From Noel Barber's "The Natives Were Friendly ..."
And this is how the same incident is described in Tom Neale's book "An Island to Oneself": Without warning in November 1960 the silence which enveloped the island - broken only by the boom of the surf and the crying of birds - was suddenly shattered by a roar which made the old cat run for her life and sent the hens fluttering into the illusionary security of their coop. It was so unexpected that for one moment I too froze with fear, and I remember it flashed though my mind that another war must have started. I ran out of the shack in a panic as the roaring became louder and more ominous. From the cover of the coconut trees I looked up and saw two enormous shadows in the sky, as monstrous and as predatory as the frigate birds now flying away in protest. Then I realised - they were two helicopters. Until they hovered almost directly over the shack I thought perhaps they were going to leave me ...