Hi Bron. Firstly, while it's certainly uncommon, there are not
infrequent reports of such rosella hybrids in Canberra. I had a couple
around here in Turner a decade or so ago, and there is one nearby at the
moment too. It may be coincidental, but in these cases the attendant
parent (and I'm not sure off-hand whether this is most likely to be the
mother) has always been a Crimson.
Re your point about spp; you're right of course, but the problem is that
we tend to think of nature of being static, whereas of course we're only
looking at the world at one arbitrary point in time along a continuum. I
hope that doesn't sound too obscure; another way of putting it is that
the time that any two species have been separated (ie since they were
part of a single population) will be different for virtually any
species/population pair. If the populations separated relatively
recently (eg in magpies or masked lapwings) the isolated populations may
have changed to the extent that they look different, but still readily
interbreed when they come back together. If they've been apart for
longer - eg rosellas - they are almost reproductively isolated, but may
occasionally interbreed (perhaps young inexperienced birds??). We would
normally expect such offspring to be infertile (though I had strong
suspicions of a second-generation hybrid here in the past). And of
course most closely related species - eg Scarlet and Flame Robins - live
side by side without ever interbreeding.
It really is all a question of time.
I hope this helps more than confounds. I'm sure there are others who can
- and hopefully will - explain it better.
best wishes
Ian
---
Ian Fraser,
Environment Tours; Vertego Environmental Wordsmithing
GPO Box 3268, Canberra, ACT 2601
ph: 61 2 6249 1560 fax: 61 2 6247 3227
---
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