POWER - L I NE

M I T I GAT ION

TO CONSERVE

BUSTARDS

Bipin C.M.

EVIDENCE OF IMPACT a) Bustards are prone to collision. Bustards have wide sideways vision to maximize predator detection, at the cost ofnarrow frontal vision. Because of this, and a habit of scanning the ground whileflying, they cannot detect power-lines ahead of them, from far. Being heavy fliers,they fail to manoeuvre across power lines within close distances. The combinationof these traits make them vulnerable to collision with power-lines. As a result, theycollide with power lines and die from the impact, injuries/trauma or electrocution(Martin and Shaw 2010). b) Evidence of bustard mortality due to power lines. Worldwide, studies have shown high mortality rates of several bustard speciesbecause of power-line collision. For example, 30% of Denham’s bustards (Neotisdenhami) die annually from power-line collisions in South Africa (Shaw 2009,Jenkins et al. 2010). In Spain, 8.5 km stretch of power-line killed a minimum of 25Great Bustards in one year (JC Alonso pers. obs.). A review (Mahood et al 2017/18)of nine studies covering six bustard species from different parts of the worldestimated 7 detected bustard mortalities per 10 km power-line per year. This factorcauses 4 - 7% mortality of Great Bustard in areas with low power line density(Martin 2008) and 13% mortality in areas with high power line density (Alonso2007).

2018 | OCTOBER

1

Graphic created to depict the situation by Devesh Gadhavi

MEMPHIS SOLUTIONS

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c) Evidence of Great Indian Bustard (GIB)collisions with power lines in India Surveys conducted by Wildlife Institute ofIndia (WII) in Thar covering 80 km ofpower lines repeated 7 times over a yearfound 289 carcasses of around 30 speciesincluding the Great Indian Bustard (GIB).The study detected 8 carcass/10 km forhigh tension and 6 carcass/10 km for lowtension power-lines. Correcting thesemortalities for the proportion of carcassesthat are decomposed before survey or aremissed during survey, mortality rate wasestimated to be ~5 bird/km/month and ~1lakh bird per/year within 4200 sq. km area.In terms of GIB, 4 mortality were recorded(2 during and 2 outside of surveys), all dueto high tension transmission lines - someof them connected to wind turbines.Extrapolating these mortalities to thepriority bustard habitat, intersected by~150 km high tension lines, about 18 GIBlikely die per year from a population ofabout 128 ± 19 individuals in Thar. Suchhigh mortality rate (at least 15% annuallydue to power lines alone) is unsustainablefor the species. WII also tagged five GreatIndian Bustard on pilot basis in Gujaratand Maharashtra, out of which two diedfrom power line collision, corroboratingthe earlier findings. One of these deadbirds was ranging across hostileinfrastructure between Naliya and thewestern costal grassland of Abdasa tehsil,where it collided with a 33kv power-lineconnected to Suzlon wind turbine nearLala Bustard Sanctuary. 

d) Impact of power line collision onbustard population. Bustards are long-lived birds where adultshave high annual survival probability(Palacín et al 2012) in original habitat. Theexcessive mortality due to power-lines areunsustainable to their populations and cancause population declines and evenextinction (Martin 2007). Power-linemortality can also disrupt importantbiological processes. Palacín et al (2012)shows that in a Great Bustard populationin Spain, where migratory individualssuffered significant power-line mortality,the proportion of sedentary individualsincreased over years against the reductionof migratory individuals. Here, power lineshave reduced the propensity of a speciesto migrate, and can result in the loss ofsuch intricate behaviours.

Devesh Gadhvi

e) Mitigation of threat.   Mitigation measures are available to reduce power-linemortality, such as under-grounding of cables and fittingoverhead wires with bird diverters. Bird mortality and crossingrate through wires reduce, if l ines are marked with diverterscompared to unmitigated segments. Studies examining theeffectiveness of these mitigation measures have shown thatcollision rate of birds reduces in marked or under-grounded linecompared to unmitigated lines (Alonso et al 1994). While under-grounding of cables eliminates bird mortality, marking power linecan reduce mortality by 10 % (Barrientos et al 2012) to 78 %(Barrientos et al 2011), depending on area and species, but noteliminate mortality.

G.S. BHARADWAJ

tags have provided information on bird movements for >1 year (May 2017 onwards) and have alsoprovided evidence of one bird mortality from collision with 33 kV power-line near Lala BustardSanctuary. Movement data obtained from tagged birds was overlaid on habitat and infrastructuremaps to identify critical areas for mitigating power-lines (see fig 1). However, individuals vary intheir movement patterns and more birds need to be tagged across bustard landscapes (Thar,Rajasthan and Kutch, Gujarat) to draw population-level inferences and achieve best conservationresults with finite resources.

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F i g u r e   1   :   M o v e m e n t o f t a g g e d G r e a t I n d i a n B u s t a r d o v e r l a i d o n n e t w o r k o f

p o w e r l i n e s a n d   c r i t i c a l a r e a s f o r m i t i g a t i n g p o w e r - l i n e s ( r e d l i n e s ) .

IMPORTANCE OF TELEMETRY IN POWER-LINE MITIGATION

Great Indian Bustard ranges over large human-dominated landscapes that are facing rapidexpansion of power-lines. Curtailing all infrastructural development across these large areas isimpracticable and calls for prioritization of areas where these infrastructure should be avoided ormitigated. Advanced telemetry approach can aide in this process, by generating fine-scaleinformation on the birds’ movement patterns that can be overlaid on existing power-linemaps to identify segments for mitigationmeasures. Thus, telemetry supplementedwith bird surveys provide a powerful tool toprioritize habitats for infrastructure mitigationin particular, and conservation managementin general.  

Wildlife Institute of India demonstrated thepotential of this tool in GIB conservation, bytagging two juvenile birds in Naliya, Gujaratusing solar powered GSM/GPS tags thatweighed <1% of the bird’s body weight. These

Avoid/divert any new

high tension power

line from priority Great

Indian Bustard habitat

that have been

mapped by Wildlife

Institute of India

(Figure 2a & 2b).

F i g u r e   2 a – M a p s h o w i n g p r o p o s e d E c o s e n s i t i v e Z o n e , H i g h - t e n s i o n p o w e r l i n e s a n d

W i n d t u r b i n e s i n T h a r , J a i s a l m e r .

SOLUTIONS This crisis can be mitigated as follows:

Undergrounding of

<66kv wires in most

risky power-lines in

priority GIB habitat

(some stretches

already mapped,

rest is being

mapped).

Retrofitting of

existing overhead

wires with bird

diverters (details of

diverter makes and

costs, and

installation design

in figure 3).

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Marker Dimensions Spacing RemarksEffectiveness

Spirals -Bird &SwanDiverters (PLP,Thailand)

Suspended objectFire Fly & Flappers(P&R Tech, USA)

Aerial Spheres SpanGuard Marker (P&RTech, USA)

9x15 sqcm More effective thanBFD/SFD

Used in 11–440 kVMin. corona for<115kV lines

5–15 m

18-60cm & 51-117 cmlength

30 cmdiameter

5–20 m 15–30 m

30–100 m

Reduced collisions,by 10 –100%

Reduced collisions, up to 50%

Used in11–500 kVMin. corona for<230kV lines

Suitable for highvoltage lines (345 –500 kV)

F i g u r e   2 b – M a p s h o w i n g G r e a t I n d i a n B u s t a r d h a b i t a t s i n A b d a s a , K u t c h , w i t h p o w e r - l i n e s m a r k e d

i n w h i t e ( i n c o m p l e t e m a p p i n g ) a n d b u s t a r d l o c a t i o n s a s r e d ( t e l e m e t r y d a t a ) a n d b l u e ( s u r v e y

l o c a t i o n s ) . R i s k y p o w e r - l i n e s t h a t n e e d t o b e m i t i g a t e d u r g e n t l y h a v e b e e n m a r k e d i n r e d l i n e s .

Cost calculations: Central 60% marking ~ 1 diverter/4m line ~3500 INR/unit (export) ~8.75 lakh INR/km (export) ~2.5 lakh INR / km (local)

Installation Marking earth wire with 1 diverter at every 10m, and marking other wires with 1 diverter at 15 m in a staggeredway, such that conductors as a whole have at least 1 diverter every 5-6 m on a line

F i g u r e 3 : D e t a i l s o f d i v e r t e r m a k e s a n d c o s t s , a n d i n s t a l l a t i o n d e s i g n

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t r a d i t i o n a l f a r m l a n d a r e a s f o r s t e p p e b i r d s : a c a s e s t u d y o f m i g r a n t f e m a l e g r e a t

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P o w e r   L i n e C o l l i s i o n R i s k f o r t h e B l u e C r a n e . M a s t e r s T h e s i s P e r c y F i t z p a t r i c k

I n s t i t u t e o f A f r i c a n O r n i t h o l o g y , U n i v e r s i t y o f C a p e T o w n .

Devesh Gadhvi

Amohela Ho Spitskop