Large Hawk-Cuckoo Hierococcyx sparverioides parasitism on the Chinese Babax Babax lanceolatus may be an evolutionarily recent host-parasite system.

We documented brood parasitism by the poorly studied Large Hawk-Cuckoo on a previously unknown host species, the Chinese Babax. Furthermore, we describe a new egg colour for the Large Hawk-Cuckoo. The parasitism rate of Chinese Babax nests over 4 years was 6.9% (11 of 159 nests), with significant temporal variation. The Large Hawk-Cuckoo laid immaculate white eggs that appeared non-mimetic to the blue Babax eggs, an impression that was confirmed by avian visual modelling. Nevertheless, most Cuckoo eggs were accepted by the host, suggesting that this host-parasite system may be evolutionarily recent. [ABSTRACT FROM AUTHOR]