tmichael

Assuming you mean the bird is on the sea, Ancient Murrelet is a possibility, on basis of greyish back, though Koel is not a very obvious comparison species.

Even a very distant shot might be enough.

Mike Turnbull

tmichael

There's your choice - Ancient Murrelet (if on sea, unlikely in a bush) or Hair-crested Drongo (unlikely on the sea, more likely in a bush).

Mike Turnbull