Continuing bid. Observed by me on that day early in the morning and late afternoon. A few notes about ELTE vs ROYT; here are the best traits to use when one only see a single bird:

Bill shape and white (ROYT) or black (ELTE) behind eye - see photos. Some people were trying to use, what they called ‘bump’ on the edge of black cap as ELTE trait – as you can see ROYT will have it as well; black cap and ‘bump’” in ROYT is not as well defined and solid as is in ELTE but if a single bird is seen it might leads to confusion.

Also as I was able to see this tern for a few hours and there is one thing worth to note. This is a young bird that was on the wing most (all?) of the time. It was not successful to get a prey (not even once I saw him succeeded, but seen many tries). Either size/kind of the available fish was not right or it has no experience to hunt on its own (many larger terns are fed and taught how to hunt by parents for extended length of time); or both. Spending so much time on the wing is very energy costly and to do that without refueling can lead to serious problems. Let’s hope that this one will find right food and be able to get it.
Even HY ROYTs were able to get finger size mullets; but they have much stronger build bills. BTW ELTE tried to pirate food from other terns – unsuccessfully as well.