Hi Laurie
I think that many bird movements in Australia are very complicated,
unlike the situation in the northern hemisphere where the whole
population tends to get up and move south in winter.
You ask if any species shows all three situations you list. A possible
contender is the Noisy Pitta - I did some preliminary work on this a few
years back but need to finish it off.
3. Some birds are present in the forests east of Brisbane all year
round.
2. There is definite evidence of some altitudinal migration with birds
appearing in the coastal lowlands in winter e.g in winter there are
often records of Nosiy Pittas in Brisbane suburbs and the islands of
Moreton Bay.
The same has been found in northern NSW
1. In Cape York, there is some indication that they (?the whole
population) move north in winter.
Note that I have been careful in my wording of (3) - just because there
are birds present all the year it doesn't mean that they don't migrate,
one population may be leaving only to be replaced by other birds. It
would take an extensive banding program to solve this. When you bring
age into it, the situation gets even more difficult to determine without
intensive studies. With the coastal Noisy Pittas, I wondered if these
birds might be either adults or immatures but could find no clear
evidence of this from the museum specimens.
The Spangled Drongo situation also seems complex - in some areas birds
are present all year round, in others there is an influx in winter and
in others there is a summer movement. The north Queensland birds seem to
migrate north.
There is still plenty to find out about our birds, even some of the most
common ones.
Peter
-----Original Message-----
From:
On Behalf Of L&L Knight
Sent: Thursday, 31 August 2006 9:32 PM
To: Birding Aus
Subject: To Migrate or Not to Migrate
Following on from Dan's description of the various migrants that visit
the Lamington Plateau in SEQ, it might be interesting to discuss
species that have populations/groups that:
1. Migrate latitudinally;
2. Migrate altitudinally;
3. Don't migrate at all.
Do we have examples of species in Australia that do all three? In
particular, are there species that have groups that fit into each of
these groups for their entire lifecycles rather than moving from one
pattern to another as they age?
Regards, Laurie.
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