The timing of clutch initiation in migratory birds is determined by many factors and affects fitness. In polygynous species the date of egg laying may also be determined by mating status. In order to identify the habitat factors enabling Eurasian bittern females to breed early, a study was carried out on nine fishpond complexes in eastern Poland during 2003-2009. The habitat characteristics of the nesting sites, including fish stock type and the breeding success were recorded for 48 monogamous, 31 primary, 30 second and 12 third or fourth females. The analysis showed that early nesting females preferred a higher density of old reed stems and chose less attractive ponds with poorer food resources. Monogamous and primary females laid first eggs eight days earlier on average and had higher
breeding success than the second, third and fourth females. The relationship between the fate of broods and the breeding success of
neighbouring nests was found for second females. Our results suggest that Eurasian bittern females benefit from early nesting, provided they can find appropriate vegetation at the nesting site.
Species composition, structure and ecological characteristics of the vegetation of two pond types with different management, fishponds and storage ponds, in the Českobudějovická pánev basin (South Bohemia), were compared. A selection of 99 relevés from fishponds and 99 from storage ponds (small ponds used for the storage of marketable fish) made in 2000–2004 were analysed using direct and indirect ordination and ANOVA. The difference between storage ponds and fishponds was found to be more important than gradients correlated with temporal changes, soil moisture and mud depth. Storage ponds had a significantly higher mean number of species, bryophytes, archaeophytes and neophytes and beta-diversity. There were no significant differences in cover values, except of moss layer, which had significantly higher cover in storage ponds. Fishponds had significantly higher mean Ellenberg indicator values for light, continentality, moisture and nutrients. Oenanthe aquatica and Rumex maritimus are typical fishpond species and Amblystegium humile and Eleocharis palustris agg. typical storage pond species. The management of storage ponds is more varied and of different intensity than that of fishponds. It is assumed that management is a crucial factor determining the species richness and influencing the vegetation of these two habitats.