Breeding success of ducks in relation to different habitat factors

Breeding success of four duck species, Teal Anas crecca , Mallard Anas platyrhynchos , Wigeon Anas penelope and Goldeneye Bucephala clangula , was studied in a boreal watershed in southern Finland during 1988–1991 in relation to habitat type (based on vegetation development) and food abundance. Of the three common breeders, breeding success (broods/ pair) was highest in Teal (1.7) and lower in Mallard (1.4) and Goldeneye (1.2). Over the years, Goldeneye brood densities were less variable than were pair densities, so breeding success varied more among years that did that of Mallard or Teal. In Teal, the yearly numbers of pairs and broods fluctuated together, whereas in Mallard neither varied appreciably. Breeding success by Goldeneye was higher where nektonic invertebrates were more abundant, whereas breeding success of the dabbling ducks had very few significant correlations with environmental factors.