Finnish Museum of Natural History
Male Osprey M-32550 "Lasse"
Lasse, the male Osprey, was captured at his nest in Utsjoki on 6 August 2001. As a nestling, he had already been ringed by Lasse Iso-Iivari with the ring M-32550, which showed that Lasse had been born seven years before, and only 3 kilometres from his present nest. When he was captured, he weighed 1410 g. He was fitted with a battery-powered radio transmitter that weighed 30 g and is manufactured by North Star. According to the available data, Lasse was the northernmost nesting male Osprey in the world in 2001.
Autumn migration 2001
Lasse stayed near his nest feeding his offspring until the 23 September, when he set off South. The same day, we had a reading from Rahajärvi in Inari, a distance of 110 km. From Rahajärvi, Lasse's migration progressed by way of Pudasjärvi, over the border to Jänisjärvi in Carelia. Lasse arrived in Shap-Navolok, East of Lake Ladoga on 29 September. The next reading could not be obtained until 36 hours and 45 minutes later, due to the transmitter's programming. The radio signal announced that Lasse was in the Ukraine, 1153 km from the shores of Lake Ladoga! After resting and filling up for a week, he continued by way of the Crimean, over the Black Sea to Turkey. Lasse arrived in Israel on 11 October after covering 4173 km in 18 days, i.e. 232 km a day counting stops.
At first we believed that Israel was just a leg on the journey and that he would continue towards the Equator, where most Finnish Ospreys winter according to ring recoveries. However, the readings came from the fish farm area of Beit-Alpha in the Jordan Valley, 30 km SE of Nazareth.
Spring migration 2002
Lasse stayed in Israel exactly six months. We had the last reading from Beit-Alpha on 11 April. The next day, Lasse was already flying over the Anti-Lebanon mountains and ended up in Syria by evening, 250 km from his winter fishing. His spring migration followed the main lines of the autumn migration; over mid-Turkey to the Crimean on the Black Sea, then over the Ukraine and Belorussia to the eastern parts of the Gulf of Finland, and then over eastern Finland to Utsjoki. To be exact, the readings were at first nearly 300 km more easterly in the spring than in the autumn, but after crossing the Black Sea, Lasse flew 100-300 km West of his autumn route. He flew c. 3100 km from Israel to the southern coast the Gulf of Finland in 11 days, i.e. an average of 282 km/24 h. The readings show that Lasse spent some time fishing at Kivijärvi in Luumäki 27 April - 1 May, and reached his nest in Utsjoki on 4 May. Because of the 'delay', his spring migration took four days longer than the autumn migration.
The transmitter battery gradually died out in mid-May. At the end of July, Lasse was recaptured and the transmitter was removed. Lasse, who weighed 1530 g or 8% more than a year earlier, and his three offspring were in excellent health, which proves that Lasse's condition was in no way affected by the transmitter.
Lasse Iso-Iivari recognized Lasse the Osprey in summer 2003 on the basis of his rings. Lasse nested at Utsjoki in the same nest as the previous years, and together with his mate he produced three eggs, from which two nestlings developed.