Evolutionary interactions of brood parasites and their hosts : recognition, communication and breeding biology : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Ecology at Massey University, Auckland, New Zealand
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Date
2009
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Massey University
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Abstract
Obligate brood parasites lay their eggs in nests of other species, relying on these host
parents to care for their offspring. This phenomenon has been a curiosity amongst
researchers since its first description and has become a model study system for testing
such ideas as coevolution and species recognition. This thesis examines a few of the
many questions that arise from this breeding system. The New Zealand Grey Warbler
(Gerygone igata) and its brood parasite, the Shining Cuckoo (Chrysococcyx lucidus) are
used as the main study species, although research on the eviction behaviour of Common
Cuckoos (Cuculus canorus) has also been conducted. First, the current state of
knowledge and recent discoveries regarding nestling rejection abilities of hosts is
reviewed in chapter one. Second, a comparative study of New Zealand passerine
begging calls has been conducted to test for begging call similarity between a brood
parasite and its host, as well as developing a new technique for detecting the mode of
coevolution that may be occurring in the parasite – host relationship. Parent-offspring
communication in Grey Warblers is also examined to test for both parental and nestlings
Parents use both alarm calls to warn offspring of potential danger, and also parental
feeding calls to elicit a begging response from nestlings. By contrast, nestlings are able
to signal both age and short term levels of need to parents through the acoustic structure
of the begging call. The evolutionary costs and benefits of egg eviction behaviour in the
Common Cuckoo are also tested. An experimental approach showed that egg eviction
had a growth cost, but this cost was temporary and restricted to during and immediately
after the egg eviction phase. A pattern of compensatory growth was observed after the
eviction period, so that during the later nestling stages there was no difference in mass,
and no difference in fledging age. Finally, variation in the Grey Warbler breeding
biology and Shining Cuckoo parasitism rates are examined through both time and
across latitudes. This research has shown a counterintuitive pattern of breeding
phenology across latitudes. These patterns have implications for Shining Cuckoos both
in terms of timing of available nests and host selection.
Keywords: Begging call, breeding phenology, brood parasitism, coevolution, Common
Cuckoo, eviction, Grey Warbler, parent-offspring communication, Shining Cuckoo.
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Keywords
Brood parasitism, Co-evolution, Grey warbler, Shining cuckoo