LUOMUS

Finnish Museum of Natural History

Finnish White-tailed Sea Eagles in satellite tracking

Kuva: Petteri LehikoinenThe White-tailed sea-eagle working group within WWF Finland decided in early 2009 to start a joint project with the Finnish Museum of Natural History (University of Helsinki). The aim is to collect detailed data of the movements of White-tailed sea-eagles as they move around in our coastal areas through the year from the south-western archipelago and the Åland Islands to the corners of the Gulf of Bothnia and the Gulf of Finland. There are many ongoing plans to build wind farms in different parts of the Finnish sea coasts and archipelagos. Thus it is very important to collect exact data to point out areas that should be left untouched, being important for the protection of White-tailed eagles. The White-tailed sea-eagle working group has elected an advisory board for the satellite project. At this moment, its chair is Petteri Tolvanen from WWF (earlier adjunct professor Torsten Stjernberg from the Finnish Museum of Natural History). Professor Pertti Saurola is responsible for the information on this site. (read more...)


Monitored individuals and links to the newest maps

Maps will open by clicking the name of the individual.

Junnu

 

Junnu (male) was ringed on June 24th 2009 as a nestling and was equipped with a satellite transmitter with solar panel on the island of Raippaluoto in Quarken area.

Meri

 

Meri (female) is Junnu’s sister and it was equipped with a satellite transmitter the same day. The nest lies in Vallgrund (Raippaluoto).

Ivar

 

Ivar (male) was ringed on June 25th 2009 as a nestling and was equipped with a satellite transmitter on the island of Björkö in the Quarken area.

Tuuli

 

Tuuli (female) was also was ringed on June 25th 2009 as a nestling and was equipped with a satellite transmitter on the island of Björkö. This bird with the others hopefully will give some information about the movements of eagles within the planned windmill areas.

Hilkka

 

Hilkka (female) got its satellite transmitter as a nestling at ringing on Jul 8 th 2010in the Archipelago Sea region.

Eetu

 

Eetu (male) was hatched in the archipelago of Uusikaupunki . It was ringed and equipped with satellite transmitter backpack on June 22nd 2011 before having fledged.

Cilla

 

Cilla (female) grew up on its nest on the island of Kemiönsaari. There are plans of building tens of windmill in the area. Cilla got the satellite transmitter on her back on June 28th 2011.

Johannes

 

Johannes (male) was equipped with a satellite transmitter Jun 21st 2011 when studying the possible effects of the windmill on the movements of eagles on Kasberget in Sottunga.

Aava

 

Aava (female) was added as a nestling to the group of four previous satellite transmitter eagles on June 28th 2011 in Quarken area to reveal the possible risks of the planned windmills to white-tailed eagles in Vallgrund area. Unfortunately there are no locations from Aava since Aug 6th 2012.

Tyrsky

 

On Jun 19th 2013 this eagle got the transmitter in Kokemäki and the bird was determined to be a male according to its measures. Unfortunately there are no locations from Tyrsky since May 2014.

Tyyni

 

This eagle was hatched in Parainen and it was equipped with a satellite transmitter on Jun 27th. It was determined to be a female.

Tulva

 

On Jun 17th 2013 the following of the third white-tailed eagle Tulva in the province on Satakunta started as the eaglet got satellite transmitter in the N part of Merikarvia. It should be a female according to measurements.

Auli

 

Auli was hatched in central part of the province of Satakunta in the border area of Pori and Luvia. The transmitter was installed to the eagle on Jun 9th 2013.

Fiia

 

On Jun 6th 2013 the transmitter was installed on the back of a young eagle FIia at the nest close to Rauma.

 

Background: Finnish White-tailed sea-eagles Haliaeetus albicilla in satellite tracking

The White-tailed sea-eagle working group within WWF Finland decided in early 2009 to start a joint project with the Finnish Museum of Natural History (University of Helsinki). The aim is to collect detailed data of the movements of White-tailed sea-eagles as they move around in our coastal areas through the year from the south-western archipelago and the Åland Islands to the corners of the Gulf of Bothnia and the Gulf of Finland. There are many ongoing plans to build wind farms in different parts of the Finnish sea coasts and archipelagos. Thus it is very important to collect exact data to point out areas that should be left untouched, being important for the protection of White-tailed eagles.

The final impulse for our long planned satellite project has been the threat of raising a vast wind farm in the Quarken area in the Vaasa region, namely Raippaluoto/Replot Island. This archipelago is one of the main breeding areas of the Sea-eagle in Finland. It is very clear that from the very beginning of the planning of the wind farm all the risks that may affect the local White-tailed sea-eagles should be eliminated beforehand.

The White-tailed sea-eagle working group has elected an advisory board for the satellite project. At this moment, its chair is Petteri Tolvanen from WWF (earlier adjunct professor Torsten Stjernberg from the Finnish Museum of Natural History). Professor Pertti Saurola is responsible for the information on this site.

Transmitters

In spring 2009 WWF Finland sponsored the purchasing of four transmitters (70 gram Argos/GPS Solar PTT) made by Microwave Telemetry. These trackers may work “forever” as they are equipped with solar cell chargers. Most of the Finnish White-tailed sea-eagles stay within Finland over winter and thus during the darkest weeks solar cells may not get enough sunlight for charging the batteries. That is why the transmitters were equipped with an extra 16 gram battery. The final weight of the transmitters with its harness is about 100 grams.

During the first study year we want to collect data of the transmitter functions in Finnish circumstances. The programming of the transmitters differs somewhat due to season and individual transmitter. During the bright season (May 16th – July 15th) tracking is recorded either every second hour day and night or once every hour between 5 to 19 o’clock. In the autumn (July 16th – Nov 15th) and in spring (Feb 16th – May 15th) tracking activity is limited to every hour between 7 to 18 o’clock. In winter (Nov 16th – Feb 15th) tracking records are collected only ten times between 8 to 17 o’clock to save the batteries.

The transmitters save the tracking records and send the data via satellite every fourth day as a data package to the main computer of Argos in France. From that computer the researchers may download the data to their own computers.

The satellite White-tailed sea-eagles of the summer 2009

During June 24th and 25th the White-tailed sea-eagle working group members Juhani Koivusaari and Timo Lumme fitted four White-tailed sea-eagle nestlings (aged c. 7 weeks) with transmitters. Two of them were from a nest with three young in Raippaluoto/Replot and the other two from separate nests in Björköby (all nests in Mustasaari/Korsholm municipality). From the measurements (bill and tarsus length, weight) Koivusaari judged that two were females and two males. According to the code of the international White-tailed sea-eagle program the right foot was ringed with a red Quarken area ring and the left with a black over blue year ring, i.e. indicating the natal year.

The satellite equipped White-tailed sea-eagles were given the following names after the announced competition by WWF Finland. The male E-24265 (with the transmitter number 92632) has however already been named “Junnu”. The name refers to Juhani “Junnu” Koivusaari, “the Quarken Emperor”, who has studied and protected the White-tailed sea-eagle for more than 40 years.

The female E-24266 (transmitter 92635) is called ”Meri” (”Sea”) which refers to the sea-eagle (merikotka in Finnish). At the same time it also reminds us of the former WWF Finland CEO Meri Saarnilahti-Becker. Meri and Junnu are siblings.

The male E-24267 (transmitter 92634) got the name ”Ivar” according to the famous Finnish ornithologist Ivar Hortling. On his initiative the Finnish Ornithological Society was founded in 1924. He has drawn the original flying White-tailed sea-eagle logo for the society.

The female E-24262 (transmitter E-92633) is called “Tuuli” (“Wind”) because this study will follow the movements of the White-tailed sea-eagles in relation to the windmills their planned building areas. Simultaneously we also appreciate Tuuli Äikäs who worked a long time at WWF Finland for the benefit of these birds.

Individual Area ring Year ring Transmitter Sex Weight Nest
Junnu E-24265 B385 92632 male 4,3 kg Raippaluoto 1
Meri E-24266 B386 92635 female 5,3 kg Raippaluoto 1
Ivar E-24267 B387 92634 male 4,2 kg Björköby 1
Tuuli E-24262 B382 92633 female 5,3 kg Björköby 2
Home ranges 2009

Tracking locations are not included on the map because of protection.

Junnu. Between June 24th and Sep 24th the eagle Junnu was tracked 957 times within its home range. According to the programming of the transmitter the theoretical amount of locations would have been 1100, and thus tracking succeeded in 87% of the cases. The bird was tracked within an area of 89 km². In June and July Junnu moved about only inside an area of 0.3 km², in August 9 km² and September 89 km². According to the satellite observations Junnu left the nest for the first time on the 26th of June. Then its distance from the nest varied between 106 and 160 metres. The first observation of a distance over 1000 m was on the 8th of August. Three weeks later this eagle spent 1.5 days more than 4 km away from its nest, and returned back to the nest in the evening. As the sister left for the mainland on the 17th of September, Junnu decided next day to fly in the opposite direction, to Valassaaret/Valsörarna which is an archipelago some 20 km away from the nest. After this trip Junnu was also tracked within the area of the planned wind farm.

Meri´s transmitter sent 977 locations during June 24th and Sep 19th. The efficiency in tracking was 90% and thus a little better than the transmitter of Junnu-eagle. All signals came from an area of 62km². This eagle spent June-July only within 0.3km², Aug 2.4km² and in Sep the area used was 62km². On the 13th of July it moved more that 100 meters from its nest for the first time. The 1000m line was first crossed on the 11th of Aug - three days later than its sibling Junnu. E-242466 was all the time closer to the nest compared to Junnu. Hence it somewhat surprising that Meri left its home range one week before Junnu. Also this bird sent signals from area where the wind farm is planned.

Ivar stayed in the Quarken area until the Christmas Day, mostly in the Björköby-Raippaluoto area. In the middle of Nov Ivar paid a one week visit to the continent and returned to its familiar environments in Björkö. Between Jun 25th and Nov 19th there were 1526 GPS-locations of Ivar. According to the programming there should have been 1813 locations, so the amount of successful locations of that period was 84 %. In Aug-Oct the successful locations varied from 89 to 94 %, but in the beginning of Nov only 49 %. After the 19th of Nov the amount of day light was not enough to charge the battery to required level for GPS-locations. During the end of Nov and beginning of Dec Ivar's movements could only be followed with a varying accuracy by Doppler-signals. They were received every 3rd day along with information packages. The whole home range of Ivar between Jun 25th and Nov 19th was according to the satellite locations 500 km². 95 % of all locations concentrated on only an area of 41 km². In Jun-Jul Ivar's home range was 0,12 km², in Aug 34 km², in Sep 55 km², in Oct 39 km² and in the beginning of Nov 464 km². The great number of Nov is due to its visit to the continent. According to the locations Ivar was for the first time more than 100 m from its nest on Jul the 7th. The 3 km limit was passed only a month later on Aug the 8th. On Nov the 11th Ivar left for a round tour of the continent. At 17 o'clock it roosted on the E coast of the strait between Raippaluoto and the continent some 2 km N of the road to Raippaluoto. The following night it roosted on the E coast of Hylpetfjärden and on the 13th it paid a visit to a fur animal farm in Petsmo village. Ivar spent a couple of more nights on the islets N of the island of Hylpet. The most remote place that Ivar visited was the island of Harapois to the E of the island of Värlax. Ivar returned to Björkö on Nov the 18th in the afternoon. During the tour its maximum distance from the nest was 31 km.

Tuuli. stayed in the Björköby-Raippaluoto area until Boxing Day. Until then altogether 1716 GPS-locations were received. According to the programming there should have been 2120 locations. Thus there were 81 % successful locations. The amount of sunlight to recharge the battery diminished clearly. In Aug-Sep the amount of successful locations was 95-96 % and in Oct 89 %, but in Nov-Dec only 55-57 %. When all the locations between Jun 25th and Dec 25th are calculated the home range of Tuuli has been 615 km². 95 % of all locations are within an area of 112 km². In Jun-Jul Tuuli´s home range was under 0,3 km², in Aug 7,8 km², in Sep as large as 492 km², in Oct 41 km², in Nov 166 km² and in Dec 302 km². According to the satellite signals Tuuli had left the nest for the first time only on the 16th of Jul. At that time the most remote location was 320 m from the nest. Only a month later Tuuli sent a signal that was more than 1 km from the nest. In Sep between 12th and 14th Tuuli made a 30 km trip to the south side of Raippaluoto, but returned to the nest area. This visit to the island of Bergö explains why Tuuli’s home range in Sep was more than 10 times bigger than in Oct. Between Sep 29th and Oct 12th Tuuli stayed closer than 1 km to its nest! Signals of Tuuli were also frequently received from the area of the planned wind farm, although the nest lies many kilometers from that area.

The satellite White-tailed sea-eagle of summer 2010

The researchers of the WWF White-tailed sea-eagle working group installed a new satellite transmitter on July the 8th 2010 on a young White-tailed eagle that grew up on a nest in the Archipelago Sea. The transmitter was bought by the funds of the late Markku Nygård who used to be a helper in winter feeding eagles. According to his will the funds were donated to the eagle protection fund of The Finnish Association for Nature Conservation (FANC). The female White-tailed sea-eagle E-23879 has the transmitter 33207 and the bird was named Hilkka according to the name of Markku Nygård's mother.

Individual Area ring Year ring Transmitter Sex Weight Nest
Hilkka E-23879 C356 33207 female 4,8 kg Archipelago Sea 1
Home ranges 2010

Hilkka. There were 886 locations between Jul 8th and Oct 8th when Hilkka still stayed within the home range. According to the programming of the transmitter there might have been 1129 locations and thus the percentage of success has been 78. The signals show that Hilkka left its nest for the first time on the 6th of Aug when the distance from the nest was calculated to have been between 270-315 m based on the satellite information. The first observation 1 km away from the nest was recorded on Aug the 10th and 2 km away on the 23rd of Sep. The previous year White-tailed sea-eagles of the Quarken area were 1 km away from the nest between 8th to 16th of Aug which means about the same time as this year. In Aug Hilkka moved around on an area of 1.7 km² and in Sep 2.3 km². Hilkka's home range between Aug 1st and Oct 8th was totally only 4.1 km². At its closest Hilkka stayed at a distance of 50 m from a wind mill in the area. Hilkka left its home range on the 8th of Oct.

The satellite White-tailed sea-eagle of summer 2011

During the summer of 2011 four new individuals were equipped with satellite transmitters. They are all GPS-Argos transmitters with solar panels and made by Microwave.

Johannes. The young eagle was fitted with a transmitter by Messrs Torsten Stjernberg, Hannu Ekblom ja Johan Franzén in the Sottunga municipality in Aland on June the 21st 2011. The eagle was named according to an Aland born painter Johannes Snellman. He was an active ornithologist and he also ringed the first White-tailed Sea Eagles in 1917 in Geta and established the birding station of Signilskär in 1927. The nest of Johannes was selected to the studies as there is a chance to follow the possible role a wind mill on Kasberget (Sottunga) on its movements.

Cilla. Mr Sami Lyytinen, Ms Christa Granroth, Mr Kari Lehtivaara and Mr Jouko Högmander fitted this eagle with a transmitter on June the 28th 2011. The site was on the west coast of Kemiönsaari in a nest on the border of the Gullkrona open sea. The individual was a female and it was named Cilla in a name contest organized by WWF. The suggestion came from Ms Satu Metsola and the name is derived from the scientific mane of the species Haliaeetus albicilla. This transmitter was donated by Nokia (Connecting people). Cilla was connected to the studies as Kemiönsaari is one of the pioneers in the field wind power. There are three windmills in action and tens of new mills are planned to be placed on the main island.

Eetu. Messrs Sven Nordqvist, Toni Laaksonen and Jouko Högmander fitted the transmitter on a young male eagle the 22nd of June 2011 on a nest in Uusikaupunki. This bird was named Eetu according to the name contest organized by WWF.  The name was suggested by Ms Satu Metsola and it is derived from the scientific mane of the species Haliaeetus albicilla. The nest of Eetu was selected to the studies as it lies in the southern part of the Bothnian Sea which is an important breeding area and additionally it is along an important migration route of eagles. The local winds are also in favor of windmills.

Aava. The fourth new transmitter was fitted on June 28th 2011  to a female young White-tailed eagle on the island of Raippaluoto in Mustasaari. This bird was named Aava according to the name contest organized by WWF.  The name was suggested by Ms Sinikka Junno, Ms Pia Harju and Ms Elina Kuusisto. The following of the Aava-eagle will hopefully add to the information of four previous eagles of 2009. The comprehensive windmill plan may, if materialized, be a potential risk to the dense White-tailed eagle population in the area. The transmitter was fitted as earlier by Messrs Juhani Koivusaari and Timo Lumme.

Individual Area ring Year ring Transmitter Sex Weight Nest
Johannes E-23255 D224 105682 male 4,0 kg Sottunga 1
Cilla E-23838 D309 105681 female   Kemiönsaari 1
Eetu E-21474 D308 105680 male   Uusikaupunki 1
Aava E-24372 ei ole 33210 female 4,0 kg Raippaluoto 2
Home ranges 2011

N.B. Tracking locations are not included on the map because of protection reasons.

Johannes sent 1237 GPS-signals during Jun 21st– Oct 13th, when the bird still stayed in its home range. According to the programming of the transmitter during the mentioned period there could have been 1656 locations and thus the success was 74 %. The satellite signals showed that Johannes moved more than 50 m from its nest already on the 27 th of June, but the 100 m limit was passed certainly only on the 11 th of July. The first location over 1 km from the nest was received on the 28 th of July and the 5 km limit was passed on the 20 th of August. In the beginning of September Johannes visited the S part of Föglö being 24 km away and further 16 km away from its nest in Kumlinge, but returned always to the nest in Sottunga. The locations in June-July were received from an area of 1,5 km², in August 176 km², in September 600 km² and in early October 219 km². The total home range between Jun 6 th and Oct 13 th was 748 km². According to satellite data on 8 separate days Johannes paid a visit closer than 300 m to the wind mill on Kasberget in Sottunga.

Cilla. During the period Jun 28 th – Oct 17 th Cilla circled on its home range and 902 out of 1390 programmed GPS-locations were successful (66 %). The first signal from Cilla being more than 100 m away from the nest was received on Jul 22 th; the 1 km limit was exceeded on Jul 30 th and the 5 km limit only on Aug 31 st. Cilla did a 24 h trip flying some 20 km and visiting nearly the center of Kemiönsaari. The locations of Cilla were received in June-July from an area of 2,8 km², in Aug 14 km², in Sep 211 km² and early Oct 44 km². Cilla’s home range was between Jun 28 th and Oct 17 th altogether 250 km² which is only about one third of that of Johannes.

Eetu stayed on its home range between Jun 22 nd and Oct 13 th. There were 743 succesful GPS-locations out of 1427 (52 %). That is the worst success percentage of all 9 transmitters during the first months. The first location being more that 100 m from the nest was received on Jul 20 th which was about equal to the other satellite birds of 2011. There after Eetu stayed only some hundred meters away from its nest until Sep 5 th , when it took a trip of more than 10 km from the nest. Eetu had a smaller home range that the other young satellite eagles of 2011. The locations both in June-July and August were received from an area of 1 km², in September 28 km² and early October 128 km². Eetu had a home range between Jun 22 nd and Oct 13 th of a total of 189 km².

Aava sent 1077 GPS-signals during Jun 28 th – Oct 7 th, when Aava was still staying in its home range in Raippaluoto and Björkö. The transmitter was programmed to send 1219 locations during that period and there were 1072 successful (88 %). That result was very good as has been with all the transmitters used in the Quarken area since the summer of 2009. According to the satellite information Aava passed the 100 m limit from the nest for the first time on Jul 25 th. The 1 km limit was passed on Sep 2 nd and the 5 km limit between Sep 30 th and Oct 1 st, when Aava visited the E coast of Raippaluoto the vicinity of the bridge the strait of Alskat. Later on 2 nd and 3 rd Aava took a long round trip to the N part of Björkö, over 15 km away from its nest. Before moving to the continent on Oct 6 th and 7 th Aava paid a visit to the planned windmill area and continued to Björkö region and the following day it passed the strait of Alskat to the continent. In June-July and August the locations of Aava were received from an area less than 1 km², in September 19 km² and early October 220 km². The home range of Aava between Jun 28 th and Oct 7th was altogether 220 km².

The White-tailed Sea Eagles of 2013 with satellite transmitters

In the summer 2013 two white-tailed sea eagles were equipped with solar panel charging GPS-Argos transmitters made by Microwave. The transmitters were achieved as in the case of Hilkka with a donation from the eagle protection fund of The Finnish Association for Nature Conservation (FANC). The origin of the funds relate to a late Markku Nygård who used to be a member of the White-tailed Sea Eagle working group of WWF Finland. The two new eagles, Tyrsky (i.e. surging wave) and Tyyni (i.e. calm) were named according to a competition organized by WWF Finland.

Tyrsky. On Jun 19th 2013 this eagle got the transmitter in Kokemäki and the bird was determined to be a male according to its measures. The field work was performed by the WWF group members Jouko Kivelä, Seppo Keränen and Sven Nordqvist.

Tyyni. This eagle was hatched in Parainen and it was equipped with a satellite transmitter on Jun 27th. It was determined to be a female. In this case the operation was performed by Jouko Kivelä with help from Teemu Honkanen, Toni Laaksonen and Sven Nordqvist.

Individual Area ring Year ring Transmitter Sex Weight Nest

Tyrsky

E-21819

F344

33211

male

 

Kokemäki 1

Tyyni

E-22735

F773

33212

female

 

Parainen 1

Nature data for planning wind energy production in the province of Satakunta –project: satellite sea eagles in 2013 (text: Asko Ijäs)

The transmitters were installed on eagles as a part of the project “Nature data for planning wind energy production in the province of Satakunta”. The aim is to collect basic data about the nature in the province of Satakunta especially for for the planning of additional wind power projects and its environmental impact. The main sponsors of the project are European Regional Development Fund (ERDF), The Centre for Economic Development, Transport and the Environment (ELY Centre) in SW-Finland and some private businesses in the field.

Fiia. On Jun 6th 2013 the transmitter was installed on the back of a young eagle at the nest close to Rauma. The local newspaper organized a competition to give a name to this eagle. Some 20 good alternative suggestions were proposed and the winner was Fiia. The name reflects old cultural heritage and islander traditions. At the time of the installation Fiia was the first eagle to get a transmitter.

Auli. This eagle was hatched in central part of the province of Satakunta in the border area of Pori and Luvia. The transmitter was installed to the eagle on Jun 9th 2013. The aim is to collect avian data for the planning of wind power plants in central Satakunta. The bird was named Auli according to name of the lady who discovered the nest.

Tulva. On Jun 17th 2013 the following of the third white-tailed eagle in the province on Satakunta started as the eaglet got satellite transmitter in the N part of Merikarvia. The individual was regarded to be a male according to some body measurements. The bird was called Tulva (Flood) as there was wide flooding in over the N part of Satakunta province. There are also comprehensive plans for wind power plants in the same area. The data collected will hopefully be used in respecting the breeding areas of the white-tailed eagles.

Individual Area ring Year ring Transmitter Sex Weight Nest

Tulva

E-23542

F343

105831 (female)

 

Merikarvia
Auli

E-24683

 

105832 (female)

 

Viasvesi
Fiia E-24680   105833 (female)   Kuolimaa
Home ranges in 2013

Tyrsky. During Jun 19th to Sep 29th there were 1072 locations from Tyrsky while still staying on its home range. Only on Jul 11th Tyrsky left the nest for the first time for a distance more than 100 m according to the satellite observations. The distance of 1, 2 and 5 km from the nest were passed on Aug 1st, Aug 12th and Aug 15th, respectively. Between Sep 3rd and 4th before leaving the home range Tyrsky visited an area 13 km away from the nest. During a period starting on Jul 11th, when Tyrsky had certainly been outside the nest, until Sep 23 rd when Tyrsky did not any more return to the vicinity of the nest, the area of the home range is calculated to be 120 km 2 (n= 797). About 90 % of the observations during that period are limited inside an area of 3,3 km 2 (n= 717). Only 2 % of the observations have been more than 2 km from the nest. Based on protection reasons the map of the home range is not published.

Tyyni. During Jun 27th and Sep 30th there were all together 869 locations of Tyyni on its home range. On Jul 27th the first observation of Tyyni being more than 100 m from the nest was recorded. On Aug 20th Tyyni was observed more than 1 km from the nest, and the 10 km line was crossed on Aug 29th. Between Sep 24th and 27th Tyyni stayed more than 20 km from the nest, but returned back to nest. Only on Sep 30th Tyyni left finally the home range. The size of the home range between Jul 24th and Sep 29th was 226 km 2 (n= 588). If we calculate 90 % of the closest observations to the nest, the center home range is 10,6 km 2 (n= 529). During the observation period 14 % of the locations were received more than 2 km from the nest.

The home ranges of the White-tailed eagles of the LTSS project in 2013

Tulva. Between Jun 17th and Sep 30th altogether 794 GPS-signals were received from Tulva as it stayed on its home range. According to satellite information Tulva left the nest the first time for a 100 m distance on Jul 17th. Thereafter Tulva stayed in the vicinity of the nest. The first signal over 500 m from the nest was received on Aug 10th when it flew over 4 km from the nest. The only long day trip took place on Sep 25th when it visited a distance of 14 km from the nest. After Sep 30th there were no GPS-signals in two weeks but the Doppler-locations show that it was still within the home range on Oct 11th. The next GPS-signals were received on Oct 13th when Tulva was on it way towards S and 30 km from its home range. Thus the exact time of its leaving the home range is rather well known. The size of the home range between Jul 7th and Sep 30th according to GPS-signals from that period, was 160 km2 (n=515). If we calculate only the 90 % of the signals that are closest to the nest, we get the area the centrally located home range that is only 6,4 km2. Some 20 % on the signals during this period were received more than 2 km from the nest.

Auli. Between Jun 9th and Sep 9th altogether 977 GPS-signals were received from Auli as it stayed on its home range. According to satellite information Auli left the nest the first time for a 100 m distance on Jul 29th. And the 500 m limit was passed the following day. On Jul 16th Auli was located one kilometer away from the nest, five kilometers on Jul 27th and ten kilometers on Aug 6th. Before final leaving of the home range on Sep 9th , it made three long patrolling trips from the nest: 72 km (Aug 23th to 24th), 20 km (Aug 8th) and 55 km (Sep 3rd to 4th). After all these trips the satellite found Auli only some hundreds of meters from the nest tree. It is a matter of taste, when Auli is regarded to have left its nest. If the line is drawn at the first long patrolling trip, the size of the home range between Jun 29th and Aug 23rd is 67 km2 (n= 584). If we calculate only the 90 % of the signals that are closest to the nest, we get the area the centrally located home range that is only 1,5 km² (n = 525). Only 2 % on the signals during this period were received more than 2 km from the nest.

Fiia. Between Jun 6th and Jul 27th altogether 527 GPS-signals were received from Fiia as it stayed on its home range. According to satellite information Auli left the nest the first time for a 100 m distance on Jun 20th. And the 500 m limit was passed on Jun 27th. One kilometer limit was passed on Jul 4th and on Jul 20th. Fiia passed the 20 km limit from its nest. In the morning of its final day (Jul 27th) on the home range Fiia was still in the middle of this area, but in the evening already 130 km away. The whole size of the home range between Jun 6th and Jul 27th was 58 km² (n = 406). If we calculate 90 % of the locations that were closest to the nest, centrally located home range is only 0.6 km² (n = 365). Only 2 % on the signals during this period were received more than 2 km from the nest. Based on protection reasons the map of the home range is not published.

Person in charge of the page: 
Text: Pertti Saurola, Translation: Ismo Nuuja, Page management: Markus Piha
8.2.2017