Siberian Flycatcher Muscicapa sibirica Brown, Siberian and Grey-streaked Flycatchers ... · 2019....

Brown Flycatcher Muscicapa dauurica,Siberian Flycatcher M. sibirica, andGrey-streaked Flycatcher M. griseisticta

are three superficially similar flycatchers whichare common, long-distance migrants in eastAsia. Brown Flycatcher has already reached

Europe on several occasions, including singlerecords from Denmark, Sweden and Greeceplus three accepted records from Britain (FairIsle 1992 and 2008 and Flamborough Head,Yorkshire, 2007; Hudson et al. 2009, Harvey2010). In addition, one was seen in Yorkshire

658 © British Birds 103 • November 2010 • 658–671

Alan

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ris

Brown, Siberian and Grey-streaked Flycatchers:identification and ageingPaul J. LeaderAbstract In the light of recent records of Brown Flycatcher Muscicapa dauuricain Britain, this short paper looks at the identification and ageing of this species andtwo closely related potential vagrants from east Asia: Siberian Flycatcher M. sibiricaand Grey-streaked Flycatcher M. griseisticta. Differences in structure and plumageare summarised, and particular attention is paid to ageing and moult.

Siberian Flycatcher Muscicapa sibirica

Throughout this paper only the northern taxa of Siberian Muscicapa s. sibirica and Brown Flycatchers M. d. dauurica arediscussed. Although there exists another ‘Brown Flycatcher’ in Asia (Sumba Brown Flycatcher M. segregata), the Englishname of Brown Flycatcher for M. dauurica has a long history in Europe and there seems little need to add the modifier‘Asian’ to avoid potential confusion with Sumba Brown Flycatcher. For M. s. sibirica, I prefer the English name Siberian Fly-catcher over Dark-sided or Sooty Flycatcher (both of which are widely used in Asia) to distinguish the northern migratorypopulations from three very similar Sino-Himalayan taxa (which are morphologically distinct from nominate sibirica,being smaller, much darker and showing more heavily marked underparts, and are either resident or short-distancemigrants; Vaurie 1959). This group (the Sino-Himalayan taxa or ‘cacabata group’) is sometimes treated as a distinct species,Dark-sided Flycatcher M. cacabata. In this context, it is of note that plates 294–295 in Bradshaw et al. (1991) showing a‘Siberian Flycatcher’ were taken in Sichuan Province, China, in May (G. Speight pers. comm.). As a consequence, theydepict the taxon rothschildi (i.e. part of the ‘cacabata group’; Vaurie 1959), which breeds in this region of China and is notrepresentative of nominate sibirica. The latter is the only taxon likely to reach Europe as a vagrant.

in early September 2010. Although neitherSiberian nor Grey-streaked Flycatchers haveyet occurred in western Europe, otherpasserine migrants that occupy a similarbreeding range have reached Europe, whichsuggests that both flycatchers are potentialvagrants. Furthermore, there is a remarkablerecord of a vagrant Siberian Flycatcher fromBermuda (Wingate 1983).While the identification of ‘brown fly-

catchers’ has been addressed in the past, mostnotably by Bradshaw et al. (1991) andAlström & Hirschfeld (1991), it seems timelyto revisit this topic in the light of the recentBritish records of Brown Flycatcher and alsoimprovements in bird photography. In thispaper, emphasis is placed on ageing thesespecies in the field, especially where this hasimplications with regard to species identifica-tion. In addition to studying all three speciesin the field, museum specimens have beenexamined and, for the biometrics presentedhere, a sample of 20 specimens of each

species were measured. These specimenscomprised a mixture of adults and first-yearsand were restricted to individuals ofnorthern migratory populations.

AgeingBrown FlycatcherIn autumn, first-winters can be separatedreadily from adults by the presence of neat,pale edges to the greater coverts and tertials,while the tips of these feathers have a broaderpale area with a characteristic ‘hook’ (or‘thorn’) extending back along the feathershaft. These differ from the narrower, greyerfringes to the tertials and greater covertsshown by adults, and which lack the obvioushook pattern. It should be noted that onsome adults the tertial fringes are paler thanthe greater-covert fringes. See plates 360–364. In broad terms, similar distinctions between

adult and first-winter birds are apparent inthe other two species, though there areimportant differences too, described below.

659British Birds 103 • November 2010 • 658–671

Brown, Siberian and Grey-streaked Flycatchers

360. First-winter Brown Flycatcher Muscicapa dauurica, Hong Kong, China, 6th September 2006. Note especially the pale, cold grey upperparts of this bird compared with Siberian M. sibirica and Grey-streaked Flycatchers M. griseisticta.The broad pale fringes to the tertials and greater coverts, andespecially the pale ‘hooks’ extending up the feather shaft at the tips of the latter are typical of first-winter Brown Flycatchers. Note also the primary projection, which is slightly shorter than the lengthof the exposed tertials, and the relatively long tail. The extensively pale lores of this individual results in the eye-ring being difficult to discern in front of the eye but very conspicuous behind it. This viewshows the typically large bill of this species as well as the predominantly pale lower mandible.

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some, the greater covertsappear uniform andunmarked. This pattern isnever shown by fresh adultBrown, although these tipscan abrade during winter andmay be lost by the spring. Seeplates 365–371.

Grey-streakedFlycatcherThe greater coverts and ter-tials of first-winter Grey-streaked have a well-definedpale edge and (broader) tipbut feathers in both tracts fre-quently lack any hook at thetip, resulting in a broad paletip of even width. See plates372–376.

Timing of post-juvenilemoultA useful character that helpswith species identification isthe timing of post-juvenilemoult. On average, this takesplace distinctly later inSiberian Flycatcher than in

either Brown or Grey-streaked, both of whichundergo a post-juvenile body moult beforethey migrate. Siberian Flycatchers that retainextensive juvenile plumage on the upperpartsand underparts are recorded regularly fromAugust to October, and occasionally intoNovember. In comparison, during the same

660 British Birds 103 • November 2010 • 658–671

Leader

Fig. 1. Wing length (mm) and tail length (mm) of Brown Muscicapa dauurica, Siberian M. sibirica andGrey-streaked Flycatchers M. griseisticta (n = 20 for each species).

65 70 75 80 85 90wing length (mm)

56

54

52

50

48

46

44

tail length (mm)

Brown Flycatcher Siberian Flycatcher Grey-streaked Flycatcher

Fig. 2. Diagram showing the relative proportions of wings andtail of first-winter Brown Muscicapa dauurica (left), Siberian M. sibirica (middle) and Grey-streaked Flycatchers M. griseisticta(right). Note the progressively longer primary projection andshorter extension of the tail beyond the wing-tip.

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Siberian FlycatcherFirst-winter Siberian Flycatchers usuallyshow a less obvious pale hook at the tip ofthe greater coverts than first-winter Brown,and often lack the pale hook at the tip of thetertials. Adults have less well-marked palefringes than adult Brown Flycatchers and, on

period, first-winter Grey-streaked may showjust a small number of retained juvenilefeathers (if present, these are usually amongthe longest uppertail-coverts), while youngBrown Flycatchers only exceptionally retainjuvenile feathers on the upperparts. There is much individual variation in the

timing of the post-juvenile moult in SiberianFlycatcher; in some, it is completed as early asmid September, while in others it has barelycommenced in mid November. Observationsin China in autumn (between August andearly November) suggest that a bird retainingmore than c. 25% juvenile body plumage isinvariably a Siberian Flycatcher.

Structural differencesWing shape and primary projectionThere are distinct structural differencesamong the three species. Most important isan increase in wing length (and wing/tailratio) from Brown through Siberian to Grey-streaked (table 1, figs. 1 & 2), which in turn



Table 1. Comparison of wing length (mm), tail length (mm) and wing/tail ratio in BrownMuscicapa dauurica, Siberian M. sibirica, and Grey-streaked Flycatchers M. griseisticta.

wing length tail length wing/tail ratiomean* range mean range range

Brown Flycatcher 69.2 ± 1.7 66.5–72.0 47.9 ± 1.7 45.0–51.0 1.36–1.52Siberian Flycatcher 79.7 ± 2.0 75.0–85.0 51.6 ± 2.0 47.0–55.0 1.48–1.62Grey-streaked Flycatcher 85.8 ± 1.9 83.0–89.0 49.5 ± 1.9 46.0–53.0 1.66–1.84

* ± standard deviation. N = 20 for each species.

Table 2. Relative length of second primary (P2) compared with other primaries in BrownMuscicapa dauurica, Siberian M. sibirica, and Grey-streaked Flycatchers M. griseisticta. Figuresrepresent percentage of individuals meeting each criterion, n = 20 for each species).

P2=P3/4 P2=P4 P2=P4/5 P2=P5 P2=P5/6Brown Flycatcher 0 0 0 45 55Siberian Flycatcher 0 10 90 0 0Grey-streaked Flycatcher 25 65 10 0 0

Table 3. Comparison of bill width (mm)measured at proximal edge of nostrils in Brown Muscicapa dauurica, Siberian M. sibirica, and Grey-streaked Flycatchers M. griseisticta (n = 20 for each species).

bill widthmean range

Brown Flycatcher 5.8 ± 0.2 5.3–6.1Siberian Flycatcher 5.4 ± 0.3 4.8–5.8Grey-streaked Flycatcher 5.4 ± 0.3 4.7–5.9

gives a progressively longer primary projec-tion and more pointed wing shape (table 2).These differences are clearly apparent in thefield. In Brown, the primary projection isshorter than the exposed tertials, in Siberianit is equal to or up to 20% longer and inGrey-streaked normally 20% longer than thelength of the exposed tertials. In both Brown and Siberian, the primary

tips typically fall level with or slightly short ofthe tips of the longest uppertail-coverts,while in Grey-streaked the primary tips typi-cally extend beyond the longest uppertail-coverts. With flycatching birds, the distinctlylong and pointed wings of Grey-streaked canbe rather obvious, as can the more roundedwing of Brown Flycatcher. Siberian Fly-catcher shows a rather pointed wing and ismore similar to Grey-streaked in this regard.

BillWhen viewed from below, Brown Flycatchertypically has a straight-sided or slightlyconvex bill, whereas both Siberian and Grey-streaked show slightly concave or straightsides to the bill, and the bill generally appearsless bulky. Note, however, that the base of thebill can be similarly broad in all three species(table 3) and that a small minority of Siberianand Grey-streaked have a bill shape identicalto that of some Brown Flycatchers. However,when viewed from the side, the bill ofSiberian is normally shorter and finer thanthat of both Brown and Grey-streaked, andboth Siberian and Grey-streaked have a

smaller pale area at the base of the lowermandible than Brown (such that on someindividuals of both species the lowermandible can appear all dark in the field).

Plumage differencesHead patternBrown Flycatcher has distinctly pale andunmarked lores; a conspicuous, whitish eye-ring; a well-defined submoustachial and aneat lateral throat stripe; and a pale ‘half-collar’, giving it a subtle but quite distinctiveappearance. In comparison, Siberian Fly-catcher typically shows less extensively palelores, a strong lateral throat stripe but lesswell-defined submoustachial, while the palehalf-collar is often ill-defined or absent.Together, these characters combine to createmore of a uniformly hooded effect. Grey-streaked Flycatcher shows less well-definedpale lores than Brown but a more conspic-uous lateral throat stripe, and some streakingon the otherwise pale submoustachial. It cansometimes have light streaking on the throat,and also shows diffuse streaking on thecrown, a feature not shown by either Brownor Siberian. Owing to the more obviouslyand extensively pale lores of Brown Fly-catcher, the part of the eye-ring in front ofthe eye can be difficult to see in that species,giving the impression of an incomplete eye-ring. The eye-ring on Grey-streaked Fly-catcher typically appears complete, owing tothe contrast with the darker lores, but is oftenrather narrow and frequently slightly thickerbehind the eye. Siberian usually shows a veryobvious eye-ring (partly a function of thedarker and plainer head of this species),which broadens conspicuously behind theeye.

UpperpartsIn fresh plumage, Brown Flycatcher has dis-tinctly greyer and colder upperparts than thedarker brown upperparts of both Siberianand Grey-streaked.

UnderpartsBrown Flycatcher is the least well marked ofthe three species on the underparts, showinggrey-brown sides to the breast, extending as adiffuse wash across the centre of the breast(sometimes, especially in adults, this can

include ill-defined streaks). A few birds showa darker and more clearly defined breast-band. Grey-streaked Flycatcher always showsvery dark, well-defined streaks on the breastand flanks; the contrast of these streaks beingenhanced by the clean white ground colourof the underparts. Siberian Flycatcher is more variable below

than either Brown or Grey-streaked. This cancause confusion as the underparts of somemay resemble those of a well-marked BrownFlycatcher, while others can appear moresimilar to Grey-streaked. Young Siberian Fly-catchers that retain largely juvenile plumagein autumn are distinctly spotted across thebreast and onto the flanks, but those moreadvanced into first-winter plumage showdark brown flanks and breast (this colourgenerally extending farther down the flanksthan in Brown). Adult Siberian Flycatchersare rather similar to first-winters but gener-ally appear more streaked. Although theunderpart streaking can be quite diffuse onsome birds (and similar to a well-markedBrown Flycatcher), in boldly marked birdsthe underparts are entirely streaked. Whencompared with Grey-streaked, the streaks aremuch less distinct and may coalesce to formmuch longer streaks down the breast.Siberian may also show diffuse dark centresto the longest undertail-coverts, a characterwhich the other two species never show.

Wing-barsFirst-winter Siberian Flycatchers tend to havemore obvious rufous tones to the palegreater-covert tips than either Brown orGrey-streaked.

Underwing-covertsThe underwing-coverts of both Siberian andGrey-streaked are dark grey-brown, conspic-uously darker than the rest of the underwing.The underwing-coverts of Brown Flycatcherare a paler mid brown, less obviously darkerthan the rest of the underwing.

Retained juvenile feathersAs well as the differences in timing of post-juvenile moult discussed above, there aresubtle differences in the pattern of theretained juvenile body feathers. The palespots on retained juvenile feathers on the


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head, mantle and scapulars of Siberian Fly-catcher tend to be rather triangular (broadestat the tip of the feather), relatively small andhave the dark part of the feather the samecolour as the replaced, adult-type feathers. InGrey-streaked these pale spots are also trian-gular, but narrow towards the feather tip andthe dark part of the feather is subtly darkerthan the replaced, adult-type feathers. InBrown Flycatcher, the pale areas are distinctlyrounded and the dark part of the feather isblackish and thus distinctly darker thanreplaced adult-type feathers.

Behavioural differencesSiberian and Grey-streaked Flycatchers tendto select conspicuous perches (often higherup in the tree canopy), and Siberian has avery conspicuous habit of frequentlyreturning to one preferred perch when for-aging. Brown Flycatcher will often forage at alower level and choose less conspicuousperches when feeding. Brown also undertakesshorter foraging flights than Grey-streakedand, especially, Siberian; the latter will oftentake long, rather acrobatic flights, whichfurther emphasises the habit of returning to a

preferred perch. Clearly these differences maycount for nothing when encountering avagrant on a treeless northern isle, but incertain circumstances they can be helpful.

Acknowledgments

I would like to thank Mark Adams at the BritishMuseum of Natural History (Tring) for arranging accessto the skin collection there. I would especially like tothank Martin Hale, Michelle Wong and Peter Wong,whose excellent photos form the basis of this paper.

References

Alström, P., & Hirschfeld, E. 1991. Field identification ofBrown, Siberian and Grey-streaked Flycatchers.Birding World 4: 271–278.

Bradshaw, C., Jepson, P. J., & Lindsey, N. J. 1991.Identification of brown flycatchers. Brit. Birds 84:527–542.

Harvey, P. 2010. Brown Flycatcher on Fair Isle: new toBritain. Brit. Birds 103: 651–657.

Hudson, N., and the Rarities Committee. 2009. Report on rare birds in Great Britain in 2008. Brit. Birds 102: 528–601.

Vaurie, C. 1959. The Birds of the Palearctic Fauna: a systematic reference. Order Passeriformes. Witherby, London.

Wingate, D. B. 1983. A Record of the SiberianFlycatcher (Muscicapa sibirica) from Bermuda: anextreme extra-limital vagrant. Auk 100: 212–213.http://elibrary.unm.edu/sora/Auk/v100n01/p0212-p0213.pdf



Paul J. Leader, c/o Asia Ecological Consultants, 127 Commercial Centre, Palm Springs, New Territories, Hong Kong

Brown Flycatcher Muscicapa dauurica

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362.First-winter Brown Flycatcher M

uscic

apa

dauu

rica, Hong Kong, China,

13th October 2007. Note the grey-toned upperparts, short primary projection,

extensively pale lores, conspicuous whitish eye-ring (but not prominent in front

of the eye) and rather neat head pattern. The bill is large, with a conspicuous

yellow base to the lower mandible.

Miche

lle &

Peter W

ong

361.First-winter Brown Flycatcher M

uscic

apa

dauu

rica, Hong Kong, China,

6th September 2006.A well-marked individual showing a sullied brown wash

to the centre and sides of the breast, similar to some Siberian Flycatchers

M. sibirica. However, note the extensively pale lores, eye-ring apparently lacking

in front of the eye, neat head pattern and extensively pale lower mandible.

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363.Adult Brown Flycatcher M

uscic

apa

dauu

rica, Hebei province, China, 12th

May 2005. In spring, adults appear worn and abraded, and have a tendency to be

brown, rather than grey-toned above. They are still readily aged by the uniform

appearance to the greater coverts, and the narrow fringes to the tertials, which

lack the hook extending back along the shaft characteristic of first-winter birds.

Some, like this adult, show tertial fringes that are paler than the greater-covert

fringes. This bird has rather limited pale feathering on the lores for this species,

yet note that the eye-ring in front of the eye remains difficult to discern.

Ran

Scho

ls

364.Adult Brown Flycatcher M

uscic

apa

dauu

rica, Perak, Malaysia, 4th

September 2003.After breeding, adults have a complete moult and appear

fresh during autumn migration. Although this individual shows broad whitish

fringes to the tertials that extend onto the inner web, it lacks the hook along

the feather shaft characteristic of first-winter birds.Also note the less well-

defined fringes to the greater coverts compared with the first-winter birds in

plates 360 & 362.

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Yen

Loon

g


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365.Juvenile/first-winter Siberian Flycatcher M

uscic

apa

sibirica, Hong Kong,

China, 15th October 2005. Note the retained juvenile plumage on the head,

scapulars, rump and flanks, which is typical of first-year Siberian in autumn.

The primary projection is obviously longer than the visible tertials, and the tail

looks relatively short when compared with Brown Flycatcher M

. dau

urica.The

pale portion of the retained juvenile feathers on the scapulars is triangular and

broadest at the feather tip. Note also the prominent eye-ring, which is narrow

in front of the eye and clearly broader behind.

Miche

lle &

Peter W

ong


uscic

apa


China, 18th September 2006.Again, the remnants of juvenile plumage, this time

on the underparts, are obvious. Note also the largely dark lores, well-defined

eye-ring broadening behind the eye, and the poorly defined submoustachial

stripe, which combine to give this species its rather dark, hooded appearance;

and the dark markings on the undertail-coverts. The rather delicate bill with a

limited pale base to the lower mandible is typical for this species.

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368.First-winter Siberian Flycatcher M

uscic

apa

sibirica, Hong Kong, China, 19th

October 2007. This bird has completed its post-juvenile moult. Note the moult

contrast between the two replaced (and rather uniformly plain) adult-type

innermost greater coverts and the remaining juvenile greater coverts, which are

conspicuously pale-edged and warmer-toned.This bird shows the classic dark,

‘hooded’ appearance of Siberian Flycatcher and the long primary projection –

slightly longer than the exposed tertials, wingtips almost level with the tip of

the longest uppertail-coverts.The obviously small bill looks all dark on this view.

Miche

lle &

Peter W

ong


uscic

apa


China, 18th September 2006 (same individual as in plate 366). Note the

retained juvenile feathers among the upperparts, the largely dark lores, well-

defined eye-ring and the long primary projection. This individual shows small,

blunt ‘hooks’ to the tips of the greater coverts and tertials.

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369.First-winter Siberian Flycatcher M

uscic

apa

sibirica, Hong Kong, China,

19th October 2007. Superficially similar to the Brown Flycatcher M

. dau

urica

in plate 361, but compare the reduced pale area on the lores, well-defined

eye-ring (including in front of the eye), the poorly defined submoustachial

stripe and the dusky streaking to the centre of the breast.

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lle &

Peter W

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370.Adult Siberian Flycatcher M

uscic

apa

sibirica, Hong Kong, China, 1st May

2007. Note the extensive streaking to the underparts, and compare with the

underparts of the Grey-streaked Flycatcher M

. gris

eistict

ain plate 376.

Miche

lle &

Peter W

ong



372.First-winter Grey-streaked Flycatcher M

uscic

apa

grise

istict

a, Hong Kong,

China, 1st October 2007. Note the well-defined streaking on the underparts,

diffuse streaking on the crown, and retained juvenile feathering on the scapulars

and uppertail-coverts. Compare the shape of the pale area on the scapulars

(which is triangular but tapers towards the feather tip) with that of the Siberian

Flycatcher M

. sibiricain plate 365.The wings and primary projection are clearly

very long, and the tail projection (beyond the wing-tip) is short.The large bill

lacks an obvious pale base to the lower mandible.

Miche

lle &

Peter W

ong

371.Adult Siberian Flycatcher M

uscic

apa

sibirica, Hong Kong, China,

15th October 2009. Compare the rather sullied underparts of this bird with

those of the more-streaked individual in plate 370.Also note the uniformity

of the head pattern and the greater coverts, and the dark marks on the

undertail-coverts.

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uscic

apa

grise

istict

a, Hong Kong,

China, 6th May 2003. As well as the well-defined underpart streaking, note the

well-defined lateral throat stripe narrow eye-ring, and large, mainly dark bill.

Miche

lle &

Peter W

ong


uscic

apa

grise

istict

a, Hong Kong,

China, 7th October 2007.The primary projection is conspicuously longer than

the length of the exposed tertials; and the head pattern very similar to that of

the first-winter in plate 374.

Miche

lle &

Peter W

ong



375.Adult Grey-streaked Flycatcher M

uscic

apa

grise

istict

a, Hong Kong, China,

1st October 2007. Note the long primary projection, the diffuse pale fringes to

the greater coverts and tertials, and the diffuse streaking to the crown.While

the lores clearly have some pale feathering, this is not as extensive as in Brown

Flycatcher M

. dau

urica, so the eye-ring is well defined.

Miche

lle &

Peter W

ong

376.Adult Grey-streaked Flycatcher M

uscic

apa

grise

istict

a, Hong Kong, China,

1st October 2007. Note the diffuse pale fringes to the greater coverts.

Miche

lle &

Peter W

ong

Siberian Flycatcher Muscicapa sibirica Brown, Siberian and Grey-streaked Flycatchers ... · 2019....

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