Egg mimicry and host selection by common cuckoos among four sympatric host species breeding within a reed habitat

In the case of cuckoo parasitism, the maintenance of host specificity may
be closely related to active host selection. In the reed wetlands of the
Yongnian National Wetland Park, China, four host species of common cuckoos
(Cuculus canorus) with similar nest structures breed sympatrically,
namely, the oriental reed warbler (Acrocephalus orientalis) (ORW),
vinous-throated parrotbill (Sinosuthora webbiana) (VP), reed parrotbill
(Paradoxornis heudei) (RP) and blunt-winged warbler (Acrocephalus
concinens) (BW). Cuckoo parasitism rates on ORW (14.5%) and BW (18.2%)
were found to be significantly higher than those on two species of
parrotbills (RP 1.4% and VP 0), and cuckoo eggs mimicked the size and
coloration of ORW eggs significantly more closely than those of the eggs
of the other three hosts. Egg recognition experiments revealed that the
ability of ORW and VP to recognize nonmimetic eggs was significantly
greater than that of BW and RP. Different life history strategies of the
four hosts, including antiparasitic strategy, breeding time period, and
population density may partly explain the difference of parasitism in this
multiple cuckoo-host system. Our study suggests that determining host life
history traits and antiparasitic strategies are important for a better
understanding of the specificity of host selection in common cuckoos.