大杜鹃和东方大苇莺卵的人工孵卵期和孵化率比较

Comparison of Incubation Period and Hatching Rate of Oriental Reed Warbler and Common Cuckoo in Artificial Incubation

大杜鹃(Cuculus canorus)是一种专性巢寄生鸟类,进化出了一系列适应对策,如雏鸟普遍出壳较早等,以更好适应寄生生活。本研究使用恒温自动孵化箱对25枚大杜鹃卵和20枚其宿主东方大苇莺(Acrocephalus orientalis)卵进行人工孵化,并对孵卵期的卵重进行连续测量。结果表明,在人工孵化条件下,大杜鹃卵的孵化率(76%)极显著高于东方大苇莺(40%)(χ~2=25.144,df=1,P<0.01)。尽管大杜鹃的卵鲜重(t=7.447,df=43,P<0.01)和卵体积(t=8.817,df=43,P<0.01)均极显著大于东方大苇莺,但两种鸟卵的孵卵期不存在显著性差异(t=1.006,df=16,P>0.05)。

Common Cuckoo（Cuculus canorus） is an obligate brood parasitic bird that has evolved a series of adaptions, such as cuckoo chicks could hatch earlier and eject the host eggs, to exploit more of the hosts. In this study, we collected fresh eggs of the Common Cuckoo（n = 25） and its host Oriental Reed Warbler（Acrocephalus orientalis）（n = 20）, and incubated them in an automatic incubator with constant temperature of 37.8 ℃. All eggs were measured soon after collection and the egg mass was weighted daily during the incubation using an electronic balance. Our results showed that hatching success of the Common Cuckoo（76%） was significantly higher than that of the Oriental Reed Warbler（40%; Chi-square, χ2 = 25.144, df = 1, P 0.01）, implying that the ecological amplitude of the embryonic development temperature of the Common Cuckoo might be wider than the host, and the incubation temperature tolerance of Cuckoo might be strongerthan the host. Although the fresh egg mass（Independent-samples T test, t = 7.447, df = 43, P 0.01） and egg volume（t = 7.447, df = 4, P 0.01） of the Common Cuckoo were much larger than those of the Oriental Reed Warbler（Fig. 1）, there was no significant difference in incubation period between the two species.