Peregrine Falcon mobs Western Marsh Harrier

posted in: Interspecific, Raptors | 6

“On the 2nd day of the Lunar New Year, January 27th, a small group of us went birding at the reclamation area, at Changi. Besides the two of us, there was Martin Daniel, my wife Shamla and my two sons, Serin and Saker.

“There were lots of birds about and over 50 species were recorded during the three and a half hours that we spent out there. Highlights for the morning included 8 species of raptors (including 3 species of harriers), a male Common Stonechat Saxicola torquata, a party of one male and 4 female Red Junglefowl Gallus gallus and 2 White-faced Plovers Charadrius dealbatus.

“A male *Western Marsh Harrier Circus aeruginosus was quartering the grassland and we took the opportunity to observe and photograph it (above left). While we were doing so, another raptor came out of nowhere and dived at the harrier. It was a Peregrine Falcon (Falco peregrinus) and on closer observation, the individual was of the local, regional, resident race ernesti (above right). After the first dive, the falcon fluttered its wings rapidly to gain height, turned around and dived at the harrier again. It repeated this a few times until the harrier descended, temporarily, to the ground. The falcon then disappeared from the scene and a few minutes later, the harrier ascended and continued its hunting.

“Peregrine Falcons are not exclusive to grassland areas and are able to hunt in a variety of settings, including urban cities. It hunts birds in mid-air, often with a fast and spectacular stooping dive. This falcon is a powerful hunter and it can catch reasonable sized birds, including pigeons in the city, shorebirds on the coast or waterfowl on a marsh.

“Why did it mob the wintering harrier? Was it displaying aggressive, territorial behaviour toward a rival? F.p.ernesti is an uncommon but regular visitor to Singapore, usually during the northern winter months. It breeds in the region, including Peninsula Malaysia, but so far, there is no evidence (yet) that it does so in Singapore. Could the mobbing behaviour displayed indicate that it may be a resident after all? Or was it merely holding a “winter” territory? More study is obviously needed.

“Whatever the reason, we were lucky to have been present to catch this brief but thrilling display.”

Subaraj Rajathurai & Benjamin Lee
1st February 2009

Images by Benjamin Lee.

*Please see HERE.

6 Responses

  1. Gim Cheong

    This is a subadult male Eastern Marsh Harrier.

    First impressions: recalls adult male harrier plumage.

    Upperparts: A full adult male would have all black primaries. In this bird, the primaries are brown with dark barring – a feature of EMH.

    More telling, the secondaries are grey with dark spots and the subterminal dark spot is particularly clear – in the flight shot this clearly forms a subterminal dark trailing edge to the upper wing – a feature of male EMH. Male WMH have plain grey secondaries.

    The white rump is rather extensive – the WMH’s white rump is rather smaller than that of the EMH.

    The uppertail appears to be barred – a feature of juvenile and female EMH not present on WMH.

  2. Tan Kok Hui

    Can BESG respond to the ID of this marsh harrier? As well as the Semakau one?

    I would be interesting to see how the WMH and Northern Harrier got into the checklist.

  3. YC

    We are still working on the ID of the harriers in the two posts. As to how the WMH and NH got into the checklist, please refer to the Annotated Checklist of the Birds of Singapore by LK Wang & C Hails (2007).

  4. stonechat

    […] … I’m glad you like the Stonechat postcard. I did send Connor a postcard too. I don’t know …Bird Ecology Study Group Peregrine Falcon mobs Western …On the 2nd day of the Lunar New Year, January 27th, a small group of us went birding at … 3 […]

  5. martin kelly

    one of the most fascinating incidents I saw was was on the Serbian Bulgarian border near a place called Belogrdcik(in Bulgaria).I was watching a buzzard doing its usual leisurely circling when a goshawk suddenly appeared from nowhere and attacked the buzzard. there was a flurry of feathers and the buzard retired to a tree presumably to lick its wounds and the goshawk disappeared.

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