Adam Zbyryt, Sebastian Menderski
Ornis Polonica 2017, 58: 178–186
https://doi.org/10.12657/ornis.2017.3.2
Abstract: The study describes the number and distribution of Grey Herons breeding in the Warmińsko-Mazurskie Province in 2016. A total of 28 breeding sites and 2413 breeding pairs were found. The average breeding density was 100 pairs/1000 km2, and 1.1 colony/1000 km2. The average colony consisted of 86 pairs (range 1–251). Most colonies were located in forest aged 28–151 years (mean 77 years). Forest patches covered the area of fewer than 25 ha (0.4–21.2) . The most common habitat type was single-species stands (70%). On average, heronries were located at a distance of 394 m from potential foraging grounds (range 0–2230). Most colonies were located up to 500 m from the buildings (79%), and the mean distance from the buildings was 403 m (range 50–2330). The majority of heronries (60.7%) were located inland, 35.7% on lake islands and 3.6% on the ground, in reedbeds. Half of the colonies were mixed-species with co-nesting Great Cormorants Phalacrocorax carbo (12 colonies) and Great Egrets Ardea alba (2 colonies).
Keywords: breeding colony, Grey Heron Ardea cinerea, population size
