Hen Harrier with ‘Northern’ trait
First seen by Ian Bartlett on 13th November, this juvenile male Hen Harrier is as much stunningly well-marked as it is difficult to catch up with.
It was next observed on 17th and has since been seen almost daily, albeit briefly on each occasion, as it flies across the South Kilworth road between the settling pond and the old railway track, at the eastern end of Stanford Reservoir. Its regular hunting area is as yet unknown so prolonged observation has not been possible and all views to date have been fleeting.
However, a series of photographs taken by both Alan Coles and Bob Bullock on 23rd have nicely captured and revealed its resemblance to a juvenile Northern Harrier. With an extensively dark face and broad – though fragmented – boa, this is a Hen Harrier at the top end of the variation scale.
Ageing and sexing it is not too difficult. The combination of a largely ochre ground colour to the underparts with relatively thin streaks, cold, dark brown upperparts and a more ‘solid’ face than an adult female puts it squarely in the juvenile camp. Adult females in comparison have a whitish ground colour to the underparts with broader, blotchier streaks, slightly warmer upperparts and a more open facial disc. Its already yellow eye indicates it is a male as juvenile females have dark eyes.
Check out the contrast between the dark head/neck/boa/upper breast and the remainder of the pale underparts. It’s very marked and this is the initial, big, eye-catching, pro-Northern feature, as is the deeply solid dark brown face pattern with dark lores and the plain buff leading edge to the wing, formed by the underwing coverts.
While initially this may be enough to set pulses racing, more detailed examination reveals that there are only five dark bars on the longest primaries (Northern usually has 5-7, Hen 4-5), the dark subterminal tips to the underside of the inner primaries are strong (weaker and paler in Northern), the middle dark bar on the underside of the secondaries is broad (usually thin in Northern) and the ground colour of the underparts is too light (rustier in Northern).
So it’s an interesting-looking bird, an individual at the dark end of the Hen Harrier variation scale – and a nice bird for the county. It would be even nicer if it stuck around long enough to watch it hunting!
Hen Harrier is a scarce migrant and winter visitor, which averages 7 records a year in Northamptonshire. Its status appears stable in this context, despite persecution on moorland further north.