121 



The occurrence of the Rock Parrot can be easily explained, considering 

 its habits, which expose it to the perils of the winds. Hunger may have, at 

 times, compelled a flight from other islands, and the Pearson Islands may have 

 served as a haven of refuge. 



The Starlings, believed to have been seen, and the very doubtful presence 

 of Sparrow^s, can only be explained by wind dispersal. Starlings would hardly 

 seek deliberately such a far-distant speck of land for food. 



The habits of Artannts persoiiatits, which in numbers at certain seasons 

 soar often to great heights into the air, would render these birds liable to 

 accidental transport. The presence of a pair only would suggest that the 

 passage had been a dangerous one and few had survived, or that a suitable 

 insect food supply was insufficiently abundant. 



We are left with the Red-cap Robin and the Pachycephala. I will deal 

 separately with the Bronze Cuckoo as coming in a category by itself. Red-cap 

 Robins are doubtless relatively numerous on the adjacent coast. They usually 

 occur, however, in pairs, though occasionally two f ull-plumaged cocks and several 

 dull-coloured birds may be seen in company. Their daintiness does not suggest 

 strong powers of flight. Doubtless an occasional bird is blown to sea, very 

 rarely two may be, and make the same haven, Pearson Islands. The chances 

 would be doubled against the two birds being mates. The origin of the birds 

 now present must be left entirely open, though I incline to the immigrant view. 



Pachycephala pectoralis remains. It occurs on the mainland. Whether 

 numerous there, I know not ; but in my experience in other parts I would 

 expect it to be, though not rare, by no means numerous — a pair of birds, say, 

 to some square miles of country. Here, it seems to me, the chances are 

 decidedly against two birds of opposite sexes making this island within a year 

 or so of each other. Pachycephala may be an autochthone. 



The presence of a Bronze Cuckoo, of which species two birds at least were 

 seen and one was secured, was a surprise. These birds are migratory, at least 

 in many parts of Australia, though North (Nests and Eggs, iii., p. 23) states 

 that Chalcococcyx basalis may be a permanent resident of the Sydney district. 

 In the Adelaide district they are numerous in the spring and early summer. 

 Whither they migrate is unexplained. Mathews (Birds of Austi-alia, vii.. 

 p. 345) suggests, into the interior of Australia, though the species has an extra- 

 Australian range. The important point to consider in connection with the 

 species is that it is migratory, at least in places, such as southern South Aus- 

 tralia, Victoria, and Tasmania. Are we to consider the birds found on Pearson 

 Islands as migrants or as stationary individuals, such as may be the case 

 amongst some in the Sydney area? If the climatic conditions in other parts 

 of South Australia do not entice these birds to remain all the year round, it 

 does not seem to me likely that the Pearson Islands would do so. If the birds 

 deliberately migrated there, there would be no reason why they might not 

 return north equally well. Such a migration and return occur in Tasmania. 

 I think we may assume that the Pearson Island birds are as much migrants as 

 Tasmanian ones. Does their occurrence on the Pearson Islands then indicate 

 that many birds, on reaching the shores of the Bight, proceed on south, though 

 islands are few — mere specks in the ocean — and many must perish, the only 

 survivors probably of those that leave the immediate vicinity of the mainland 

 being the Pearson Island ones? I think this view is quite a likely one. But 

 why do they pass on south? It is perhaps too much to surmise that they seek 

 a land which is now submerged, that part of southern Australia that originally 

 reached as far as the Pearson Islands and beyond them till the limits of the 

 continental shelf are reached. This would presuppose that the instinct, directing 

 them to a particular area, had remained unabated and unmodified by changed 



