HELLEBREKERS WPJ & VOOUS KH (1964) Nest parasitism by Red-Crested Pochard. LIMOSA 37 (1): 5-11.

Red-crested Pochard Netta rufina New cases of nest parasitism of the Red-crested Pochard (Netta rufina) have been described from the Veluwemeer-Zuid during the breeding seasons of 1962 and 1963. The data are summarized in Tables 1 and 2. Red-crested Pochard eggs were found in nests containing eggs of Mallards (Anas platyrhynchos; 6 instances) and Gadwalls (Anas strepera; 4 instances). These nests contained a maximum of 15 and 24 eggs, respectively. In none of these cases a Red-crested Pochard female was found incubating. Apart from these 7 nests with mixed eggs, 21 nests were found containing eggs ascribed to the Red-crested Pochard only; in most of these cases a female Red-crested Pochard was flushed from the nest, or had been observed by one of the wardens. These nests contained from one up to 39 eggs. In the nests containing 17, 22, 24, 24, 38 and 39 eggs, respectively, probably more than one female had been laying in the same nest. There was ample evidence that while one female was incubating, other females had been depositing their eggs among the clutch. At least 70 eggs were taken out of the nests and laid under domestic pigeons or tame ducks. The combination of young of two species (Red-crested Pochard and Gadwall) resulting from one nest was demonstrated in this way in two instances. Eggs taken from very large clutches of Redcrested Pochard hatched at very irregular intervals, proving the fact that eggs had been added to the nest while incubation was under way. Reference is made to previous cases of nest parasitism in the Netherlands, Denmark and South Germany

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