Behavior
The main diet of the Horsfield’s bronze cuckoo is insects and they are nomadic, travelling to different regions of Australia to breed and find food. Small insects are taken from leaves, branches, caught on the wing and in breeding season, Horsfield’s bronze cuckoos feed each other in a courtship ritual.The Horsfield’s bronze cuckoo is known as a brood parasite, this means that they lay their eggs in a host species nest. They mainly parasitise the fairy-wrens in the genus Malurus. It has been well documented that the superb fairy-wren and the splendid fairy-wren are the two main species to bare host to the Horsfield’s bronze cuckoo, although they may also parasitise other small Passeriformes including thornbills, warblers and scrub-wrens that can be utilised as a secondary host in certain locations.
Although the behavioural attributes of a host species may play a role in parasitism, it is thought that the female selects its host through imprinting, remembering the species that it was raised by and ultimately using that species to raise its brood.
Reproduction
The Horsfield’s bronze cuckoos are known to form monogamous pairs in the breeding season and occupy the same breeding territories as their host species, however partnerships are short lived as a female will only occupy the breeding territory for a few weeks, as another female takes her place, she may form a pairing with the same male. Females that leave a breeding site after several weeks may move to another site and continue to breed with another male, forming another bond in a new breeding territory. Breeding territories of the Horsfield’s bronze cuckoo generally do not overlap giving rise to the possibility that a pair will defend an area through the season.Food
The main diet of the Horsfield’s bronze cuckoo is insects and they are nomadic, travelling to different regions of Australia to breed and find food. Small insects are taken from leaves, branches, caught on the wing and in breeding season, Horsfield’s bronze cuckoos feed each other in a courtship ritual.The Horsfield’s bronze cuckoo is known as a brood parasite, this means that they lay their eggs in a host species nest. They mainly parasitise the fairy-wrens in the genus Malurus. It has been well documented that the superb fairy-wren and the splendid fairy-wren are the two main species to bare host to the Horsfield’s bronze cuckoo, although they may also parasitise other small Passeriformes including thornbills, warblers and scrub-wrens that can be utilised as a secondary host in certain locations.
Although the behavioural attributes of a host species may play a role in parasitism, it is thought that the female selects its host through imprinting, remembering the species that it was raised by and ultimately using that species to raise its brood.
Evolution
Counter-adaptations have been documented for host species and cuckoos alike, as each adapts to the other in a coevolutionary "arms race". Studies show that coevolutions happen at all stages of the growth cycle, not just the early stages.Fairy wrens have adapted some host defences to reduce parasitism. The high cost of hosting a parasitic species, in energy and genetics, drives the host to improve its defences, which in turn drive the parasite to improve its offences.
Among the host's defensive adaptations:
⤷ Hosts like to nest in large colonies, to cooperate in spotting cuckoos and chasing them away.
⤷ Helpers in large colonies provision the female so she can spend more time guarding the nest.
⤷ Hosts learn and recognise their own eggs, and abandon any that are in the nest before they have started their own.
Among the cuckoo's adaptations:
⤷ Mimicry of host eggs.
⤷ Eggs that are cryptic and therefore unable to be seen in the dark nest.
⤷ Thickened egg shells.
⤷ Efficiency in laying the egg, being able to lay an egg secretly and quickly while the host is absent.
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