This adult Great Northern Diver is a real poser and showed exceptionally well today at Long Rock Pool. It seems to like following a circuit round the edge of the pool. Every ten minutes or so it swam to the extreme south west corner to within 15 yards of me. Unbelievably, it then called twice. I have only heard the call on tape so was surprised and pleased to witness this today.
The bird is just starting to moult out of summer plumage and this seems quite late. I have only seen first winter birds previously in the Autumn. I normally only see adults in full summer plumage in Cornwall in late Spring. So, with the calls and this plumage at this time of year, does seem unusual.
According to BWP though, post breeding adults start the moult from late July to early October; the moult is complete from October to January.
The species mainly breeds in Iceland and Greenland. Approx 150 birds regularly winter around the Cornish coast with the highest concentration being from Gribbin Head to the Helford.