Thulin, C.-G., Sörhammar, M., & Bohlin, J. (2022). Black Stork Back: Species distribution model predictions of potential habitats for Black Stork Ciconia nigra in Sweden. Ornis Svecica, 32, 14–25. https://doi.org/10.34080/os.v32.22081
Increased understanding of the need to save endangered and locally extinct species has led to restoration or preservation of populations through reintroductions. Reintroduction of a species is worthwhile if the prerequisites for existence at the historical location have improved. Thus, background information about the habitat requirements of a target species is important for introduction programmes to be successful. The Black Stork Ciconia nigra was lost as a breeding species in Sweden during the 20th century, but recent observations and reports of potential breeding indicate that habitat conditions for Black Stork in Sweden may have improved. In this study, we used species characteristics and references to identify habitats in Sweden suitable for potential reintroduction of Black Stork. We identified several suitable areas in the former distribution range of this species in southern Sweden. Seven Swedish counties contained more than 18 % suitable habitat within their total area, with highest proportions in Jönköping County (25.8 %), Blekinge County (23.9 %), Västra Götaland County (22.1 %) and Kronoberg County (20.7 %). We suggest these areas to be made the primary targets for Black Stork reintroduction in Sweden.
The estimated habitat area for a breeding Black Stork pair is reported to range from 5,000 to 15,000 hectares (Tucker & Heath 1994, Jiguet & Villarubias 2004, Artfakta 2020a). However, in a study in Lithuania the area of 2,500 hectares surrounding each of 81 nests was described in detail, revealing that on average the habitat comprised at least 13 % forest cover, at least 10 km of watercourses longer than 10 km, and less than 5.5 % disturbance objects (Treinys et al. 2008). Thus, in this study, we used the detailed criteria identified by Treinys et al. (2008) and a habitat area of 2,500 hectares around each nest as minimum environmental requirements (Table 1). Watercourses in the analysis were defined as running water including everything from a small brook to a large river (SVAR 2011). Smaller water bodies of stagnant water, such as flooded ditches, were not included in the analysis, due to lack of data. Furthermore, at least 125 hectares (5 %) within 2,500 hectares of suitable habitat for Black Stork had to meet the requirements for suitable nesting sites (Treinys et al. 2009)
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