Re: unsubscribe

Subject: Re: unsubscribe
From: Ricki Coughlan <>
Date: Fri, 10 Dec 2010 12:09:51 +1100
Hi folks

All efforts to unsubscribe from the list have failed. Can you please unsubscribe me from your end.

Thanks and happy birding

Ricki Coughlan

On 10/12/2010, at 12:03 PM,  wrote:

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Today's Topics:

  1. Re: Silver Gull Aerial Predation (Ben Hope)


Message: 1
Date: Fri, 10 Dec 2010 10:29:13 +1100
From: Ben Hope <>
Subject: Re: [Birding-Aus] Silver Gull Aerial Predation
Content-Type: text/plain; charset=ISO-8859-1


I agree that the availability of rubbish leads to over abundance of many species, particularly at land fill sites. Although if the rubbish were to disappear over night (or even over a longer period as silver gulls can live ~30 years) it would probably result in prey switching by the scavengers. This may result in depleted insect and other prey taxa numbers while the scavenger numbers correct themselves. THe birds may also become aggressive as food resource become more limited. As some one else pointed out reducing
silver gull numbers may also impact on other fauna (notably predators
feeding on silver gull and other species competing for the same resources)
now dependant on the over abundance species as a food resource.

It is an interesting problem, but not one with an easy answer!


Date: Thu, 9 Dec 2010 23:21:40 +1100
From: "michael norris" <>
Subject: Re: [Birding-Aus] Silver Gull Aerial Predation
To: "Jon Irvine" <>,       "'birding-aus'"
Message-ID: <
Content-Type: text/plain; format=flowed; charset="iso-8859-1";

Hi Jon

No - it's not good to see them catching live prey, especially at night.

German research has indicated, if not proved, that light pollution has
serious effects on insect diversity and abundance. For instance, the "vacuum cleaner" impact sucks insects into the light and, for some species where one sex does not fly, this means the potential partners die in disproportionate
numbers when they are killed by bats... and silver gulls....

And why are the gulls feeding on live prey? Because their vastly increased numbers, and now all-year round breeding, in urban areas as a result of trash means there are many more individuals short of day time food that need
to hunt at night.

I guess we agree the trash is the issue to be tackled. Ian Temby's work on silver gulls in Melbourne includes accounts of roof top nests surrounded by chicken bones. And estimates the damage caused by their excretions etc in
the millions.

Michael Norris


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