The Wilson Journal of Ornithology 123(3):479-485, 2011 
CONSPECIFIC BROOD PARASITISM AND NESTING BIOLOGY OF 
MANDARIN DUCKS (AIX GALERICULATA) 
IN NORTHEASTERN CHINA 
QIU-XIANG DENG, 1 - HAI-TAO WANG,'' DI YAO. 1 XING-YANG WANG, 1 MING-JU E, 1 
TUO WANG,' AND WEI GAO' 3 
ABSTRACT.—Conspecific brood parasitism (CBP) is a widespread alternative female reproductive tactic in birds. We 
monitored CBP and nesting biology of Mandarin Ducks (Ai.\ galericulata) using nest boxes for six breeding seasons in 
Zuojia. northeast China. CBP occurred commonly (46.2% of completed clutches) during the study and frequency was 
positively associated with nest densities. The frequency of CBP declined as the nesting season progressed. On average, 
2.s lemales laid eggs in each parasitized nest. There were significant differences in clutch initiation dates and mean 
laying period between parasitized and un-parusitized nests: no difference was detected for the mean incubation period. 
< lutcli size for un-parasitized nests decreased with advancing initiation dute, but not for parasitized nests. The hatching rate 
lor eggs in successful nests was 87,1%. and no significant difference was detected between parasitized and un-parasitized 
nesh I he average number of ducklings that left from successful un-parasitized and parasitized nests was 8.4 and 15.4, 
respectively. Nest desertion was the main cause for nest failure and sibling trampling was the only cause of duckling loss 
belorc departure from nests, Received 9 September 2010. Accepted 26 February 201L 
Conspecific brood parasitism (CBP), a wide¬ 
spread alternative female reproductive strategy, 
has been documented for 236 avian species 
(Yom-Tov 2001); several potential benefits may 
enhance its’ occurrence. Females that lay eggs in 
nests of others could avoid the physiological costs 
and dangers associated with incubation and 
parental care (Andersson 1984). Nest parasitism 
may be associated with an increase in total 
fecundity (McRae 1998, Ahlund and Andersson 
2001). Parasitism could benefit females that can 
not lind a suitable nest site or have lost a nest due 
to destruction (Semel ct al. 1988, Lank et al. 
1989). Dispersing eggs into several nests may also 
eliminate the risk of a failed clutch jeopardizing 
their entire reproductive effort (Payne 1977 
Brown and Brown 1988), CBP is disproportion¬ 
ately common among waterfowl relative to other 
taxa (Eadie el al. 1998). Waterfowl have precocial 
young that require less post-hatch parental care 
than altricial young, which may minimize costs to 
hosts, and possibly explain the prevalence of this 
behavior (Roy Nielsen et al. 2006a), 
CBP behavior of Wood Ducks (Alt sponsa) has 
received substantial attention (Heusmann et al. 
School of Life Sciences, Jilin Key Laboratory of 
Animal Resource Conservation and Utilization, Northeast 
Norma! University, 5268 Renmin Street. Changchun 
120024. China. 
Current address: College of Chemistry and Biology, 
Beihua University, Jilin. 132013, China. 
Corresponding author; e-mail: 
gaowei 1937@yahoo.com.cn 
1980, Semel and Sherman 1986). The costs and 
benefits to parasitic females and their hosts, and 
the ecological factors influencing the frequency of 
CBP within and among Wood Duck populations 
are well documented (Semel and Sherman 2001, 
Roy Nielsen et al. 2006b). High levels of CBP 
may lead to increased levels of nest desertion 
(Jones and Leopold 1967, Semel and Sherman 
1986), reduced hatching success of eggs or 
fledging success of young (Semel et al. 1988, 
Semel and Sherman 2001), and higher predation 
risk and energetic costs due to longer incubation 
periods (Hepp et ul. 1990. Roy Nielsen et al. 
2006a). Frequency of CBP has been associated 
with nest densities (Clawson et al. 1979, Haramis 
and Thompson 1985), A possible benefit of CBP 
to hosts is higher inclusive fitness, if parasites are 
relatives (Roy Nielsen et al. 2006b). 
The Mandarin Duck (Aix galericulata) is the 
most widely introduced waterbird within the 
Afriean-Eurasian Migratory Waterbird Agreement 
area and perhaps in the world due to their 
attractive appearance (Rchfisch et al. 2006). An 
introduced population has been breeding in 
Britain since the 1930s (Savage 1952). Native 
Mandarin Ducks breed in Russian Ussuriland in 
Amur. Khabarovsk, and Primorye regions as far 
west as Zeya Estuary, northern China. Sakhalin 
Island. Kunsshir in Kuril Islands, and in Hok- 
ka'do the "’ost northerly ofJap»' s mrun islands 
(Kear 2005). 
The Mandarin Duck incubates clutches that 
vary greatly in size. Davies and Baggott (1989a. 
