Spolni dimorfizam kod mladih jedinki ĉaplji nije izražen, te je jedna od pouzdanih metoda utvrđivanja spola mladih ptica putem molekularnih biljega. Cilj diplomskog rada je usporedba metoda za izolaciju DNA iz pera i ljuski jaja ĉaplji, te utvrđivanje spola prstenovanih jedinki ĉaplji. Rezultati pokazuju da je najveći prinos DNK dobiven iz pera koja su u razvoju (prokrvljena pera) i ljuski jaja. Prinos DNA je bio manji kad se koristio komercijalni kit za izolaciju u odnosu na izolaciju standardnim protokolom. Određen je spol deset prstenovanih ĉaplji na ribnjacima Jasinje. U dva gnijezda ĉaplje dangube (Ardea purpurea) utvrđeno je ukupno šest mužjaka(tri po gnijezdu), dok su u dva gnijezda velike bijele ĉaplje (Ardea alba) utvrđene ĉetiri ženke, tri iz jednog i jedna iz drugog gnijezda. Ovo je prvo utvrđivanje spola ĉaplji putem CHD gena u Hrvatskoj. Opsežnijim višegodišnjim istraživanjima mogao bi se utvrditi odnos spolova u populaciji, stabilnost populacije, te poduzeti potrebne mjere zaštite gnijezdeće populacije ĉaplji u Hrvatskoj.

In sexually monomorphic species like herons one of the most reliable method of sex determination in young birds are molecular markers. The aim this work is a comparison of methods for the isolation of DNA from feathers and eggshells in herons, and sex determination of ringed young birds. Results showed that the highest yield of DNA was obtained from the young chick feathers, which are in development, and egg shells. The yield of DNA was lower when a commercial kit was used for isolation compared to the isolation with the standard protocol. Sex-typing was performed in ten ringed herons in the fishponds Jasinje. In two nests of purple heron(Ardea purpurea) a total of six males (three per nest) were found while in two nests of the great white egret(Ardea alba) we identified four females, three in one and one in another nest. This is the first time in Croatia that molecular approach was used for sex determination in herons by using CHD gene. More extensive research trough years would determine sex ratio in the population, population stability, and to lead to the necessary measures in order to protect nesting population of herons in Croatia.