I must say I find brood parasitism one of the most fascinating
topics in ornithology. Does anyone have a short bibliography on
the subject they might wish to suggest? I find hard references
on the subject pretty sparse.
There is an interesting, if rather simple, article on the subject
in Ian Rowley's book if anyone wants to get a start on it.
We often think of it as the peculiar perversion of the cuckoos,
but of course it's not confined to them, nor are all the cuckoos
all so affected. In fact in Australia the Pheasant coucal is a
champion nest builder, and a very doting parent.
Other brood parasites include the notorious American cowbird (a
passerine, I think), the Honeyguides of Africa and parts of Asia
(Piciformes (?)) and the Black headed duck. The latter seems to
be almost an innocuous parasite in that it simply lays an extra
egg in some other species nest, it hatches, and the duckling just
joins the brood. None of the nasty infanticide stuff of the
others.
The questions that occur to me is what evolutionary pressures led
to such an adaptation, what are the signs of a new species that
might be headed in that direction, why does it arise in so many
families and what vestigial parenting behaviour is left in the
species that have gone down the brood parasite route? Also, of
the migratrory species, how do the chicks know where to go, since
they often leave well after the parents have departed?
Fascinating stuff.
John> The European Cuckoo has various host species, but a Cuckoo
John> hatched from the nest of, say, a Reed Warbler, will return
John> to a Reed Warbler's nest to lay its eggs and its eggs are
John> closer in colour, pattern and even size to those of a Reed
John> Warbler, than those of cuckoos hatched in the nest of
John> another species.
I have a pretty large, rather classical data set that gives
length and breadth of eggs of European cuckoos, classified by
host species. Size separation is there, but it's not by any
means totally striking. There is a palpable separation between
host species but much overlap. It would be much more interesting
to have colour and texture measurments as well, but this is data
from the British museums before the first world war, and that
information is not recorded.
If anyone is interested I can forward an electronic copy.
John> I wonder if any of the Australian cuckoos have similar
John> adaptations?
Study of the Australian species seems pretty neglected all round.
It seems to me that since they are about the only avian predators
of some of the more noxious hairy catepillars, they must have
some economic as well as ecological importance.
The question that most intrigues me, is whether they could be
re-programmed in some way. Do you suppose that by putting koel's
eggs into, say, starling's nests, or channel billed's eggs into
feral Pigeon's nests, you could somehow exert a measure of self
sustaining biological control on the little beggars? (Only
kidding...I suppose.)
Bill Venables.
_________________________________________________________________
William Venables, Department of Statistics, Tel.: +61 8 303 3026
The University of Adelaide, Fax.: +61 8 303 3696
South AUSTRALIA. 5005. Email:
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