Greater spotted eagles Ann and Mart
Ann is one greater spotted eagle with an unusual fate. To be more specific, Ann had been caught and ringed earlier in 2001. Ann was at that time already over 5 years old, thus she is more than 10 years old now…
We managed to catch her in the net on 14 July when we had been trying to catch her for a week. Just in case, we left the shelter near the nest and checked back five days later to see if things were ok. It turned out that nothing had changed in Ann’s behaviour since we had placed a 45 g backpack on her – she was feeding her eaglet and brought fresh branches to the nest just like before. And the eaglet had become considerably stronger. When Ann brought food to the eaglet, she stayed in the nest for a longer period of time, arranging the branches and sitting at the edge of the nest or on some nearby branch. When the male bird brought food to the eaglet, he threw it to the nest and never stayed there longer. On some days Ann did not bring any food, only the male bird brought food. All in all, the food brought by the female bird was about one-fifth, i.e. the main supplier was the male bird. It is possible that starting the migration early increases the chances of survival of female birds during migration – anyway there is a deficit of male birds among greater spotted eagles. In Estonia up to half of the female greater spotted eagles mate with the male lesser spotted eagles.
Ann’s eaglet learned to fly normally and thus Ann left the nesting site at the beginning of August. The male bird stayed near the nest of the eaglet for more than one month. We were not able to identify the exact time when they left but probably they set off to migrate in the first half of September.
When the eaglet was still in the nest, Ann already went wandering around several times and quite far from the nest, and her flights were sometimes up to 20 kilometres. On 5 August Ann did not fly back to the nest, and by the evening she was already 60 kilometres away on the Latvian coast. On 9 August she took a longer trip towards Lithuania; however, for some reason Ann did not want to fly towards the south but turned to the east and ended up in the northeastern part of Lithuania where she stayed for four days. From there, Ann actually took the “wrong” direction to the northeast – she flew over the southeast part of Latvia to Pskov oblast near Ostrov. Ann stayed in Pskov oblast for nearly one month. On 15 October she started her journey again, went through Belarus and by the end of October arrived in Poland in the southeast, 100 kilometres from Warsaw by the Visla River. After that Ann has not sent us any coordinates anymore.
Mart represents the true bred greater spotted eagles of Estonia which is proven by his appearance as well as DNA. We do not have many such pairs of spotted eagles left where both older birds would be pure greater spotted eagles. Mart’s territory in Läänemaa is at the same time one of the biggest known places where greater spotted eagles nest in Estonia.
It took us more than one month to catch Mart. We tried with the stuffed eagle/owl and bait but Mart was suspicious of all nets. Finally we used a net with a radio transmitter-receiver that we received from our Czech colleagues. We managed to catch Mart and place a transmitter on him on 29 August 2006. The eaglet had become independent by this time, i.e. he was flying around freely but was still begging for food from the male bird. Probably the female bird had already started the migration. At the same time there were two strangers, greater spotted eagles, circling around Mart’s territory but we were not able to identify their origin. The purpose of catching Mart was to explore the feeding habits, migration and wintering of endangered greater spotted eagles. After we caught Mart, the points of location we received were from ten and more kilometres away from the nest. It appeared that Mart liked to spy on combine harvesters during harvest. Earlier we had known that such behaviour is characteristic to lesser spotted eagles only…
Mart started his fall migration from Läänema on 15 October (like Juku in previous years) and made at once a record in the daily flying distance – 440 kilometres. By the evening of the same day Mart was by the Nemunas River near the border of Kaliningrad oblast. There he rested for ten days. During the next two weeks, he made it through another 440 kilometres, visiting probably the most famous place of greater spotted eagles in Europe – Biebrza National Park in the northeast of Poland. Unfortunately since 24 November the transmitter of Mart has not sent us any signals.