Ecological Research at FINO 2

During their migration between breeding and wintering grounds, millions of birds cross the southwestern Baltic Sea each year. At FINO 2, we have been investigating the effects of offshore wind farms on these migrations and the underlying mechanisms since 2007. In particular at night, when the majority of individuals are migrating, offshore wind turbines may provide an elevated collision risk under adverse weather conditions, leading to birds being attracted to artificial light sources. But also during daylight hours, wind farms may influence birds, acting as barriers or inducing an increased collision risk under low visibility conditions (fog).
Given this background, we continuously record migrating birds (day and night) with various methods developed and/or modified for the application at FINO 2, including:

• ertically-rotating ship surveillance radar
• “BirdScanMT1” fixed-beam radar
• “VARS” automatic camera system
• Automatic radio tracking
• Monitoring of collision victims

Vertically-rotating ship surveillance radar

In the context of offshore-planning in German waters, vertically-rotating ship surveillance radars are used as standard tools to record intensity, seasonal occurrence (phenology) and flight altitude of migrating birds. In 2007, we installed a ship surveillance radar with an output of 25 W at FINO 2 at an altitude of 35 m, which operated until 2011. In 2011, we replaced the ship surveillance radar by a fixed-beam radar developed specifically for this purpose, and have since been utilizing this technology.

Fixed-beam radar

Vertically-rotating ship surveillance radars have two disadvantages: their ability to distinguish between birds and other objects (e. g. insects) is limited, and their broad radar beam is subject to strong disturbance signals from wind turbines, hampering statements about bird migration in their immediate surroundings.

To tackle such problems, we use a specifically-developed fixed-beam radar. In contrast to conventional ship radar, this radar records raw signals and is characterized by a more focused radar beam. Recording raw signals allows identification of specific wingbeat patterns and the derivation of information regarding bird species groups involved. The focused radar beam enables a greater operating distance and facilitates recording of migration rates in the vicinity of wind turbines. The fixed-beam radar (BirdScan M1 model) was developed in cooperation with the Swiss Ornithological Institute (www.vogelwarte.com) and was installed at FINO 2 in 2011. It is used to record nocturnal bird migration, which comprises the majority of all migrating individuals.

After a modification in the first half of 2015, upgrading the BirdScan M1 to a BirdScan MT1 model, the radar beam can be oriented in various horizontal directions. Currently, we record bird migration both inside and outside the “EnBW Baltic 2” offshore wind farm to test to what extent migrants will avoid, cross or approach the wind farm. Utilizing a comparable study design conducted at the research platform FINO 1, we previously investigated bird migration between 2010 and 2013 at “alpha ventus”, the first German offshore wind farm situated in the North Sea (http://www.bsh.de/de/Meeresnutzung/Wirtschaft/Windparks/StUKplus/Berichte/Abschlussberichte/20140815_StUKplus_Schlussbericht_IfAOe_1%2b2_0327689A_FINAL.pdf). Due to deviating geographical preconditions, average migration intensities at FINO 1 have proven to be lower than in the Baltic Sea and the array of species dominating bird migration has been different. In consequence, the mechanisms behind the effects observed may also differ.

VARS automatic camera system

Since October 2007, we have been recording flying birds (and bats) in the vicinity of the mast of FINO 2 with two specificallydeveloped infrared camera systems (Visual Automatic Recording System = VARS). Both during the day and at night, VARS automatically detects moving objects and records these objects within a short video stream. The development of the system is based on a research project funded by the former German Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (Bundesministerium für Umwelt, Naturschutz und Reaktorsicherheit = BMU). We performed continuous bird detection to determine how often and under which weather conditions major numbers of migrating birds are attracted to illuminated offshore installations (such as FINO 2). In most cases, we are able to identify recorded birds to species level or at least to species groups. The successful use of VARS for a period of several years under offshore conditions at FINO 2 was the prerequisite for also installing the system at offshore wind turbines. A modified VARS was running continuously from 2010 to 2013 on the nacelle of a wind turbine at “alpha ventus”, the first German offshore wind farm (http://www.bsh.de/de/Meeresnutzung/Wirtschaft/Windparks/StUKplus/Berichte/Abschlussberichte/20140815_StUKplus_Schlussbericht_IfAOe_1%2b2_0327689A_FINAL.pdf).

Automatic radio-tracking

Through radio-tagging, small passerines can be tracked individually over small and medium distances. To do so, birds are equipped with small radio transmitters whose signals are automatically recorded with specialized antennas.

At Falsterbo Peninsula, the southwestern tip of Sweden and one of the most important concentration points of migrating birds in Northern Europe, the University of Lund (Sweden) is conducting a radio tracking study on behavioral strategies of migrating passerines (http://canmove.lu.se/research/migration_patterns/telemetry_studies). In this study, a species array of mainly nocturnal migrants is equipped with radio transmitters during several autumn seasons.

Given the fact that birds need to cross the Baltic Sea on their southward migration, IfAÖ installed an automatic recording station at FINO 2. The objective of this approach is to determine to what extent various passerine species departing from the migration concentration point at Falsterbo (situated in a distance of about 45 km) will pass through airspace in the vicinity of FINO 2, although the platform is situated to the SSE and, thus, outside of the assumed main migration flyway (SW). A comparison of these individual detections with migration intensities recorded by radar can help to determine whether individuals recorded are part of major migration waves crossing the Baltic Sea in a south-southeasterly direction.

Monitoring of collision victims

From the installation of FINO 2 in summer 2007 onwards, we have documented corpses of birds found on the platform deck and on horizontal structures of the mast. We assume that nearly all of these birds collided with platform structures, as confirmed by video streams and pathological examinations. Monitoring of collision victims permits statements regarding the species composition potentially affected by offshore installations. However, these findings cannot be transferred directly to the circumstances of offshore wind turbines in a quantitative manner.

Results

Bird migration over the southwestern Baltic Sea was characterized by a pronounced seasonality, indicating high migration intensities during the spring and autumn migration periods. However, bird migration did not entirely cease outside of these main migration periods. For instance, a cold snap in winter can cause migration movements of a variety of species.

The fixed-beam measurements demonstrated strong short-term fluctuation in migration intensity within the migration seasons, involving all groups of bird species studied (passerine type, wader type, etc.). Passerines represented the most numerous species group, recorded in peak nights with migration rates of several thousands of individuals per hour and kilometer. Thus, migration rates were several times higher than those recorded by a comparable radar installed at FINO 1 in the German North Sea. With the fixed-beam radar, bird migration was monitored to an altitude of 3,400 m. Dividing altitude into bands of 200 m, the strongest migration intensities were recorded in the lowest 200 m. Even above an altitude of 1,500 m, the highest altitude monitored with conventional ship surveillance radars, we still recorded bird migration, continuing with decreasing proportion to the detection limit at an altitude of 3,400 m.

With the VARS camera system, we recorded nocturnal light attraction of migrating birds at FINO 2 over a period of several years. We detected a quantitative dominance of passerines. Nights with high numbers of attracted birds occurred rarely, but regularly during the migration periods in spring and autumn. These nights were characterized by low visibility, onset of precipitation, adverse winds (changes from tailwinds to headwinds) and/or a decreasing cloud cover. As a result of light attraction, birds collided with structures associated with the research platform, and a certain proportion of their corpses were found lying on the gratings in the mast or on the platform deck. Species were almost exclusively nocturnally-migrating passerines. In contrast to the FINO research platforms in the North Sea, where mainly thrushes were recorded as collision victims, the willow warbler dominated the species composition recorded at FINO 2.

The use of radio transmitters and their automatic detection at FINO 2 allowed tracking of individual nocturnal migrants which were crossing the southwestern Baltic Sea. The proportion of individuals passing the airspace around FINO 2 after departing from Falsterbo, an internationally important concentration point, proved to be surprisingly high, although the platform is situated outside of the generally-assumed main migration route of these birds. Comparisons with results of the fixed-beam radar revealed that most radio-tracked individuals were passing FINO 2 when migration intensity of passerines was generally high around FINO 2. In addition, these migration waves were in accordance with the occurrence of increased numbers of frequent passerine species captured with mist nets at a ringing station on the “Greifswalder Oie”, (www.jordsand.eu/index.php?id=53), an islet near the German Baltic Sea Coast.

 

Publications und presentations concerning research on avian migration at FINO 2:

Coppack T, Sjöberg S., Schulz A., Schleicher K, Weidauer A., Muheim R., Åkesson S. & T. Alerstam 2013. Tracking needles in a misty haystack – The challenge of assessing impacts of offshore wind farms on night-migrating songbird at the species level. Naturvårdsverket Rapport 6546: 45-46

Dittmann T, Åkesson S, Alerstam T, Kulemeyer C, Liechti F, Muheim R, Schulz A, Sjöberg S, Steuri T, Weidauer A & T Coppack 2013. From individual decisions to mass migration events: factors shaping migration patterns in songbirds crossing the open sea. EOU2013UK – the 9th Conference of the European Ornithologists’ Union. Norwich. Programme & Abstracts: 74.

Schulz A, Kulemeyer C, Röhrbein V & T. Coppack 2011. The extent of phototactic attraction of night-migrating birds passing an illuminated steel mast in the western Baltic Sea. International Conference on wind energy and wildlife impacts, Trondheim, Norway. NINA Report 693: 102.

Schulz A, Röhrbein V, Schleicher K, Kulemeyer C & T. Coppack 2011. Die Forschungsplattform FINO 2 – eine automatisierte Vogelwarte inmitten der Ostsee. Seevögel 32: 99-101.

Schulz A, Sjöberg S, Schleicher K, Weidauer A, Muheim R, Coppack T 2012. Von Falsterbo ins Nirgendwo? – Automatisierte Telemetrie des herbstlichen Singvogelzugs auf der Offshore-Plattform FINO 2 in der Ostsee. 145. Jahresversammlung der Deutschen Ornithologen-Gesellschaft, Saarbrücken. Vogelwarte 50. Heft 4: 257-258.

Coppack T. 2013. Bird migration measurements performed at FINO2. FINO Conference 2013: 10 years of FINO Offshore Wind Energy research and analysis, Kiel.

 

The studies performed by IfAÖ at FINO 2 prior to 2013 were part of the following major projects funded by BMU: „Aufbau und Betrieb einer Messplattform zur Erprobung der westlichen Ostsee als Unterstützung zur Untersuchung aller Haupt- und Nebenbedingungen für langfristige windenergetische Nutzung (FINO II)“ (FKZ 0329990), „Wissenschaftlich-technische Ausrüstung der Forschungsmessplattform zur Erforschung der westlichen Ostsee FINO 2 – Equipment“ (FKZ 0329990A) and „Betrieb der Forschungsplattform FINO 2“ (BMU; FKZ 0329905D). The current research conducted by IfAÖ is funded by the German Federal Ministry for the Environment, Nature Conservation, Building and Nuclear Safety (Bundesministerium für Umwelt, Naturschutz, Bau und Reaktorsicherheit = BMUB)