长白山中华秋沙鸭的种内巢寄生

雁形目鸟类的种内巢寄生现象十分普遍,但有关中华秋沙鸭(Mergussquamatus)的种内巢寄生现象未见报道。2019年4和5月,从长白山1个中华秋沙鸭人工巢的视频监控发现,1只雌鸭在亲鸟孵卵时强行进入巢箱趴卧约29 min。其后根据该巢窝卵数的增加、超常窝卵数和窝卵不同步孵化3个指标,确认该巢存在种内巢寄生现象。宿主对进入巢内寄生的个体表现出强烈的攻击行为,但对寄生卵未表现出明显的拒卵行为。由于区域内仍有较多巢箱未被利用,中华秋沙鸭的种内巢寄生行为是否源于对有限巢址资源的竞争,有待进一步研究。

A Case of Conspecific Brood Parasitism in the Scaly-sided Merganser (Mergus squamatus) in the Changbai Mountains, China

Conspecific brood parasitism (CBP) is widespread in Anseriformes. For the Scaly-sided Merganser (Mergus squamatus), however, there is no report on the occurrence of CBP. On 13th of April of 2019, in our study area at the Manjiang, Fusong in the Changbai Mountains of China, we found one female of Scaly-sided Merganser breeding in the nest-box with 15 eggs in the nest (Fig. 1a, b). During April to May, we monitored the nest by video camera, and found that one parasitic female intruded into the nest when the parent female was incubating, and stayed inside the nest box for 29 min (Fig. 1c, d). The host female showed aggressive behavior against the parasitic female (Fig. 1e), but no egg rejection occurred after being parasitized. Thereafter, an increase in clutch size from 15 to 18 eggs was recorded (Fig.1b, f). After 11 ducklings leaving the nest-box, 7 eggs were left unhatched (Fig.1 g, h) and were immediately collected and checked, among which 5 were infertile and 2 were artificially hatched and released to the wild (Fig. 1i). Based on combined evidence from an increase in clutch size, the abnormally large clutch, and asynchronous hatchling, we suggest the occurrence of CBP in this nest. At our study area, there were still 22 nest-boxes unoccupied, the causes of CBP in Scaly-sided Merganser need further investigation.