Since the Long-legged Buzzard has been admitted to the British List by the BOU, I thought I'd share a blog post that goes through its key identification features. First of all, I need to give Dave Cooper full credit and thank him for identifying this bird and providing a wonderful accompanying explanation. The majority of features I'm going to present here were picked up by him, so it's important to stress that this post compiles the features Dave noted, along with some of the features Dick Forsman commented on and then a bit about my impressions of the bird whilst viewing it and then subsequent thoughts following its identification. Without Dave's skill and attention to detail, who knows where this record would be right now?
Age
It's useful to understand the age of the bird, since this helps explain some of the plumage features. The bird was in extensive moult and can be aged as a second calendar year (2cy, aka. 'first adult' plumage) based on the retained juvenile secondaries and primaries, which appear more faded and with less distinct trailing edges in comparison to the adult feathers.
Adult-type tail = Diagnostic Plumage Feature for LLB
As Dick Forsman pointed out, the tail has helpfully been moulted to adult-type, which was useful since the combination of features shown by the tail are diagnostic and not found in any other buzzard species, showing an entirely unbarred tail with a rufous outer half and more whitish inner half. Presumably this feature would have been more obvious at the time had the views been more prolonged.
I'm not an expert on the timings of buzzard moult, but I presume not all 2cys in autumn would show the diagnostic adult tail pattern, so these birds would be a bit more tricky.
General Plumage Features
Because the bird was in such a heavy state of moult, I initially did not give that much consideration to the bird's plumage features on its body. Common Buzzards are highly variable and I've seen plenty of weird and whacky ones in the South West. However, this bird was unlike anything I'd seen before. See the extract from my initial description:
"It was clearly a Buteo sp., although its strikingly pale aberrant (?) plumage,
combined with heavy moult in the wing feather confused me initially ... Whilst I have seen lots of different plumage
variations of Common Buzzard in South West England, this bird was unlike the
typical variation I am used to, possibly due to the extent of moult and
potentially some aberration in plumage. In some photos, the tail also appears
quite long when closed. Certainly an interesting bird in my opinion – not sure
what the Common Buzzards that turn up on Shetland usually look like!"
The bird's plumage features were, in fact, not an abberation, but classic for a worn second calendar year pale form Long-legged Buzzard:
Underparts:
- Generally uniform pale whitish head and upper breast with lack of darker streaking. Faint darker streak behind the eye
- Lower belly similarly pale but with darker brownish streaking and dark reddish-brown patches on flanks/thighs
- Underwing coverts rather uniform pale whitish
- Black carpal patch - despite being blotchy (supposedly due to wear/moult), the carpal patch is still quite extensive
- Rather thin blackish trailing edge to wing feathers (would be broader in Common Buzzard)
I didn't get any photos really showing the bird's upperparts, although managed to video the bird, which as Dave pointed out, reveals some useful details:
- Pale sandy brown wing coverts contrast with darker wing feathers
- Distinct white flash on wing due to unmoulted juvenile primaries, which have uniform white inner half and black outer half, contrasting with dark greyish adult type feathers.
- White head and inner tail contrast clearly with brownish back
Video montage showing bird's upperparts - also dark carpal patch on underwing obvious on top right images
Structure:
From my photos you can see the bird is long-winged, although they don't reveal as much detail as the video does. Whilst noting the bird did appear long-tailed in some photos, I definitely underestimated just how different this bird's structure was to a Common Buzzard - I like to tell myself this probably wasn't as evident through a bridge camera's viewfinder! I think one mistake I made was focussing too heavily on a couple of photos - I almost forgot the video existed after a while. However, the video reveals the bird's heavy, eagle-like/Rough-legged Buzzard-like jizz much more clearly. The video montage below illustrates this, with one of the Ravens that was mobbing the bird included for comparison.
Another useful aspect of the bird's structure is how long-necked and long-tailed it can appear in some photos in comparison to Common Buzzard. The tail length appears closer to that of Honey Buzzard at times. It's also rather deep-bellied and the wing has a more distinct 'hand' than a Common Buzzard would. In the top row of images, the trailing edge of the wing forms a distinct S shape. The general wing shape is more rectangular than Common Buzzard, which would have more rounded wings.
Chris Batty helpfully pointed out Ferruginous Hawk as a potential confusion species to eliminate, since escaped birds have been recorded in the past and can exhibit some plumage similarities to LLB. This bird exhibits a couple of features that rule this possibility out.
1. Extent of black on primaries. My Dad pointed this out and after looking at many photos online, this seems to be a consistent difference in plumage between the two species. See figure below:
2. Structural features. As Dick Forsman pointed out, Ferruginous Hawk has a rather different wing structure to LLB, with a rather broad base, tapering in at the primaries. This bird has more evenly broad wings and a distinct 'hand' despite appearing to be missing a primary.
3. Extent of feather on tarsi. Ferruginous Hawk often/always/can (?) show feathered tarsi. This bird appears to show unfeathered yellow tarsi supporting Long-legged Buzzard.
At the time I found the bird, the main feeling I had was confusion. Often when I see a Common Buzzard, there isn't much internal debate in my head (ironically they're one of the birds I see most frequently whilst looking out of my bedroom window in Devon), but when I first saw this bird I found myself immediately baffled and went straight for my camera. It is worth noting that Common Buzzards are rare on Shetland so it would've been a good bird anyway. Looking at my photos afterwards, it clearly wasn't a Honey Buzzard and the plumage was wrong for Rough-legged, so I found it difficult to convice myself it wasn't anything other than a Common Buzzard. However, looking back in retrospect, I know now that I still wasn't 100% sure of this. Additionally, the fact that the people who saw it briefly on Fair Isle thought it was more likely a Honey Buzzard was very confusing.
All of this uncertainty should have raised the alarm bells, especially given it was in Shetland in autumn. Most of the time I've imagined finding a first for Britain, I've pictured clapping my eyes on something like a male Prothonotary Warbler before immediately going bezerk and running off like a maniac. I now think in reality this sort of situation is just as, if not more likely (in relative terms), in that it'll be something you won't have thought of and it won't be immediately obvious. If something doesn't seem right then make sure you follow it up!
Useful references:
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