Spotted Eagle Aquila clanga

DISTRIBUTION AND ABUNDANCE

Poland is situated on the western margin of the Spotted Eagle distribution range, and therefore the species has always been rare in our country. In the 19th and at the beginning of the 20th century Spotted Eagles nested in a few regions, mainly in the eastern part of Poland. According to Taczanowskiego, in Lublin Province this species was then to be almost as abundant as the Lesser Spotted Eagle. In the first half of the 20th century a few Spotted Eagle nests were discovered in the Masurian Lake District. One should remember, however, that drawing conclusions on the numbers of the Polish Spotted Eagle population is rendered difficult on account of many past identifications being uncertain. For instance, of the numerous observations made in the Masurian Lakeland, a mere one record of the species probable nesting in the environs of Mikołajki has been acknowledged as reliable by the Faunistic Commission. It is also meaningful that very intensive controls of the region, carried out by KOO members, able to distinguish between the two species mentioned in the field, resulted in discovery of a few hundred new nest-sites of the Lesser Spotted Eagle exclusively.

The only Polish region of Spotted Eagles regular breeding is the Biebrza River Basin, where 1-3 pairs were observed in 1966-1970, 2 breeding pairs were recorded in the period of 1979-1982, and one nest with a nestling was found in 1988 (middle Biebrza). In 1989-1997, owing to systematic search of water-logged alder carrs and birch woods in the entire Basin, a total of over 30 nests belonging to 14-15 pairs were discovered. The faithfulness of birds to the occupied breeding territories should be emphasized here, e.g. two territories localized in the 70s were also found occupied in the 90s. Within the last 30 years the numbers of the Spotted Eagle in the Biebrza River Basin have probably increased, although it is difficult to determine the pace of this growth, as it is only recently that the area was penetrated with sufficient precision. Also, the previously published numbers are very likely to have been underestimated. Recently, the Spotted Eagle population displays a high stability.

In the Lublin region one pair of Spotted Eagles probably bred in Lasy Sobiborskie near Włodawa in the 60s and 1981, no nests discovered though, whereas one nest was found in Lasy Janowskie in 1985. Besides, one pair was known to nest in 1959 in the Bieszczady Mts (Bukowy Berd). In the next year a dead bird was found between Rajsk and Wołkowyja. The Spotted Eagle may still be breeding in this region, which is testified to by records coming from this area.

Below is a list of observations of adult Spotted Eagles, made in the breeding season, accepted by the Faunistic Commission (data from the Biebrza River valley omitted). These records can serve as hints for further investigations, as none of them led to discovery of a nest, and also no behaviour indicative of nesting was observed.

26.05.1986 - 2 inds., Polany, Comm. Krempno (Beskid Niski), Prov. Krosno;
23.06.1987 - 1 ads., Tarnawa, Comm. Zagórz, Prov. Krosno;
03.08.1987 - 2 ads., Niedrzwica, Comm. Gołdap, Prov. Suwałki;
13.05.1989 - 1 ads., Hieronimowo, Comm. Michałowo, Prov. Białystok;
10.06.1989 - 2 ads., Wiązownica, Prov. Przemyśl;
09.05.1990 - 1 ads., Pniewo, Comm. Węgorzewo, Prov. Suwałki;
01 and 04.05.1991 - ads. on each day, Comm. Gołdap, Prov. Suwałki;
01-02.05.1991 -1 inds., Comm. Strzelcowizna, Prov. Suwałki;
16.06.1994 - 2 ads. and 26.06.1994 - 1 ad., Grąziowa, Comm. Bircza, Prov. Przemyśl.

In spite of the recent marked growth in the intensity of field research, for a dozen or so years no information has been acquired about the Spotted Eagle breeding beyond the Biebrza River Basin. Supposedly, the birds once nesting elsewhere in Poland have withdrawn from their sites, and the whole Polish population of this species has dropped to numbers not exceeding 20 breeding pairs. The Spotted Eagle has remained in our country only in its typical habitats, i.e. vast bogs of a river valley.

MONITORING

Nowadays, the only breeding grounds of the Spotted Eagle in Poland fall within the Biebrza River valley. The species population is estimated at 15-20 breeding pairs, seemingly almost all breeding sites known and controlled. The results of monitoring conducted in 2001 and 2002 are presented in the table below.

Table. Results of the Spotted Eagle monitoring in 2001 and 2002. (1) - total number of controlled sites, (2) - total number of controlled nests, (3) - number of sites where birds were recorded, (4) - number of nests at which zone protection regulations were found violated, (5) - number of nests newly found in the territories known from previous years, (6) - number of newly found territories with a nest, (7) - number of newly found territories without a nest

Region	Controlled sites (1) 2001 2002	Controlled nests (2) 2001 2002	Sites with birds (3) 2001 2002	Regulations violated (4) 2001 2002	New nests in territory (5) 2001 2002	New territory with nest (6) 2001 2002	New territory without nest (7) 2001 2002
Podlaskie	19 20	24 20	13 13	1 -	6 4	- -	- -

REPRODUCTIVE PARAMETERS

The results of the Spotted Eagle broods in 1999, 2000 and 2001 are as follows: