IDENTIFICATION ARTICLES



Identification of Wilson's and Common Snipes.

The Snipe (Gallinago sp.) is an annual winter visitor to the Hawaiian Islands in small numbers. Often birds are simply recorded as just Common Snipe, however individuals of both the North American Wilson's Snipe (Gallinago delicata) and Common Snipe (Gallinago gallinago) are involved.

Wilson's Snipe of the Nearctic breeds across much of North America and Canada and winters in the southern States and south to northern South America. The Common Snipe of the Palearctic region breeds across Europe and Asia to the very eastern edge of Russia and China and winters across nw and middle Europe, across central Africa (but rarely south of the Equator) and across to the Middle East, India and SE Asia. Recent observations have shown that Wilson's breed west to the Aleutian Islands and Common Snipe regularly displays east to Attu (though not found breeding yet) (Hayman et al. 1996).

Although Snipe show a wide range of plumage differences across their range and even between individuals it is possible with care and good enough views to identify most individuals to either gallinago or delicata. The picture above right depicts a Wilson's Snipe in the foreground and a Common (Eurasian) Snipe in the background.


Different Species?

Sir Joseph Banks collected the first New World specimen of a Snipe in 1766 it was not considered different to that found in the Old World, which had been described by Linnaeus. In 1925 however the American ornithologist Alexander Wilson recognised it as a different species and it remained that way for almost one hundred years. In 1921 Oberholser proposed that it should be given sub-species status. Meinertzhagen discussed the differences between Eurasian and North American Common Snipes at a meeting of the British Ornithologists' Club in 1924 and concluded that the only difference was the width of the outer tail feathers. Bland (1999) states that this in itself is significant as it produces different drumming sounds, which he argues are an important feature in keeping Common and Wilson's Snipes reproductively isolated.

At an earlier meeting of the BOC in 1912 Dr. P.H. Manson-Bahr discussed the importance of the definite specialised outer tail feathers in the various Snipe:

In Eurasian Common Snipe " these feathers differ from others in the tail not only in their gross, but also in their minute structure, and can be recognised at a glance. That they are definite musical instruments there can be no doubt, as with them the identical well-known "bleat" can be reproduced by actual experiment, as was pointed out by Meves in 1856. The radii of the inner web of these feathers are firm and stiff and fashioned as the strings of a harp. To keep them taught during the performance and to ensure their vibration when acted on by the aerial resistance, a band of specialised muscle fibres runs to each of these feathers, so that when the tail is spread they project beyond the others. These facts are now well known; but what is not so well known or appreciated is the fact that in the different geographical races and species of Snipe these specialised structures have become more and more specialised.

In Wilson's Snipe not only are there four of these musical instruments in the tail, but in them specialisation has gone still further, and the inner web of the feather has become attenuated; while in two other South American species ( G. nobilis and G. frenato) the number of specialised feathers has increased and the attenuation has become more marked. In the African species (G. aequatorialis) and in the eastern Asian (G. solitaria, G. australis and G. megala), this specialisation has become even more marked, and reaches its climax in the Pin-tailed Snipe (G. stenura). In that species there are a variable number of feathers (generally sixteen) in the tail, which have become so attenuated that the shaft has become more or less bereft of all rami and radii. Thus, being shorn of their strings, so to speak, only the frame remains.

From Taczanowski and Alan Owston we have good accounts of breeding habits of G. solitaria and G. australis; and they perform in much the same manner as the CommonSnipe, but the "bleat" is of higher pitch and is much louder.

Of the breeding habits of G. stenura little appears to be known. Buturlin says it spreads its tail in the same manner, but that in rushing through the air no sound is produced. This statement is confirmed by my experiments in which I was unable to produce any sounds with these feathers. So in this species specialisation has proceeded to such an extent as to defeat the object for which these feathers were created".

In 1956, Aldrich stated that the coloration of the bars on the axillaries can separate the two (sub)species. In 1995, Carey and Olsen discussed the case for re-splitting in some detail and this has been adopted by Birding World and the Dutch CDNA. Genetic work by Zink was apparently inconclusive in regard of their taxonomic position.

Also of interest was the observation by Tuck that " although the colour and markings of the Eurasian Common Snipe vary in its wide distribution from the British Isles to Kamchatka in eastern Asia, in only a single population have those variables become sufficiently stabilised to be recognised as a geographical race or subspecies". The Faeroes Snipe to which he is talking about was once considered a full species (Brekim 1831) and later a sub-species (Hartert 1916), however in 1950 the British Ornithologists' Union merely considered it a variant or colour phase of Common Snipe.

On the basis of plumage and distribution and lack of integration in breeding of the two (gallinago and delicata) it seems best that the two should be regarded as different species, and it is likely that DNA work will show consistent differences between North American and Eurasian birds. The American Ornithologists Union in its 43rd Supplement (2002) decided to treat both species as distinct from one another and they are therefore countable as two species.

Identification

In Flight

Common Snipe has rather pointed wings and a bill which often looks longer than Wilson's, especially due to the often slimmer build of Common. Wilson's Snipe has a shorter tail and its toes are usually visible just beyond the tail tip.

The general plumage tones of Common Snipe are a contrasting mix of brown, buff and white. The wings which are dark brown contrast with the warmer and paler brown of the mantle and the usually bright, buff-tinged mantle lines. The upperwings are rather subdued and indistinct on the median covert panel and the secondaries are almost always broadly and evenly tipped white, although very worn birds might not show this, however this is unusual. A few of the greater secondary coverts are barred pale and the median covert panel appears small. The tips of the greater primary coverts are rather inconspicuous and do not form an obvious wing bar. Compared to Wilson's Snipe the median and greater underwing coverts have much broader white tips which makes the underwing either appear dark with two broad white bars or largely pale, especially when viewed from behind. Very occasionally the underwing may appear all dark.

Wilson's Snipe displays an underwing pattern which is similar to that of the Common Snipe but possesses narrower white tips to the secondaries and broader white tips to the primary coverts. Wilson's Snipe has barred lesser and median underwing-coverts, and therefore the underwing appears dark. The white tips to the underwing greater secondary coverts are quite broad but do not usually show in flight (Bland 1998, 1999; Cramp 1985).

At Rest

Wilson's Snipe is usually a generally colder toned bird and much blacker on the mantle than Common. The underparts are much whiter and paler. The scapular feathers of Wilson's have relatively narrow white fringes, whilst the upperwing feathers show distinct markings - the tertials are dark and finely marked with gradually fading transverse bars and the lesser and median coverts are intricately patterned with white-tipped dark-centred feathers, which contrast with the dark blackish-brown greater covert bar.

The head pattern is similar in both species although the rear supercilium is on average narrower on Wilson's and broadens out more in front of the eye. Wilson's Snipe is rather coarsely patterned on the neck sides with a brown-ginger wash mostly confined to the mid and upper breast. The flank barring is very striking and quite extensive which is pronounced by the white background coloration of the flanks, which are usually buff-brown in Common Snipe.

Common Snipe usually exhibits 14 tail feathers, although occasionally they exhibit 16 or 18, whereas Wilson's Snipe predominately has 16. Also the outer tail feathers are white with black bars on Wilson's but whitish and not well defined and sometimes washed brown in Common. The shape of the tail feather is also apparently diagnostic with Wilson's showing a more parallel and square-ended tail whereas Common exhibits round-tipped feathers (Bland 1998, 1999; Carey 1992 & 1995; Evans 1999).

Figure 1. Wilson's and Common Snipe upperpart and underpart features.

Wilson's Snipe at James Campbell NWR, O'ahu, November 2003.

Photograph © Peter Donaldson

   
     

Wilson's Snipe at James Campbell NWR, O'ahu, November 2003.

Photograph © Peter Donaldson

   

Figure 2. Quick summary of identification features for Wilson's & Common Snipe. Based on Carey and Olsson 1995.

  In Flight At Rest
Common Snipe

(Gallinago gallinago)
Slim, with pointed wings and long bill: contrasting brown, buff and white appearance. Inconspicuous median covert panel. Inconspicuous primary covert wing-bar; broad white trailing edge to secondaries and broad white areas on underwing coverts. Usually calls with the tone urgent and rasping. Erratic flight, often going high and far. Head rather mealy, tinged buff. Buff supercilium contrasting with white cheeks. Strongly buff-tinged mantle lines, duller on upper scapulars. Only outer edge of scapulars conspicuous often visible as diagonal streaks. Poorly defined wing panel appears spotted. Long tail projection.
Wilson's Snipe

(Gallinago (g) delicata)
Fairly faint median covert panel with narrow white secondary tips. Primary covert wing bar sometimes visible. Uniformly dark underwing. Toes usually extend beyond tail tip. Often calls similar to Common Snipe. Erratic flight, often flying far. Scapulars may appear scalloped as both outer and inner edges pale. Blackish barring on flanks. Upper breast streaked on brown background, lower breast barred on whitish background.

One other species of Snipe is currently on the Hawaii State list - Pintail Snipe, and it seems likely that it occurs more often but goes undetected due to the species retiring habits. Pintail Snipe breeds across northern and eastern Siberia and winters from Pakistan to southeast Asia and Indonesia and so is a likely candidate for further observations in the Islands. Compared with the other species it differs in appearing brown overall, including it's flight feathers, with buff or sandy-buff tinged pale areas. Its mantle lines are dull and brown and its median covert panel is well-marked, paler and more extensive, partly because a number of inner greater secondary coverts are heavily barred pale brown. The white tips to the greater primary coverts are slightly more prominent. The pale tips to the secondaries are absent thus showing as an all-dark trailing edge, although this can sometimes look slightly pale from certain angles depending on the light, but never appears as bright or conspicuous as on Common and Wilson's Snipes. The median and lesser underwing-coverts are heavily and darkly barred and therefore the underwing appears uniformly dark in flight (Viney 1982, Olsson 1987, Carey 1992).

The call of Pintail is apparently more throaty than in Common or Wilson's and its tone has been likened to that of the quack of a Mallard.

At rest Pintail Snipe has a broader supercilium which bulges immediately before the eye, which appears as a rather bare-faced expression. There is usually little contrast between the color of the supercilium and the are just above the cheek stripe.The tail is rather short and does not usually project much beyond the closed primary tips, and there is usually no primary projection beyond the tertials, whereas on Common & Wilson's the tail projects well beyond the wing tips.

Having stated all this however, not every feature is always confined to each species, but with a combination of features it is possible to identify most individuals. Perhaps with closer study the distribution and occurrence of Hawai'i's visiting Snipes may show a wider and more unexpected geographical source.


References

BLAND, B. 1998. The Wilson's Snipe on the Isles of Scilly. Birding World 11/10, pp.382-385.

BLAND, B. 1999. The Wilson's Snipe on Scilly revisited. Birding World 12/2, pp.56-61.

CAREY, G. J. 1992. The status and field identification of Snipe in Hong Kong. Hong Kong Bird Report 1992:139-152.

CAREY, G. and OLSSON, U. 1995. Field identification of Common, Wilson's, Pintail and Swinhoe's Snipes. Birding World 8/5, pp. 179-190.

CRAMP, S. 1983. The Birds of the Western Palearctic. Volume 3.

EVANS, LGR. 1999. Wilson's Snipes on the Isles of Scilly. Rare Birds Magazine 5/1, pp. 50-53.

HAYMAN, P., MARCHANT, J. and PRATER, T. 1986. Shorebirds - An Identification Guide. Helm, London.

OLSSON, M. 1987. The identification of Snipes. International bird identification. Proceedings of the 4th International identification meeting, Eilat, Israel, 1st-8th November 1986. International Birdwatching Centre, Eilat Israel.

TUCK, L.M. 1972. The Snipes. Canadian Wildlife Service monograph series No.5. Ottowa.

VINEY, C.A. 1982. Field identification of Snipe in Hong Kong. Hong Kong Bird Report, 1980:47-51.

Christian Melgar, Worthing, West Sussex. UK. 2001, updated 2004.


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