canberrabirds

Re: An exceptional year?

To: "Geoffrey Dabb" <>, "chat line" <>
Subject: Re: An exceptional year?
From: "Michael and Janette Lenz" <>
Date: Wed, 13 Apr 2011 13:29:06 +1000

An exceptional year?

 

?certainly a very interesting year! Just a few comments to the questions raised by Geoffrey.

 

For up to 10 years the local bird scene has been shaped by local and distant drought. We had influxes of species normally found more to the West of us (such as White-browed Woodswallow, Masked Woodswallow, higher numbers of White-winged Triller, Rufous and Brown Songlark), and we have seen declines in some of our local breeding birds, at least breeding success has often been poor. With the rains since late 2009 things have changed markedly. Importantly, conditions inland are now very good. This has meant that there was no need for inland species to move East to find suitable conditions for breeding. Hence, no White-browed and Masked Woodswallow have been recorded in 2010 in our area, and to judge by sites I visit, many Dusky Woodswallows have also left their former breeding areas here, and no doubt have moved westward, further I have not recorded this species this autumn over my GBS site while at the same time last year they passed through often.

 

White-winged Triller and both species of Songlark were present in quite small numbers during the last breeding season: most birds had no need to come eastwards, however, sites that have those species present probably present optimal habitat for them.

 

We had notable influxes of Stubble Quail in summer, and it seems both species of Pardalote and Grey Fantail had very good breeding success to judge by high numbers recorded everywhere this late summer/autumn. Most pleasing were more sightings of Speckled Warblers this year during woodland surveys than in previous years. And numbers of Diamond Firetails have also increased. No doubt there are many other similar examples.

 

The rains in early 2010 triggered late breeding not just in waterbirds, but also in a number of woodland species, most notably in Thornbills. It seems that we may not see the same success this autumn. However, some species, especially the Red Wattlebird, had an extended breeding season (although I still think that a very wet 2010 spring often resulted in failed first broods for this species; when I raised this once on the chat line, I had both confirmation and statements to the contrary, so the impact may have been patchy), and the Koel made good use of these late broods and a notable number of late Koel fledglings were reported. This is quite intriguing. Are late host broods more vulnerable to parasitism? (Perhaps adult hosts have to spend already more time foraging than in spring/summer, hence nest attendance may be lower, giving the Koel female more opportunities to deposit an egg?)

 

In the 2010/11 breeding season Noisy Miners have bred from early spring well into autumn at all sites I have visited. In 2009/10 late broods were only recorded from one population.

 

The widespread good rains had another amazing impact ? this time on waterbirds. At urban and farmland water bodies, Australian Grebes and Wood Ducks had a good and extended breeding season, with the latest breeding record for the latter at the ANU from Robin Hide only the other day. Although both Lake George and Lake Bathurst partially filled (I am always astonished how much more it has to rain before the lakes would properly fill; both lakes have still a very long way to go: right now they are shrinking again), this was not matched by numbers nor species composition of waterbirds. Shortly after the initial partial flooding, good numbers of birds were recorded, but soon most waterbirds moved inland with only relatively small numbers of ducks and swans staying behind.

 

Apart from one record of a Golden Plover by Dan Mantle, we had no records of any northern hemisphere waders at those lakes for the last wader season (matching stories of much lower wader numbers than usual being reported from key wader sites in southern Australia). However, Australian waders have done well locally. Banded Lapwings were recorded in good numbers, Black-winged Stilts have bred, and Masked Lapwings formed larger flocks at both lakes.

 

Certainly a fascinating time to watch birds and to follow what ever may unfold in our local (and further afield) bird fauna. More than ever we need many, many records from COG members documenting the changes and events, so that we can answer questions such as whether or not a given year is exceptional or not.

 

Michael Lenz

 


From:
Sent: Sunday, April 10, 2011 12:55 PM
To:
Subject: RE: [canberrabirds] Late breeding

Thank you Martin, another informative graphic.  When this year is analysed we shall see the height of the W14 bar, but shall we ever be certain that a taller bar represents an exceptional year.  I would be interested to know whether such a careful observer as Michael has any feeling that this year is exceptional.    

 

From: martin butterfield [
Sent: Sunday, 10 April 2011 12:11 PM
To: Michael and Janette Lenz
Cc: chat line
Subject: Re: [canberrabirds] Late breeding

 

Last friday was in GBS week 14.  See attached in support of these being late records. 

Martin

On Sun, Apr 10, 2011 at 11:02 AM, Michael and Janette Lenz <> wrote:

On Friday, 8. April, at the ANU a pair of Red Wattlebirds with a fully grown but still begging young. Parents fed it repeatedly.

On the same day in Civic a pair of Galahs feeding a young that looked as if it had left the nest hollow only very recently.

 

Michael Lenz

 

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