Ageing of HEN HARRIERS respective to Gallows Bridge Farm

Discussing Hen Harrier ageing with Warren Claydon this afternoon, I decided to write this short piece. Warren and I had seen a Hen Harrier at Gallows Bridge Farm on 6 and 7 November 2011 which we both considered to be an adult female on field views. Subsequently, there has been much discussion as to the ageing of this bird, and it remains a real possibility that more than one bird is involved in the sightings. Over the past few days, some reasonable images have appeared of the bird present this weekend, allowing some comparable discussions to take place

http://www.goingbirding.co.uk/bucks/show_photo.asp?photo_id=1788

The above image by Rod Scarfe is taken of a HEN HARRIER recently at Gallows Bridge Farm; it clearly shows a JUVENILE FEMALE.......

Critical features to consider when ageing Hen Harriers are the eye colour, saturation and colour of the underparts and the wing patterning.

The image here http://www.goingbirding.co.uk/bucks/show_photo.asp?photo_id=1787 taken by Tim Watts, shows a bird with FIVE obvious fingered primaries, ruling out Pallid Harrier

The eye colour appears to be uniform dark brown, both adult male and females having a pale yellow iris, whilst the facial disc pattern is clearly of a juvenile, with the dark brown circumnavigating the paler eye crescents and being bordered behind by a thin pale collar.

Juvenile Hen Harriers possess an orange-brown ground colour to the underparts whereas second-winters and adult females are invariably whitish in terms of basal colour. Juveniles generally show a contrast between the darker breast and the paler belly and the streaks on the underparts gradually become narrower from the breast towards the belly, with the undertail-coverts uniformly paler.

The adult females have the underparts boldly striped dark brown and essentially (and critically) have BARRED greater coverts and secondaries in the upperwing. Juveniles have a more uniformly patterned upperwing pattern.