They are relatively common, based on calls. But they are by no means easily seen. This one was called in. The only other one I have seen (last year) was also called in.
Each September the only tour company on the island, in conjunction with CI Tourism, organises Bird 'N' Nature Week. This year there are 28 guests joining us on island, and five 'guides' - scientists studying the wildlife. The guests are split into four groups and each day they have a different guide, so everyone gets to do all the activities. We've been out banding tropicbird chicks and CI Goshawks, spotting Abbott's Booby nests, catching introduced Wolf Snakes and Flowerpot Snakes, feeding the orphaned Booby chicks and a few frigatebirds at the National Parks rehab facility, stumbled upon some Green Turtle hatchlings flapping their way down Dolly Beach, looked at a variety of crabs, seen the Blue-tailed Skinks and their breeding facility (the skink is now extinct in the wild), and done some general birdwatching and sightseeing. We did the Owl one night after dinner.
I've taken two weeks off work to help out the Tour operator, and my assistance involves participation. And taking photographs.