“I was enjoying a small flock of 7-8 Chestnut (Black-headed) Munia (Lonchura atricapilla). I watch when I get the opportunity at they are becoming uncommon and should be considered Near-threatened locally. The feeding activity turned to nest material collection and I managed to follow a pair to their nest.
“The above (left) image shows an overview of the nest. It was built 1.5 meters up from a muddy ditch in lalang grass (Imperata cylindrica). The background is a rice field. Nesting is noted in wet environments (see Wells 2007). The image on the right shows the pair at the nest. They were using lalang grass to weave the nest (beginning stages) as well as pad the inside with the soft flowering heads of the grass.
Note: The above images show the adult with an inflorescence of the lalang (left) and a spikelet of the pennisetum grass (Pennisetum sp.). They did not collect material close to the nest but flew 5-10 meters away.
“…I noticed some odd differences in the plumage colour of some adults.
“If you look at the two composites shown in this post: The above shows the nesting pair on two different occasions. You notice that one adult is lighter both in body and head (foreground on left, background on right). Four out of seven birds I imaged had lighter plumage (below).
“I considered a number of possibilities for this variation in plumage colour/shade:
1. Colour contrast due to shade, lighting, processing. None are possible as I see it in all images (have close to 90) and processing is similar. The most telling is all the images of birds together show them having a variation in plumage.
2. I considered if these were immature. I have seen and photographed immature before and the plumage has pale brown upperparts but is usually patchy at transition to adulthood and the head is usually not pure black. More importantly, these birds are nesting so not immature.
3. Hybridisation or crossbreeding with other munia species should be considered as there have been a few reports but the plumage is very uniform here, just lighter.
4. Could this be a nutritional deficiency of sorts (the doctor in me reasoning)? Not possible to be sure but the birds look healthy and were accepted in the flock, even as breeding partners.
5. I considered sex differences. In literature (and my observation over many years) sexes are similar. But could these be breeding males having a darker tone? I have looked for nesting images to see if there are similar findings but very few nests have been posted on line. It could mean that few nesting adults have been adequately observed. It is not possible to determine which is male and both partners were building the nest on equal terms. But could the adult male attain a slight darker tone at breeding?
“In summary, these birds have less rich tones than I expect in a normal Black-headed Munia.
“I would appreciate any opinions and personal observations.”
Dato’ Dr Amar-Singh HSS
Ulu Dedap, Perak, Malaysia
24th January 2013