White-tailed Robin – Nesting Issues

I was in Cameron Highlands on 25th April 2022 and observed a number of White-tailed Robins (Myiomela leucura leucura) nesting. One of the nesting birds interested me as I had seen this unusual behaviour before. I saw what appeared to be an immature (1^st year) bird being a nest helper. I saw the bird bringing food to the nesting site a number of times.

Attached are two images of the bird. Note that the bird has a shining blue forehead which is not described in females (Wells 2007, Birds of the World 2022). If we follow the literature then this should be a first-year male.

I have seen similar nesting behaviour in the past and now am considered some options:

1. Some first-year birds act as nest helpers. I am spotting the males (easier) but may miss the young females.
2. Plumage change and development to full adult form in young males is slow (more than 1 year). Hence this could be the male partner involved in the nesting. However, in the past I have also seen full adult males at the same nesting site, so this option is doubtful.
3. A third possibility is that some females have transient plumage changes during breeding. Hence this could be an adult female. But these are well imaged birds and I would expect more reports.

Appreciate other observations and experiences.

Note: There is one publication on White-tailed Robin plumage that suggests “both a light and darker plumage”. But it does not describe blue in the plumage of females.

Renner and Rappole (2011). Description Of First Basic Plumage Of Three Muscicapid Species Found In The Southeastern Sub-Himalayan Foothills, With Notes On Their Taxonomy And Ecology. Ornithological Monographs, Volume (2011), No. 70, 142–152. The American Ornithologists’.

Dato’ Dr Amar-Singh HSS – Ipoh, Perak, Malaysia