>(ii) Why do not more species of birds utilise the taller bits
>of the Australian Alps in summer?
Questions that arise in my mind include:
- what resources are there in summer?
- What kinds of birds might make use of these resources?
- what birds do make use of these resources?
- white factors might inhibit other birds from making use of these resources?
I don't really know what resources are availble in Australian alpine zones,
but on the few occasions I've actually been in the high country in summer I
recall seeing many lizards, insects (particularly horse-flies!). Also
alpine flowers, ti-tree, snow-gum etc. I also seem to remember seeing lots
of small scarabs which might well be pollinators - does this suggest that
polination might be predominantly pollen/insect rather than nectar/bird
driven.
So lizard eaters, insect eaters, and pollen/nectar/seed eaters might
potentially make use of these resources. I don't know what birds do occur
in the high country in summer, the only ones I can think are corvids.
It seems to me that for birds to exploit the alpine resources they would
have to vacate territories elsewhere that they might rely on at other times
of year. It might be more worthwhile to stay put and protect their own
territories which can support year round occupation. Longer-distance
migrants would not be under these constraints but there may be better areas
for them in summer than the alpine environment.
Nesting might be another issue - perhaps the alpine environment doesn't
provide suitable nesting options for seasonal opportunistic exploiters of
the alpine food resources. Perhaps the alpine resources are, practacally,
only available to birds that can move in and out on more of a daily rather
than a seasonal basis.
I feel I must apologise for this emabrassingly disjointed ramble of
thoughts - but it's an issue lawrie has raised which I also find very
interesting...
Harvey
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