Eastern  v.s. Western Marsh Harrier males

Triggered by claims of potential Eastern Marsh Harriers (Circus spilonotus) males in the Netherlands, which turned out to be Western (Circus aeruginosus), I wanted to get some more info about EMH identification. As I googled "Eastern Marsh Harrier" and checked the images I came across a selection of images of stunning males EMH. Looking at these birds my first impression was that these adult males more look like male Hen Harriers (Circus cyaneus) and in some the head pattern reminded of Bonelli's Eagle (Aquila fasciata).

A quick look on adult males Eastern Marsh Harriers:

  • Flying EMH adult males seen from below give a more Hen Harrier like impression;
  • Adult males don't show any warm brown on the body as in WMH, some striping on the breast has a more dark grey colour;
  • The underparts are very pale grey;
  • The dark (striped) head which gives the bird a hooded impression, like Northern Harrier (Circus hudsonius);
  • The line of the dark wing tips of the primaries aren't as neatly as in WMH and also show more light parts (mirrors);
  • When perched the males give a Goshawk (Accipiter gentilis) impression, the head has a very strong look.

Perched males

EMH (left) gives a Goshawk-like impression. The head has a more grey undertone, brown in WMH, with contrasting dark ear-coverts. This male doesn't have a strong hood as other males EMH on the other images suggesting this is a sub-adult male. The mantle and wing-coverts have more details while in WMH they are more uniform. The wing coverts show more grey were you see more brown in WMH. The underparts are light grey or white lacking any brown on the belly. The bird in the middle reminds a bit of EMH, due to the more detailed mantle, but misses the strong dark-grey streaking on head. The bird on the right is a typical warm brown WMH.

Flying males, seen from below

The left image of an EMH hardly reminds of WMH and one might think to look at an adult male Hen- or Northern Harrier, The pale underparts without any markings on the underwing coverts, a slightly darker edge of the secondaries, less darker and defined black primaries and a dark-grey hood don't resemble a WMS at all. The WMH in the center, still the same bird, has less brown as you would expect with WMH but has an overall cream color on the underparts and lacks the dark hood. Compared to the WMH on the right it hasn't as much details on the underwings and misses the darker edge on the primaries. The right bird shows the well defined all black primary tips.

Flying males, seen from above

Again the EMH (left) gives a grey impression. The primaries aren't as dark compared to WMH and therefor some markings within are visible. The tail is more uniform grey were WMH has some kind of a slight tail-band. The wing coverts and mantle are more warm brown in WMH In WMH these darker parts are more defined while in WMH they give a more "messy" impression. The dark head of this EMH, especially the ear-coverts, is very striking.

Thanks to Kris De Rouck for sharing his images and sighting of the (old) Western Marsh Harrier photographed in the province of Zeeland, the Netherland. Terry Townshend of Birding Beijing for his images of the Eastern Marsh Harriers and Corine Oste, Adri Joose and Cees Struijck for their images published at waarneming.nl.

Additional information and comments are most welcome.

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