Silver Gulls in Canberra behave in a similar way around the National
LIbrary, which is on the shores of Lake Burely Griffin and floodlit at
night. They roost in flocks on the lawns right in the bright light and
some flocks are always flying aroud, even in the depths of the night.
I suspect it's a predator free environment, or at least one where
predators are easier to spot. Insects attracted to the lights could be
a bonus.
John Leonard
On 20 April 2010 17:07, Kurtis Lindsay <> wrote:
> Hi all,
>
>
>
> For many years I have noticed large flocks (~100) of Silver Gulls flying
> high over the Sydney Harbour bridge at night.
>
> The birds seem to fly in loose flocks, and fly around in circles.
>
>
>
> I have always wondered about what might be the cause for this behaviour.
> Here are some of my theories:
>
>
>
> 1. The gulls are hunting insects attracted by the lights on the wing -
> has anyone seen gulls catch an insect on the wing before? Would there be
> enough insects up there to sustain such a large flock for such an extended
> period of time? If so is it the migratory Bogong moth they're attracted to?
>
>
>
> 2. The gulls are courting/mating - so loaded up with hormones the
> gulls continue courtship through the night, in the only place lit-up enough
> to do so ,under the bright lights of the bridge.
>
> At times birds are seen flying close to each other but there
> doesn't appear to be any obvious courtship. What does Silver Gull courtship
> involve?
>
>
>
> 3. The gulls are dazed and confused by the bright lights, and continue
> to fly around in circles. If this is so, why aren't there more dead/stressed
> seagulls found on the harbour bridge in the mornings?
>
>
>
> 4. The gulls choose to stay awake in a lit-up area as a predator
> avoidance technique, the bridge providing a safe haven and a clear flight
> path for a continuous safe flight throughout the night.
>
>
>
> Can anyone else shed light on this bizarre phenomenon?
>
>
>
> Kurtis
>
>
>
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--
John Leonard
Canberra
Australia
www.jleonard.net
I want to be with the 99,999 other things.
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