Irina Samusenko, Alexander Pyshko
Ornis Polonica 2023, 64: 1–16
https://doi.org/10.12657/ornis.2023.1.1
Abstract: For the first time since 2009, the population status and dynamics of large white-headed gulls from the genus Larus have been assessed based on all known breeding cases in Belarus. We collated all the available (both published and unpublished) data and results of our own censuses in most important breeding sites. The total population size was estimated at 8,000–9,500 breeding pairs in 2018–2022 and have increased about 3.5 times since 2009. 70–80% of gulls nested in 8 large colonies with more than 100 pairs, including the largest Gatovo colony, which grew to 5,000 pairs. About 75% of gulls nested on the roofs in 9 cities and towns, and 25% in the natural habitats. During the study period, there were at least 4,800 pairs of Caspian Gulls L. cachinnans and 800 pairs of Herring Gulls L. argentatus. Several Lesser Black-backed L. fuscus and Yellow-legged Gulls L. michahellis nested in Gatovo colony, mostly paired with other species. The rest of the estimated population may include both mixed and ‘pure’ pairs, as well as hybrids, the number of which could not be more accurately determined. Two numerous species entered Belarus in the 1980s: Herring Gulls – probably from the north, Caspian Gulls – from the south. By now, the Caspian Gull can be found almost all over the country and dominates most of the known nesting sites, except for a few sites on raised bogs and lakes in the north, where the Herring Gull can still be the most numerous. The increase of the Herring Gull’s population was much stronger until the 2000s and has slowed down more recently, but the growth rate of the Caspian Gull exceeded it by more than an order of magnitude in the last two decades. The newly observed rooftop nesting of the Caspian Gull contributed to the rapid expansion and current high numbers of this species in Belarus, and, interestingly, this phenomenon is extremely rare elsewhere. The rapid growth of populations of large gulls in the area of Minsk city is most likely linked to the vicinity of an abundant foraging ground in the largest landfill in the country as well as availability of secure nesting sites (rooftops).
Keywords: abundance, Belarus, breeding pairs, Caspian Gull, distribution, Herring Gull, Larus argentatus, Larus cachinnans, Larus fuscus, Larus michahellis, Lesser Black-backed Gull, population trends, Yellow-legged Gull
