At 09:57 AM 15/09/2007, Geoffrey Dabb wrote:
(1) Naomi Langmore worked
on this a few (5?) years ago at Campbell Park,
with particular attention to the HBC/SFW relationship. She gave
a
presentation to COG.
In case COG members haven't seen them, there are two new papers from
research by Langmore and colleagues on aspects of Horsfield's
bronze-cuckoos breeding in Campbell Park...
Animal Behaviour (2007) Vol. 74, No. 3: Pages 403-412
"The spatial organization and mating system of Horsfield's
bronze-cuckoos, Chalcites basalis "
N.E. Langmore, G.J. Adcock and R.M.
Kilner'
In theory, liberation from parental care in brood parasites should
facilitate polygamous matings by both sexes. We used a combination of
mtDNA and microsatellite analysis to reconstruct sibling groups of
Horsfield's bronze-cuckoo chicks to infer the mating system of this
species. By mapping the distribution of sibling groups we also inferred
the breeding ranges and breeding duration of individual cuckoos. Genetic
analysis revealed that individual female cuckoos laid distinctive egg
types, enabling inclusion of data based on egg morphology. Pairs of
Horsfield's bronze-cuckoos occupied exclusive breeding ranges
encompassing clusters of host territories. There was a bimodal pattern in
the timing and duration of breeding: early-arriving females laid eggs
over a period of up to 5 weeks and were then replaced by late-arriving
females, which continued laying periodically over at least 2 months. In
other brood-parasitic birds polygamy is widespread. By contrast,
Horsfield's bronze-cuckoo females were genetically monogamous, and males
were either monogamous or sequentially monogamous. Polygamy may be
constrained in Horsfield's bronze-cuckoos by the exclusive home ranges of
females.
Keywords: brood parasite; Chalcites basalis; egg
morphology; Horsfield's bronze-cuckoo; mating system; monogamy;
territoriality
and
Animal Behaviour (Article in Press, available online)
Breeding site and host selection by Horsfield's bronze-cuckoos,
Chalcites basalis
N.E. Langmore and R.M. Kilner
Cuckoos are faced with a series of reproductive decisions unique to
the brood-parasitic lifestyle. Choice of the appropriate host to rear
their young requires decision making at three levels. First, selection of
a breeding site may take into account host densities in addition to
environmental considerations. Second, once they have selected a breeding
site, female cuckoos must ensure that they choose the nests of an
appropriate host species to rear their young. Third, cuckoos may also
choose among individuals of the host species in relation to the
likelihood that the host will successfully rear their young. By
observation and experiment, we investigated the factors that influenced
annual parasitism rates and the mechanisms of host choice in Horsfield's
bronze-cuckoos, Chalcites basalis. Parasitism rates varied from 0%
to 37% annually, and were influenced by host density and spring rainfall.
Despite the availability of several suitable hosts with similar nest
sites within the same habitat, over 99% of Horsfield's bronze-cuckoo eggs
were laid in superb fairy-wren, Malurus cyaneus, nests, lending
strong support to the Host Preference Hypothesis for host choice.
Patterns of parasitism were nonrandom with respect to host female age and
identity, but we found no evidence that cuckoos preferentially
parasitized those individuals that were most likely to successfully rear
their young.
Keywords: avian brood parasitism; Chalcites basalis;
Horsfield's bronze-cuckoo; maternal effect; habitat imprinting; host
density; host partitioning; host preference
Robin Hide
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