Dato’ Dr Amar-Singh HSS encountered a pair of Pacific Swallow (Hirundo tahitica javanica) at Tambun Interior, Perak, Malaysia on 18th July 2009. An adult was carrying a piece of nesting material accompanied by its mate.
“Notice that in the composite image on the left, the pair is very different in their colour scheme. The one in the foreground with the straw for the nest has a less rich plumage, especially the mantle.
“The difference is not just due to lighting (they were in the same light, same angle, just could not focus on both together). It is not supposedly possible to separate male from females (in filed guides, literature) but I would say the lighter one is a female.
“One possibility is the lighter one has recently become an adult and has not developed full plumage yet? Another is that the male has developed a richer “breeding” plumage? Any comments would be welcome. Usually only one of the pair collects nesting material (Smythies, 1999).”
Smythies, B. E., 1999. Birds of Borneo. Natural History Publications & The Sabah Society, Kota Kinabalu. (4th ed., revised). 853 pp.
All images by Amar-Singh HSS (Dato, Dr)