Both Shining and Horsfield’s Bronze-cuckoos have been regular visitors to the home garden since their arrival in the spring. Their distinctive penetrating, mournful calls announce their presence, often causing a commotion among small birds such as wrens and thornbills that fall victim to the parasitic cuckoos. Both species are similar in appearance with a coppery sheen to the upperparts and a barred breast – this latter feature is incomplete in Horsfield’s Bronze-cuckoo.
The arrival of a male Superb-Fairy-wren provoked a clear reaction from the cuckoo – it opened its bill, raised its crest and fanned the tail wide open, revealing the beautiful rufous bases to the tail feathers – Shining Bronze-cuckoos lack this colouration – another way of separating the two species. It’s no wonder the tiny wren caused such a response – I’ve heard local reports this season of them actually mobbing and killing adult cuckoos.
The relationship between cuckoos and their hosts is a complex and ever-evolving one – this fascinating article on a study conducted by the Australian National University describes the ‘evolutionary arms race’ between Horsfied’s Bronze-cuckoos and their fairy-wren hosts.