THE BIRDS OF AUSTRALIA. 
unable to make “ due allowance for differences of age ” with any certainty 
and I do not conclude that “it agrees perfectly.” The fact that van Oort 
determined his specimen as the other race indicates re-examination when 
more specimens are available. It is also noteworthy that the specimen 
which Ogilvie-Grant considered immature was killed on November 5, 1912, 
the date the Australian birds are fully plumaged. It cannot therefore be 
definitely accepted that the Australian birds migrate as far to the north-west 
as the Setakwa River. 
I separated the Tully River birds as being paler below, thus approach- 
ing the south-east New Guinea form, but rmtil the exact relationsliips and 
migrations are better known, this subspecies may be ignored. There is, 
however, no reason why the more southern birds should not constitute 
a recognisable subspecies as their migration may be quite distinct from 
that of the northern birds. Such migrations are known in connection 
with Palsearctic birds, and may occur in Austraha as will be shown in 
connection with the Cuckoos later in this volume. 
A peculiar coincidence must here be recorded. Since the above was 
written I have been visited by Dr. MacgiUivray and Mr. W. Maclennan, 
the discoverers and explorers of the Claudie River and Lloyd’s Bay district. 
Ignorant of the views I have expressed above, they informed me that to 
their knowledge the birds which migrated from New Guinea to the above 
named district did not pass through Cape York, but followed the old 
land line now represented by the Great Barrier Reef. This unexpected 
confirmation of my conjecture is worthy of great emphasis, and the 
subspecific state may thus be explained in such migratory birds. As these 
well-known naturaUsts are also familiar with the Cape York fauna, they 
could speak with authority, especially as the migration of North Australian 
birds had peculiarly interested them. 
204 
