Eastern Marsh Harriers breed at Yeyahu Nature Reserve in Beijing. They are one of the star birds of any visit from late March through to October. The spring males are simply stunning and quite different from the closely-related Western Marsh Harrier, some almost resembling one of the other regional specialities, Pied Harrier. Adult females also look very different from Western Marsh and, in my experience, it is only really juveniles/first winters/probable 2 cy birds that could be mistaken for Western Marsh.
I couldn’t find any literature on aging or sexing Eastern Marsh Harriers (is there any out there?). So here are some images of adult males, females, a probable first summer and juvenile birds with some personal comments. Comments from others are very welcome. Having had a bit of difficulty separating a dark juvenile Pied recently, I have much to learn about these wonderful raptors.
Eastern Marsh Harrier (adult male), Yeyahu NR, May 2012. Spring males are hard to beat!
Eastern Marsh Harrier (adult male), Yeyahu NR, April 2012
Eastern Marsh Harrier (adult female), Yeyahu NR, Beijing, April 2012. Paired with the male above.
Eastern Marsh Harrier (first summer male or female?), Miyun Reservoir, Beijing, April 2012. Similar to juvenile plumage (below) but primaries have been moulted – note the light barring. A pale breast-band is a feature of juvenile and probable 2cy birds.
Eastern Marsh Harrier (juvenile), Yeyahu NR, Beijing, September 2012
Eastern Marsh Harrier (juvenile). Same bird as above showing upperparts. Compare the extent of pale markings with the bird below. Does this variation indicate sex?
Eastern Marsh Harrier (juvenile – male or female?), Yeyahu NR, September 2012.
Eastern Marsh Harrier (juvenile). Same as above. Do the extensive pale markings indicate sex or is the difference in juvenile plumage just natural variation?