There are a range of variables included in the question, as already suggested by others, plus the obvious ones, as in to what extent do you wish to include
the many rare visitor species in the count or just regular residents and migrants, and what constitutes a species e.g. the recent one, do they wish to regard the Shrike-tit as 1 or 3. I would suggest you could come up with an approximate number. So if your
colleague has any intention at coming up with an accurate number, then it would need to define the question better.
Going beyond that, you could find an answer fairly simply from 3 different books that are based in those three regions. However I notice your question is only
about passerines. That makes it harder if you just want to get an answer from a book, because I doubt that books will give that information in regard to just one order of birds. Although easier if you want to do a manual count, as something less than half
as many to count. Most of the birds that occur as vagrants at that geographic level are not passerines (they are sea birds or waders).
From: Bill Hall [
Sent: Saturday, 4 August, 2018 7:39 AM
To: 'Ken Black'; 'Jack & Andrea Holland'; 'Philip Veerman'
Subject: Species numbers
Dear All, I have had this request from a colleague at St Louis University in St Louis Missouri. “ How many native species passerines are found in New Guinea vs. continental Australia vs. Tasmania?”
Can any-one give me numbers? I poste this to the COG website last night but it hasn’t appeared yet.