Using radar to assess and mitigate collision risk to birds on wind farms - an example of good practice - Wind Farm & Wildlife Impact Workshop ...
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Using radar to assess and mitigate collision risk to birds
on wind farms - an example of good practice
Wind Farm & Wildlife Impact Workshop, Helsinki
Date: 19th September 2018
Presenter: Pawel Plonczkier
1
Presentation agenda
Part 1 Part 2
Principles of radar monitoring An example of good practice
19/09/2018
This presentation consists of two parts. The first part outlines basic principles of
designing a radar monitoring campaign, from planning and study design to execution
and interpretation of results. The second part shows the practical implementation of
these principles based on the recent Natural Power’s radar study conducted in the
western Scotland to assess the collision risk for white-fronted geese at a proposed
onshore wind farm.
2
Principles of using radar for bird monitoring
Identify the risks
Formulate the monitoring and mitigation aims
Evaluate the need for using radar
Choose the right tool for the job
Design a monitoring protocol to answer key questions
Analyse data and contextualise information
19/09/2018
Here are six steps which help to guide the process of designing a radar study. Although
it may be not an exhaustive list, it highlights the important questions that need to be
answered before a decision on using radar is made, and also, it provides clues on how to
use radar effectively.
3
1. Identify the risks
• Single species or groups
• Resident, migratory (spring and autumn), wintering
• Conservation status
Key species • Sensitivity, abundance
• Collisions with turbines resulting in mortality
• Displacement resulting in mortality or sub-lethal effects
• Barrier effect resulting in increased energy expenditure
Key impacts • Lighting causing disorientation at night
• Key seasons
Key periods • Protected sites (SPA, Ramsar, Nature Reserves)
and areas
19/09/2018
The first step when considering the use of radar in mitigation is to identify key risks: (1)
what are the key species of interest; (2) what are the key impacts on those species; and
(3) where and when may those species be affected.
Important aspects to consider when identifying key species is how easy or difficult they
will be to detect by radar. When describing risks associated with a wind farm
development, two or more types of impact can be identified depending on the key
species. Finally, birds’ biology and ecology as well as geographical aspects of a site
(proximity to roosting, foraging or protected sites) will define temporal and spatial
boundaries of the risks.
4
2. Formulate the monitoring and mitigation aims
Seasonality
Flux of birds Abundance
Foraging
Flight height
patterns
MONITORING
AIMS?
Wind farm
Migration
or turbine
timing
avoidance
Species
Habitat loss
composition
19/09/2018
Having identified all the risks, the next step is to define the monitoring aims. Often
ecologists are interested in all aspects of birds’ behaviour and by employing
sophisticated tools such as radar, the tendency is to gather as much information as
possible. However, such an approach can easily backfire as not a single monitoring
method is suitable to provide information needed to answer multiple monitoring aims.
The more specific the monitoring aims can be, the easier it will be to find a method
suitable for providing the information required.
5
3. Evaluate the need for using radar
Be aware of both strengths and limitations of radar technology
Unlike other techniques that use visual, infrared or acoustic sensors,
avian radar can:
Provide unbiased and automatic data collection 24/7
Track multiple targets simultaneously
Cover large spatial scales
Operate in reduced visibility conditions (night, fog, light rain)
Limitations of radar technology:
Cannot detect stationary targets
Cannot reliably detect low-flying targets (ground and wave clutter)
Limited capabilities to identify birds to species
Prone to interference from other radars
Difficult to operate in remote and harsh conditions
Not a substitute for human observations
19/09/2018
Would radar be a suitable monitoring method to answer the monitoring aim as defined
during the preceding step? Radar is a very sophisticated tool but it may not be the best
tool for the job. There could be other monitoring techniques that are cheaper or better
suited for specific tasks.
There is no denying that radar technology offers some unique capabilities that other
methods cannot. For detecting and tracking multiple targets over large scales during the
hours of darkness - radar is the only tool able to achieve this.
Conversely, in some situations radar will be an inappropriate tool to use because of the
limitations that are inherently associated with this technology. For example, for
continuous and uninterrupted tracking of single targets (e.g. large birds of prey), it may
be better to use some kind of tagging technology (radio or satellite tagging). For
assessing the abundance of waterfowl congregating on large areas of water, boat or
aerial surveys will be best.
Last thing to mention here is that radar is never going to replace ornithologists on the
ground. This is of course not a limitation of radar technology however it is often
perceived as one. Radar is yet another tool in the arsenal of ornithologists, not their
substitute.
6
4. Choose the right tool for the job
Types of avian radars
Surveillance radars
OPERATION MODE: Scanning the airspace throughout a 360° field of view
DATA TYPE: 2D information on bird activity over a wide area (position and velocity)
PURPOSE: Spatial and temporal distribution, patterns of behaviour, abundance studies
Staring radars
OPERATION MODE: Fixed antenna orientated in azimuth and elevation
DATA TYPE: Altitudinal profile over a limited sector
PURPOSE: Passage rates, flock density and height measurements, group/species ID
Tracking radars
OPERATION MODE: Following individual targets over a shorter range
DATA TYPE: 3D information on individual targets, including wingbeat frequency
PURPOSE: Species ID, accurate speed measurements, behavioural studies
19/09/2018
There are different types of radars being used for bird monitoring. Radars can differ in
antenna design, transmitter technology, frequency of electromagnetic signal, operation
mode, detection range, target resolution, etc. The implications of this is that different
types of radars provide different type of information.
In simple terms, there are three main types of radars used for bird monitoring:
surveillance, staring and tracking radars.
Surveillance radars scan the airspace in 360 view and provide 2D information on targets
position, trajectory and speed. Staring radars can be fixed in azimuth and elevation, and
provide accurate height information on targets passing through a limited sector. Tracking
radars can follow individual targets and provide 3D information on single targets,
including wing beat frequency.
7
4. Choose the right tool for the job
Each radar type is suitable for addressing specific research questions
Distribution and
abundance
studies?
Quantification
Species
of flight
identification?
activity?
19/09/2018
Depending on the monitoring aims, the type of radar that is designed to provide certain
type of information shall be used .
If the monitoring aim is to assess the flux of birds passing over a proposed wind farm
site, then staring radar should be used as this type of radar provides altitudinal profile
over a selected viewshed. If the monitoring aim is to map the flight paths of wintering
geese commuting between feeding and roosting sites, then surveillance radar should be
employed as this type of radar provides information on spatial distribution over a larger
range.
It often happens that some studies require multidisciplinary approach and multiple
sensors. For this reason some avian radar manufacturers combine two radar sensors into
one radar system – to collect many types of data to answer multiple monitoring aims.
8
5. Design a monitoring protocol to answer key questions
Survey • Sampling period (timing and duration)
• Data ground-truthing (radar ornithologists)
design • Integration of other methods (sensors)
Radar • Sampling area (radar siting, multiple locations,
clutter modelling, probability of detection)
calibration • Testing (initial data collection, review of radar
target data)
• Automated reporting procedures
19/09/2018
There are many practical aspects to be considered when designing a monitoring protocol
for radar monitoring so not all can be listed here, however the following considerations
are necessary to be included in the planning process:
• The study should be long enough to be able to detect patterns of behaviour;
• The study timing should be tailored to the birds’ ecology (and phenology);
• Radar ornithologists have a crucial role to play - to verify radar recording and provide
ecological context to the radar output; and
• Radar monitoring could be integrated with other sensors (cameras).
Logistics of radar operation in the field depend on local topography, ground cover, road
access, network and power connections. Often, the operation of radar is subject to a
site-specific frequency clearance issued by local civil aviation authorities. A lot of effort
should go into selecting the optimum location for the radar which provides sufficient
viewshed and range for data collection. It is important to allow time (and resources) to
carry out field tests, to check the quality of recorded data and to make necessary
amendments if needed (radar location, recording parameters).
9
6. Analyse data and contextualise information
Data Information
19/09/2018
Radar produces terabytes of data but raw data is worthless unless properly analysed and
interpreted. It’s a radar ornithologist’s task to sift through the dataset, select and analyse
the relevant data, and provide ecological context so data becomes information.
The radar data reports that are often automatically produced by radar software
rarely give satisfying answers - it’s more of a tool to ensure that data acquisition process
goes interrupted or to highlight some behaviours that are out of ordinary.
10Radar monitoring to assess collision risk – an example of good practice
1. Identify the risks
• Greenland white-fronted goose Anser albifrons flavirostris
• Wintering
• High conservation status (Endangered, Annex 1, Red-listed)
Key species • Global population in 2017 - 20,556 individuals
• Collisions with turbines resulting in mortality
• Barrier effect resulting in increased energy expenditure
Key impacts
• Key seasons - winter
Key periods • Protected sites - goose designated SPA
and areas
19/09/2018
This is a recent (2016-2017) example of Natural Power’s project using radar technology
to assess collision risk for Greenland white-fronted geese (GWFG) at a proposed wind
farm site in western Scotland.
Due to its limited geographic range and relatively small population size, GFWG is a
species on Birds of Conservation Concern Red List, classified as Endangered under IUCN
Red Data List criteria and listed on Annex 1 of the EC Bird Directive.
The proposed development lies in close proximity to a Special Protection Area which
regularly supports an internationally important wintering population of GWFG. GWFG
had been known to transit over the proposed site between the hill lochs (roosting sites)
and their day-time foraging areas, during morning and evening commute, potentially
risking collision with turbines.
11Radar monitoring to assess collision risk – an example of good practice
2. Formulate the monitoring aims
Foraging sites Roosting sites
Seasonality
Flux of
Abundance
birds
Dawn and dusk commuting
Flight Foraging
height
MONITORING patterns
Nocturnal flight activity
AIMS
Wind farm
Migration
or turbine
timing
avoidance
Species Habitat
composition loss
19/09/2018
Given the proximity of the proposed development to the SPA, the foraging patterns of
GWFG needed to be assessed. The purpose of radar monitoring at the proposed
development was two-fold:
• To assess the GWFG activity over the proposed development, especially during dawn
and dusk commute; and
• To determine the levels of goose nocturnal flight activity.
12Radar monitoring to assess collision risk – an example of good practice
3. Evaluate the need for using radar
Unbiased and
automatic data
collection 24/7
Simultaneous
tracking of multiple
targets
Large spatial
coverage
Ability to operate in
reduced visibility
conditions
19/09/2018
To answer the monitoring aims (describing the foraging patterns of geese), continuous
tracking of multiple targets over large areas (up to 10 km in radius), including night-time
periods, was required. Only radar technology offers such capabilities, therefore avian
radar was used for this study.
13Radar monitoring to assess collision risk – an example of good practice
4. Choose the right tool for the job
Surveillance S-band radar
Scanning the
airspace throughout
a 360° field of view
2D information on
bird activity over a
wide area (position
and velocity)
Spatial and temporal
distribution, patterns
of behaviour
No height
information needed
– no need for X-band
radar
19/09/2018
A surveillance S-band radar was chosen to provide information on geese flight activity,
including position, flight trajectory and speed. As the monitoring aims did not require
investigating the flight height, no X-band radar was used for this study (flight height was
investigated during previous radar studies on this site).
14Radar monitoring to assess collision risk – an example of good practice
5. Design a monitoring protocol to answer key questions
• Sampling period - four 10-day deployments in winter season
Surveillance S-band radar
• Data ground-truthing - dawn and dusk goose watches
• Day-time goose census
• Integration of other methods - night-time auditory goose surveys
Survey
design
Radar • Sampling area – single radar location
calibration • Testing - radar track comparison in four
control areas
• Automated reporting procedures –
radar output review
19/09/2018
GWFG are present in the UK only in winter and the radar monitoring programme was
designed to collect data at each key phase of the goose wintering season (post-arrival,
mid-winter and pre-departure). Four radar deployments were carried out in total, each
including ten days (240 hours) of continuous radar monitoring.
Ornithological observations were conducted in tandem with radar monitoring to
complement radar recordings and visually confirm goose flocks. This consisted of:
• Dawn and dusk goose watches to provide information on goose distribution and
utilisation of roosting sites;
• Night-time auditory surveys to confirm goose presence/absence at key areas; and
• Day-time goose census at coastal foraging sites to monitor the wintering population
size.
A single radar location was used for all four deployments. The radar detected bird flight
activity in real time and saved all bird targets in a PostgreSQL database as vector flight
paths (tracks). These tracks were displayed on the radar screen in real time; they were
also available to view remotely on external laptop. Typically, a radar operator would
inform a field ornithologist of any relevant flight activity observed on a radar display so
visual confirmation of the radar target could be made by the ornithologist. By using the
laptop in the field, an ornithologist is able to positively identify bird targets onto the
laptop and store information on bird species and numbers directly to the radar database.
The statistical comparison of radar tracks in four control areas was carried out to test
whether the radar was detecting, tracking and recording birds correctly, and also that
the site coverage and bird detection rates were adequate for the purpose of the study.
15Radar monitoring to assess collision risk – an example of good practice
6. Analyse data and contextualise information – radar data analysis (1)
1. Radar track classification based on eight size classes detected over the entirety of the radar detection
range during ten-day monitoring period (red line marks the height of the sun in relation to the horizon)
Surveillance S-band radar
Radar tracks representing all size classes
Radar tracks representing large flocks of birds
19/09/2018
As type of the radar used for this study is not capable of species recognition, the geese
related information needed to be extracted from the radar dataset during post-
processing. The first step of this process was classification of radar tracks into size
classes which allowed the analysis of temporal distribution of different size birds.
To be able to match radar tracks with the corresponding bird groups, a ‘trained dataset’
was used to reference the radar data (i.e. to build a set of recognisers for bird size
classes). The trained dataset was created by matching visually identified bird records
collected during various field observations with the radar recordings. For the referenced
group of radar tracks, the relationship between the average mass of a species and the
so-called corrected mass parameter was investigated. This ratio is expressed as the
difference (decrease) in the reflective power of the radar beam from the object
compared to the power of the emitted beam [dB]. Based on the corrected mass
parameters, eight bird size classes were identified and used in the analysis.
The top plot shows tracks of all sizes recorded during a 10-day deployment, the bottom
plot shows only large flocks during the same period, which gives clear indication of key
periods when the goose flocks were flying.
16Radar monitoring to assess collision risk – an example of good practice
6. Analyse data and contextualise information – radar data analysis (2)
2. Goose track identification
Goose reference dataset - visually observed goose flocks were matched with radar
Surveillance tracks
S-band radarand
statistically analysed to identify the “goose classifiers”
Parametric verification of radar data - entire radar dataset was verified using “goose classifiers”
Visual analysis of radar output – cross-examination of data based on tracks’ trajectory, location, the
place of origin, timing and repetitiveness of occurrence; track stitching to represent factual number
of goose flocks
70 200
60 180
5%
160
50
140
40 120
Flocks
Dawn
Flocks
30 100
Outwith wind farm Day
39% 80
20 Within wind farm Dusk
52% 60
10 Night 40
0 20
0
4% 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
Date Hour
19/09/2018
The second step was the goose track identification and it comprised three stages:
• Creation of the ‘goose reference dataset’;
• Parametric verification of radar data; and
• Visual analysis of radar video files.
GWFG field records collected during dawn and dusk watches were matched with the
corresponding flight tracks recorded by the radar. Using verified radar tracks (‘goose
reference dataset’), certain radar parameters were statistically analysed to identify the
‘goose classifiers’, i.e. groups of parameters that are always characteristic to goose flock
tracks. These ‘goose classifiers’ were used during parametric verification of the whole
radar dataset to identify goose-like tracks. These were then analysed visually using the
videos from the radar display. Finally, based on timing and trajectory, all identified goose
tracks were linked together to represent the factual number of goose flocks (one goose
flock can be represented on radar by several intermittent tracks).
This approach allowed to reliably extract goose tracks from the radar dataset and use
this information to describe patterns of goose flight behaviour. These sample plots show
how this information can be presented and used in assessing the collision risk.
17Radar monitoring to assess collision risk – an example of good practice
6. Analyse data and contextualise information – results (1)
Surveillance
Post-arrival S-band radar
19/09/2018
The results of the radar track identification analysis can be also shown on flight activity
maps. This is a 10-day composite image of radar tracks representing goose flight activity
recorded in November (post-arrival period).
The majority of goose flight activity occurred over the land - 78% of flocks were recorded
heading to or from roosting sites to the east of the proposed site. The remaining flocks
were commuting between the mainland and the nearby islands to the west. There was
no distinct flight corridor between the foraging sites located along the coastline and the
roosting sites to the east, as geese were using different flyways each day. A quarter of all
flights occurred over the proposed development.
18Radar monitoring to assess collision risk – an example of good practice
6. Analyse data and contextualise information – results (2)
Surveillance
Mid-winter 1 S-band radar
19/09/2018
This is a 10-day composite image of radar tracks representing goose flight activity
recorded in December (mid-winter 1 period).
The majority of goose flight activity occurred between the mainland and the nearby
islands to the west, and there was no distinct pattern of movements towards the
roosting sites to the east. The GWFG were also found roosting near foraging sites close
to the coast. The majority of flights recorded in the vicinity of the proposed
development occurred during one night only (as a result of disturbance at the roost).
19Radar monitoring to assess collision risk – an example of good practice
6. Analyse data and contextualise information – results (3)
Surveillance
Mid-winter 2 S-band radar
19/09/2018
This is a 10-day composite image of radar tracks representing goose flight activity
recorded in February (mid-winter 2 period).
The majority of goose flight activity occurred between the mainland and the nearby
islands, and there was no distinct pattern of movements towards the roosting sites to
the east. The vast majority of flights occurred outwith the proposed development; only
12 flocks were recorded transiting over the proposed site during this period.
20Radar monitoring to assess collision risk – an example of good practice
6. Analyse data and contextualise information – results (4)
Surveillance S-band radar
Pre-departure
19/09/2018
This is a 10-day composite image of radar tracks representing goose flight activity
recorded in March (pre-departure period).
The majority of goose flight activity occurred between the mainland and the nearby
islands, with only a handful of flight towards the roosting lochs to the east. No flights
were detected over the proposed development.
21Radar monitoring to assess collision risk – an example of good practice
6. Analyse data and contextualise information – main findings (1)
Monitoring aim: to quantify goose activity over the proposed development
Surveillance S-band radar
A total of 122 goose flocks were recorded
transiting over the proposed development
80% of flights were recorded during post-
arrival period
93% of flight activity was concentrated
around dawn and dusk periods
19/09/2018
One of the monitoring aims of this radar study was to quantify the goose flight activity
over the proposed wind farm development. The main findings were:
• A clear commuting pattern was discernible during all stages of the wintering season;
• The majority of GWFG movements over the site occurred during post-arrival period
(80%), and during dawn and dusk (93%); and
• In November, 98 GWFG flocks transited over the site. In both December and February,
12 flocks transited over the site, in March no flocks were recorded flying over or near
the site.
22Radar monitoring to assess collision risk – an example of good practice
6. Analyse data and contextualise information – main findings (2)
Monitoring aim: to quantify levels of nocturnal goose activity
Surveillance S-band radar
A quarter of all flight activity was recorded
during hours of darkness
Three-quarters of night-time activity occurred
in mid-winter
97.42% of night-time activity was associated
with movements outwith the proposed
development
19/09/2018
The second monitoring aim was to quantify the levels of nocturnal goose activity. These
are the main findings:
• Nocturnal goose activity constituted 26% of all flights recorded;
• The vast majority of the nocturnal activity (97.42%) was associated with movements
outwith the proposed development; largely with geese commuting between the
mainland and the nearby islands;
• The peak in the nocturnal goose activity occurred in the first hour after dusk and
could be associated with regular commuting between the foraging and roosting sites;
and
• No flights over the site were recorded during the core night hours (between 23:00
and 06:00 hours) or during the day (between dawn and dusk periods).
23Radar monitoring to assess collision risk – an example of good practice
6. Analyse data and contextualise information – conclusions
Surveillance S-band radar
The results of the radar study will be used in
collision risk and population viability modelling to
quantify the impact to the goose population
Adaptive operational management
plans should be investigated as
potential mitigation measures
19/09/2018
The information collected during this radar study can be used to evaluate the collision
risk for GWFG in the planning phase of development. A collision model based on goose
avoidance behaviour should be carried out and considered in the context of the GWFG
population model. The possibility of undertaking a potential biological removal (PBR)
analysis to determine the maximum allowable mortality whilst maintaining a sustainable
GWFG population can be also considered for this site.
24EIA Quality Mark
Surveillance S-band radar
19/09/2018
25Our successes
Clients
19/09/2018
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