Andrew,
you cannot tick ship assists, aviary escapes, dead birds or birds held in
rehabilitation-human captivity. These are the basic conventions of a healthy
list.
Christidis and Boles is the working list for Australia. Clements covers the
world. Following these conventions House Crow does not qualify for the
Australian list. The supplementary list is for such unqualified species.
Always there will be suspected ship assists and escapes so committees such
as BARC need to make decisions. If species are long distance migrants like
Sabine's and Franklin's Gulls or Blue Rock Thrush or Red-throated Pipit
maybe you can rest assured they flew at least most of the way themselves.
It gets greyer with short distance movement species such as Laughing and
Black-tailed Gull. Currently they are considered to be on the list.
House Crows typically present as definite ship assists possible-probable
escapees. Was the reported dark grey cowl of the Phillip Island bird an
indicator of juvenile plumage or geographical variation?
As one Newcastle birder exclaimed- "two wings, no rings, I saw it and it was
one-on the list!"
Happy listing
Dion
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