Compared distribution within a disturbed fishpond ecosystem of breeding ducks and bird species indicators of habitat quality

• Published in: Journal für Ornithologie 2009, Vol.150 (4), p.761-768
• Main Author: Broyer, Joël
• Format: Article
• Language: English
• Subjects: Aggressive behavior; Anas platyrhynchos; Anas strepera; Ardea purpurea; Aythya ferina; Aythya fuligula; Breeding; Colonies; Cygnus olor; Ecology; Fish & Wildlife Biology & Management; Geographical distribution; Habitat preferences; Larus ridibundus; Life Sciences; Netta rufina; Original Article; Ponds; Predation; Zoology
• ISSN: 0021-8375; 2193-7192; 1439-0361; 2193-7206
• DOI: 10.1007/s10336-009-0396-0

The distribution of breeding ducks versus three other bird species (Mute Swan Cygnus olor, Black-headed Gull Larus ridibundus and Purple Heron Ardea purpurea) among waterbodies was investigated in the Dombes area, Eastern France, where breeding duck populations have undergone a severe decline following a large-scale transformation of meadow habitat into cropland. Higher Pochard Aythya ferina, Tufted Duck Aythya fuligula, Red-crested Pochard Netta rufina and Gadwall Anas strepera pair densities were recorded in fishponds where Black-headed Gulls were nesting. In these ponds however, nesting success (assessed by the number of broods divided by the number of pairs) was not significantly higher. Similarly, Pochard pair density was higher in ponds with a Purple Heron colony, but brood densities were not. We hypothesise that, in the study region, clutch concentration in the most attractive areas could compensate for the anti-predation effect of gull colonies or overwater nesting in shore vegetation. We could not confirm the expected negative impact of Mute Swan aggressive behaviour on duck distribution. Even though Mallard Anas platyrhynchos pair density was lower in ponds with breeding swans, we did not observe difference for Mallard broods. Moreover, Red-crested Pochard pair density and nesting success were higher in ponds where swans were breeding, probably as a consequence of shared habitat preferences.