

The construction of access roads in sensitive wetland habitat should be avoided.


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LIST OF CONTENTS

1 BACKGROUND

1.1...... Scope .............................................................................................................. 51.2...... Terms of reference ............................................................................................ 51.3 Sources of information ....................................................................................... 51.4 Assumptions & Limitations .................................................................................. 6

2 DESCRIPTIONS ........................................................................................................... 61.5 Vegetation ........................................................................................................ 61.6 Bird micro-habitats ............................................................................................ 7

3 TYPICAL IMPACTS OF POWER LINES ON BIRDS ............................................................... 81.7 Electrocutions ................................................................................................... 81.8 Collisions .......................................................................................................... 91.9 Habitat destruction ........................................................................................... 101.10 Disturbance ..................................................................................................... 11

4 PROPOSED STRUCTURE TYPES ..................................................................................... 11

5 POWER LINE SENSITIVE BIRDS .................................................................................... 11

6 DISCUSSION ............................................................................................................. 131.11 Electrocutions .................................................................................................. 131.12 Collisions ......................................................................................................... 131.13 Habitat destruction ........................................................................................... 141.14 Disturbance ..................................................................................................... 14

7 IDENTIFYING A PREFERRED ALIGNMENT ....................................................................... 14

8 CONCLUSIONS ........................................................................................................... 16

9 RECOMMENDATIONS .................................................................................................. 17

10 REFERENCES ............................................................................................................. 17

LIST OF TABLES

Table 1: Vegetation composition of 2529CC and 2528DD (Harrison et al. 1997) ....................... 6Table 2: Red Data species potentially occurring in the study area .......................................... 11Table 3: The results of the measurements for each option .................................................... 15

Table 4: Weights assigned to factors ................................................................................. 15Table 5: The final scores for the respective options ............................................................. 16

APPENDICES

APPENDIX A: Map of study areaAPPENDIX B: Bird habitatAPPENDIX C: Sensitivity map


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1 BACKGROUND

1.1 Scope

Proposed mining operations to the east of the Kusile Power Station necessitates the deviation of theDuvha-Minerva 400kV transmission line, because it is currently located in the area where proposedmining operations will be undertaken. In order to deviate the 400kV Duvha-Minerva power line, aportion of the existing line must be decommissioned and the deviation (or new portion of the powerline) must be constructed, which requires an EIA to be undertaken.

The following components for the deviation are being taken into consideration (See the Draft ScopingReport for full details (Zitholele Consulting 2011)):

Location of the deviation: The existing power line located on the coal reserve needs to bedecommissioned by cutting the power line to the east and west of the coal reserve anddismantling the towers / pylons in the coal reserve footprint. Additionally a new route to deviatethe power line around the coal reserve needs to be assessed.

Size of the servitude:It is proposed that a 150 metre wide corridor be assessed for the required55m wide servitude (27.5m on either side). This is to enable Eskom to deviate slightly aroundsensitivities identified within the corridor once approved.

Length of the line to be deviated:The length of the deviation is dependent on the alternativeapproved by the DEA (approximately 15 km). Additionally the length of the portion of the line tobe decommissioned is between 13 and 16 km.

See Appendix A for a map showing the study area with the proposed alignments.

Zitholele Consulting was appointed by Eskom Transmission to facilitate the Environmental ImpactAssessment process as required by legislation. Chris van Rooyen Consulting was appointed to conduct

the investigations into the potential bird impacts that might occur as a result of the construction of thedeviation.

1.2 Terms of reference

The terms of reference for this bird impact assessment report are as follows:

a description of the existing environment, bird communities and micro habitats; a description of potential impacts; indication of confidence levels; selection of a preferred alternative; rating of impacts; and

proposed mitigation measures.

1.3 Sources of information

The following information sources were consulted in order to conduct this study:

Bird distribution data of the Southern African Bird Atlas Project 2 (SABAP2) was obtained fromthe Animal Demography Unit website (http://sabap2.adu.org.za, 2009), for the Quarter-DegreeGrid Cells (QDGCs) traversed by the proposed line (2529CC and 2528DD).

The conservation status of all species considered likely to occur in the area was determined asper the most recent iteration of the southern African Red Data list for birds (Barnes 2000), andthe most recent and comprehensive summary of southern African bird biology (Hockey et al.
http://sabap2.adu.org.za/http://sabap2.adu.org.za/


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2005). QDGCs are grid cells that cover 15 minutes of latitude by 15 minutes of longitude (15. 15.), which correspond to the area shown on a 1:50 000 map.

The power line bird mortality incident database of the Eskom - Endangered Wildlife Trust

Strategic Partnership (1996 to 2007) was consulted to determine which of the species occurringin the study area are typically impacted upon by power lines and the extent to which they areimpacted on.

A classification of the vegetation types in the QDGCs was obtained from Southern African BirdAtlas Project 1 (Harrison et al.1997).

Information on the micro habitat level was obtained through visiting the area in February 2011and obtaining a first-hand perspective.

Data from the Co-ordinated Avifaunal Road count project (CAR) for the Mpumalanga precinctswere obtained (Young, Harrison, Navarro, Anderson and Colahan, 2003). This data was ofparticular importance in order to establish what densities of large terrestrial birds could beexpected to occur in the study area, and especially what the habitat preferences of those speciesare.

1.4 Assumptions & LimitationsThis study made the assumption that the above sources of information are adequately reliable.However, there are factors that may potentially detract from the accuracy of the predicted results:

Bird distribution patterns may fluctuate in response to climatic conditions, particularly rainfall. Sources of error in the SABAP2 database, particularly limited coverage of some QDGCs. This

means that the reporting rates of species may not be an accurate reflection of the true densitiesin QDGCs that has to date been sparsely covered during the data collecting. The 2529CC QDGChas not yet been well covered by SABAP2 with a total of only 38 checklists to date, but it doesprovide an up to date set of data with regard to the species that are likely to occur. The 2528DDQDGC has been better covered with a total of 80 checklists to date.

Predictions in this study are based on experience of these and similar species in different parts ofSouth Africa. Bird behaviour can never be entirely reduced to formulas that will hold true underall circumstances. However, power line and substation impacts can be predicted with a fairamount of certainty, based on experience gained by the author through the investigation ofhundreds of localities in southern Africa, since 1996, where birds have interacted electricalinfrastructure.

2 DESCRIPTION OF AFFECTED ENVIRONMENT

2.1 Vegetation

Table 1 below shows the vegetation composition of the two relevant QDGCs (Harrison et al1997). It isgenerally accepted that vegetation structure, rather than the actual plant species, influences birdspecies distribution and abundance (in Harrison et al1997). Therefore, the vegetation description belowdoes not focus on lists of plant species, but rather on factors which are relevant to bird distribution. Thedescription makes extensive use of the work of Harrison et al(1997).

Table 1. Vegetation composition of 2529CC and 2528DD (Harrison et al1997).

Biome Vegetation type 2529CC 2528DD

Grassland Sour grassland 94% 95%

Woodland Moist Woodland 6% 5%

The study area falls predominantly within the Grassland biome, with Sour Grassland being the dominantvegetation type.


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The dominant plants in the grassland biome are grass species, with geophytes and herbs also wellrepresented. Grasslands are maintained mainly by a combination of the following factors: relatively high

summer rainfall; frequent fires; frost and grazing. These factors preclude the growth of trees andshrubs. This biome has been largely transformed in South Africa through various land uses such asafforestation, and in Mpumalanga and Gauteng, by crop cultivation. Sweet grassland is generallyfound in the lower rainfall areas - vegetation is taller and sparser, and nutrients are retained in theleaves during winter. Sour grassland generally occurs in the higher rainfall areas on leached soils.Many grassland bird species show a preference for sour grassland over sweet or mixed grassland.Mixed grassland is a combination or a transition between the two grassland types above. GrasslandRed Data species that have been recorded in 2528DD by SABAP2 include Secretarybird Sagittariusserpentarius,White-bellied Korhaan Eupodotis senegalensis and Southern Bald Ibis Geronticus calvuswhich could potentially be impacted by the power line. Secretarybird and Southern Bald Ibis were alsorecorded in 2529CC.

Woodland (or savanna) also occurs marginally in the study area and it is defined as having a grassyunder-storey and a distinct woody upper-storey of trees and tall shrubs (Harrison et al.1997). Moistwoodland comprises predominantly broadleaved, winter deciduous woodland. Soil types are varied butare generally nutrient poor.

The savanna biome is relatively well conserved compared to the grassland biome and contains a largevariety of bird species (it is the most species-rich community in southern Africa) although very few birdspecies are restricted to this biome. The biome is particularly rich in large raptors, and forms thestronghold of Red Data species such as White-backed Vulture Gyps africanus, Martial Eagle Polemaetusbellicosus, Tawny Eagle Aquila rapax, and Lappet-faced Vulture Torgos tracheliotis. Apart from RedData species, it also serves as the stronghold of several non-Red Data raptor species, such as theBrown Snake-Eagle Circaetus cinereus, Black-chested Snake-Eagle Circaetus pectoralis, and a multitudeof medium-sized raptors for example the migratory Steppe Buzzard Buteo vulpinus, African Harrier-

Hawk (Gymnogene) Polyboroides typus, Wahlbergs Eagle Aquila wahlbergi and African Hawk-EagleAquila spilogaster. Apart from raptors, woodland in its undisturbed state is suitable for a wide range ofother power line sensitive birds, including the Kori BustardArdeotis kori.

In the study area natural woodland is evident in scattered patches, with mostly small Acacia karrootrees in areas of natural grassland. Some of the woodland in the area consists of invader species,particularly Eucalyptus, of which substantial pockets are evident. Generally, the original woodland hasbeen cleared to make way for agricultural activity and the absence of woodland in the study area isreflected in the Red Data bird species composition, with none of the above species having beenrecorded in the study area by SABAP2.

2.2 Bird micro-habitatsWhilst much of the distribution and abundance of the bird species in the study area can be explained bythe description of the broad vegetation types above, it is even more important to examine the microhabitats available to birds. These are generally evident at a much smaller spatial scale than thevegetation types, and are determined by a host of factors, such as vegetation type, topography, landuse and man made infrastructure. The most important bird micro-habitats that were identified duringthe field visit are the following (see also Appendix B):

Wetlands and dams: This habitat is represented in the study area by several man-madeimpoundments (farm dams), natural wetlands and small drainage lines. Amongst largeterrestrial birds, it is especially cranes species that depend on shallow, vegetated wetlands thatare unpolluted and not excessively disturbed by live-stock and fire. When wetlands are madedeeper by dredging or the construction of weirs (as is the case in some instances in the study


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area), or made shallower by the digging of drainage ditches or infilling, their ecological functionsare disrupted (Young et al.2003). Many of the waterbodies in the study area have modified thenatural drainage in wetlands and watercourses to such an extent that they will not be suitable

for cranes anymore. Blue Crane Anthropoidesparadiseus and Grey Crowned Crane Balearicaregulorumwere recorded in 2529CC QDGC by SABAP1 but it is unlikely that these species arestill found in the study area, due to extensive transformation of habitat, particularly forindustrial purposes (mining and infrastructure construction). Some of the dams and wetlands,including the modified ones, might be suitable for other species such as various species ofducks, cormorants, African Marsh-Harriers Circus ranivorus and (possibly) Greater FlamingoPhoenicopterus ruber, which was recorded in both QDGCs by SABAP2.

Dryland cultivation: The study area has been extensively transformed through drylandcultivation. The land is used for a variety of mixed farming practices. Grazing is developed inparallel with crop farming. The region has summer rainfall and therefore intensive crop farmingis practiced on a wide scale. Data from the CAR project indicates that agricultural land in theMpumalanga Highveld is used to a limited extent by large terrestrial birds, and that they prefergrassland. Although the preference is for grassland, fallow fields are used to a limited extent byBlue Cranes in summer whilst they might use recently ploughed fields in winter (Young et al.2003), but, as mentioned earlier, it is very unlikely that the species still occur in the study area.Other species that may make limited use of agricultural areas is the Blue Korhaan (Harrison etal.1997) and Lesser Kestrel Falco naumanni (pers. obs.).

Grassland: Large tracts of grassland are found in the study area, some of it is comprised of oldlands that have been abandoned and have now been transformed into a form of grassland. TheCAR data indicates that grassland remains the preferred habitat of large terrestrial birds in theMpumalanga Highveld (Young et al. 2003) and the importance of the grassland in the studyarea is reflected in the presence of several typical grassland bird species recorded by SABAP2.These include Secretarybird Sagittarius serpentarius, White-bellied Korhaan Eupodotissenegalensis, Monotonous Lark Mirafra cheniana, Southern Bald Ibis Geronticus calvus andLesser Kestrel Falco naumanni. A potential problem for the grassland species is the high level of

disturbance and habitat fragmentation that is evident in the study area, especially in thewestern part of the study area, close to site of the Kusile power station.

3 TYPICAL IMPACTS OF POWER LINES ON BIRDS

Because of their size and prominence, electrical infrastructures constitute an important interfacebetween wildlife and man. Negative interactions between wildlife and electricity structures take manyforms but two common problems in southern Africa are (a) electrocution of birds and other animals and(b) birds colliding with power lines (Ledger & Annegarn 1981; Ledger 1983; Ledger 1984; Hobbs &Ledger 1986a; Hobbs & Ledger 1986b; Ledger et al. 1992; Verdoorn 1996; Kruger & Van Rooyen1998; Van Rooyen 1998; Kruger 1999; Van Rooyen 1999; Van Rooyen 2000, Anderson 2001). Otherproblems include electrical faults caused by bird excreta when roosting or breeding on electricityinfrastructure (Van Rooyen et.al. 2002), disturbance and habitat destruction during construction andmaintenance activities.

3.1 ElectrocutionsLarge birds of prey are the most commonly electrocuted on power lines. The large transmission linesfrom 220kV to the massive 765kV structures usually do not pose an electrocution threat to largebirds, because the pylons are designed in such a manner that the birds do not perch in closeproximity to the potentially lethal conductors. In fact, these power lines have proved to be beneficialto birds such as Martial Eagles, Tawny Eagles, White-backed Vultures, and even occasionallyVerreauxs Eagles Aquila verreauxii by providing safe nesting and roosting sites in areas wheresuitable natural alternatives are scarce (pers. obs). Cape Vultures Gyps coprothereshave also taken


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to roosting on power lines in certain areas in large numbers, while Lappet-faced Vultures Torgostracheliotisare increasingly using power lines as roosts, especially in the Northern Cape (pers. obs.).

Unfortunately the same can not be said of the smaller sub-transmission and reticulation lines of 11kVto 132kV (Van Rooyen 1998; 2000). Raptors and vultures instinctively seek out the highest vantagepoint as suitable perches from where they scan the surrounding area for prey or carrion. In flat,treeless habitat power pylons often provide ideal vantage points for this purpose. The vast majority ofelectrical structures were designed and constructed at a time when the awareness of the danger thatthey pose for raptors was very limited or totally absent. Depending on the design of the pole, a largeraptor can potentially touch two live components or a live and earthed component simultaneously,almost inevitably resulting in instant electrocution and a concomitant disruption in the electricalsupply (Van Rooyen 1998).

3.2 CollisionsAnderson (2001) summarizes collisions as a source of avian mortality as follows:

The collision of large terrestrial birds with the wires of utility structures, and especially power lines, hasbeen determined to be one of the most important mortality factors for this group of birds in SouthAfrica (Herholdt 1988; Johnsgard 1991; Allan 1997). It is possible that the populations of two southernAfrican endemic bird species, i.e., the Ludwigs Bustard Neotis ludwigiiand Blue Crane Anthropoidesparadiseus, may be in decline because of this single mortality factor (Anderson 2000; McCann 2000).The Ludwigs Bustard (Anderson 2000) and Blue Crane (McCann 2000) are both listed as vulnerable inThe Eskom Red Data Book of Birds of South Africa, Lesotho & Swaziland (Barnes 2000) and it has beensuggested that power line collisions is are one of the factors responsible for these birds presentprecarious conservation status.

Collisions with power lines and especially overhead earth-wires have been documented as a source of

mortality for a large number of avian species (for example,. Beaulaurier et al. 1982; Bevanger 1994,1998). In southern Africa, this problem has until recently received only limited attention. Severalstudies however have identified bird collisions with power lines as a potentially important mortalityfactor (for example, Brown & Lawson 1989; Longridge 1989). Ledger et al.(1993), Ledger (1994) andVan Rooyen & Ledger (1999) have also provided overviews of bird interactions with power lines inSouth Africa. Bird collisions in this country have been mainly limited to; Greater and Lesser Flamingos,various species of waterbirds (ducks, geese, and waders), Stanleys Neotis denhami, Ludwigs Bustards,White Storks Ciconia ciconia, Wattled Grus carunculatus, Grey Crowned Balearica regulorumand BlueCranes (for example, Jarvis 1974; Johnson 1984; Hobbs 1987; Longridge 1989; Van Rooyen & Ledger(1999).

Certain groups of birds are more susceptible to collisions, namely the species which are slow fliers andwhich have limited maneuverability (as a result of high wing loading) (Bevanger 1994), and birds whichregularly fly between roosting and feeding grounds undertake regular migratory or nomadicmovements. Birds flying in flocks or that fly during low-light conditions are also vulnerable.

Other factors which can influence collision frequency include; the age of the bird (younger birds are lessexperienced fliers), weather factors (decreased visibility, strong winds, etc.), terrain characteristics andpower line placement (lines that cross the flight paths of birds), power line configuration (the largerstructures are more hazardous [for collisions; with electrocutions the opposite is the case]), humanactivity (which may cause birds to panic and fly into the overhead lines), and familiarity of the birdswith the area (therefore nomadic Ludwigs Bustards would be more susceptible) (Anderson 1978; APLIC1994).


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Although collision mortality rarely affects healthy populations with good reproductive success, collisionscan be biologically significant to local populations (Beer & Ogilvie 1972) and endangered species(Thompson 1978; Faanes 1987). The loss of hundreds of Northern Black Korhaans Eupodotis afraoides

due to power line collisions would probably not affect the success of the total population of this speciesand would probably not be biologically significant, but if one Wattled Crane was killed due to a collision,that event could have an effect on the population that would be considered biologically significant.Biological significance is an important factor that should be considered when prioritizing mitigationmeasures. Biological significance is the effect of collision mortality upon a bird populations ability tosustain or increase its numbers locally and throughout the range of the species.

There are many methods that can be used to mitigate avian power line interactions (for example, APLIC1994) and several investigations dealing with the collision problem have recently focused on findingsuitable mitigation measures (see APLIC 1994 for an overview). The most proactive measures are;power line route planning (and the subsequent avoidance of areas with a high potential for bird strikes)and the modification of power line designs (this option includes line relocations, underground burial of

lines, removal of over-head ground wires, and the marking of ground wires to make them more visibleto birds in flight). In many instances, decisions on power line placement and possible mitigationmeasures are however eventually based on economic factors. The relocation of an existing line is thelast option that is usually considered when trying to mitigate avian collisions. The huge expense ofcreating a new line and servitude usually cannot be justified unless there are biologically significantmortalities. Underground burial of power lines is another option available to managers in areas of highcollision risk. This will obviously eliminate collisions, but the method has many drawbacks. The costsof burying lines can be from 20 30 times (or more) higher than constructing overhead lines (Hobbs1987), and such costs are related to the line voltage, type and length of cable, cable insulation, soilconditions, local regulations, reliability requirements, and requirement of termination areas. Limitationsof cable burial include: no economically feasible methods of burying extra high voltage lines have beendeveloped, there is a potential to contaminate underground water supplies if leakage of oil used ininsulating the lines occurs, and extended outage risks due to the difficulty in locating cable failures

(APLIC 1994).

Since most strikes involve earth-wires (more than 80% of observed bird collisions) (for example,Beaulaurier 1981; Faanes 1987; Longridge 1989), the removal of these wires would decrease thenumber of collisions (Beaulaurier 1981; Brown et al. 1987). Faanes (1987) has argued that the largenumber of earth-wire collisions is because birds react to the more visible conductors by flaring andclimbing and then collide with the thinner earth-wires. Earth-wire removal is however, not a simplematter. Due to the need for lightning protection and other types of electricity overload, it is onlypossible on lower-voltage power lines (where polymer lightning arresters can be used).

The marking of overhead earth-wires to increase their visibility is usually considered to be the mosteconomical mitigation option for reducing collision mortality (Morkill & Anderson 1991; Brown &

Drewien 1995). This is particularly so for the thousands of kilometres of established power linesthrough areas of high potential for avian interaction which cannot be rerouted.

3.3 Habitat destructionDuring the construction phase and maintenance of power lines, some habitat destruction and alterationinevitably takes place. This happens with the construction of access roads and the clearing ofservitudes. Servitudes have to be cleared of excess vegetation at regular intervals in order to allowaccess to the line for maintenance, prevent vegetation from intruding into the legally prescribedclearance gap between the ground and the conductors, and to minimize the risk of fire under the linewhich can result in electrical flashovers. These activities could have an impact on birds breeding,foraging and roosting in or in close proximity of the servitude, through destruction of habitat.


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3.4 DisturbanceThe construction of a power line can be highly disturbing to birds breeding in the vicinity of the

construction activities. Many birds are highly susceptible to disturbance and should this disturbancetake place during a critical time in the breeding cycle, for example, when the eggs have not hatched orjust prior to the chick fledging, it could lead to temporary or permanent abandonment of the nest orpremature fledging. In both instances, the consequences are almost invariably fatal for the eggs or thefledgling. Such a sequence of events can have far reaching implications for certain large, rare speciesthat only breed once a year or once every two years.

4 PROPOSED STRUCTURE TYPES

The self-supporting tower design is the one that is considered to be suitable for the proposed deviation.This was supported by the technical requirements of the proposed deviation as well as considering theneeds of the land owners whereby this tower design does not require big portion of land. Furthermore,

the existing Duvha-Minerva power line design is a self-supporting suspension tower and thereforeEskom would like to keep uniformity of tower designs within that specific project. Details of the towerdesign are contained in the Draft Scoping Report (Zitholele 2011).

5 POWER LINE SENSITIVE BIRD SPECIES

Generally speaking, it is unavoidable that birds get killed through interaction with electricityinfrastructure, including power lines, despite the best possible mitigation measures. It is thereforeimportant to direct risk assessments and mitigation efforts towards species that have a high biologicalsignificance, in order to achieve maximum results with the available resources at hand.

In accordance with this principle, the risk assessment is primarily aimed at determining the potentialthreat to Red Data species (see the concept of biological significance under 3.2).

Table 2 below, lists the Red Data species that have been recorded in the relevant QDGCs by SABAP1and SABAP2, together with an indication of their favourite habitat, power line sensitivity and thechances of them occurring along the proposed alignments. It must be stressed that while the studyconcentrates on Red Data species, the non-Red Data species that share the habitat with the Red Dataspecies will benefit equally from the proposed mitigation measures.

Table 2: Red Data species potentially occurring in the study area

Species Conservationstatus(Barnes

2000)

Preferred habitat(Harrison et al1997,Barnes 2000, Hockey et

al2005, personalobservations)

Likelihood ofinteraction with theproposed power line

YELLOW-BILLED STORKMycteria ibis

near threatened Always associated withwater dams, wetlands,rivers, marshes, even smallpools. Vulnerable tocollision with power lines

Not recorded by SABAP2.Could be a visitor tolarger waterbodies in thestudy area.

SECRETARYBIRDSagittarius serpentarius

near threatened Prefers open grassland,densities low in maizegrowing areas. Vulnerableto collisions with powerlines.

Could be encounteredanywhere in thegrassland areas, wherecollisions with the powerline are possible.


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AFRICAN MARSH-HARRIERCircus ranivorus

vulnerable Favours large permanentwetlands with dense reedbeds. Sometimes forages

over smaller wetlands andgrassland. Vulnerable tocollisions with powerlines.

Not recorded by SABAP2.Could be present at someof the wetlands in the

area, but probably onlyas an occasional visitor.Likelihood of interactionsis low.

BLUE KORHAANEupodotis caurulescens

near threatened Prefers natural grassland.Very limited use of fallowlands. Vulnerability topower line collisionstempered by reluctance tofly long distances.

Not recorded by SABAP2.Could be encounteredanywhere in the studyarea away from densesettlements, particularlyin grassland areas, wherecollisions with the powerline are possible.

WHITE-BELLIED KORHAANEupodotis senegalensis

vulnerable Often in the interfacebetween grassland andsavanna. Avoids severelygrazed and recently burntsites. Vulnerability topower line collisionstempered by reluctance tofly long distances

Could be encounteredanywhere in thegrassland areas, wherecollisions with the powerline are possible.

LESSER KESTRELFalco naumanni

vulnerable Small and nimble species,likely to use the power lineas hunting perch.

Could be encounteredanywhere in thegrassland and agriculturalareas. No negativeimpacts expected from

power line.LANNER FALCONFalco biarmicus

near threatened Generally prefers openhabitat, but exploits a widerange of habitats.Vulnerable to collisionswith power lines.

Not recorded by SABAP2.Could be encounteredanywhere in thegrassland and agriculturalareas, where collisionswith the power line arepossible.

BLUE CRANEAnthropoides paradiseus

vulnerable Potential occurrence due topresence of suitable largetracts of grassland andwetlands. Vulnerable tocollisions with powerlines.

Not recorded by SABAP2.Could be encounteredanywhere in the studyarea away from densesettlements, particularlyin grassland areas, wherecollisions with the powerline are possible.However, unlikely tooccur in the study areaanymore.

BLACK STORKCiconia nigra

near threatened Rivers, large dams, cliffs.Vulnerable to collisionswith power lines.

Not recorded by SABAP2.Could be a visitor tolarger waterbodies in thestudy area.


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PEREGRINE FALCONFalco peregrinus

near threatened High cliff faces, also urbanareas. Vulnerable tocollisions with power

lines.

Not recorded by SABAP2.Young birds could beencountered anywhere in

the study area asvagrants, away fromdense settlements,particularly in grasslandareas, where collisionswith the power line arepossible.

GREATER FLAMINGOPhoenicopterus ruber

near threatened Open shallow, euthropicwetlands. Vulnerable tocollisions with powerlines.

Could be encountered onsome of the biggerwaterbodies in the studyarea.

LESSER FLAMINGOPhoenicopterus ruber

near threatened Open shallow, euthropicwetlands. Vulnerable tocollisions with powerlines.

Not recorded by SABAP2.Could be encountered onsome of the biggerwaterbodies in the studyarea.

AFRICAN GRASS-OWLTyto capensis

vulnerable Normally associated withpristine, well managedgrasslands usually in closeproximity of water, but alsoin alien vegetationstructurally resembling tallgrass. Susceptibility tocollisions unknown.

Not recorded by SABAP2.Could be encountered onthe fringes of wetlands inthe study area.

MELODIOUS LARK

Mirafra cheniana

Near

threatened

Open climax Themeda

grassland, pastures andfallow lands.

Could be encountered in

remnant patches ofgrassland. No interactionwith the power lines isenvisaged.

6 DISCUSSION

6.1 Electrocutions

Electrocution refers to the scenario where a bird is perched or attempts to perch on the electricalstructure and causes an electrical short circuit by physically bridging the air gap between livecomponents and/or live and earthed components (van Rooyen 2004). Due to the large size of theclearances on overhead lines of 400kV, electrocutions are ruled out as even the largest birdscannot physically bridge the gap between energised and/or energised and earthedcomponents.

6.2 Collisions

The most likely impact that the proposed line could potentially have on Red Data birds are collisionswith the overhead earth wire. This impact is most likely to occur close to wetlands, where the line skirtsa dam or where it is positioned across a drainage line. Species at risk are water birds of several specieswhere it skirts larger dams, including the Yellow-billed Stork and Black Stork. Another collision hazardexists where the line will cross patches of grassland, as this is the preferred habitat of most of theremaining large terrestrial Red Data species, including the Blue Crane (if it still occurs), Secretarybirdand two species of Korhaan (Young 2003).


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6.3 Habitat destruction

A limited degree of habitat destruction always takes place when a power line is constructed. In this

instance some areas of the study area has been intensively transformed through agriculture andmining, which has destroyed some of the original grassland. However, some wetlands have survivedand this could be damaged in the course of construction activities. This could in turn impact on birdsusing in the wetlands. Generally speaking though, habitat destruction is not foreseen as a majorimpact, because of the extensive impacts already evident in the study area.

6.4 Disturbance

No significant disturbance of birds is foreseen. Such disturbance as would take place is likely to betemporary and should cease after the dismantling of the existing line and the construction of thedeviation.

7 IDENTIFYING A PREFERRED ALIGNMENT

One of the objectives of this study is to arrive at a preferred alignment for the proposed power line interms of impacts on avifauna. The following factors were incorporated in the formula to arrive at apreferred alignment, primarily using high resolution Google Earth imagery as the main source of data:

Wetlands and dams: Wetlands and dams are always of particular importance for birds. Thepresence of wetlands and dams are an indicator of a higher collision risk.

Rivers: The study area contains a few small drainage lines. These drainage lines are obviouslyimportant for birds and many water bird species occur along these drainage lines. Drainagelines are therefore an indication of a higher collision risk.

Transmission lines: It is a proven fact that placing a new line next to an existing line reducesthe risk of collisions to birds. The reasons for that are two-fold, namely it creates a morevisible obstacle to birds and the resident birds, particularly breeding adults, which areaccustomed to an obstacle in that geographic location and have learnt to avoid it (APLIC 1994;Sundar & Choudhury 2005). Other transmission lines running parallel to the proposedalignments were therefore treated as a risk reducing factor.

Roads: These were taken as an indication of human activity and particularly vehicle andpedestrian traffic. It was assumed that the birds will avoid the immediate vicinity of largerroads due to the presence of traffic and pedestrians, and therefore it will reduce the risk ofcollision with lines running next to roads (small farm tracks were discounted).

Towns and industrial activity: These are obvious centres of human activity and are generallyavoided by large power line sensitive species. The presence of towns, settlements andindustrial activity is therefore a risk reducing factor.

Grassland: According to Young et al. (2003) the large terrestrial species on the MpumalangaHighveld favour grassland habitat in contrast to agricultural landscapes. Grassland wastherefore taken as a higher collision risk.

Agricultural lands. Although some Red Data species make use of agricultural lands, e.g.Secretarybird, they are overall not as important as natural grassland. Agricultural lands weretreated as a risk reducing factor.


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The factors mentioned above were incorporated into a formula to arrive at a risk rating for eachalignment. The formula was designed as follows:

Wetlands and dams: The length of alignment running across or within 100m of a dam orwetland was measured.

The number of drainage lines crossed by each alignment was counted. The distance, of which the proposed alignments are running parallel to existing roads within a

200m zone, was measured. The length of line running through or within 500m of settlements/industrial activity was

measured.

The distance, of which the proposed alignments are running directly next to existingtransmission lines, was measured.

The length of alignment skirting or running across grassland was measured. The length of alignment skirting or running across agricultural lands was measured.

Table 3: The results of the measurements for each option (km).

Factor Alternative 1 Alternative 2 Alternative 3 Alternative 4

Number of drainage3 3 3 3

Dams and wetlands 1.24 2.27 2.48 1.99

TX lines 0 2.1 1.7 3.87

Roads 0 0 0 1.6

Suburban/industrial 0 0 0 0.6

Grassland 4.14 3.73 5.08 6.41

Agricultural lands 5.09 4.44 4 4.45

Obviously all these factors do not have an equal impact on the size of the risk, therefore a weightingwas assigned to each factor, based on the authors judgment on how important the factor is within thetotal equation.

The following weights were assigned. Risk reducing factors were assigned a negative weight:

Table 4: Weights assigned to factors

Factor Weighting

Dams/wetlands 5

Drainage lines 3

Existing TX lines -1

Roads -2

Sub-urban/industrial -5

Grassland 4

Agricultural lands -2

The final risk score for a factorwas calculated as follows: measurements/counts x weighting. The finalrisk rating for an alignmentwas calculated as the sum of the risk scores of the individual factors:


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Table 5:The final scores for the respective options

Factor Alternative 1 Alternative 2 Alternative 3 Alternative 4

Drainage lines 9 9 9 9

Dams and wetlands 6.2 11.35 12.4 9.95

TX lines 0 -2.1 -1.7 -3.87

Roads 0 0 0 -3.2

Suburban/industrial 0 0 0 -3

Grassland 4.14 3.73 5.08 6.41

Agricultural lands -10.18 -8.88 -8 -8.9

Total 9.16 13.1 16.78 6.39

From the analysis above alternative 4has emerged as the preferred option from a bird interaction

perspective.

8 IMPACT ANALYSIS

The significance (quantification) of potential avifaunal impacts identified during the specialistinvestigations was determined using a ranking scale, based on the following:

Probability of occurrence (how likely is it that the impact may occur?) Duration of occurrence (how long may it last?) Magnitude (severity) of impact (will the impact be of high, moderate or low severity?), and Scale/extent of impact (will the impact affect the national, regional or local environment, or

only that of the site?)

Each of these factors has been assessed for each potential impact using the following ranking scales:

Probability:5 Definite/dont know4 Highly probable3 Medium probability2 Low probability1 Improbable0 None

Duration:

5 Permanent4 - Long-term (ceases with the operational life)3 - Medium-term (5-15 years)2 - Short-term (0-5 years)1 Immediate

Magnitude:10 - Very high/dont know8 High6 Moderate4 Low2 Minor


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Scale:5 International

4 National3 Regional2 Local1 Site only0 None

The environmental significance of each potential impact was assessed using the following formula:

Significance Points (SP) = (Magnitude + Duration + Scale) x Probability

The maximum value is 100 Significance Points (SP).

Potential environmental impacts were rated as high, moderate or low significance on the followingbasis:

More than 60 significance points indicates high environmental significance. Between 30 and 60 significance points indicates moderate environmental significance. Less than 30 significance points indicates low environmental significance.

Table 6: Impact assessment table

Impact Probability Duration Magnitude Scale SP

Collisions withthe earthwire

3 4 6 3 39 (moderate)

Habitat

destruction

3 4 4 2 30 (moderate)

Disturbance 3 2 4 2 24 (low)

9 RECOMMENDATIONS

Those sections of line that will require the application of bird flight diverters (BFDs) are indicatedon the accompanying sensitivity map (Appendix C). Sensitive sections will include dams,wetlands, drainage crossings and areas of grassland. The proposed BFD is the Double Loop BirdFlight Diverter. BFDs should be placed on the earthwires, staggered, alternating black and white,10 metres apart.

The construction of access roads in sensitive wetland habitat should be avoided.

10 REFERENCES

ANIMAL DEMOGRAPHY UNIT (ADU). 2011. The southern African Bird Atlas Project 2. University of CapeTown. http://sabap2.adu.org.za. Accessed 05/03/2011.

AVIAN POWER LINE INTERACTION COMMITTEE (APLIC). 1994. Mitigating Bird Collisions with PowerLines: The State of the Art in 1994. Edison Electric Institute. Washington D.C.
http://sabap2.adu.org.za/http://sabap2.adu.org.za/


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ANDERSON, M.D. 2001. The effectiveness of two different marking devices to reduce large terrestrialbird collisions with overhead electricity cables in the eastern Karoo, South Africa. Karoo LargeTerrestrial Bird Power line Project. Kimberley (SA): Directorate Conservation & Environment -

Northern Cape. (Eskom Report No. 1).

BARNES, K.N. (ed.) 2000. The Eskom Red Data Book of Birds of South Africa, Lesotho and Swaziland.BirdLife South Africa. Johannesburg.

HARRISON, J.A., ALLAN, D.G., UNDERHILL, L.G., HERREMANS, M., TREE, A.J., PARKER, V & BROWN,C.J. (eds). 1997. The atlas of Southern African birds. BirdLife South Africa, Vol. 1 & 2.

HOBBS, J.C.A. & LEDGER J.A. 1986a. The Environmental Impact of Linear Developments; Power linesand Avifauna. Proceedings of the Third International Conference on Environmental Quality andEcosystem Stability. Israel, June 1986.

HOBBS, J.C.A. & LEDGER J.A. 1986b. Power lines, Birdlife and the Golden Mean. Fauna and Flora,44:23-27.

KRUGER, R. & VAN ROOYEN, C.S. 1998. Evaluating the risk that existing power lines pose to largeraptors by using risk assessment methodology: The Molopo Case Study. Proceedings of the 5thWorld Conference on Birds of Prey and Owls. August 4-8,1998. Midrand, South Africa.

KRUGER, R. 1999. Towards solving raptor electrocutions on Eskom Distribution Structures in SouthAfrica. Bloemfontein (South Africa): University of the Orange Free State. (M. Phil. Mini-thesis)

LEDGER, J. 1983. Guidelines for Dealing with Bird Problems of Transmission Lines and Towers. EskomTest and Research Division. (Technical Note TRR/N83/005).

LEDGER, J.A. & ANNEGARN H.J. 1981. Electrocution Hazards to the Cape Vulture (Gyps coprotheres) inSouth Africa. Biological Conservation20:15-24.

LEDGER, J.A. 1984. Engineering Solutions to the Problem of Vulture Electrocutions on ElectricityTowers. The Certificated Engineer, 57:92-95.

LEDGER, J.A., J.C.A. HOBBS & SMITH T.V. 1992. Avian Interactions with Utility Structures: SouthernAfrican Experiences. Proceedings of the International Workshop on Avian Interactions with UtilityStructures. Miami (Florida), Sept. 13-15, 1992. Electric Power Research Institute.

SUNDAR, K.S.G. and CHOUDHURY, B.C. 2005. Mortality of Sarus Cranes (Grus antigone) due toelectricity wires in Uttar Pradesh, India. Environmental Conservation, 32(3): 260269.

(Foundation for Environmental Conservation)

VAN ROOYEN, C.S. & LEDGER, J.A. 1999. Birds andutility structures: Developments in southern Africa.Pp 205-230, in Ferrer, M. & G.F.M. Janns. (eds.). Birds and Power lines. Quercus, Madrid (Spain).Pp 238.

VAN ROOYEN, C.S. 1998. Raptor mortality on power lines in South Africa. Proceedings of the 5thWorldConference on Birds of Prey and Owls. Midrand (South Africa), Aug.4 8, 1998. .

VAN ROOYEN, C.S. 1999. An overview of the Eskom-EWT Strategic Partnership in South Africa. EPRIWorkshop on Avian Interactions with Utility Structure.s Charleston (South Carolina), Dec. 2-31999.


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VAN ROOYEN, C.S. 2000. An overview of Vulture Electrocutions in South Africa. Vulture News,43: 5- 22. (Vulture Study Group, Johannesburg, South Africa).

VAN ROOYEN, C.S. VOSLOO, H.F. & R.E. HARNESS. 2002. Eliminating bird streamers as a cause offaulting on transmission lines in South Africa. Proceedings of the IEEE 46thRural Electric PowerConference.Colorado Springs (Colorado), May. 2002.

VERDOORN, G.H. 1996. Mortality of Cape Griffons Gyps coprotheresand African Whitebacked VulturesPseudogyps africanus on 88kV and 132kV power lines in Western Transvaal, South Africa, andmitigation measures to prevent future problems. Proceedings of the 2ndInternational Conferenceon Raptors: Urbino (Italy), Oct. 2-5, 1996.

YOUNG, D.J. HARRISON, J.A. NAVARRO, R.A. ANDERSON, M.D. & B.D. COLAHAN (ed). 2003. Big Birdson Farms. Mazda CAR Report,1993 2001. (Avian Demography Unit. University of Cape Town).

ZITHOLELE CONSULTING. 2011. The proposed deviation of a portion of the 400kV Duvha-Minervapower line to the east of Kusile Power Station. Draft Scoping Report.

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APPENDIX A: MAP OF STUDY AREA


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APPENDIX B BIRD HABITAT

Figure 1: Old lands reverting to grasslands

Figure 2: Agricultural activity in the study area, and an existing 400kV transmission line


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Figure 3: Old lands with mining activity in the background

Figure 4: A man-made dam


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Figure 5: Natural grassland

Figure 6: Industrial activity


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Sections to be markedwith BFDs

APPENDIX C SENSITIVITY MAP


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bird impact assessment study

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