Szymon Beuch, Arkadiusz Sikora, Przemysław Wylegała
Ornis Polonica 2026, 67: 94-109
https://doi.org/10.12657/ornis.2026.2.2
Abstract: The first breeding attempts in Poland were recorded in 1997, and since 2010 the species has shown a rapid expansion in both breeding range and population size. Between 2013 and 2025, the breeding population increased by 84%, corresponding to an average annual growth rate of 7%. During 2020–2025, all known breeding sites of the Great Egret in Poland were monitored to assess changes in the distribution and size of the breeding population. Breeding was recorded exclusively in eastern and north-eastern Poland at 31 sites, including 15 in the Lublin region, 11 in Warmia and Masuria, and five in Podlasie. In addition, eight historical breeding sites recorded during 1997–2019 were no longer occupied. The national breeding population reached its highest numbers in the last three decades and was estimated at 1,150–1,250 pairs in 2023–2025. On average, 39% of the national population occurred in Warmia and Masuria, 32% in Podlasie and 29% in the Lublin region. In 2020–2025, the population trend showed a moderate increase of 11.6% annually (λ = 1.1162; SE = 0.0418). Individual heronries contained 1–251 nests, averaging 64.2 occupied nests (SD = 56.4). Colonies holding up to 25 pairs predominated and accounted for 45.2% of all sites (N = 14). Three colonies contained on average 100–125 nests, whereas only one colony, Lake Gaładuś in Podlasie, exceeded 200 nests on average. Great Egrets most frequently nested on lakes (N = 13) and reservoirs (N = 9), which together accounted for 71% of breeding sites and 73.1% of all nests. Most colonies (N = 20; 64.5%) were located in reedbeds, which supported 56.7% of all nests. Single-species colonies accounted for 35.5% of sites (N = 11), whereas mixed colonies with Grey Heron A. cinerea occurred at 66.7% of sites (N = 19), with Great Cormorant Phalacrocorax carbo at 11.1% (N = 3), and with Black-crowned Night Heron Nycticorax nycticorax at 3.7% (N = 1). Breeding colonies were located 50–3,700 m from the nearest buildings, with a mean distance of 814 m (SD = 1,084).
Keywords: Ardea alba, changes in distribution, Great Egret, population growth, range expansion
