Breeding data collecting
The data on Sečovlje Salina breeders were gathered through a planned quantitative mapping in the UTM 100 x 100 m survey area.
During the 1983-2009 breeding seasons, the entire area of Sečovlje salt-pans suitable for breeding was carefully surveyed. Surfaces without mud islets were not checked. Of a total of 787 100 x 100 m squares, a little less than 500 were found suitable for breeding (Fig. 117). During our field work, various vessels were occasionally used as well (Fig. 119). The data gathered with the aid of GPS receiver, were also transferred to the 100 x 100 m survey grid or were used for the composition of concrete nest sites of separate bird species. Earlier data were suitably converted and transferred from the already made distribution maps to the UTM 100 x 100 m survey grid.
The quantitative surveys have been supplemented with results of numerous reports and special research into certain species. In the past, basic research on the breeding biology of individual species has been carried out for the Yellow-legged Gull Larus michahellis (Škornik, 1992), Common Kestrel Falco tinnunculus (Lipej, 1993; Marčeta, 1994), and Kentish Plover Charadrius alexandrinus (Makovec, 1994). After 2002, this research was followed by accurate quantitative surveys of breeders as well as research into the breeding biology of indicator species characteristic and significant for Sečovlje Salina Nature Park, i.e.: Yellow-legged Gull Larus michahellis, Common Tern Sterna hirundo, Little Tern Sternula albifrons, Black-winged Stilt Himantopus himantopus, Kentish Plover Charadrius alexandrinus, Avocet Recurvirostra avosetta, Shelduck Tadorna tadorna, Redshank Tringa totanus, Yellow Wagtail Motacilla flava, and Fan-tailed Warbler Cisticola juncidis. The results are published in annual reports by the manager of Sečovlje Salina Nature Park.
Unsystematically collected data from the wider survey period (1973-2009) have also been added to the picture of the breeding distribution apart from quantitative surveys and special research from the 1983-2009 period. These unsystematically gathered data constitute only a minor share of breeding records.