Saturday 29 August 2015

Black Kite at Barton-in-Fabis -- one that got away?

This is an account of a Black Kite seen from the tower hide at Attenborough last weekend.  How much I wish the bird could have come a bit closer.  You win some - you lose some.

On 22 August at around 4.30pm, I was watching Gadwall Anas strepera from the Corbett hide, when Sandy Aitken drew my attention to a raptor, which he thought was not a Common Buzzard Buteo buteo. I got onto the bird immediately.  It was at medium height in the direction of Thrumpton.   My initial impression was that the bird was a kite Milvus sp. but not a Red Kite, so I considered if the bird was a Marsh Harrier Circus aeruginosus.  However, I didn't think it looked right for a harrier of any kind, mainly owing to the shape of the bird and the persistently flat profile of the wings in flight.  I have seen a few migrant Marsh Harriers over the years and I think they are quite distinctive, after the initial 'it's not a buzzard' moment.  The light conditions though bright, meant that the bird was largely in silhouette. 

After about a minute, I noticed the bird twist the tail and I saw a shallow but definite 'fork' or notch, though far less pronounced than the blunt scissors of Red Kite Milvus milvus.  At this point I first seriously considered that the bird was a Black Kite Milvus migrans.

I continued to watch the bird in my bins, as Sandy switched to his scope.  It began to drift closer but changed tack and headed away towards Barton. It continued to fly steadily away and then lost height as it flew in front of Brandshill Wood.  It was very hard to see at that time and we both lost the bird to view for about 15 seconds. However I did manage a very brief glimpse when it showed dark brown upperparts.  It then reappeared on the top of the tree line at the far left of Brandshill and then soared for a while before drifting out of sight at around 4.32pm.

We had discussed the identification as we watched the bird, effectively ruling out Red Kite and Marsh Harrier and both reaching the conclusion that it was a Black Kite.  

We put the news out and Rob Hoare searched for the bird from his side, but to no avail.  We waited for a good hour, in case the bird returned but it appeared to have left the area.

Description

A medium large buzzard-sized raptor.  The bird was a fairly concolorous dark brown.  The cloud cover and position of the sun made assessment of colour tone and detail impossible.

The bird glided mostly, always on flat wings, never once showing a shallow 'V'.  When it did flap, the flight was very elastic on what were rather angular-looking wings, compared with Marsh Harrier.  The tail was seen to twist a few times, on one occasion revealing a very shallow fork, but in the main, the tail appeared to be straight ended.

The structure of the bird was somewhat more compact than Red Kite but looser than Marsh Harrier or Common Buzzard.  The tail was long like a kite.  Although there were no birds for comparison, my impression that it was smaller than Red Kite.

Despite my best efforts, I saw no plumage features at all, though Sandy saw a paler contrasting area on the upper wing near the carpal area.

After considering all the options, including juv Red Kite, I was convinced of the identification of Black Kite.

I have seen hundreds of Black Kites in France in the last six years, at every angle and distance.  I am 100% certain of the ID.

Confusion species

In considering Black Kite in all but ideal conditions, one must eliminate Marsh Harrier.  However, the shallow tail fork, flat wings and angular wing shape, bent at the carpals were all wrong for Marsh Harrier.  

The bird was more compact than Red Kite and we would have seen the more obvious tail fork of an adult.  On juvenile Red Kite, while the tail fork is less pronounced, these are considerably paler birds and this would have been evident in the brief views I had against Brandshill Wood.

Weather conditions:
Very warm and humid, with tall white and dark grey cumulonimbus.  Light good, but scattered and diffused in cloud. The winds were south easterly force 4 with thundery outbreaks of torrential showers following our observation.

Optics:
Opticron Verano 8 x 40

I was all ready to submit this record, but unfortunately Sandy, having lost valuable time finding the bird in his scope, just when it showed best, admitted he could only be 99% sure of the id and therefore could not submit the record.  I feel a good record has been lost, but credit for Sandy for sticking to his credentials.  In the circumstances, I felt I could not proceed with the submission.