by Jochen Dierschke
Many thanks to all comments either received privately or on this blog!
In the meantime I received some much better pictures taken bei Oliver Nüssen:
Especially the last picture shows that also the lesser underwing-coverts are faintly barred and that the primaries have too many white bars for Oriental. Some people suggested that this bird might be a female. I am not very experienced in sexing Cuckoos, but most pictures of birds I’ve seen ringed and sexed do not fit the bird.
In Summary: Although the bird looks like being within the variation of Oriental, it seems more likely to be a Common Cuckoo. As the calls were never definitely heard from the bird in question, it may have been a different bird calling. The calls heard were also “three-note-calls”, making an Oriental unlikely.
At least we learnt some lessons on Cuckoo-ID, but it seems a nightmare to get an Oriental Cuckoo accepted in Europe outside Russia!