The island seem to have these everywhere at the moment.
very difficult to capture holding still.
A fast moving bird that doesn't pause for more than a few seconds.

Elbert - you are so right! And I understand these with the yellow instead of red are either females or juveniles.

I'm not sure.
Its 'American' Redstart, they have them in Europe also, I assumed that might be where the red in Redstart comes from.