Research on determining the population size, population changes and factors effecting population and migration dynamics of white stork (Ciconia ciconia L., 1758)in the Gediz river basin

Our study aimed to determine the population size and changes of White Stork (Ciconia ciconia Linnaeus, 1758) between 2011-2013. We analyzed the underlying reasons behind these changes, the threats on population and the migration dynamics in Gediz river basin. Thematic maps were developed using Mapinfo 8,5 GIS software on Landsat satellite images to demonstrate population distribution, breeding, activity, position etc. of White Stork nests in Gediz river basin. Between 2011-2013 we assessed totally 276 nests which are in 123 of 414 settlements and 22 nests outside of the settlements in the Gediz river basin. The nest density is high in the plains around the Gediz river bed and its tributaries and lower in Bozdağ ranges in the south and mountainous areas in Gördes, Demirci, Gediz and Selendi districts in the north. We determined that White Stork nests are most prevalent on low voltage pylons. Mosque domes, medium and high voltage pylons, building roofs and chimneys, street lights, factory smokestacks, trees and some other structures are also used by White Storks for making their nests. We did not obtain any correlation between nest site selection and breeding success. However, nests located on building roofs are declining faster than other nesting sites. During the 2011-2013 study period, 38 nests disappeared and 22 new nest were established in Gediz river basin. This equates to an active nest decrease of 8,17% in 3 years. We did not ascertain significant effect on breeding success on artificial nest platforms that were placed on low voltage pylons but these platforms provided protection against electrocution on existing nests. This is especially important as electrocution is the leading cause of mortality in young White storks. We determined that most of the nest (60%) were occupied by the end of March and White storks mostly leave the area before August 15 every year. In order to obtain migration data, 73 white stork chicks were ringed between 2012 and 2014 in the Gediz river basin. 7 individuals were also ringed at İzmir Natural Life Park (zoo) after their rehabilitation and released in nature.According to the data collected in our study, we conclude that the White stork population in the Gediz river basin is decreasing. If the same conditions continue, we predict that these trends will persist. Thus in order to protect the White stork population, it is imperative to protect existing nests and encourage the development of new nests in the future. Keywords: White Stork, Ciconia ciconia, Gediz River Basin, White Stork nest, Gediz Delta, Population changes, Nesting platforms.