@Summer Tanager according to zootierliste that species is only held in russia, but it certainly does look like it and walsrode could most certainly get their hands on one so i wouldnt be shocked if so!!
Instead of Gray Imperial-Pigeon, I wonder if this is a pale individual of Pink-headed Imperial Pigeon (Ducula rosacea)? I saw that Walsrode has that species at it's very similar to the Gray Imperial-Pigeon except for a pinkish tint to the head which might not show up under certain lighting conditions.
