Keep Calm and Study Snipes! Part 2

I admit it – you have to be a certain kind of crazy to be ‘into’ snipes! But, if you are afflicted with the condition – is there any hope?

I’ll base this post largely on Identification of Pintail Snipe and Swinhoe’s Snipe by Paul Leader and Geoff Carey, a paper published in British Birds in 2003, which is downloadable here. Their research was based on detailed study of 68 Pintail Snipes and 19 Swinhoe’s Snipes in the hand during ringing studies carried out 1999-2001, as well as data from a further 25 Pintail and 14 Swinhoe’s trapped prior to this, all in Hong Kong, and examination of skins from two museum collections. It remains the best starting point published to date from which to start addressing this thorny identification issue.

They evaluated a number of field characteristics which had been previously considered reliable in distinguishing the two species and came to the following conclusions:

STRUCTURAL FEATURES

Overall size

Assumption: Swinhoe’s is commonly stated to be 10-20% larger than Pintail.

Leader and Carey: Although Swinhoe’s Snipe is larger than Pintail Snipe on average, size and structure are extremely variable, with extensive overlap on all standard measurements. Accordingly, their separation based on size, even if both are together for direct comparison, is not possible in the field.

Bill length

Assumption: Swinhoe’s bill is commonly stated to be longer than Pintail, approaching that of Common.

Leader and Carey: Complete overlap in measurements.

Wing length

Assumption: Swinhoe’s wing length is commonly stated to be 5-10% longer than Pintail.

Leader and Carey: Large degree of overlap and the difference does not translate into a discernible field character.

Primary projection beyond tertials

Assumption: Primary projection beyond the longest tertial has been suggested as a useful structural difference –  short in Pintail Snipe, and long in Swinhoe’s.

Leader and Carey: Pintail Snipe is particularly variable and sometimes exhibits a longer primary projection than Swinhoe’s. About half of all Pintail Snipe and Swinhoe’s Snipe show no primary projection.

Tail projection beyond the wingtips

Assumption: On Pintail, the tail barely projects beyond the primaries. Viewed in profile, the short tail projection gives Pintail Snipe a truncated rear end and squat appearance, quite different to that of Swinhoe’s, which has a longer tail approaching that of Common Snipe.

Leader and Carey: On average, Swinhoe’s Snipe has a tail which is 5.8 mm longer than that of Pintail Snipe. However, in terms of relative structure, this is largely negated by the difference in wing length between the two species, which averages 6.5 mm longer on Swinhoe’s. This results in a very similar wing/tail ratio for the two species, averaging 2.98 for Pintail Snipe and 2.80 for Swinhoe’s Snipe.

Toe projection beyond the tail in flight

Assumption: Due to the shortness of the tail, on Pintail Snipe the toes project further beyond the tail tip in flight.

Leader and Carey: Observations of released birds of confirmed identity do indicate that this may be a useful feature. This is, however, based only on a small sample of Swinhoe’s Snipes and the validity of this feature is best treated as tentative, pending further research.

Head Shape

Assumption: Swinhoe’s has a squarer head which peaks behind the eye

Leader and Carey: Pintail Snipe tends to have a more rounded head profile and a steeper forehead, whereas on Swinhoe’s Snipe, the forehead tends to appear more shallow and sloping, giving that species a more angular head profile. In addition, the eye seems to be set closer to the centre of the head in Pintail Snipe, but further back on many Swinhoe’s Snipes. Indeed, occasionally on Swinhoe’s Snipe, most of the eye appears to lie in the rear half of the head. There is, however, much variation.

Leg Thickness

Swinhoe’s Snipe tends to have significantly thicker legs than Pintail Snipe, with most Swinhoe’s Snipes taking a larger ring size than Pintail Snipes. Some Swinhoe’s Snipes do, however, have thinner legs, resembling those of Pintail Snipe, so this is a ‘one-way character’. A bird with thicker legs than a Common Snipe is probably Swinhoe’s. This feature is extremely difficult to assess in the field, but may be possible to discern on good quality photographs.

Shape of the outer tail feathers

The outer tail feathers of both species are distinctly narrow when compared with those of Common Snipe. On Pintail Snipe, the outer eight pairs of tail feathers (sometimes six to nine pairs) are all less than 2 mm wide (see here). On Swinhoe’s Snipe, only the outermost pair is narrow, varying between two and four millimetres in width, 20 mm from the tip. The next one to four pairs are slightly broader, and the rest increasingly so towards the central pair (see here). Observing this is, however, extremely difficult under normal field conditions, and requires exceptional views (assuming the bird is not in tail moult!).

BARE PART COLOURATION

Leg colour

Assumption:  Pintail Snipe tends to show grey-green legs and Swinhoe’s Snipe has yellower legs.

Leader and Carey: There is extensive overlap in this feature also between the two species.

PLUMAGE FEATURES

Loral stripe thickness

Assumption:  The loral stripe of Pintail Snipe is rather narrow, at times almost disappearing in front of the eye.

Leader and Carey: Shape, colour and definition variable, overlapping completely with Swinhoe’s.

Median crown stripe

Assumption: The median crown-stripe of Pintail Snipe sometimes reaches the bill base, but this is unusual on Swinhoe’s Snipe.

Leader and Carey: This feature varies widely, with the median crown-stripe reaching the bill base on about 30% of of Swinhoe’s Snipes and 40% of Pintail Snipes.

Pale fringe to lower scapulars

Assumption: The fringes are broader on Swinhoe’s Snipe.

Leader and Carey: The width of the fringes is variable in both species, with no consistent differences.

Amount of white in the tail

Assumption: Swinhoe’s Snipe  shows more white in the tail than Pintail Snipe.

Leader and Carey: This does not take into account the variation in tail pattern of Swinhoe’s. Pintail Snipe consistently shows white tips and inner webs to the narrow outer rectrices. If present, the pale tips to the central rectrices are buffish, and rarely whitish. In comparison, although Swinhoe’s Snipe usually has white tips to the outer rectrices, these may also be rich buff or pale ginger, colours rarely, if ever, shown by Pintail Snipe. The central rectrices of Swinhoe’s Snipe may also be conspicuously tipped pale, often white, unlike Pintail. Swinhoe’s Snipe consistently shows barred or chequered outer rectrices, however. On Pintail, these are typically plain, except for white tips. Patterned (barred or chequered) outer tail feathers are exceptional in Pintail, and while some Swinhoe’s occasionally show plain outer tail feathers, and thus appear extremely
similar to Pintail, a bird with white tips to the central rectrices and chequered or barred outer rectrices is most probably a Swinhoe’s Snipe.

VOCALIZATIONS

Assumption: Differences exist between the normal flight calls of the two species. Pintail Snipe is believed to have a more slurred, throaty and nasal call which sometimes resembles the ‘quack’ of a duck. The call of Swinhoe’s Snipe is described as similar in pitch, though at times rather flat and low. When flushed, Swinhoe’s Snipe calls less frequently than Pintail Snipe, and a flushed snipe which is silent is most likely to be the former.

Leader and Carey: Vocalisations of flushed Pintail or Swinhoe’s Snipes in Hong Kong fall into two distinct types which agree broadly with those described above. The first call type, generally the most frequently heard and believed to be given by Pintail Snipe, is higher pitched, more nasal, slightly more urgent and does, indeed, resemble a duck’s ‘quack’.

The second call type, tentatively attributed to Swinhoe’s Snipe, is lower pitched and flatter, with a more throaty quality. This call was heard (though not recorded) from a known Swinhoe’s Snipe released after ringing. This second call type is less frequently heard among migrant snipe in Hong Kong, certainly proportionately less so than would be expected by the relative numbers of the two species trapped. If this second call type is attributable exclusively to Swinhoe’s Snipe, it would appear that Swinhoe’s Snipe calls more reluctantly than Pintail Snipe. Given the difficulties of field identification, more research is needed to establish whether these two call types are diagnostic. It should be stressed that these calls, although different from the calls of Common Snipe, are sufficiently similar to each other to confuse observers unfamiliar with the calls of Swinhoe’s or Pintail Snipes. Even to experienced ears, some poorly heard calls can be confusingly ambiguous.

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So, after this exhaustive study of Pintail and Swinhoe’s Snipes by Carey and Leader, what are we left with?

Suggestive of Swinhoe’s

• Short toe projection beyond tail in flight (but how short is short?)
• Less rounded, more angular head, with eye set rear of centre on the head
• Legs thicker than those of Common
• White tips to central tail feathers
• Barred or chequered outer tail feathers
• Flat, low call lacking nasal, slurred or throaty qualities

Diagnostic of Swinhoe’s

• Outer tail feather shape

So, is that it?

Almost certainly not. Positively, the Leader and Carey study focused mainly on birds in the hand. There may yet be field characters, such as aspects of jizz, which are apparent in birds in the field and visible in photographs, which were not picked up by the Hong Kong study.

Negatively, views of the outer tail feathers in the field, even on high quality photographs, do not usually present the shape and number of outer tail feathers with the same clarity as on a bird in the hand.

More on the tail

Pintail Snipe, Penang, 13 Mar 2014

Pintail Snipe, Penang, 13 Mar 2014

Two photos of the tail of the same Pintail Snipe showing white tips to all tail feathers, including the centrals. However, the white tips to the central tail feathers are very narrow (and possibly exaggerated due to the photo being slightly overexposed). It may be that broad white tips to the central tail feathers are indeed indicative of Swinhoe’s (see below)

The pattern on the outer tail feathers of both species may be related to gender. Ayuwat has a great post here, in which he states that males have more solidly black (white-tipped) outer feathers  than females. The photo of the female Swinhoe’s in his post (on the left) shows the barred/chequered pattern mentioned by Leader and Carey.

However, the chances of seeing the outer tail feathers of any snipe in the field well enough to see their colour and shape are slim and require both perseverance and luck. A snipe is most likely to fan its tail momentarily when preening, stretching, landing, sunbathing or adopting an alarm/threat posture. Even then, the tail may not be fully spread, and more often than not, the outermost tail feathers remain tucked out of sight. So, can anything useful be gleaned from the rest of the tail?

Initial perusal of the tail photos accompanying the Leader and Carey paper suggests that, while Swinhoe’s tail feathers become progressively narrower from the central to the outer tail feathers (see this example), Pintail has very broad centrals and then very narrow outers, with no intermediate-width feathers between (see this photo). However, even this difference doesn’t seem to be consistent! This photo of a Pintail Snipe tail shows one feather of intermediate width between the broad centrals and pin-like outers, as does this one. So real care needs to be taken when evaluating the width of feathers between the centrals and the outers. Are there enough intermediate-width feathers visible to support identification as Swinhoe’s?

For example, in this photo, it’s impossible to see how narrow or broad the outer tail feathers are, and only one intermediate-width feather is visible between the outers and the centrals. I would say that id is unproven on this view.

Only one outer tail feather is visible, and again, it’s hard to be certain of its width, though it does not look pin-like. Only one intermediate-width feather is visible, so again, I would say that identification is not certain in this view.

Swinhoe’s Snipe, Penang, 16 Feb 2014

Finally I can see two intermediate-width feathers, the first narrower than the centrals and the outer of the two narrower again. On this view I can be certain that this is a Swinhoe’s. Incidentally, the central tail feathers do seem to be clearly tipped white.

Pintail or Swinhoe’s Snipe, Penang, 13 Mar 2014

Pintail or Swinhoe’s Snipe, Penang, 14 Feb 2014

A couple of flight shots which show the tail partially spread, but not enough, in my view, to enable identification.

Swinhoe’s Snipe, Penang, 10 Feb 2014

This one, on the other hand, spread the tail wide enough for the full tail to be seen. The width of the outers, and the gradation between outer and central feathers show that this is a Swinhoe’s.

Pintail Snipe, Penang, 27 Feb 2014. (c) Neoh Hor Kee

This Pintail shows a single intermediate-width feather between the broad centrals and pin-like, slightly club-ended outers. But there is a second (white-tipped) feather between this and the broad, chestnut central feathers. It’s impossible to say how wide it is, but it does not look like a typical broad central feather. These feathers and the outers look as if they are new and still growing.

Pintail or Swinhoe’s Snipe, Penang, 3 Mar 2014

This bird shows a single intermediate-width tail feather. My guess would be that this is a Pintail, but without a clear view of the feathers outside this one, it’s hard to be certain.

Pintail Snipe, Penang, Feb 2014. (c) Neoh Hor Kee

This is an interesting tail shot. At first sight it appears to show two intermediate-width feathers. However, on closer inspection, I believe the outermost white-tipped feather is actually the innermost of the pinlike outer tail feathers (the same feather as that shown two photos up). Pintail Snipe outer tail feathers are slightly club-shaped, whereas Swinhoe’s are tapered. This feather, I believe, shows the clubbed shape of a typical Pintail Snipe.

Pintail Snipe, Penang, 13 Mar 2014

Occasionally, the pins of a Pintail Snipe may be visible even when the tail is fully closed.

Swinhoe’s Snipe, Penang, 10 Feb 2014

The even gradation from wide to narrow is visible on this Swinhoe’s tail spread.

Against the sky, it sometimes possible to see the width of the outer tail feathers. See this photo of a displaying Swinhoe’s Snipe (a vagrant in Finland!).

Pintail Snipe, northern Thailand, 2 Dec 2008

Swinhoe’s Snipe, Penang, 13 Mar 2010

However, the width of the outer tail feathers  is not always easily discernible in the field, or even on good photos, as the angle of the bird to the viewer can distort apparent feather width.

Hard isn’t it?

What about toe projection in flight?

The Finland Swinhoe’s Snipe showed almost no toe projection.

Swinhoe’s Snipe, Penang, 13 Mar 2010

Swinhoe’s Snipe, Penang, 13 Mar 2010

This Swinhoe’s Snipe (positively identified while on the ground), similarly showed a relatively short toe projection. However, I’ve found it hard to find a “Swintail” Snipe  in flight on the web with a markedly different toe projection from this. The longest I could find was this one, but the difference, if there is one, is in millimeters!

What about jizz?

Swinhoe’s Snipe, Penang, 10 Feb 2014

Pintail Snipe, Penang, 13 Mar 2014

These are all snipes of known identity (I photographed the outer tail feathers).

Swinhoe’s Snipe, Penang, 10 Feb 2014

Swinhoe’s Snipe, Penang, 10 Feb 2014

Pintail Snipe, Penang, 13 Mar 2014

There does seem to be something different about the head and eye position, along the lines of Leader and Carey’s findings. This Swinhoe’s seems larger-headed and thicker necked and the eye seems to be set higher in the head than the Pintail. The Swinhoe’s also seems much deeper-chested.

Swinhoe’s Snipe, Penang, 16 Feb 2014

Pintail Snipe, Penang, 13 Mar 2014

Pintail looks better-proportioned and more delicate.

The problem is that these are ‘reverse engineered’ distinguishing features after having seen the outer tail feathers. I doubt I would be confident enough to certainly identify these using jizz alone.

Lateral crown stripes – a possible plumage feature?

I’m grateful to Danny Rogers for bringing my attention to the possibility that Swinhoe’s may have darker lateral crown stripes, less densely flecked with brown marks than Pintail. The difference is relatively clear between individuals trapped in Australia – Pintail here and Swinhoe’s here and here.

Swinhoe’s Snipe, Penang, 16 Feb 2014

Pintail Snipe, Penang, 13 Mar 2014

Encouragingly, the difference also seems to hold good on these two birds of known identity here in Penang. This is certainly a feature worth checking further.

Lastly, habitat

In the years since I have been studying snipes, the only Swintail Snipes I have definitely identified in wet paddyfields have been Swinhoe’s. Conversely, when I have found Swintail Snipes in drier habitats such as cow pasture, the ones that have showed me their tails have invariably turned out to be Pintail. I have also photographed Pintail Snipes in canalized streams and ditches, where they seem equally at home foraging in running water and on the dry sandy banks and grassy tops of bunds. Swinhoe’s on the other hand are more likely to be found in standing freshwater and muddy substrate, often sharing the habitat with Common Snipes.

This leads me to a hypothesis that Swinhoe’s prefer wetter habitat than Pintail. A perusal of the photos in this post bear this out. I should add that I doubt the habitat preference is strong enough for it to constitute an identification feature.

Well, this is certainly not the last word on snipe identification, but I hope it serves as a useful collection of hard facts and unproven hypotheses. There’s still lots to learn!