David Burren wrote:
>
> In April I was in Bunga Arm (the Gippsland Lakes) at anchor near
> the First Blowhole and noticed a Silver Gull acting strangely. At
> least, it was not behaviour I was used to - hopefully someone here
> can shed some light on this behaviour for me.
>
> This gull was following around a pair of swans, usually swimming
> alongside them as they fed. Then every now and then it decided to
> dive. Not just bob under the water, but fly up a feet or so and
> dive into the water right near the swans. It would do this over and
> over again.
>
> Being a photographer by trade of course I have photos:)
> I have two JPEGs of this online:
> http://burren.cx/david/misc/32A.jpg
> and
> http://burren.cx/david/misc/swansNgull.jpg
> (this actually has two photos in it)
>
> The image where the bird is in the air with its wings raised and
> the one where it seems to be balanced on the water by its bill are
> only 1/3rd of a second apart in time - the bird really wasn't going
> very high. In those two images the 2nd swan's head was below water.
>
> This behaviour went on for at least 20 minutes that I noticed. The
> swans moved around a fair bit, and the gull followed. This was a
> fresh-water (brackish actually) lake seperated from Bass Strait by
> a dune system. The water under the birds was probably ~1m deep
> with lots of plant life.
>
> Can anyone offer a theory for me?
>
> Thanks
> __
> David Burr
Dear David -
Havent been able to retrieve your photos (wonky old computer), I'll try
again later.
But what the gull was almost certainly doing was using the Swans as
beaters. The Swans take water plants from the bottom and mid-water;
their long necks let them feed deeper than other Anatidae. As they do so
they would disturb small water-life, fish, shrimps, even pull up a few
small bivalves as they uprooted the plants. The Gull would be grabbing
and diving for this prey.
I have a photo of a Gull similarly dancing attendance on a great Egret
in the Gippsland Lakes, swimming while the Egret waded.
Gulls are very keen on any labour-saving means of getting a feed ..
no wonder they are successful.
Anthea Fleming in Ivanhoe, Vic.
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