At this time of year, sexing and ageing RING OUZELS can be very difficult and is reliant on extremely good views being obtained - separating some first-year males from females is almost impossible. Anyway, Martin Parr has obtained some nice images from Ivinghoe Beacon today illustrating some of the differences -
The bottom two images are of a cracking adult male, with extensive yellow bill and well defined black and white plumage, whilst the next four are most likely an adult female. The two birds at the very top of the page seem most likely to be first-summer males.