THE BIRDS OF AUSTRALIA. 
that of the typical subspecies, the bill is noticeably smaller. The wings measure: 
512, 518, 525 ; ? 525, 542 mm. ; while the bills give ^ 75, 77, 78, 78, 80 ; 
$ 80, 82 mm. These measurements differ appreciably from those of the 
Bedout Island birds, while from East of Torres Straits the shortest billed 
birds gave d 82, $ 83 mm., and these were from the furthest eastern 
locality and perhaps were representatives of another subspecies distinct 
from F. arid arid. 
There is probably another easily-separated subspecies resident in the 
Atlantic Ocean, but only two immature specimens are yet available. NicoU 
wrote : “ I saw several examples of this species at South Trinidad, but 
obtained only one, an adult male, which was shot by Mr. Lindsay from the 
yacht as she lay off the island.” The specimen in the British Museum is in 
immature plumage, and as it was obtained in January it is probable that the 
species breeds there. It cannot be the one Nicoll records {Ibis 1906, p. 673), 
as he wrote: “ BiU black, pouch bright brick-red; tarsi and toes black.” 
The immature has the data : “ Bill black with greenish tip ; round eye black ; 
sac red ; feet black above, yellowish flesh-colour below, a patch of same colour 
on upper side of each web ” (M. Nicoll). 
Although the juvenile plumages in this species and F. minor are very 
similar, the method of change seems different. Thus the immature of the 
present species has a rust-coloured head as in the other species, but in this 
the rust colour appears to be evenly retained while the black breast-band 
vanishes. In F. minor the rust colour on the head vanishes first, a rusty 
coloured spot remaining on the breast and disappearing with the black 
breast-band, both disappearing simultaneously, the red perhaps lasting longest. 
A phase in F. minor in which the bird breeds has the head, neck and 
all the under-parts white. F. arid shows no such phase as far as can be 
judged, nothing at all like it being seen, and from observations on the 
immature available the bird seems to moult from the rusty-red coloured 
juvenile dress direct into the fully adult plumage. This brings up the question 
of sea-birds such as the present, Gannets and Albatrosses being subspecific- 
ally distinguished by their moulting phases. 
From some localities Fregata minor is represented by black adult males 
commonly : from others practically none such are available. Observers such 
as Dr. Percy Lowe state that black males are very scarce and immature 
birds commonly breed. At the present time, since no attention has been 
given to such problems, it is impossible to put forward any reliable data from 
Museum specimens, as it is probable that the majority are selected specimens. 
As an example, take the Rothschild Collection of Galapagos Fregata minor. 
Adult black males are common from the Northern Islands, and reference to 
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