Breeding Ecology Of Mandarin Ducks (Aix Galericulata)

Conspecific brood parasitism (CBP) is a widespread alternative female reproductive tactic in birds. We monitored the nesting biology of Mandarin Duck (Aix galericulata) nesting in nest-box in the natural protective area of Zuojia, Jilin province in 2004-2010. Forty-six nestboxes were occupied by Mandarin Duck with an average of 6.7±4.5 boxes used per year (range = 2 to 14 nests annually). The result showed that CBP occurred commonly in Mandarin Duck in the study. Approximately 2.5 females laid eggs in a same parasitized nest. Frequency of CBP was positively associated with population size. Clutch initiation dates ranged from 22 April to 11 June. The median first-egg date for parasitized nests was 5 May, and was 16 May for un-parasitized nests. The laying period for parasitized was 12.0 days, while the un-parasitized was 15.4 days. Clutch size of complete un-parasitized and parasitized nests was 10.0 eggs, and 18.8 eggs, respectively. The mean incubation period for successful nests was 32.6 days. There existed significantly differences in clutch size, clutch initiation dates, mean laying period, clutch size, weight of egg and nestling between parasitized and unparasitized nests. However, no obvious difference was detected for the incubation period. Most CBP occurred during early breeding seasons. For unparasitized nests, clutch size decreased with egg initiation dates, but not for parasitized nests. There was significantly negative correlation between clutch size and hatching rate. There wasn't correlation between breeding time and reproductive success. The hatching rate of unparasitized nests was significantly higher than that of parasitized nests. CBP may lead to the reproductive success of Mandarin Duck decrease. The rate of nest hatching in unparasitized nests was 79.2%, while the parasitized was 38.9%. Only seven ducklings left nests for a mean clutch size of 18.8 eggs. The total hatching rate of Mandarin Duck was 44.4%. The rate of the ducklings left nests was 97.4%. Nest desertion was the main cause for nest failure. Sibling trampling was the only cause responsible for duckling loss before leaving nest. Our results indicated that the sex ratio of Mandarin Duck was 1.23:1(♂:♀), population size skew to male, but not remarkable skew 1:1.