The compact radar system quantitative research on aerial fauna
The bio monitoring systems measures the bird and bat movement using a rotating horn antenna. In addition to the analyses of the spatiotemporal distribution, the system offers real time classification and quantification represented as mean traffic rate. Data are stored in raw format and is available for further processing.
BirdScan MR1 is a compact radar system for the quantitative long-term monitoring of birds and bats. It uses a vertically directed conically shaped wide aperture beam with a nutating movement. This setup allows to record a rich set of information for each target:
- Precise recording of target’s height above ground.
- Wing flapping pattern which is necessary to exclude non-bird and non-bat echos like insects and allows classification of bird echos into sub-groups.
- Precise knowledge of surveyed volume which is necessary to estimate the number of birds aloft per volume, i.e. to compute Migration Traffic Rate for specific altitude layers (birds / horizontal km * hour).
- Flight direction and speed of target is obtained from the nutating beam.
- Shape of target (long vs. round) is obtained from circularly polarized beam.
- X-band radar which can detect even small birds (e.g. small passerines) and bats up to 1000 m and large birds (e.g. gulls) up to 2000 m.
Comparison to traditional bird-radars
Traditional horizontally or vertically rotating bird-radars only illuminate a target for a fraction of second and wing-flapping pattern cannot be recorded. Therefore non-bird echos like insects cannot be properly excluded. In traditional rotating radars the surveyed volume is generally not well-defined and therefore computation of MTR is problematic.
Example of echo from a bird recorded by MR1 system
The wing-flapping pattern is recorded and can be extracted automatically, here a continuously flapping bird with 8 wing-beats per second.
Characteristics in detail
Birds and bats are detected using pulsed radar that emits beams vertically across a conically-shaped field from a corrugated Horn-antenna with a wide aperture angle. BirdScan consists of a transmitter/receiver unit and a computer and analysis unit. The system can be monitored remotely if connected to the internet.
The MR1 radar can be placed as close as 150 m off the turbine. Like for any radar, a rotating blade within the measurement range would produce strong disturbances and would make it hard to properly detect all birds.
BirdScan MR1 can also be deployed offshore on any platform. It needs to be protected for offshore conditions. See following images:
Option 1: container
Server and processing module protected in a container; radar antenna on top of container protected by a small Radome.
Option 2: large radome
Standard compact MR1 system protected by a larger Radome (approx. 1.5 m width * 1.6 m height).
Option 3: research platform
BirdScan MT1 has been used by Schulz et al. (2014) at Alpha Ventus. It was situated at the FINO1 research platform.
High quality offline-analytics
BirdScan MR1 radar systems can reliably detect even small passerines and small bats. Hundreds of thousands echos per month can be recorded. To leverage the full potential of this data, our experts can provide detailed off-line analytic services to crunch the data and deliver high quality analyses and reports for impact assessment reports or scientific publications. A few examples of display items are shown in the following illustrations:
Precise estimation of altitude
BirdScan radar systems provide a precise estimation of altitude above ground of each detected bird or bat allowing to compute Migration Traffic Rate for specific altitude layers. Here standard altitude of 100 m (left) or 50 m (right).
Migration traffic rate per day
Based on onset of dawn and dusk, the Migration Traffic Rate can be computed on a per day basis. Here for altitudes in 50 – 1000 m. Custom altitude and time resolutions are also possible.
Time and height migration profile
Detailed time*height migration profile. For each day and each night altitude distribution is plotted as box-plots. This allows a detailed assessment of collision risks at specific heights.
Per-hour mean MTR
Per-hour mean MTR can be computed from seasonal or monthly data. Relevant information can be plotted jointly (herelight/dark periods).
Detailed flight direction profiles
Thanks to its slight rotation, MR1 can measure the flight directions of individual birds and bats. This allows to derive detailed flight direction profiles. In this example for four consecutive nights.
Functionality of BirdScan MR1
|Features and functionality||Details|
|area of application||research, environmental studies, continuous long term monitoring|
|sensing technology||pulse radar|
|antenna system||corrugated horn (rotating)|
|transmitter frequency||x-band fixed|
|transmitting power||25 kW peak|
|range (height)||2000 m|
|resolution in space||10m|
|spatiotemporal distribution||height, speed, direction|
|classification||per species group|
|mean traffic rate||selectable heights|
|raw data||available for offline analyses|
|operation||automatic 24 h|
|electrical connection||1x230V 300W|
|communication||LAN / WAN / GPRS|
|weight||Approx. 100 kg|
|environmental design||MIL STD 810 F|
|climate kit (optional)||HVAC, 1x230V 700W, 30kg|
|offshore kit (optional)||available|
Cecilia Nilsson, Adriaan M. Dokter, Baptiste Schmid, Martina Scacco, Liesbeth Verlinden, Johan Bäckman, Günther Haase, Giacomo Dell’Omo, Jason W. Chapman, Hidde Leijnse, Felix Liechti (2018)
Field validation of radar systems for monitoring bird migration
Journal of Applied Ecology; 2018;00:1–13. https://doi.org/10.1111/1365-2664.13174
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