Of marsh harriers and other exotic species

In an earlier post on Common Moorhen (Gallinula chloropus), it was mentioned that Western Marsh Harriers (Circus aeruginosus) and Steppe Eagles (Aquila nipalensis) were seen above the paddy fields in Malaysia where Allan Teo was observing and photographing the moorhens.

Yong Ding Li made a pertinent comment, “Take note on the point about Western Marsh Harrier... It is actually a very very rare migrant to South East Asia and more so for Singapore (I suspect only one recent record and even then it is probably mis-IDed many times). Instead here it is replaced by Eastern Marsh Harriers (Circus spilonotus). In the oriental region, western is only regular in the subcontinent, occuring in wetlands and plains of places like Rann of Kutch, Bharatpur where it can be rather common.

However, R. Subaraj has this to say: “To me, the birds in the photo (above) look like a young female Western Marsh Harrier (on left) and a juvenile Steppe Eagle.

“With regards to Ding Li's statement regarding the status of marsh harriers here, it is a little out-dated. Until 2005, he is right, as reflected in Robson's guide. It was common in Myanmar but rare or a vagrant to Thailand and Peninsula Malaysia... no confirmed Singapore records! At the end of 2005, both Western and Eastern Marsh Harriers were reported from Changi Reclaimed Land and in the weeks to follow, several birders had visited the site and confirmed the presence of both species... with as many as 3 Westerns.

“Being a skeptic myself, I visited the area a few times during that period and personally confirmed at least three Western Marsh Harriers, along with a few Eastern, with excellent views. Reliable collegues and visiting birders, with me or independently, concurred. Hence, the Western Marsh Harrier does occur in Singapore as a vagrant, at least. “It is worth monitoring our area for the next few months to see if they visit again and become a regular occurrence... or if the last season was just unusual. In the last two decades, unexpected raptors have kept turning up in Singapore. Himalayan Griffon (Gyps himalayensis) (above) and Lesser Kestrel (Falco naumanni) are two others that fall into a similar category as the Western Marsh Harrier... birds that formerly only occurred no nearer than India and Myanmar. Other unexpected raptors that have turned up include Oriental Hobby and Jerdon's Baza (Aviceda jerdoni)... normally sedentary species found no closer than the northern half of Malaysia, where they were considered rare.

“So what is going on! Why are these species suddenly turning up in Singapore? Perhaps it is the changing climate conditions? Or the continued deforestation and/or persecution of birds further north and south of us? Perhaps a bit of both!

“Other factors that certainly contribute are the superior optics available, the better field guides and identification books and the increased number of observers covering various parts of our nation. The digital photography age is also making a significant difference in confirming species.

“Finally, and equally significantly, the shrinking habitats available due to development means that birds have less choices if they turn up in Singapore and birders have a better chance of finding them!”

Input by Yong Ding Li and R. Subaraj; images by Allan Teo (top) and Wang Luan Keng (bottom).