Re: Avocets at Koorangang

Subject: Re: Avocets at Koorangang
Date: Thu, 7 Jun 2001 10:02:21 +0800
Steve Roderick" <> wrote :
> The first year birds of some species of migratory waders 
> over-winter in Australia in small numbers. This has two benefits
> to those species - the young birds build there strength by cutting
> out the migration to the north and back, and the breeding birds
> have less competition at the breeding grounds.

I can agree with the first benefit.  The second benefit is harder to agree 
with.  The numbers on the breeding grounds would reach the current 
capacity.  This would result in a lower overall population, but the same 
numbers on the breeding grounds.

The first year birds of quite a lot of the migratory waders over winter.  
For Red-necked Stint and Curlew Sandpiper the results from wader banding 
have shown that they mostly return in their second year.  However the 
larger waders stay longer.  Great Knots (and I think Red Knots?) stay in 
Australia for two seasons.  Bar-tailed Godwits (and I guess Black-tailed 
Godwits) usually stay for at least three seasons before they make their 
first return.  I don't know the results for even larger waders such as 
Whimbrel and Eastern Curlew.

And they stay in large numbers as anyone visiting Broome, 80 Mile Beach, 
Port Hedland etc in the dry season will attest.  Even in July you will 
find 15,000+ waders in Roebuck Bay at Broome.
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