For few years now I pay special attention to tern plumages. I am trying to find out how often and what dates were recorded in the past of terns in breeding plumage during fall/winter.

I cannot find any useful published information about this phenomenon. I also have hard time to find photos with dates which are showing ROTE individuals with black caps during fall/winter months. Circa 1% of Royal Terns are known to have a ‘summer’ head in late August to early September (Olsen and Larsson, 1995; page 31) but cases I would like to present and discuss are individuals that freshly molted head feathers and have fresh black cap in late September, October and November (at present I have no records from later, winter months); - usually in November prebasic molt is well advanced or even about to be completed in other ROTEs. BTW in September individuals in breeding plumage might have much fresher plumage compare to the ‘normal’ Royals as those still have many feathers left to molt.