Graylag Goose - status in Victoria amongst other "tickable ferals"

To: Birding Aus <>
Subject: Graylag Goose - status in Victoria amongst other "tickable ferals"
From: David James <>
Date: Mon, 18 Nov 2013 14:45:31 -0800 (PST)
It is an interesting point raised by Paul Rose, when do populations of escapee 
birds become a feral population or an introduced species and how or when do we 
decide to put them on the Australian list? 

Part 1: Criteria
There used to be a guideline rule that the species has been self sustaining and 
breeding in the wild for a minimum of 10 years. !0 years is pretty arbitrary 
and some birds might not even breed in some 10 year periods (e.g. Ostrich?). In 
the sort of parallel case of looking at population changes in threatened 
species the IUCN moved from "10 years" to "10 years or 3 generations, whichever 
is greater". A generation is defined as the average age of first breeding in 
females. Problem is that this is virtually impossible to know for most species, 
so I think it is not just impractical but inhibitive. So the 10 year rule, 
though rubbish, is better.  Criteria normally don't consider a minimum size of 
the population. If one family of say an escaped parrot or finch started 
breeding and after 10 years and there was one nest and 6 birds, would they be 
an introduced bird? Would they be the same as Common Myna or just a temporary 
aviary escapee? The lines are
 difficult to draw.

Part 2: Collating information.
Atlas databases are probably the best way to document long-term sustaining 
populations of feral birds. However, natural history studies are also suitable. 
A few years ago I co-authored a paper in Sunbird on breeding records of 
Helmeted Guineafowl and Indian Peafowl in N Qld, in which we documented 
population persistence and breeding records over a decade or more. 
Nevertheless, the fact that some peafowl and guineafowl meet the 10 year 
criterion, does not mean that all feral birds do. 

Part 3: Making a decision to include
In the case of published papers, decisions can be made whether to accept 
species as introduced during literature reviews for checklists (e.g. Christidis 
& Boles) and handbooks (e.g. HANZAB, DAB). HANZAB Vol 2 (1993) found 
insufficient evidence to accept  Helmeted Guineafowl as introduced anywhere in 
Australia. Christidis & Boles (1994). C&B 2008 wrote:  "Populations of Numida 
meleagris (Helmeted Guineafowl)
in Australia were not considered by Marchant and Higgins (1993) to be self
sustaining and viable, on which basis Christidis and Boles (1994) placed it on
the supplementary list.  Britton and
Britton (2000) and Wieneke and James (2006) provided evidence that there are low
numbers at several locations in northern Queensland where this species has
persisted and bred.  It is transferred to
the main list." 
Likewise C&B 1994 did not accept Green Junglefowl because HANZAB considered 
them extinct, but Mike Carter (in an article in Wingspan) pointed out they were 
still extant, so C&B 2008 listed them. 
Reviewing atlas data to make decisions is something that I don't think has 
occurred in Australia before, though I don't know for sure.  It could be 
included in reviews if there were appropriate communication and cooperation.

David Torr wrote: "I guess the arbiter is the BARC list, which does not include 
the Greylag".

That's a problem. The taxonomy, nomenclature and sequence of the BARC checklist 
is done by the IOC. The decisions about the regular species come from 
historical texts (checklists, HANZAB, etc). BARC assesses occurrences of rare 
birds and thereby monitors and adds new vagrants to the list. But BARC doesn't 
assess introduced birds. Currently, as I described above, assessing introduced 
species is a piece meal process at best, and not something that BARC cannot be 
involved in. I don't that there has ever been a systematic process in place.

Jeremy O'Wheel  wrote "I don't think Graylag Goose would be tickable in 
Australia at all, since
>all are escaped domestic breeds (as far as we know)"
It is true that they are domestic geese, but "tickable" populations in 
Australia of Gallus gallus are also derived from domestic stock, not Red 
Junglefowl. It's messy having these domestic strains of wild birds introduced 
and wild, but if they exist they should be recognised. 

Whether any Greylag Geese of domestic origin occur in sustained feral 
populations in Vic (and on Norfolk I) meeting the 10 year criterion (or any 
other criterion)  I can't say.  Data are needed.

David James

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