birding-aus
Hi,
David Eades, Jeff Davies and I tried to nut out the snipe ID problem when
working on volume 3 of HANZAB (field ID, plates and the plumage sections
respectively). We made a bit of progress, but like everyone else found it an
awfully difficult problem. Fuller details are in HANZAB, but here some brief
thoughts on the characters mentioned in HANZAB which I found most helpful
when I got to see reasonable numbers of Swinhoe's Snipe in north-west
Australia last year.
Rear end structure is well worth examining when trying to distinguish
Lathams and Swinhoes. In the hand the number and pattern of the outer tail
feathers is diagnostic but I have never succeeded in seeing this adequately
in the field. There are some other features to look for though. Lathams is a
large, long-winged and long-tailed snipe. This shows up pretty well if you
see the bird standing from side-on: the whole rear-end looks elongate and
smoothly attenuated with the tail projecting well beyond the tip of the
folded wing, and generally with virtually no 'step' in the outline of the
bird between the vent and the under-tail coverts, which appear to merge
together. Swinhoe's Snipe is a bit smaller and looks more stumpy at the
back (though less stumpy than Pin-tailed Snipe): although the tail projects
beyond the wings (as it does in Lathams) both the wings and tail are
proportionately shorter and the bird does not look so elongated; they
usually show a 'step' in their outline between the vent and undertail coverts.
In flight, the toes of Latham's Snipe do not trail beyond the tail (except
very briefly during the take-off jump when the legs are extended to
full-stretch). The toes of Swinhoes trail just beyond the tail-tip, with the
distal two or so joints showing. This is shown very nicely in Jeff Davies'
HANZAB plate, and quite well in Simpson and Day; the snipe plates in Pizzey
and Knight get toe-trailing (and pretty much every other feature) completely
wrong. Toe-trailing might sound an easy difference to work with - but it
isn't. It can be extremely difficult to assess in the field; you really need
repeated views of flushed/flying birds in which you have focussed on seeing
this character before you can be sure that you have interpreted it properly.
Awkward though this feature is to use, I know of anything better in flight.
The notion (mentioned by Chris Corben) that Swinhoes looks a bit smaller and
rounder-winged than Lathams certainly seems consistent with my experience,
but it is quite hard to judge objectively in the field. Calls might be worth
playing with - arguably a bit higher pitched, less raspy and briefer in
Swinhoes? - but could well vary with the circumstances in which birds are
flushed and heard.
HANZAB describes a number of other plumage characters which differ on
average between the two species, but there is almost always some overlap (in
general snipe plumage colours fade quite a bit with wear, which doesn't
help). Of these, I am keenest on face pattern (perhaps as it is quite an
easy feature to memorise); the eyestripe and cheek-bar of Swinhoes Snipe are
generally a bit broader and less broken than in Lathams, with the lower
margin of the loral stripe typically reaching to the gape (it runs just
above the gape in most Lathams). We didn't notice Chris Corben's lateral
uppertail covert character when preparing HANZAB - which doesn't mean that
it doesn't work.
There is still heaps to learn about snipe ID in Australia. It would be worth
the effort, as there is a great Latham's Snipe mystery to be solved: what is
their northwards migration route? From about late March to mid-May no-one
really knows where they occur; hardly any have been found outside their
breeding areas (northern Japan, Sakhalin, and adjacent Ussuriland) and their
non-breeding grounds (mainly south-eastern Australia). South-east Australian
birds put on some weight before they migrate, but flight range equations
suggest this is only enough to fuel migration to northern Australia or New
Guinea. There must be an undiscovered staging area/areas. One hunch (which I
like myself) is that they fuel up in flooded northern Australian woodlands
at the end of the wet season, and then fly directly to Japan in one flight -
one of the longest direct flights made by any wader, and certainly the
longest made by any species of snipe. Stephen Garnett has reported
intriguing sightings from Cape York Peninsula that support this theory, but
there are still many thousands of migrating Lathams Snipe to account for. To
add to the fun of snipe watching in north Queensland: a year or two ago,
Bill Cooper found a dead snipe on a barbed wire fence on the Atherton
Tablelands (where he has seen quite a few living snipes). It turned out to
be a Swinhoes, well south of their usually accepted range.
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