Egg sizes in Oriental cuckoo and its host species

An international study into the sizes of oriental cuckoo eggs compared with the egg sizes of their four corresponding hosts in Russia. The study involved Alla Mashanova from University of Hertfordshire (data analysis), a team of researchers from The Institute of Plant and Animal Ecology, Ural branch of the Russian Academy of Sciences (Ekaterinburg, Russia) and the National University of Life and Environmental Science of Ukraine (Kiev, Ukraine) and has shown, that cuckoos vary the size of their eggs to match those of their hosts, providing evidence of evolutionary adaptation. A match between cuckoo and host egg breadth could have evolved as a response to host rejection behaviour, as it has been shown that a host is likely to reject an egg larger than the rest of the clutch.