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Low hatching success due to nest depredation has frequently been reported from waterfowl breeding sites, but current knowledge on relationships between duck nests and their predators, which should form a basis for successful management, remains incomplete. We used a 13‐year data set to test whether specific predator species are more successful in finding certain types of natural duck nests and whether there are interspecific differences in nest characteristics. Multinomial logistic regression allowed simultaneous evaluation of the effects of different factors, including their interactions. Significant predictors of duck nest fate were the presence of water edge and 3‐way interaction among presence of gull colonies, island type and clutch initiation date. Significant predictors of nest site use by duck species were: 3‐way interaction among presence of gull colonies, island type and clutch initiation date, 3‐way interaction among presence of gull colonies, island type and presence of water edge and 2‐way interaction between presence of water edge and clutch initiation date. The above interactions led to certain associations between duck species and predator species. Corvids (hooded crow Corvus corone cornix and raven Corvus corax) were responsible for depredating more mallard Anas platyrhynchos nests, but fewer common pochard Aythya ferina and tufted duck Aythya fuligula nests than expected. American mink Mustela vison was responsible for destroying more small Anas species (northern shoveler Anas clypeata, garganey Anas querquedula and gadwall Anas strepera) and tufted duck nests, but fewer mallard nests than expected. Marsh harrier Circus aeruginosus was apparently a generalist predator since we were not able to detect significant associations between this predator and nests of any specific duck species. We believe that examination of interactions between different factors affecting the probability that nests will be either successful or depredated by certain predator species may help waterfowl managers increase management success.

ABS1'RACTIn summer 1997 a project of duck research using radio-telemetry was carried out on the Lake Engure, Latvia. 10 females of Mallards, 10 females of Shovelers, 9 females of Pochards and 6 females of Tufted Ducks were radio -tracked during the period from the hatching of their ducklings till fledging. Information about effect of the harness-type radio-transmitters on different species of ducks has been collected. For 15 ducks home range sizes and distances between nests and range locations were calculated. Mallards used to move further from their nest sites; one Mallard brood after one week spent near the nest site dislocated 8 km to the Southern part of the lake during one day. Problems of estimating habitat use and habitat selection of duck broods have also been discussed.

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