Send birding-aus mailing list submissions to
To subscribe or unsubscribe via the World Wide Web, visit
http://lists.vicnet.net.au/mailman/listinfo/birding-aus
or, via email, send a message with subject or body 'help' to
You can reach the person managing the list at
When replying, please edit your Subject line so it is more specific
than "Re: Contents of birding-aus digest..."
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
To:
Message-ID:
<>
Content-Type: text/plain; charset=ISO-8859-1
Michael,
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!
Cheers,
Ben
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";
reply-type=original
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
------------------------------
_______________________________________________
birding-aus mailing list
http://lists.vicnet.net.au/mailman/listinfo/birding-aus
End of birding-aus Digest, Vol 57, Issue 16
*******************************************
