We have been seeing numerous posts recently on juvenile cuckoos being fed by Common Ioras and Golden-bellied Gerygones in Singapore. Based on Francis Yap’s article “Resident Cuckoos and their host parents- A Pictorial Guide”, (https://wp.me/p4VGho-hJ), it seems that different species of our resident cuckoos prefer one or two specific bird species as hosts. Examples:
- Rusty-breasted Cuckoos choosing Malaysian Pied Fantails as hosts.
- Drongo Cuckoos choosing Bulbuls or Pin-striped Tit-babblers
- Plantive Cuckoos choosing Common or Ashy Tailorbirds
- Banded Bay Cuckoos choosing Common Ioras
- Little Bronze Cuckoos choosing Golden-bellied Gerygone or Olive-backed Sunbirds.
Kaikee Leong’s dramatic photo of a Common Iora feeding a Banded Bay Cuckoo at Kranji Marshes taken in July 2019.
The current feeding of the Little Bronze Cuckoo by a pair of Golden-bellied Gerygones at Jurong West Neighbourhood Park was first reported by Lee Kia Chong on 23 July 2018 at the same park. (https://wp.me/p4VGho-4Gb). The residents there said that this feeding had been going on for some years now ( per comms Koh Lian Heng)
The abundance of fruit flies around the mango trees at the park must be the reason for these Golden-bellied Gerygones to nest there year after year.
So why do the Little Bronze Cuckoo choose the Golden-bellied Gerygones as host parents year after year? There were a few theories if you do a search on line. One was that the similar colour of the eggs and another was the imprint of the host parents on the cuckoo chick. But there were no evidence to support these theories.
Based on a study by Barbara Taborsky and colleagues of Konrad Lorenz Institute in Vienna, it is the habitat ( Nature. 28 Jan. 1999). The cuckoos return to the same place that reminds them of where they fledged and where they they will most likely to encounter the same host parents.
A Rusty-breasted Cuckoo chick begging for food from a Malaysian Pied Fantail at Tampines Eco Green. A 2015 photo by Seng Alvin.
In another study by Yang et al 2014 on Common Cuckoos hosted by Oriental Reed Warblers at the Zhalong National Reserves, China, reported in “Behaviour Ecology”, the female cuckoos spent some time monitoring the nests and will only lay the eggs if the nest is active and attended to.
The super busy parents were feeding the cuckoo chick almost non stop. The Golden-bellied Gerygone at 10 cm is the smallest bird in Singapore.
This may explain why the Cacomantis cuckoos choose the mangrove species like Pied Fantails and Ashy Tailorbirds, forest dwelling Drongo Cuckoos going for forest edge Pin-striped Tit-babblers and Olive-winged Bulbuls and the Little Bronze and Banded Bay cuckoos seeking out the garden and parkland species.
Thank you all for sharing your sightings, records and photos of one of the more fascinating behaviours of our resident birds and help us to learn more about them.
Many thanks to KaiKee Leong and Seng Alvin for the use of their photos. Kevin Ng for the location.
Ref: Lim Kim Seng. The Avifauna of Singapore. 2009.
Craig Robson. A Field Guide to the Birds of Thailand and South-East Asia. Asia Books Co. Ltd.