Earlier this year, IOC (and therefore HKBWS) adopted a split in Siberian Stonechat, separating the Eastern stejnegeri as a separate species (Stejneger's Stonechat) from the more westerly maurus (and other subspecies). The common form in Hong Kong is Stejneger's, thus this bird is a potential new species for Hong Kong!
Separation of the two is still slightly uncertain: Paul Leader is looking into how they are different. The most notable differences compared to typical Hong Kong birds are that this individual seems paler (above and below), with a stronger supercilium.
