Egg laying behavior of the common cuckoo (Cuculus canorus): data based on field video-recordings

The egg laying behavior of brood parasites is at the heart of studies on
their co-evolution with hosts. Updating and reporting more egg laying
behavior can improve our perception and insight on the brood parasitism
process. During a 7 years’ study period, we monitored 455 Oriental reed
warbler (Acrocephalus orientalis) nests during the egg laying period, of
which 250 were parasitized by common cuckoos (Cuculus canorus). We
randomly recorded 53 clear videos of cuckoo parasitism, analyzed and
recorded all parasitic behavior of cuckoo in details, summarized the
process of brood parasitism displayed by the common cuckoo. Based on
analyses of these field video-recordings, we proposed a new explanation
for the egg removal behavior, namely the delivery hypothesis, i.e. the egg
pecking and biting may help parasitic cuckoos lay eggs faster, thereby
avoiding the host’s attention and reducing host attacks, whilst egg
removal is the side effect of egg pecking and biting. We concluded that
common cuckoos do not care whether the host is around the nest, as they
have a set of methods to deal with host attacks and can complete
parasitism boldly and smoothly at any time.