Here's a few notes on some of the Shrike identification challenges we had in Kuwait recently. Thanks to Pierre-Andre Crochet for discussion / corrections.
References for these notes: ID Handbook of European Birds by Nils van Duivendijk and Marc Guyt/Agami and Handbook of Western Palearctic Birds by Hadarom Shirihai and Lars Svensson.
Shrike sp. Presumed adult female Red-backed Shrike (pics by Vince) . There are a few features which are not typical for Red-backed Shrike including the concolorous brown upperparts, the five visible primaries projecting beyond the tertials (on the left wing shown in photo above) and the strongly graduated tail including a t6 on the right which appears to be 25% shorter than the tail length shown in the photo below. These features are all consistent with Brown Shrike but on closer inspection there are several features which are also not right for Brown Shrike.
The tail was heavily graduated and was also in moult. Typically the tail should moult from the inner rectrices out and it appears that the inner rectrices are being replaced. If the moult progression is typical than the outer tail features should not be growing so the graduated tail should not be an artefact of moult but should be fully grown feathers. On the right side of the tail (left in this image) t6 appears really quite short and less than 25% of the tail length (especially when you consider that the inner rectrices are not fully grown) and this is more typical of Brown Shrike. However on the left side t6 appears longer and probably 20% or less of the tail length- a proportion which is more typical of Red-backed Shrike. Typically in Red-backed Shrike the tail is squared off but with a shorter t6 and the rest of the rectrices are more equal in length- that is clearly not the case here. Here the tail is strongly graduated.
Ageing a bird is always a good start in the identification process. Red-backed Shrike typically has a complete moult in late winter for both adults and birds born the previous summer. By the time they migrate back to Europe/North it is very difficult to age them due this complete moult across the age classes. This bird is clearly worn and has not yet moulted (commencing moult in the tail only). If it was a first-winter Red-backed Shrike there should be lots of barring and specifically there should be dark sub-terminal marks to the greater coverts and tertials (see photos further below). Furthermore there should be a contrast between the upperparts and a grey nape (see photos further below). An adult female Red-backed Shrike should also show a contrasting grey neck but has plainer upperparts without the dark sub-terminal marks on the coverts and tertials. Based on that, this is either a strangley uniform adult Red-backed Shrike or a Brown Shrike (a more uniform upperpart colouration like this would be expected).
A closer look at the primary projection on the left wing shows 5-6 primaries projecting beyond the tertials which is typical of Brown Shrike. However the spacing and wing formula is unusual in that typically Brown has a short p2 which falls level with p5-6 and the amount of primary projection is short (about 60% whereas in Red-backed it is up to 100%) . Also typically but not visible in this image p1 is relatively long in Brown, extending well beyond the primary coverts. However a quick look on the internet seems to show quite a bit of variation with this.
One of the unusual aspects of this bird was the asymetry. On the right wing there appears to be 7-8 primaries projecting beyond the tertials (consistent with Red-backed) and also as mentioned above the tail was symmetrical too which may not have been a moult artefact if the tail was moulting from the inner rectrices out.
In Red-backed Shrike there are emarginations on p3-4 but on Brown and Isabelline Shrikes there are emarginations on p3-5. It's difficult to be sure here but there seems to be emarginations on p3-4 (although p2 seems emarginated too?) p1 seems to be shown here which also projects beyond the primary coverts but not too significantly. Overall the wing formula particularly on this wing (the right wing) is closer to Red-backed Shrike.
An adult female Red-backed Shrike from Bulgaria in June. Not much chance of mistaking this for a Brown Shrike with 7-8 primaries beyong the tertials with a 100% primary projection, a contrasting grey nape and rump and from what we can see an un-graduated tail. Note the lack of dark sub-terminal markings to the tertials and coverts on an adult compared to the juvenile below- this is a useful ageing feature.
A first-winter Red-backed Shrike, Bulgaria, September. Again no chance of confusing this with a Brown Shrike with rufous upperparts, a squared off tail and clearly aged as a first-winter by the presence of dark sub-terminal marks on the greater coverts and tertials.
Another first-winter Red-backed, Bulgaria, September. The rufous tones, squared off tail, long primary projection etc all present little confusion risk with Brown Shrike.
Presumed adult female Red-backed Shrike, Bulgaria, September. This was a bird I saw at Cape Kaliakra which was quite uniform and invoked Brown Shrike vibes but I didn't get any better photos. However it looks like the primary projection was quite long and the tail appear squared off from this image. There is an image in HEB which shows a second-calender year female Red-backed with more uniform brown upperparts so prehaps a second-calender year female Red-backed Shrike could present one solution to a more Brown shrike looking uniform brown specimen ? I guess the conclusion on all the above is the bird seems to fit Red-backed Shrike more than Brown but with several aytpical features and the only age and sex that would make some sense is an adult female possibly a second-calender feamle that has not started it's winter moult yet.
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This was the first Brown Shrike for Kuwait (Omar Alshaheen via eBird Kuwait Whatsapp). A very obvious bird with large head and heavy bill and a dark mask (another pro-Red-backed feature of our bird was a rufous tone in the mask). Seems to show a classic wing formula with long p1 and relatively short p2.
Brown Shrike in India, November. The classic short-winged, long tailed, large head and thick billed appearance is apparant here and it appears to show a very long p1 too. Not sure what's going on with those pale fringes- clearly a variable species.
However not all Brown Shrikes are that obvious (extract from HWPB).
Seems like the best fit for these two Isabelline Shrikes (above and below) is a male Durian (above) and a female Durian (below). The buff on the forehead, pale base to bill, buff in supercilium, sandy tones in upperparts and buff underparts fit Durian (Red-tailed Shrike should show darker upperparts, broad white supercilium over a dark mask across the ear coverts to lores and dark bill) and the black ear coverts is a better fit for a male than a female. The uniform buff colour across the underparts and upperparts on the female below also fits Durian (Red-tailed should show contrasting white underparts with some vermiculations too). Seems like ageing 'Isabellines' also involves dark markings on the greater coverts which I'm not seeing here so presumably either adults or newly moulted birds (they also have a complete moult in winter across all age classes- unlike the grey shrikes that typical for passerines the adults have a compelte moult and the second calender years don't moult until the following summer)
Seems like the thick black bill, white supercilium, thick toes, overall pale colouration, large white tips to tertials and a break between the primary patch and the white on tertials which seems to indicate a lack of black on the secondaries- all seems good for a Steppe Grey Shrike. The other possibility in the region is Levant Shrike, aucheri, but this should be darker with smaller super which I guess is difficult to exclude from one photo but I think Steppe Grey is the expected taxon.
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