The above image of a group of eight Javan Mynas (Acridotheres javanicus) with four having a yellow collar each, was posted on Facebook in early March 2014 by photographer Ah Pin at Neo Tiew Lane 2 LINK. People were wondering what caused the yellow collar.
According to wildlife consultant Subaraj Rajathurai LINK, they all appear to be Javan Mynas Four of the perched birds appear to have pollen dusted on their throats. These are juvenile birds, as they have a brown wash to their grey plumage. The dark ones may simply be full adults.
This interesting phenomenon surfaced in September 2007 when Richard Hale noted: “…when I first came back to Singapore in the late eighties I was puzzled by some apparent Asian Glossy Starlings (Aplonis panayensis) which had yellow breasts. It took some time before I caught some with their heads inside the African Tulip tree (Spathodea campanulata) flowers and realised that the yellow was in fact pollen.” – LINK.
In April 2010 Samson Tan encountered a number of Javan Mynas with similar yellow collars LINK. And these birds were also feeding on nectar from flowers of the African Tulip trees.
These large African Tulip trees were once relatively common in our urban areas. As they can cause some danger to pedestrians and motorists with their unstable branches, they were systematically removed. Now most trees are confined to rural areas. The flowers are large, in big bunches, each producing copious nectar – see HERE for an image. Birds like starlings and mynas dip their heads into the open flowers to sip on the nectar. In the process the many stamens come into contact with the upper parts of the birds, leaving the yellowish collar. These pollen will be transferred to the next flower and thus the birds will assist in the pollination of the flowers.
Ah Pin & Subaraj Rajathurai