An adult sea eagle was ringed for the first time in the Nordic countries, when the bird was injured and fell into the hands of people. Now one of the riddles related to it is getting a solution.
Monitoring the movements of the sea eagle named Minna has brought new information about the behavior of adult sea eagles.
– Its age cannot be determined exactly, but it was more than 6 years old then, so now it is at least 9 years old, probably even older. We thought that a bird of that age would start nesting right away, says Osala.
However, this did not happen, and the bird spent three years in Sinkuelämä. Only now has the female sea eagle found a mate.
– It has been wondered why it doesn’t start nesting. At the sea eagle researchers’ 50th anniversary seminar, it raised thoughts that apparently there are old maids and backroom boys among sea eagles, says Osala.
Minna’s origin being solved
The background of the Minna sea eagle has been a mystery to researchers, as the bird ringed in Northern Savo has spent its summers in Finland and winters in Germany. Now it has found a German spouse, whom Osala has named Helmut. The couple has formed a territory on the island of Rügen.
According to Osala, sea eagles choose a nesting place less than a hundred kilometers from their own place of birth, so it seems that Minna is German.
– We have a big study going on, where DNA is used to find out the family trees of sea eagles. We also have Minna’s DNA test, but her family tree is still not clear.
So what can explain the fact that a sexually mature bird does not start breeding right away? According to Osala, finding the right partner does not necessarily explain the matter. By following the pairs of sea eagles living in Pohjois Savo, it has become clear that they do not immediately start building a nest either.
– When a pair of sea eagles had found each other, they hung out for a couple of years before they started nesting. The behavior of adult sea eagles is now better understood.
Now let’s start nesting
Sea eagles have been protected in Finland for 50 years. According to Osala, thanks to the protection, sea eagles have increased in number, their preferred nesting places have been filled and they have started to move inland.
Osala offers one explanation for postponing nesting:
– If the potential nesting sites and areas are full, then you just don’t start nesting.
Bald eagles can live to be over 30 years old if they survive infancy. After that, they are especially threatened by human activities. According to Osala, the most common cause of death is lead. Colliding with wind turbines also kills sea eagles.
Minna and Helmut probably have many years together ahead of them, as sea eagles mate for life.
– Unless one of the spouses dies, in which case they can accept a new spouse, Osala says.
Now the researchers are excited whether the pair of sea eagles will succeed in their first nesting.