Monday, April 15, 2013

Identifying Silhouettes

Bird Watching too is not free from assertion ….it is noted that certain birds are only identified by their silhouetted flight profile and one may not see them rested on a branch or sitting on a nest in one's lifetime.

Two such birds have lingered my memory until recent. The Indian Swiftlet [Collocalia uniclor] and the Brown-backed Needle Tail [Hirundapus giganteus] seen just once in September 2, 2002 in the Sinharaja Forest Reserve Sri  Lanka ; just five birds wheeling overhead, silhouetted against a gloomy sky. Never to have seen them anywhere since.

Unlike the Needle Tail; the Indian Swiftlet is a common occurrence all over Sri Lanka and more commoner in the hills. It was also known as the Indian Edible Nest Swift, until the species was split taxonomically. The species occurring in the Andamans and the Nicobars are now named the Edible-nest Swiftlet [Collocalia fuciphaga] while those occurring in the Western Ghats, the Islets on the Malabar coast and Sri Lanka the Indian Swiftlet.

It should be noted that the name change does not indicate the Indian Swiftlet is free from its nest being harvested by man. However it is the East Asian species that is vulnerable and declared endangered as its nest is harvested by man through superstition for its aphrodisiac properties. The refined and processed nest fibers turned into a soup fetches high price and is in high demand.

There has been instances where the Sri Lankan customs detecting nest fibers from Sri Lanka being exported to East Asia, but it is said to be of poor quality  to those of East Asia.

I was lucky  way back in May 2012, to have run into a nesting colony of the resident Indian Swiftlet while hiking in the hill country and was able to photograph a few birds sitting on their nests. They are said to re-use the nests which compensate with time taken to make them anew to the time spent sitting on them, as their feeding and drinking habit is always while on the wing. 

It is for this reason that the Sri Lankan folklore suggest that seeing swifts in large numbers in a cloud laden sky predicts on coming rain. Many swift species drink on the wing and is said to survive prolonged drought. 

On the other hand identifying Needle Tails has its difficulties as well. The needles or extended spines on the tail feathers are seen only when the bird turns in flight and the bird being at close range; so identifying silhouettes is as difficult as identifying persons by shadows. 

1 comment:

  1. Very interesting study of swifts.
    Thanks for sharing.