At 11:38 23/06/98 +1000, you wrote:
>In Townsville, Mackay and Ingham (and no doubt elsewhere) Rainbow
>Lorrikeets roost in the thosands in the trees in well lit sections of the
>"city" centres. In Townsville, Figbirds, White-breasted Woodswallows and
>Common Mynas also roost in communally in well lit areas. Mynas also like to
>roost solitarily inside the sun visas of traffic lights, but I haven't
>noticed if they have a colour prefrenece. In the tropics I doubt that it's
>the heat they are after, and for the first three it's not the city garbage.
>I think it's the midnight twilight, but it also could be the grey noise I
>suppose. Does anyone have any thoughts or suggestions as to why?
>
>
>
>David James
>PO BOX 5225
>Townsville Mail Centre 4810
>
>
I haven't searched the literature, but I presume that one of the reasons
for a bird species to roost communally is to reduce the risk of predation.
One night in late May I counted > 340 little corellas in a tree behind the
BP servo on the corner of Anne St & Ross River Road, Aitkenvale
(Townsville). Could the floodlit forecourt, traffic and street lights and
buzz of vehicles afford the little corella some added sense of security?
The tree was not in flower so was being used as a roost rather than a food
source. At dawn the birds assembled along the powerlines calling, but I
was unable to remain long enough to see when they left or in what direction.
For the purposes of the Atlas should we approximate the number of birds of
a species communally roosting?
Alex Appleman
Townsville
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