"Migrants": is this early?

To: <>
Subject: "Migrants": is this early?
From: "Geoffrey Dabb" <>
Date: Tue, 2 Sep 2008 15:55:45 +1000

Like Peter Ormay, I think Martin’s work on this is interesting and valuable  -  including his note on ‘tight-arrival’ migrants in this months Gang-gang.  However, I sometimes think it can be misleading to focus, like the figurative eagle-eyed contributor to The Times, on the ‘first arrival’ of migrants -  in relation to so-called partial migrants.  For one thing it diverts attention from the true migrants, whose movement variation might conceivably reflect climate shift and not just local food availability.


Clearly enough, the GBS records movement of birds through the suburbs.  Thus there is clearly a seasonal element to the garden appearance of Grey Fantails for example.  With such birds there is quite likely (a) an altitudinal element and/or (b) a vegetation element eg to/from woodlands.


Taking ‘Canberra’ as including its woodlands, it seems to me that insufficient work has been done to be certain of the annual movement pattern of birds that are present in our area during Winter, although in much reduced numbers:  eg Noisy Friarbird, Dusky Woodswallow, Olive-backed Oriole (remember Graeme Clifton’s report in July).  The second BA atlas, with the first COG atlas, is a start.  Other movers that can be present in Winter in reasonable numbers include Welcome Swallow, Black-faced Cuckoo-shrike, Rufous Whistler, Yellow-faced and White-naped Honeyeaters and Fan-tailed Cuckoo.  I have difficulty with the idea that any of those birds have ‘just arrived’ when they are reported in Spring.


The term ‘partial migrant’ seems to me to be confusing shorthand.  It might suggest that some members of a population migrate only a short distance, or that some members do not migrate at all.  With regard to the species in question it may be that Canberra is properly regarded as at the fringe of the Winter range and a few members of more southerly populations range about our area.


To me the ‘true migrants’ among our land birds are those that are absent from South-east Australia in Winter, eg Koel, Bee-eater, Dollarbird.  Significantly, it is these that seem to have ‘tight’ arrival schedules (which makes all the more interesting the ‘early Koel’ reports).  I would also include the Painted Honeyeater, which you can set your calendar by at Cocoparra.   









From: martin butterfield [
Sent: Monday, 1 September 2008 5:04 PM
Subject: [canberrabirds] Dusky Woodswallows


This afternoon a flock of about 6 Dusky Woodswallows were hawking along Whiskers Creek Road (about 200m outside my GBS site).

In terms of GBS observations this coincides nicely with the expected upturn in number of observations.  A graph is attached: note that this shows the raw number of observations rather than the F% value, since the two lines are similar and this one is slightly simpler to plot.  I have also extended the graph to show that the observations (after the initial 'surge") are less consistent than was the case for the Noisy Friarbird.

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