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Hi
Denis,
Yes
all fair enough. Off the top of my head, the issue about actions that benefit
the species is a big debate in a whole range of different cases of any number of
groups of species (well beyond birds) and has been for decades. There are good
suggestions but few if any, truly proven cases, not because it won't be real but
because it is hard to be sure and there are so many other possibilities (just
like this one). The debate is about how it can benefit the individual. The
problem is that benefit to the species, at least in theory, doesn't work, and it
is hard to imagine how it can work, unless we use the "kin selection" model.
Ultimately there does not really need to be a reason for everything. We often
discuss as though there is a reason. The birds might just like biting bark.
Philip Veerman
24 Castley Circuit
Kambah ACT 2902
02 - 62314041
Hi
Philip
Yes it is an interesting
speculation.
At the individual level, one could simply
say Galahs have a compulsion to chew bark on Gum Trees.
But whether it is merely sharpening of the
beak, "marking" and maintenance of territory or whatever, it does not rule out
an indirect benefit to the species.
Once the tree is wounded, rain and then
fungi and insects can make their own inroads, leading to formation of a breeding
hole (which these birds then do actively develop and maintain).
Cheers
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