Arkadiusz Sikora, Dominik Marchowski, Waldemar Półtorak
Ornis Polonica 2022, 63: 199–214
https://doi.org/10.12657/ornis.2022.3.2
Abstract: In the year 2021, in water bodies at Górowo Heights (402.4 km2) in north-eastern Poland 91 breeding pairs of two species of swans were recorded, including 35 pairs of the Whooper Swan Cygnus cygnus (density 8.7 pairs/100 km2) and 56 pairs of the Mute Swan C. olor (13.9 pairs/100 km2). In the study area, 31% of 2 x 2 km sample plots were inhabited by Whooper Swan, whereas Mute Swan inhabited 40% of plots; in 10% of these areas, both species were nesting simultaneously. The strong increase of the Whooper Swan (from 1 to 8 pairs) at Górowo Heights in the years 2007–2021 is convergent with the increase of population in Poland which was estimated in the year 2021 at 290–330 pairs. The swans were breeding on 86 water bodies, out of which 32 were inhabited by single pairs of Whooper Swan and 51 by single pairs of Mute Swan, on two bodies of water there was one pair of each species and on one – 3 pairs of Mute Swan and 1 pair of Whooper Swan. Beaver ponds were the main habitat of breeding swans, whereby they were more frequently occupied by Whooper Swan (74% of breeding sites were located on ponds) than Mute Swan (50%). Recommended conservation measure for both species’ breeding populations is to protect the beaver ponds in the study area and in the entire Special Protection Area of Ostoja Warmińska. This area is one of the most important Whooper Swan breeding grounds in Poland, gathering a dozen or so percent of the national population. It is also recommended to use drones for the monitoring that species in inaccessible areas of beaver ponds.
Keywords: conservation of species and habitats, expansion, Natura 2000 Special Protection Area Ostoja Warmińska, sympatry, waterbirds
