Hi Tweets,

Kelly McAllister writes:

>There were probably a dozen
>yellowlegs in the vicinity of the Willet.

In between the south- and northbound migrations, any yellowlegs in this area
of Cascadia, will *typically* be Greater Yellowlegs Tringa melanoleuca, with
Lesser Yellowlegs T. flavipes as a rarity, seemingly of gradually increasing
frequency, though whether this is due to an actual increase in the number of
birds wintering north or an increase in observer sophistication in
separating these two species is an open question.

(snip)
>I find the descriptions
>of calls in field guides worthless.

Hey, give the field guide writers a break: the guides aren't entirely
useless as they give pretty good renditions of the typical flight calls of
each species; they just don't necessarily give other calls: contact,
alert/alarm, courtship/territorial. If they did this for every species, as
well as all the non-definitive plumages, you'd have to remove the word
'field' from 'field guide' and subsitute 'wheelbarrow' or 'pack-mule'.

>The yellowleg's calls are generally
>described as a two note versus three note call and I stand out there in
>the mud and listen to series of 4 or 6 notes coming from the yellowlegs nearby
>and wonder what good the book could be to anyone (not to mention that you
>have to decide whether you are hearing a "whew whew whew" or a "yu yu").

Yep, have that trouble myself. Part of the trouble is that we're not
listening to flight calls as often as social contact calls, which are
slightly different in pitch and frequency of utterance. Secondly, I suspect
we're listening to subadult birds, not adults (I think the adults winter
further south), and their repertoire might be subtly different to the
adults. Third, I believe the field guides are depicting the calls given
primarily by migrants, not breeding birds up north or wintering birds in the
region.

Normally, the Greater has a deliberate, loud 'Teu-Teu-Teu!' pitching down as
the typical flight and alert call, whereas in the same context, Lesser gives
a higher-pitched abrupt 'tutu' or 'tututu' flight call more like a
Short-billed Dowitcher Limnodromus griseus than the Greater Yellowlegs. The
kicker is the Lesser's alert/alarm call, a one-syllabled 'Teu!' which is of
similar quality to the Greater's flight call. That's the confusing one,
watching a Lesser sound like a Greater.

>From another list, James Barton writes:

> Greater calls with a distinct cadence, dropping the pitch in the second
>half of the phrase--"TEW tew-tew, TEW tew-tew, TEW tew-tew." By my notation,
>I'm suggesting that " TEW" be regarded as analogous to a whole note and
>"tew-tew" to two half notes. (Sorry about that.) The dash is intended to
>suggest a shorter interval.
>
> Hower loudly it calls, Lesser, in my experience, calls on a single pitch
>lacking cadence, sometimes producing a surprisingly long burst of whole notes
>at equal intervals--"Tyuh Tyuh Tyuh Tyuh Tyuh Tyuh Tyuh."
>
> Pronounced dynamics strongly favor Greater, I suggest, while absence of
>dynamics strongly favors Lesser.

Jim McCoy writes:

>(1) The greater tends to have a very subtle upturn to its bill;

With the caveat that this might apply only to adult birds, and then it's
often not so subtle; juvenile/First Basic birds may not have developed a
fully definitive bill, nor the Greater its uptilt yet and, like the larger
loons, the two species may share characteristics. If you see the Greater's
bill in good light, you'll note that it's distinctly bi-colored: basal half
pale grey or slightly greenish--grey, distal half dark grey or
blackish-grey; Lesser's shows pale only at the very base.

>the lesser's is straight

And so are some Greater juveniles and subadults I've seen: I'm beginning to
think the godwit-like recurve is an age-related feature found mostly on
adult birds.

>and has a sturdier appearance.

Not so: a Lesser Yellowleg's bill has a *finer* structure, a 'needle' bill
compared to the Greater's more robust, deeper-based bill. An exemplary
Lesser Yellowlegs is on the cover photo of Dennis Paulson's book, Shorebirds
of the Pacific Northwest.

>(2) If the bill appears to be close to twice the length of the head,
>you're probably looking at a greater; if it's <= one and a half times
>the length of the head, it's probably a lesser.

Well, the actual proportions are somewhat different to these: to quote from
Shorebirds (Hayman et al) on the relative bill-lengths: "...Greater's is
roughly one-and-a-half times the distance from bill-base to nape, usually
faintly uptilted, often with greenish, greyish or yellowish basal third
(although it looks more like basal half on maxilla, basal two-thirds on
mandible in the accompanying illo--m); on Lesser, bill is shorter, just over
head-length, thinner and straighter, all-dark or with some brownish or
yellowish at the extreme base."

This time, the caveat is age- and sex-related: juvenile and First-Basic
birds-- especially males-- may not have yet grown the bill out to the
'textbook' length. This is an important consideration in that it may be the
youngest males which winter the furthest north (ie, here)--this is the case
in regionally-wintering Western Sandpipers Calidris mauri and likely the
same in Least Sandpiper C. minutilla--in which case you may have shorter
bill-lengths due to both age *and* sex. Secondly, some first-years Greaters
will have straighter bills, not having yet developed the uptilt. Referring
again to Dennis' book, see the comparative photograph of a juvenile of each
yellowlegs species on p. 152; note that the juv Greater shows *no* upturn.

So what plumage or other structural cues are there for separating First- and
Definitive Basic yellowlegs? Nearly all of the Basic yellowlegs I've seen
this time of year have been Greaters in flocks at Reifel, Iona and
Serpentine Fen, or foraging in the plowed fields of the aglands surrounding
Boundary Bay. They tend to be dark grey and heavily-streaked grey on the
upper breast with a line or two of coarse streaking or smudging along the
sides and flanks.

I'm not familiar with First- or Definitive Basic Lesser Yellowlegs, having
seen only one overwintering bird many years ago, but one feature in most
photographs or illustrations which *may* be useful for separation of Basic
birds is the area between the bill-base and the eye, which seems to be more
contrastingly patterned in Lesser. The Lesser seems to show a more distinct
white anterior supercilium made whiter by a distinct black loral stripe
connecting the bill and the eye: this area and the loral stripe seems to be
much more diffuse on the Greater Yellowlegs. Can anyone comment on this mark?

Another possible separating feature is the number of primaries visible
beyond the tertials in definitive plumages: typically, the more that are
visible, the longer-distance migrant the bird tends to be and the
longer-winged it is; as an example, look at the difference in primary
extension between Pacific Golden-Plover Pluvialis fulva and the much
further-travelling American Golden-Plover P. dominica. Generalising in the
absence of hard data is always iffy, but I'd bet that Lesser Yellowlegs in
any definitive plumage, since it migrates further, has a correspondingly
longer wing and shows more primary-tips beyond the tertials than Greater
Yellowlegs.

In his book (a must-have title for shorebirds of the Cascadian Region, in my
opinion) Dennis points out two other features: primary projection beyond the
tail tends to be noticeable in Lesser, barely present in Greater; the other
involves tarsus-to-bill ratio--Greater's bill-length is slightly shorter
than tarsal length where Lesser's typical bill length is 2/3 to 3/4 of
tarsal length. Close observation would tell if these ratios hold true for
First-Basic birds as for older.

Lastly, I'd suggest checking out every bird in a wintering
yellowlegs/dowitcher flock: it seems if we ever see Spotted Redshank T.
erythropus, this is the time of year for it.

Michael Price
Vancouver BC Canada
mprice at mindlink.net

"She's psychic....we've decided to find it charming."
--Frasier