I took an early shift this morning, got to the hideout around 8-15am and was supposed to leave just before Richard arrived. A few moments later it was a woman Marsh Harrier patrolled up and down the far side before disappearing to the east. While he was doing this the Pallid Harrier appeared, quickly passed in front of the shelter before crossing the Corse, climbing the hill opposite and disappearing towards Roscrowther. By the time I left I didn’t see it coming back. 2 Buzzards and a Merlin finished the raptor count for me and a herd of c90 Stock Doves in the distance is noticeable.
What a beautiful bird Pallid Harrier yes! All the more attractive for having 5th primary toe on the right wing – a feature not commonly seen in pure-bred Pallid Harriers. Could it be a cross with a Hen Harrier or is there something else going on? I finally got a picture of the right wing where the crossover is from the secondary to the primary feathers appears good defined enough to throw some light on it.
The two pictures below compare the left and right wings. The left wing has a projected 10 primary feathers. The right wing, however, seems to have an additional, 11th, primarily. The extra feather appears to be one of the primary toes, a false feather between P6 and P8 in this bird (or P6 and P7 in a normal bird).
How common is this feature in raptors? Unsurprising, perhaps, unusual but also unknown. In a study of c11000 raptors, Clark et al. (1988) found nine instances of extra primary feathers and eight extra tail feathers. Intriguingly, in 89% of cases where an extra feather was found, it occurred on the right side, just like our bird.
So, we may have a very rare bird here – not a hybrid but a Pallid Harrier with an aberrant growth of an additional primary feather. This is made even more unusual by the fact that the extra feathers are inside the outer primaries – those found in the above study are all between P2 and P3 or P3 and P4 feathers and none of these occurred in any of the 385 harriers studied.
