During my brief lunch break on Monday I saw an interesting ringtail Harrier at Thornham (Norfolk, England). A Pallid Harrier had been reported earlier that morning nearby (and was reported again at Thornham later on) so I was mindful of that when I picked up a ringtail Harrier showing distinctly orange underparts. However it was immediately obvious that this bird was no Pallid Harrier - the orange wasn't intense enough, the underparts were well streaked and it lacked the pale collar.
I also tentatively discounted Northern Harrier as I recalled that they are relatively unstreaked below, although I did note that it looked quite dark-headed and the upperwing seemed relatively dark. I took a few record photos knowing that evening commitments this week meant I wouldn't get a chance to look at them until at least Thursday. I have seen much variation in Hen Harriers, including some strikingly orange-looking individuals, and I wasn't overly concerned that I might find the photos suggested it was anything other than a Hen Harrier.
Last night I looked at the photos which perhaps don't show quite the intensity of orange that I saw in the field, and I checked them against various online photos of Northern and Hen Harriers, plus Killian Mullarney & Dick Forsman's article in January's Birding World (Birding World 23 (12): 509-523). One thing that stood out from perusal of a number of images is that the extent of streaking was not too great for Northern Harrier and, as that was the main reason I had dismissed Northern Harrier this immediately made it more interesting. I soliticted opinion from a local birder with a good track record for nailing Northern Harrier and he thought it was interesting enough to share more widely.
My question is this - are my photos sufficient to rule out Northern Harrier (or better, if more unlikely, to rule it in)? Also for those here in Norfolk, has anyone else seen this bird?