Page:The Emu volume 18.djvu/322

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240
Whitlock, Birds Breeding in Dampier Archipelago.
[ Emu 1st April

Notes on Birds Breeding in Dampier Archipelago, N.W. Coast of Australia.


By F. Lawson Whitlock, "Chiltern," Tudor, via Albany (W.A.)


The Dampier Archipelago extends along our north-west coast for a distance of about 200 miles. In travelling north the first islands are met with before reaching Ashburton Roads, and the last (Depuch Island) at Balla Balla Anchorage, about 30 miles north-east of Point Samson.

Viewed from the deck of a steamboat, the islands present a very unattractive appearance. As a rule, they appear much the same—long, low, treeless islands, utterly barren were it not for a low scrub just discernible with the aid of a field-glass. To the field ornithologist, however, they suggest possibilities of breeding Petrels, Gulls, Terns, and the larger birds of prey, with the chance, on the larger islands, of isolated families of land-birds, differing in plumage from kindred families on the mainland, and specially interesting on that account.

The majority of the larger islands are too near the coast to promise much in this respect, but in the case of Barrow Island, the largest of the group and over 30 miles distant from the mainland, and still more so in the further isolated Montebello Group, one may look with confidence to the discovery of interesting islands forms and varieties.

Geologically speaking, all the islands have at no very distant date formed part of the mainland, and the surrounding seas are for the most part shallow.

I have previously written a brief account of my former visit to Barrow Island (see Emu, xvii., pp. 171-179). This was accompanied by a map copied from an almost illegible Admiralty chart. I regret to say, from observations made during the present trip, I find the chart unreliable. I refer chiefly to the long axis of the island, which is shown on the chart to be almost north and south. I had a good boat's compass on the cutter, and often took an observation about mid-day to confirm our time by clock; also, I usually saw the sun rise and again set, and when camping out noted the positions of the early morning constellations. My observations point to the fact that the long axis of Barrow Island approximates much nearer to east and west than to north and south. Again, the neighbouring Double Island has a long axis running almost at right angles to the true axis of Barrow Island, and not parallel to the latter, as shown in the chart. Furthermore, a large island immediately adjoining Double Island is not shown in the chart at all. At the eastern end of this island is a huge rocky islet, rising to a height of about 200 feet—a most conspicuous landmark. This, too, is not marked on the chart—an unfortunate omission, in an ornithological sense, as it is the home of a small colony of Caspian Terns