Finnish Museum of Natural History
Osprey Jukka in summer 2010
The treetop, where the natural nest in which Jukka raised three nestlings with his female in summer 2009, is an 18-metre tall, thin pine tree that stands on a windswept hillock with seedlings, so it was to be expected that the nest might fall down during the winter. When it was discovered in early spring that the nest had fallen, Juhani Koivu, Harri Koskinen and Pertti Nikkanen of the Osprey foundation went to build a new artificial nest in Jukka's territory, about a kilometre from the original natural nest. They could not find a suitable tree any closer!
Jukka stayed in his nesting territory for 160 days, i.e. five months and one week. All in all, we received 1,476 fixes on Jukka between the evening of 15 April, when he returned to his territory from the south, and the morning of 22 September, when he set out southwards again. In theory, we could have received 1,612 GPS fixes on him during the summer if all the programmed fixes had been successful. This means that, in summer 2010, the success rate of the fixes was 91.5% (93% in summer 2009), i.e. still good, not to say excellent.
In summer 2010, Jukka's home territory was 715 km² in all, i.e. much larger than the previous year. The difference comes from a few longer scouting trips and the fact that in 2009, Jukka was only monitored for 55 days during late summer. If we calculate with 90% or 75% of the fixes, we will have areas of only 29 km² and 14 km², respectively.
After his arrival on 15 April, Jukka's fixes came precisely from the Pohtiolampi Osprey basins twice, on the 16th and 24th. Birdwatchers looking out for Ospreys also witnessed Jukka's visits at Pohtiolampi in April. What undoubtedly happened was that Jukka thought it best – or he may even have been forced – to make a 40-kilometre fishing trip to Pohtiolampi in the spring, when natural bodies of water were still covered with ice. After his visits in April, Jukka seemingly/possibly visited Pohtiolampi only on 11 June, 23 July, 11 September and 16 September according to the fixes, i.e. very seldom. Even the nature photographers constantly watching at the Pohtiolampi Osprey haven never saw Jukka after April. Once the ice had broken, the pink fish of Pohtiolampi were no longer motivation enough for Jukka to go on a long fishing trip over the natural waters full of fish.
As in previous years, we have omitted all the fixes from the attached maps that could reveal Jukka's exact nesting location. However, they do give a clear overview of Jukka's fishing range. We received a wealth of readings from different parts of Mallasvesi and the lush Tykölänjärvi, i.e. mostly only a few kilometres from the nest.
On the 1st of August, Jukka made an extraordinary visit to Tampere. At 19 o'clock Finnish summer time, Jukka was flying northwest over Liuksiala in Kangasala at an elevation of 765 m and a speed of 35 km per hour. At 22, he surprisingly flew 401 metres above the Sorsapuisto park in Tampere! The fixes from 1 and 4 o'clock, on their part, show that Jukka had stayed the night at the shores of Särkijärvi, west of Hervanta, 30 km from his nest!
For summer 2010, the last fix from Jukka's home territory was received on 22 Sept at 4 summer time, after which Jukka headed away from autumnal Finland – maybe he grew tired of the rain that lasted the whole previous day?