Notes on the identification of a Brown Shrike - Johnny Brown's Common, North Elmsall

A shrike found at Johnny Brown's Common was provisionally identified as Brown (Lanius cristata) on the morning of 18th October but as photographs started to circulate the bird was reported as a possible Turkestan Shrike (also called Red-tailed Shrike, Lanius phoenicuroides ). As more birders saw the bird the 'headline' identity returned to Brown Shrike but still referred to the possibility of it being Red-tailed. 

The bird remained in the same area until the 22nd October and it is thought that agricultural work in the fields next to its preferred area on the 23rd may have displaced it. 

I had good views of the bird on 20th October in both direct sunshine and light cloud and took the photos referred to below with other photos provided by Tom Tams and Pete Garrity as noted below.

Old World shrikes have a complicated taxonomy which is not yet fully resolved but in relation to this bird there were two similar looking species to consider; Brown Shrike Lanius cristata cristata and Turkestan Shrike Lanius phoenicuroides phoenicuroides.

Figure 1 Brown Shrike Johnny Brown's Common

Age and moult

The bird was in good condition with a complete set of primaries, two tertials had been replaced on the birds right which were black centred and white edged and it looked to me that the shortest tertials were both missing, possibly just growing and the middle tertial was missing on the left wing. There were several feathers missing in the tail. 

The post-breeding moult in Brown Shrike is complex starting on the breeding grounds often involving the inner 2 or 3 primaries several tertials and tail feathers. Moult is then suspended and finished on stop overs or on wintering grounds in Oct-Nov (Dec). In Turkestan Shrike the post breeding moult is completed on the breeding grounds in Jul-Sept involving head, body, tertials and several tail feathers (Shirihai & Svensson). 

The fact that the bird was in moult is consistent with the identification as Brown Shrike.

The jet black mask, including the lores, and absence of any barring on the sides of the breast, flanks or mantle indicate that the bird is an adult male.

General appearance

Assessing the size and structure of a lone bird is notoriously difficult but to me the bird looked larger and stouter billed than Red-backed Shrike with a size and shape more akin to a long-tailed Woodchat Shrike. The tail looked narrow as well as long but as noted above several tail feathers were missing.

The underparts were off white with a yellowish tinge to the throat, flanks and undertail coverts. 

The upperparts were earth brown on the mantle and nape with a warm brown crown fading to paler buff above the bill. There was no sign of any white at the base of the primaries on the closed wing but some white was visible in flight on the spread wing.

The rump and uppertail coverts were a warm brown similar to the crown whilst the tail was more earth brown like the mantle. The tail lacked any sign of white bases in any of the feathers.

On the head a black eyestripe extended broadly from the ear coverts to the eye and narrowed in front of the eye to the bill base. A whitish supercilium extended from the bill, joining narrowly above the bill, over the eye where it broadened slightly ending short of the black eyestripe. The bill was extensively blue-grey with dark tip to the lower mandible and dark culmen and more extensive dark tip to the upper mandible.

The eye, legs and feet were black.

Identification

Adult male Turkestan Shrike has a striking white throat and supercilium with underparts that are either whitish or tinged pale orangey/pink. The eyestripe is broad and the black tends not to narrow on the lores creating a more even mask with the black often narrowly extending over the bill. 

Figure 2 Adult male Turkestan Shrike (left) © Steve Young/Birdwatch from Worfolk 2000¹ in a similar pose to the Brown Shrike (right)

The bill looks less bulbous compared to Brown Shrike and is usually black in adult males but can be pale based. 

The head features all support identification of the shrike as Brown. 

Underparts

The off white base colouration with yellowish tinges to the upper breast, flanks, undertail and underwing coverts are indicative of Brown Shrike, Turkestan Shrike should be whiter with pinkish or orangey tones. 

The colouration has doubtless faded when compared with Spring male Brown Shrike but supports the identification.

Figure 3 Underpart and underwing colouration

Upperparts

In adult male Turkestan Shrike the uppertail coverts and tail tend to be the same rufous colour and contrast with the browner mantle. In adult male Brown Shrike the mantle and tail are a similar brown with rusty uppertail coverts as was the case with the shrike at Johnny Brown's Common Figure 4. 

Figure 4 view of the upperparts

Primaries

Primary projection is similar for both species, some photographs and comments on the Brown Shrike indicated that the primary projection was too long. The bird had a habitat of lowering its primaries so that they sat well below the tertials thus exposing more primary tips extending from the base of the secondaries. There were indications of moult in the tertials, as noted above and it seems likely that these feathers were still growing. 

When the primaries were held below the secondaries the primary extension did not look particularly long, exposing 4 to 5 primary tips which is typical for Brown, Figure 5. A longer primary extension with more exposed primary tips could have been indicative of hybridisation.

Figure 5 Brown Shrike primary projection (left ©Tom Tams and right © Pete Garrity) Note the right hand image has been flipped to facilitate the comparison

Both Brown Shrike and Turkestan Shrike show emargination on p3-5 but this was not visible in the field or on photos.

Note also the effect of light on the plumage tones in Figure 5 the left hand image in sunshine whilst that on the right is in overcast conditions.

Brown Shrike has a shorter second primary than Turkestan. According to Shirihai & Svensson(2); p2 falls short of the wing tip by 7-13mm and on the closed wing falls between the 6th and 7th primary in 44% of birds measured, is equal to the 6th primary in 29% of birds measured , falls between the 5th and 6th primary in 20% of birds measured or is equal to the 7th primary in 7% of birds measured. 

In Turkestan Shrike p2 falls short of the wing tip by 4.5-10 mm and on the closed wing falls between the 5th and 6th primaries on 58% of birds measured, equals the 6th primary in 26% of birds measured or falls between the 6th and 7th primary in 16% of birds measured.

Figure 6 Comparison of wing formula

Clearly, the assessment of these features are intended for trapped birds. The second primary is hidden below primaries p3 and p4 which form the wing tip when the bird is at rest. I have been unable to locate any photographs which show p2 on a sitting bird but see the measurements made below on the bird in flight. 

Tail

As mentioned above several tail feathers were missing on the birds righthand side. If you look closely at Figure 3 and 7 and the left hand image in Figure 5 a growing feather is visible at the base of the tail on the right hand side.

Figure 7 Spread tail © Pete Garrity

Looking at Figure 7 nine tail feathers are visible including the short, growing t6 on the birds right as mentioned above. It looks like the outer 4 feathers on the birds left are full grown without any gaps. So the missing feathers look like t2 on both sides plus t3 on the right.

Brown Shrike has a very graduated tail with the outer tail feather (t6) only 70% to 80% of the central (longest) feathers. On Turkestan Shrike the outer feathers are 80% to 90% of the longest feather.

In Figures 7,9 and 10 the short outer tail feather, t6 on the birds left is clearly visible and is perhaps 70% to 75% of the length of the central tail feathers thus supporting identification as Brown Shrike.

In March 2015 a shrike was found in Mendocino County, California, the Mendocino Shrike. It was present for 8 weeks and was subject to a detailed analysis including 100 of photographs in order to establish its identity. They took a number of measurements from photographs taken in the field and compared them with data obtained from museum specimens Figure 8 (Pyle et al 2015 (3)).

Figure 8 Adapted from Pyle et al 2015 see caption to Figure 9 for definitions

I've adapted Table 1b from Pyle et al and renumbered the primaries with number 1 as the small outer primary in accordance with European practice. I didn't include their actual measurements as it is the ratio which is important. Clearly the tail measurements are restricted to the feathers on the birds left side as outer feathers are missing on the right.

Figure 9 Showing measurements from Pyle et al in white, yellow line shows intersection of p2 with p5/p6 © Tom Tams, a= p3-p2 and b= p3 to primary coverts. c= t5-t6 and d= t5 to point of tail feather insertion

Figure 10 Pyle et al measurements using upperside of wing

Results 

Figure 7 ratio a/b = 0.229 c/d = 0.245      Average = 0.237

Figure 8 ratio a/b = 0.244 c/d = 0.233      Average = 0.239

Ratio a/b came just within the range for Brown Shrike whilst ration c/d was slightly low for Brown Shrike but way above the range for Turkestan Shrike. Clearly, there are a lot of variables that can affect these figures but look like they could be of assistance in separating this group of shrikes if decent photographs can be obtained and it is not possible to trap the bird.

Summary

I have checked a range of features used to identify Brown Shrike; upper and underpart colouration, moult, head structure and markings and wing and tail shape all of which are consistent with the identification of the bird at Johnny Brown's Common as an adult male Brown Shrike. 

I have also used measurements described in Pyle et al to confirm that structural differences in the primaries and tail are consistent with this identification and can be used to separate Brown from Turkestan Shrike.

I saw no indication of any form of hybridisation and concluded that this was an adult male Brown Shrike of the nominate race cristata. 

Notes on the photos; the photos which are not attributed to other photographers have had no alterations or enhancement made to the colours 

Acknowledgements

Thanks to the finders of the bird at Johnny Brown's Common for the chance to study this bird. Thanks to Tom Tams and Pete Garrity for use of their photos and I recommend Pete's video, available on Youtube via this link if you are interested in this bird.

I'm happy to receive any feedback or comments on this blog. via Twitter or via email to andysbutler@aol.com.

References

1. Worfolk, T. 2000. Identification of Red-backed, Isabelline, and Brown Shrikes. Dutch Birding 22: 323-362.

2. Shirihai & Svensson 2018 Handbook of Western Palearctic Birds

3. Pyle et al 2015 The Mendocino Shrike: Red-backed Shrike (Lanius collurio) x Turkestan Shrike (L.phoenicuroides) hybrid. North American Birds Vol 69: 4-35

4. Birding Frontiers Challenge Series - Autumn 2014

5. Panov E On the nomenclature of so called Isabelline Shrikes Sandgrouse 31 (2009) p163-170

6. Ganpule P 2017 Red-backed, Brown, Isabelline and Red-tailed Shrike in Gujarat Flamingo Vol. XV-3 July - Sep, 2017