Adam Zbyryt, Sebastian Menderski, Sławomir Niedźwiecki, Roman Kalski, Karol Zub
Ornis Polonica 2014, 55: 240–256
https://doi.org/10.12657/ornis.2014.4.1
Abstract: During 7 breeding seasons (2004, 2006, 2008 and 2010–2013) a breeding population of the White Stork Ciconia ciconia was studied within Warmińska Refuge – Natura 2000 SPA (central point: 54°31′N; 20°80’E). Standard methods, used during the International White Stork Census, were applied. This area is one of the key breeding sites of the species in the world. The average density ranged from 50.2 pairs/100 km2 in 2008 to 70.6 pairs/100 km2 in 2004. The average number of fledglings reared by a breeding pair varied from 2.02 in 2004 to 2.81 in 2011 (JZa x=2.58; SD=0.29), and the average number of fledglings reared by a successful pair from 2.31 in 2004 to 3.05 in 2013 (JZm x=2.75; SD=0.27). In all study years the population of White Stork in Warmińska Refuge produced at least 12 329 fledglings. On average, ca. 1761 chicks were produced annually. The largest share of couples without young (%HPo) was recorded in 2004 and the lowest in 2006 (x=7.3%; SD=3.7). The largest colonies were situated in the northern part of the studied area. In 19 colonies in 2013 the decrease of nesting pairs by 11% (Krzewno) to 49% (Żywkowo) was observed (mean 32%; SD=11.5) in comparison to 2004, 2008, 2010. The biggest drops concerned large colonies, gathering >30 pairs. The increase in numbers was recorded in 4 small- and medium-sized colonies (range 5–15 nests) and only in one big colony in Lwowiec. Frequency of nest location type in Warmińska Refuge changed considerably in 2004–2013. In 2013 the share of nests located on pylons raised by almost 20% compared to 2004. At the same time the number of nests placed on roofs of buildings dropped by 23%.
Keywords: breeding success, Ciconia ciconia, distribution, numbers, Warmińska Refuge, White Stork
