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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