On Wed, Sep 03, 2003 at 09:45:24AM +1000, jilldening wrote:
> Bill's posting makes me wonder: have parasitic cuckoos ever been observed to
> raise their own young? Are they capable of building a nest, and if not, why
> not? If they ever built nests and raised their own young in times past, I
> wonder how far back they abandoned the practice. I don't expect anyone will
> be able to answer this, but it's an interesting question to me.
The majority of cuckoos, e.g. Coucals, always raise their young
themselves, a few species may parasitize other species or raise young
themselves, within-species parasitism occurs in a few species and about
40 species are obligate interspecifc brood parasites - they rely on
other species to raise their young.
Cuckoos must stem from a species with parent care. There is debate
about how many times brood parasitism evolved within the cuckoos.
It also evolved at least 5 other times in other groups. There are
suggestions that some or all cuckoo species which raise their young
had an ancestor which was a brood-parasite. There are suggestions that
ecological changes may have produced obligate brood parasitism and then
co-evolution with the host-species became important. There might be a
link betwen cooperative breeding and the evolution of brood parasitism.
I haven't seen an estimate of when brood parasitism arose in the cuckoos
- I assume it'd be 10+ million years ago and outside Australia.
Andrew
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