Raptor migration and the siting of utilityscale wind energy plants in Pennsylvania

1
Raptor migration and the siting of utility-scale
wind energy plantsin Pennsylvania
D. Brandes. Wind-Wildlife Collaborative Workshop,
Jan 2007

• Dr. David Brandes
• Dept of Civil Environmental Engineering
• Lafayette College
• Easton, PA

R. Flament
2
Overview / Major Points
D. Brandes. Wind-Wildlife Collaborative Workshop,
Jan 2007

• Wind energy facilities on plateaus pose very low
  risk to migrating raptors
• Risk posed by wind energy development on narrow
  ridge-tops to raptors is currently unknown
• Golden eagles appear to be at higher risk than
  other raptor species south-central ridges of PA
  an area of particular concern due to high energy
  potential and high use by golden eagles
• If ridges are to be developed, need a
  collaborative research effort between wind energy
  industry and scientific community to quantify
  risk, study behavioral response of raptors to
  turbines, and develop mitigation methods if
  necessary
• Proper siting of wind plants and individual
  turbines is the key to risk reduction

3
Terrain influence on raptor migration
D. Brandes. Wind-Wildlife Collaborative Workshop,
Jan 2007

• Migrating raptors concentrate along ridges and
  escarpments (leading lines), due to lift
  provided by updrafts from deflected surface winds
  (e.g. Broun, 1935 Mueller Berger 1967
  Kerlinger, 1989)
• Pennsylvania is famous for its raptor migration
  along the Kittatinny Ridge however all of
  Pennsylvanias ridges and escarpments concentrate
  raptors to a greater or lesser degree
• High daily and annual variability in flights at
  most sites

Birds-eye view of Tussey Mountain looking
northeast toward State College
M. Lanzone
4
Altitude of raptor migration
D. Brandes. Wind-Wildlife Collaborative Workshop,
Jan 2007

• Raptors using ridge updrafts for migration are
  often below 400-450 ft a.g.s. (typical new
  generation turbine height) (pers. obs.
  Kerlinger, 1989 Farmer et al, 2006)
• When thermals are strong, flight is typically
  much higher than 400-450 ft a.g.s. flight
  patterns are not closely tied to topography
  (pers. obs. Hopkins, 1979 Kerlinger, 1989)

D. Brandes
data from Farmer et al, 2006
5
Potential vs. Actual Risk
D. Brandes. Wind-Wildlife Collaborative Workshop,
Jan 2007

• Potential risk raptors known to migrate at the
  location and elevation of proposed turbines
  (within the turbine-swept area)
• Raptors will adjust flight patterns to avoid
  turbines, so potential risk actual risk
• However, poor visibility, motion smear due to
  high blade tip speeds, foraging behavior will
  compromise avoidance
• Actual risk must account for exposure, i.e.,
  numbers of raptors moving through and around the
  turbine-swept area
• Requires carcass searches with concurrent raptor
  migration monitoring

6
Data from wind energy sites in PA
D. Brandes. Wind-Wildlife Collaborative Workshop,
Jan 2007
Meyersdale facility on Meadow Mountain - no
post-construction data, i.e., unknown impact
D. Brandes
7
Limitations of existing data
D. Brandes. Wind-Wildlife Collaborative Workshop,
Jan 2007

• Existing fatality data are from low-exposure
  plateau sites (Garrett, Somerset) - as expected,
  few fatalities
• With one exception (one year of fatality data at
  Mountaineer, WV), no data from narrow ridges that
  form raptor migration pathways
• No data from ridge-and-valley physiographic
  region
• Therefore
• Cant extrapolate Erickson et al. national
  estimate of 0.033 fatalities per turbine per yr
  to proposed ridge-top developments with high
  exposure during migration
• Until further data are collected, we dont know
  the actual risk posed by turbines to raptors
  migrating along narrow ridge-tops

8
Cooperative Agreement three-tiered approach (PGC,
Dec 2006)
D. Brandes. Wind-Wildlife Collaborative Workshop,
Jan 2007

• Monitoring effort varies from site to site based
  on potential risk
• No raptor monitoring at low-exposure sites (away
  from updrafts/sloping terrain)
• Encourage development of plateau sites like
  Garrett, Somerset, Mill Run
• Increased monitoring as potential risk increases
• One year of pre- and post-construction migration
  monitoring and two years of carcass searches
• Additional year of data collection may be
  required depending on results of first year

(see comments on methodology on final slide)
9
Why PGC focus on eagles?
D. Brandes. Wind-Wildlife Collaborative Workshop,
Jan 2007
R. Flament

• Bald eagle is a recovering endangered species,
  national symbol, charismatic bird
• Prior history of Golden Eagle collisions (at
  Altamont Pass)
• Variety of potential risk factors suggest Golden
  Eagles are at higher risk than other raptor
  species in Pennsylvania

10
Potential Risk Factors
D. Brandes. Wind-Wildlife Collaborative Workshop,
Jan 2007

• Location of the migration route(s) coincides with
  regions of high wind energy potential
• The migration primarily occurs late in fall and
  early in spring when thermals are weak
• The raptor species routinely glides along ridges
  at low altitude during migration
• The raptor species forages by hovering/kiting
  during migration
• The raptor species travels in flocks
• The raptor is a species of concern (rare or
  declining)

(from Brandes, 2006)
11

D. Brandes. Wind-Wildlife Collaborative Workshop,
Jan 2007
Potential risk factors (cont.)

• Insufficient data to quantify the relative
  importance of these potential risk factors to
  actual risk, but the Golden Eagle meets five of
  the six criteria!
• Thus, of 16 raptor species migrating through PA,
  Golden Eagle appears to be the species at highest
  risk from wind energy developmentand is one of
  the few species known to be susceptible to
  turbine strikes

R. Flament
R. Flament
12
D. Brandes. Wind-Wildlife Collaborative Workshop,
Jan 2007
Fall Migration of Golden Eagles

• highest counts in the eastern U.S. are at
  Waggoners Gap (PA) and Franklin Mtn (NY) also
  Allegheny Front (PA), Bald Eagle-Brush Mtn (PA)
• late flight - peaks in late Oct to mid-Nov on
  Kittatinny Ridge and mid-Nov through mid- Dec on
  south-central ridges
• Strong NW winds Kittatinny Ridge, Bald
  Eagle-Brush Mtn, Stone Mtn
• Light SE-E winds Allegheny Front
• largest flights at Franklin Mtn (NY) reach
  Allegheny Front 3 days later route in-between
  is unknown

13
Fall Golden Eagle Migration Routes through PA
D. Brandes. Wind-Wildlife Collaborative Workshop,
Jan 2007
Franklin Mtn
Laurel Hill
?

Bald Eagle Mtn
Western sites have peak flights mid Nov to mid Dec

Hawk Mountain

Allegheny Front
Kittatinny Ridge peak flights from late Oct
through mid Nov
Waggoners Gap
?
?
V. High counts (150-200)
High counts (75-125)
Moderate counts (50-75)

14
Spring Migration of Golden Eagles
D. Brandes. Wind-Wildlife Collaborative Workshop,
Jan 2007

• very early flight (peaking in early March) when
  thermal lift is weak
• different route taken than in fall few seen in
  spring at traditional fall monitoring sites along
  the Kittatinny
• flight is apparently concentrated along a narrow
  corridor from Allegheny Front to Sideling
  Hill-Jacks Mtn
• largest known spring flights in the eastern U.S.
  are at Tussey Mountain (discovered in late-1990s)

D. Brandes
15
D. Brandes. Wind-Wildlife Collaborative Workshop,
Jan 2007
Spring Golden Eagle Migration Routes through PA
?

?
Laurel Hill
?
Peak flights from late February through late March
?
Tussey Mtn
Hawk Mountain
Allegheny Front
Waggoners Gap
High counts (50-100)
Moderate counts (25-50)
Very high counts (150)
Low counts (

16
Research/Data Needs
D. Brandes. Wind-Wildlife Collaborative Workshop,
Jan 2007

• 1. Actual risk data at ridge-top developments
• Collision risk carcass searches coupled with
  numbers of migrating raptors allow actual risk to
  be determined
• Avoidance pre- and post-construction visual
  monitoring over multiple years (high annual
  variation in numbers)
• 2. Behavioral response of migrating raptors to
  new generation turbines along ridge-tops visual
  and/or radar monitoring
• (Smallwood et al found higher mortality for
  Golden Eagles at tubular towers vs. lattice at
  Altamont)
• 3. Regional migration patterns and hot spots
  i.e., where are the critical migration
  routes/bottlenecks (many ridges currently have no
  data)
• Satellite telemetry of migrating raptors
• DEM-based migration modeling

17
New Research Projects
D. Brandes. Wind-Wildlife Collaborative Workshop,
Jan 2007
Simulated spring migration tracks on SE winds
through south-central PA (Brandes Ombalski,
2004)
T. Katzner
DEM-based migration modeling (Brandes, Katzner,
Bildstein) - funded through Lafayette College,
WRCP grant, Hawk Mountain, National Aviary
GPS satellite telemetry (Katzner, Lanzone,
Mulvihill, Miller, Brandes) - funded through
National Aviary, Carnegie Museum, pending SWG
grant
18
High resolution satellite tracking data
D. Brandes. Wind-Wildlife Collaborative Workshop,
Jan 2007
(see www.aviary.org)
19
Risk reduction / mitigation methods
D. Brandes. Wind-Wildlife Collaborative Workshop,
Jan 2007

• Avoid major migration pathways or bottlenecks
  (e.g., Kittatinny Ridge, edge of Allegheny Front,
  Tussey Mountain, Bald Eagle-Brush Mountain, Lake
  Erie shoreline)
• Setbacks from steeply sloping terrain (50 m at
  Foote Creek Rim, WY) likely applicable in PA
  near escarpments (Allegheny Front, Laurel Hill
  site north of Williamsport) but not feasible on
  narrow ridge-tops

20
Risk reduction / mitigation methods
D. Brandes. Wind-Wildlife Collaborative Workshop,
Jan 2007

• Turbine blade feathering for site-specific high
  risk weather conditions during migration
• Based on pre-construction monitoring and
  experience at sites with similar topography,
  large flights should be predictable at many
  sites, e.g. late fall migration along ridges on
  NW winds
• Visual deterrents on rotors (NREL research
  inconclusive), or at end of turbine strings -
  tower w/o spinning rotor?
• Reforestation of cleared areas beneath towers

21
Summary
D. Brandes. Wind-Wildlife Collaborative Workshop,
Jan 2007

• Wind energy facilities on plateaus pose very low
  risk to migrating raptors
• Risk posed by wind energy development on narrow
  ridge-tops to raptors is currently unknown
• Golden eagles appear to be at higher risk than
  other raptor species south-central ridges of PA
  an area of particular concern due to high energy
  potential and high use by golden eagles
• If ridges are to be developed, need a
  collaborative research effort between wind energy
  industry and scientific community to quantify
  risk, study behavioral response of raptors to
  turbines, and develop mitigation methods if
  necessary
• Proper siting of wind plants and individual
  turbines is the key to risk reduction

22
D. Brandes. Wind-Wildlife Collaborative Workshop,
Jan 2007
Questions?
T. Katzner
D. Brandes
23
Attachment detailed comments on PGC Cooperative
Agreement
D. Brandes. Wind-Wildlife Collaborative Workshop,
Jan 2007

• Raptor surveys for 5 days per week have a 28.5
  chance of missing large flights
• Because daily raptor migration counts typically
  have high variability, resulting data will be
  suspect
• Not consistent with standard practice in raptor
  migration monitoring, which is to monitor 7 days
  per week
• Mortality monitoring period (March 15 to November
  15) misses the majority of the peak flight period
  for golden eagles, esp on south-central ridges
• Should be revised to March 1 through December 15
  for sites where golden eagles are documented
  during pre-construction monitoring