Suomen merikotkat 2013-2015

Summary: Population size and nesting success of the White-tailed Sea Eagle (Haliaeetus albicilla) in Finland, 2013–2015.
■  In an earlier paper (Stjernberg et al. 2013) the population size and nesting success of the White-tailed Sea Eagle in Finland in 1970–2012 was reported. In this paper we examine the re-covery during the last three years (2013–2015).
The Sea Eagles in Finland have been monitored by a voluntary Sea Eagle working group within WWF Finland since 1973. Every known territory has been checked annually, and new territories and nests located by seven regional working groups. For surveyors, see under the heading “Kiitokset”. The number of occupied territories (with eggs or nestlings or at least a decorated nest) was 428
in 2013 and 458 in 2015 (Fig. 1). In 1990 there were 75 occupied territories. If also “lost pairs” are considered, i.e. known pairs whose nesting attempt of the year had not been found (78 in 2015), and if also for the surveyors totally unknown pairs are taken into account, then the number of Sea Eagle pairs in Finland in 2015 was about 550. Of the known occupied territories ca 370 are at the Baltic coast or in the archipelago, i.e. brackish water, and about 90 in Northern and Eastern Finland, and about 25 in Southern and Central Finland, i.e. fresh water breeders. The absolute number of recorded nestlings has risen. In 2013 422, in 2014 459 and in 2015 417 half-grown living nestlings were recorded (Fig. 2). The nesting success was reasonably good, 63,1 %, 63,8 % and 60,5 %, respectively (cf. Fig. 3). The numbers of nestlings per occupied territory for the whole country was 0,99 in 2013, 1,02 in 2014 and 0,91 in 2015. For the situation in different regions, see Fig 4. The nesting success on the Åland Islands is still lower than in other coastal regions (Fig. 3). In the Quark the nesting success in 2013 was the best ever recorded: 57 successful nesting attempts were found, 75,3 % of all nesting attempts were successful, 90 nestlings were re-
corded, and the average number of nestlings/occupied territory was 1,23. However, in 2015 the nesting success was low: 40 successful nesting attempts, 59,7 % of all nesting attempts weresuccessful, 65 nestlings were recorded and the average number of nestlings/occupied territory was 0,60. The number of “lost pairs” in 2015 was extremely high, 25, compared to 10 in 2013, 11 in 2014. An eventual causal effect of an exceptional high number of sea eagles with
lethal amounts of lead within the very last three years within the Quark is discussed. During the time period 13.6.2011–3.2.2016 Evira/Oulu analysed 19 sea eagles found dead in the Quark. The first specimen with diagnosis lead poisoning was found 16.12.2013, the following four specimens 27.1.2015–3.2.2016. The last specimen had 4 lead shots in its gizzard and the amount of lead in its liver was even as high as 53mg/kg.Fig. 5 presents the development of the Sea Eagle population in the whole country in 1980–2015 and for SW and W Finland (brackish water) in 1972–2015.Fig. 6. presents the average numbers of White-tailed Sea Eagle nestlings/occupied territory and successful nesting attempts (%) in pentads in different regions in Finland 1970–2014. During the last decades an expansion of the White-tailed Sea Eagle to freshwater habitats in the southern and central parts of Finland has been going on, cf. Fig. 7, which shows the geographical distribution of the territories and Fig. 8 the temporal development of the inland population south of Northern Finland. In 2015 the number of these freshwater territories was 23.
There are extensive plans to build wind power plants in and off the Finnish coastal zone. Several of these projects are similar to that in Smøla, Norway, where about 40 Sea Eagles were found dead after colliding with turbine blades in a wind power park during 2005–2012.

Also breeding success was reduced. Good planning is needed to eliminate or at least reduce the conflict between wind power and the Sea Eagle. WWF Finland has issued Guidelines, in Finnish and Swedish, on how already during the planning process conflicts between Sea Eagles and windmills can and should be avoided. http://wwf.fi/mediabank/7088.pdf In the Guidelines there is a recommendation that the distance between a wind mill and a Sea Eagle nest should be at least 2 kilometers. This recommendation gets support of the results of two new Finnish studies. The nesting success is lower in nests in the neighborhood of a wind mill than in more distant nests (Balotari-Chiebao et al. 2016a). The pattern of movements of eaglets, equipped with GPS-satellite transmitters, after leaving their nests also give support to the recommendation “at least 2 kilometer” (Balotari-Chiebao et al. 2016b). More detailed knowledge of how Sea Eagles move is needed, also elder age classes. In 2009 as a pilot project, four Sea Eagle nestlings were equipped with GPS-satellite transmitters in
the Quark, on the island of replot/raippaluoto, where the first example of a conflicting situation is taken place, in an area of central importance for the Sea Eagle. Since 2009 a total of 14 ea-glets have got a transmitter. Ten of them still provide fixes. During the last six and a half years the transmitters have in total produced more than 125 000 exact fixes (Table 1). The eagle “Junnu” has according to the fixes moved around more than 60 000 kilometers. Preliminary analyses already show that there are distinct types of young Sea Eagles viz-a-viz movement: some represents a migratory type, other are more sedentary. Only
one eagle has so far started to breed. “Hilkka”, hatched in 2010, made an unsuccessful nesting attempt in 2015. The movements of the Satellite Eagles can be seen on the web page of the Finnish Museum of Natural History (cf. also Saurola et al. 2010):http://www.luomus.fi/zoology/english/zoology/ satellite_eagles/index.htm