birding-aus Giant Petrel ID

Subject: birding-aus Giant Petrel ID
From: SOSSA-Smith&Jenkin-Smith <>
Date: Sat, 14 Aug 1999 03:22:04 -0700
-- I read with interest the comments of Rod Gardner & PJ Milburn regarding the 
identification of Giant Petrels.  The two sibling species were only separated 
in 1966 
after some research carried out at Macquarie Is by Bourne & Warham (1966).  
Identification of the two species is thought to be quite strait forward, those 
with a 
dark reddish tinge to the unguis (Bill tip) Northern GP (Red for north where it 
warm). Green Bill tip Southern GP (Green for south where it is cooler). 

It is our experience here at Wollongong that the vast majority of GPs that 
occur here 
and along the NSW coast are (birds of the year) Juveniles, therefore Bill 
coloration may 
not be fully developed making specific identification of some individuals at 
sea very 
difficult/if not impossible even in the hand.  In such cases these birds are 
described as Macronectes Sp. 

The problem of specific identification does not however end here.  At several 
stations throughout the Sub-Antarctic the two sibling species breed 
sympatrically and a 
small number of inter-specific pairs occur. 

At Bird Island South Georgia (South Atlantic) inter-specific pairs represent 
1.5 percent 
of the population. Inter-specific pairings were of two distinct types. In Type 
A, a male 
M.giganteus was paired to a female M.halli:  In Type B, a male M.giganteus was 
paired to 
a female bird that could not be identified using bill colour.  These birds had 
that were a weak horn colour throughout, lacking the dark red tip of M.halli or 
the pale 
green tip of M.giganteus. 

All six chicks of type A pairs fledged successfully; four of the nine chicks 
from type B 
pairs fledged successfully.  All of these chicks showed the plumage 
characteristic of 
both M.halli and M. giganteus fledglings, but had a bill rather paler and less 
than M.halli chicks and lacking both the reddish tip that some show and the 
green tip of 
M.giganteus chicks.(Hunter 1982 EMU 82 supplement). 

As though this is not confusing enough, the Giant Petrels breeding on Gough 
Island in 
the Atlantic Ocean show characteristics of both M.giganteus and M.halli.  Some 
suggest that a third species may exist (Voisin & Bester 1981).  These birds 
have green 
bill tips as in M.giganteus and a breeding biology similar to that of M.halli.

Banding studies and recoveries indicate that GPs from many different breeding 
throughout the Sub-Antarctic occur in Australian seas particularly on the east 
coast of 

Our own studies here at Wollongong clearly indicate that the Northern Giant 
M.halli is more abundant in NSW waters than the NSW Rarities Committee would 
have us 
believe!!  Recent studies at several breeding stations indicate that the NGP 
actually be increasing in numbers.

Cheers :-))
Lindsay Smith
SOSSA  "Wildlife Research" H.Q - Wollongong
Southern Oceans Seabird Study Association Inc

Lindsay E. Smith & Janice G. Jenkin-Smith

Janice G. Jenkin.JP.,CMC. Civil Marriage Celebrant
P.O. Box 142, Unanderra NSW Australia 2526

Phone +61 (02) 4271 6004
Fax   +61 (02) 4272 4626
Mobile 0418 603 007

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