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Numbers and survival of diving duck broods in fishpond systems in South Bohemia
Čehovská, Markéta ; Musil, Petr (advisor) ; Bílý, Michal (referee)
This paper is aimed at investigation of numbers of broods and ducklings of diving ducks and the individual reproductive success of marked females expressed by survival of ducklings. The studied area was located in fishpond systems of South Bohemian in the region of Třeboň, Soběslav, Jindřichův Hradec and České Budějovice. Between years 2014 and 2015, there were recorded 139 broods and 963 ducklings of Common Pochard (Aythya ferina), 140 broods and 948 ducklings of Tufted Duck (Aythya fuligula) and 47 broods and 312 ducklings of Red-crested Pochard (Netta rufina). The most important environmental factor influencing their occurrence on the fishpond was water transparency. Brood numbers and numbers of ducklings are affected also by other environmental characteristics, such as water surface area, mean depth, number of islands and presence of surrounding wetlands and open landscape.
Monitoring individually marked females Common Pochard and Tufted Duck was carried out between years 2004 and 2015. It was found that the survival rate is the lowest in the hatchlings (from 1 to 10 day after hatching), overall survival probability was 0.395 for Common Pochard ducklings and 0.383 for Tufted Duck ducklings. Survival was negatively correlated with distance of duckling movements. The most frequent movements were within 2 km from the breeding fishpond, the maximum distance passed by broods was 5 km. The impact of environmental factors and intraspecific differences on surviving ducklings was not confirmed.
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