1. Turbine collision risk for birds
Ian Smales
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2. Effects on populations of relevant species
Where are we at with pre-approval estimation of turbine collision risk?
Effects on populations of relevant species
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3. Review of collision risk models
Four quantitative models of risk to estimate collision rate for species of concern
Input data required:
rate of bird flights collected at the site – the more the better
turbine specifications & array
One (USFWS) for eagles uses Bayesian approach (data from other sites)
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4. Avoidance rates
Birds can generally avoid collisions with large pale obstacles
‘Micro-avoidance’ capacity of bird to fly toward turbine but not collide
Empirical avoidance rates are generally not known, so models provide results for a range of ‘reasonable’ avoidance rates expressed as percentage of flights at risk
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5. Model validation?
Risk estimates are undertaken to provide a basis for decision process pre-approval
Internationally validation of estimates against results at operational wind farms have rarely been undertaken
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6. Model validation
Biosis model for two species of eagles at three Tasmanian wind farms. Methods used to minimize scavenging.
Bluff Point 37 x V66 turbines 10 years
Studland Bay 25 x V90 turbines 5 years
Musselroe 56 x V90 turbines 3 years
White-bellied Sea-eagle
Wedge-tailed Eagle
Bluff Point
Studland Bay
Musselroe
Mortalities detected p.a.
0.4
0.0
0.3
1.6
1.1
2.3
CRM estimate 90% avoidance
0.9
0.8
2.7
1.9
2.5
CRM estimate 95% avoidance
0.5
0.6
1.5
1.4
CRM estimate 99% avoidance
0.1
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7. Distribution of collisions in time
If the model estimate is correct it will represent the average number of collisions distributed over relatively long timeframes
Probability distribution of modelled collisions and real collisions
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8. Brolgas
Brolga activity largely consists of walking Problematic to obtain data representative of flights
Risk modelling for assessment of some wind farms using scenarios informed by some flight data – none yet operational
Three wind farms operating in Brolga range for 6+ years turbine-years of operation
No Brolga collisions detected to-date
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9. Effects on populations?
Calls for assessments of cumulative impact
Low number of fatalities could have effects on critically threatened population in decline
Population viability analysis
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10. Effects on populations
Population models
Need to understand demographic functioning of population – basic parameters generally unknown
Wedge-tailed Eagle – population example
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11. Population science
BirdLife Int (2019) entire Australian continent (106,000,000 km2) occupied, population increasing
Conservative estimates: 1000 km2 per pair = 106,000 prs. (212,000 adult WTEs)
20+ yrs lifespan ~ 10 yrs reproductive life ~ 1 fledgling p.a. = 10 juveniles produced
Replacement needs just 2
80% of juveniles do not survive
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12. Where to from here? DELWP review species of concern existing data
Clean Energy Council initiatives
bird & bat assessments
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