Between 1999 and 2010, an annual census of the White Stork Ciconia ciconia breeding population was carried out in Slovenia using standardised methods. The Stork's population was concentrated in the ...NE and SE parts of Slovenia. In the 1999-2010 period, the breeding range of its population in Slovenia expanded in NW direction (the Savska ravan region), in SW direction (the Notranjsko podolje and Pivško podolje regions), but the species also colonized a part between Central and SE Slovenia (Dolenjsko podolje). Between 193 and 240 pairs were breeding during the study period, 209 pairs on average (HPa). The largest number of breeding pairs was recorded in 2004, the smallest in 2005. During the study period, breeding pairs (HPa) occupied 350 discrete nests in total. Average number of breeding pairs that raised juveniles (HPm) was 161. The highest fecundity was recorded in 2004, when 534 juveniles (JZG) fledged, the lowest in 2006, with only 219 fledged juveniles. On average, 414 juveniles fledged per year. The breeding pairs' (JZa) average breeding success in these 12 years was 2.02, the highest in 2000 (2.41), the lowest in 2006 (1.09). Average breeding success for the successful breeding pairs (JZm) was 2.57. The highest was in 2007 (2.94), the lowest in 2006 (2.07). The largest number of breeding pairs in 2004 and 2008 can be explained by the favourable fecundity in the population in 2000 and 2004, as juveniles become sexually mature at the age of 3-5 years, and at that age they generally return to the breeding grounds for the first time. The lowest number of breeding pairs and poor breeding success in 2005 and 2006 was caused by late arrival of White Storks to the breeding grounds and by unfavourable weather conditions during the breeding period. The pattern of nests placement did not change generally during the last 12 years. The largest proportion of nests was positioned on various kinds of poles (81%) and on chimneys (18%). In total, 27 area surveyors and 239 assistants helped in census realisation.
Populacijska dinamika bele štorklje Ciconia ciconia v Sloveniji med letoma 1999 in 2010
Prey remains found in the pellets of the White Stork Ciconia ciconia are known not to reveal the actual prey intake by the White Storks. The exceptions are the chitinous remains of insects that are ...quite well preserved in the pellets, and thus potentially good indicators of the actual intake of White Storks. Since insects are selected by White Storks in proportion to their abundance in the environment, they can be used as indicators of the quality of the bird foraging habitat. A preliminary test of this was carried out at three nests in NE Slovenia differing in their breeding success in 1997. In contrast to habitat analysis around the nest the proportions of Orthoptera and Coleoptera in the pellets corresponded well to the breeding success. Orthoptera species were dominant in high success, and Coleoptera (especially Carrion beetles Silphidae) in low success nests. In this paper the value of insects in White Stork pellets as indicators of the quality of the bird foraging microhabitat patches is set out. However, the indicative power of these insects needs to be tested further.
Žuželke v prehrani bele štorklje Ciconia ciconia kot indikatorji njenih prehranskih razmer: prva raziskava prehrane vrste v Sloveniji
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