BIJLSMA RG (1994) Short contributions: Establishment and growth of a population of Mandarin Ducks Aix galericulata. LIMOSA 67 (4): 173-174.

After several observations of Mandarin Ducks in the 1970s and early 1980s near the towns of Wageningen and Renkum, the first successful breeding attempt was 174 recorded near Renkum in 1987. Since then, the local population has increased and stabilized, with respectively 1,3,5,9,7,6,7 and 6 breeding pairs in 1987-94. The breeding area encompasses several brooks (length 1800 m) in a narrow valley (width 150-200 m), bordered by old deciduous forest (mainly Beech of >200 years old). Nests were found in cavities in Beech (9), Ash (1), Alder (1) and Lime (1). All nests in Beech were old nests of Black Woodpeckers. Mean nesting height was 12.6 m (SD=4.6, range 4-18 m, N=12). In the vicinity ofthe study area, two more nests were found in a nestbox for Tawny Owls and possibly in the chimney of a factory. Mean start of laying was 20 April (SD=8.4, range 3 April - 1 May, N=ll). Four completed clutches contained 10, 10, 11 and 12 eggs. Egg dumping was not recorded. Three out of 14 nests failed: twice desertion and once predation (probably marten). Females took their young to nearby streams or marshland. Losses of ducklings were apparently most severe during the first three weeks of life. The average number of ducklings per female decreased from 9.5 in the age class of 1-10 days old (N=4), 8 of 11-20 days old (N=l), 6.3 of 21-30 days old (N=3) and 6.2 of >30 days old (N=4). The causes of brood reduction are unknown, although aggression of Coots against ducklings, thereby preventing them to forage, was observed. Adult Mandarin Ducks are furthermore prone to predation by Goshawks (one plucking found among >15000 prey items). Aix galericulata Mandarin Duck

[free pdf] [dutch summary]