The following are extracts from the ACT Conservation Advice published earlier this year. That document included the reporting rate graph from the
COG website. Any questioning of the listing should, begin by looking at the concept of ‘extinction’ in relation to the ACT given the wide range and movements (’irruptive’ if you like) of this species.
From: Philip Veerman <>
Sent: Monday, 4 November 2019 3:01 PM
To: 'COG List' <>
Subject: RE: [canberrabirds] Triller
It is curious that there has been no response to my message below. I will for convenience now append Mark Clayton’s comment to the list here, because it is relevant:
I note that, unlike on prior years, there has been surprisingly little chat on this facility, emanating from Blitz surveys and what people found. I suppose we are all willing to wait until Barbara tells us, meticulously as usual, every tiny detail of the results.
Notable among the little chat has been several mentions of many Trillers. Certainly I found many. So as an irruptive species, this appears to be a good year for them. Maybe going back to what it was on the first year of the GBS. I don’t know. I will now add
the extra opinion that to have implicated The GBS Report as having a role in the declaration of the species as vulnerable, was of course quite idiotic and based on failure to understand the data. But I certainly did hear the rumour at a COG meeting………
From: Philip Veerman
Sent: Wednesday, 16 October, 2019 3:35 PM To: 'COG List'
Subject: RE: [canberrabirds] Triller
That may well be. I will add a little historical perspective here. Oh good that I see Mark’s good question after I typed this message and just add this sentence
The GBS started in July 1981. The early GBS records showed that the numbers observed were exceptionally high in year one (1981-82) (and somewhat high for a few
of the other early years). Until (years later when) the data were compiled and available in The GBS Report, there was no way of seeing the trend. Now that it happened to be very high in year one produced a graph that suggested that the species was in strong
decline from a high start. Thus a thought of a baseline. I think this contributed to its listing as “vulnerable”. This may not have been valid (at least on that basis), the comparison may only have been high that year. We don’t know what it was in prior years.
I even think I heard whispers blaming The GBS report, but that did nothing more than show the data…… The GBS report text states these issues as below. I am not suggesting I know the answers but I suggest that, as with many migrants, prevalence locally can
vary a lot from year to year and that the factors that cause this are very likely things occurring outside our area. So high numbers again this year? Believable and probably true. The blitz weekend should provide a very good pointer as the species inhabits
areas that should get a lot of survey effort. And they are easy to find.
Note of course that “16
records” means that, it does not mean “16 observations”.
A summer migrant that inhabits woodland. It is not a suburban bird but passes through the city or stays on
the edges in suitable habitat. Almost absent in autumn and winter, most arrive in September then it rises to a
November peak and declines again quickly. The birds are quite vocal when they arrive. There is no sign of a
second peak as the birds go north again. Maybe they leave quietly or through another route. In Year 1 the
numbers were extraordinarily high and with 16 records, it was recorded at a high 28% of sites (compared with
the mean F% over all years of 8.33%). Birds stayed from start of September to end of December at some
sites. This included many pairs and larger groups. By contrast, there have only been nine records in the last
six years. Unfortunately we do not know whether Year 1 was a peak year or part of a downward trend that
has continued for this species since then.
Breeding records are in decline, all 10 records are from the first nine years. Apparently a compact breeding
period, activities at nest from early November to late December and dependent young from late November to
Graphs on page: 102, Rank: 85, Breeding Rank: 44, A = 0.01394, F = 8.33%, W = 11.2, R = 0.829%,
G = 1.68.
Why this species is on the ACT's Threatened Species list is beyond me.
It is an eruptive species in the local area with hundreds at times arriving and at other times only a few. Typical of a bird of the "inland".
From: Martin Butterfield
Sent: Wednesday, 16 October, 2019 2:55 PM
To: Hawkins, Brian Cc: COG List
Subject: Re: [canberrabirds] Triller
Certainly. There seems to be one calling permanently in Glebe Park and another was in full voice by NLA on Monday. Several at Isabella Pond the past two days and a pretty male at Gambles TSR this
On Wed, 16 Oct 2019 at 13:54, Hawkins, Brian <> wrote:
Does it seem to anyone else that there are a lot more WW Trillers in Canberra at the moment that in previous springs? In the last day I have heard them at Mawson, Curtin and Yarralumla.
-----Original Message-----From: Martin <> Sent: Sunday, October 13, 2019 5:33 PMTo: COG List <m("canberrabirds.org.au","canberrabirds");" target="_blank">>
I was very surprised to hear a White-winged Triller in full voice in Glebe Park this arvo.