Monday, January 31, 2011

ID Feature - Pectoral Sandpipers

Pectoral Sandpipers at Lake McLarty.

For our first 'real' post, we thought we'd start with an ID feature from one of the easier bird groups - the waders! Pectoral Sandpipers are being reported more frequently than ever before in the south-west and this summer in particular has seen 'Pecs' turning up at an almost unprecedented number of wetlands.

The primary ID pitfall for Pectoral Sandpiper is Sharp-tailed Sandpiper, which is very similar in appearance. Moreover, in the south-west, Pectoral Sandpipers are typically found in small numbers within Sharp-tailed Sandpiper flocks, which often means some searching is required to locate the Pectorals. However, this also means that it is usually possible to compare the two species side-by-side if you do find a Pec, which can be useful.

In the south-west, any freshwater site where Sharp-tailed Sandpipers occur is a chance for Pectoral Sandpiper, and they are occasionally reported on the Peel Inlet. The best site is Lake McLarty near Pinjarra. When the water level at Lake McLarty is good for waders (typically December-January, but varies with rainfall), there are usually several Pectoral Sandpipers present, although locating them in the flocks of 'Sharpies' (which regularly number in the thousands) can be a challenge. Other sites that can be good for Pectoral Sandpipers with the right water level include Forrestdale Lake and Thomsons Lake.

Key Features
Bill
The Pectoral Sandpiper's bill has a distinctly different shape compared to a Sharp-tailed Sandpiper's, which with practice can provide an excellent indication of Pectoral Sandpiper, even with relatively brief views. The bill of a Pectoral is typically noticeably longer and gives the impression of a drooped tip. Pectorals also have a more extensive pale base to the bill, whereas Sharp-tails have a small pale base.

Two close-up headshots of a Pectoral Sandpiper (left) with two similar headshots of Sharp-tailed Sandpipers, illustrating the longer bill of the Pectoral, and its more extensive pale base. All photos from Forrestdale Lake.

Head
Generally, Pectoral Sandpipers have a less contrastingly marked head, as a result of a less distinct pale supercilium (eyebrow), especially behind the eye, and a less obvious cap. Pecs also lack rufous colouration in the cap, which is usually (but not always) evident on Sharp-tailed Sandpipers.

Two Pectoral Sandpipers (left & centre) with a Sharp-tailed Sandpiper at Kogolup Swamp, showing the less capped appearance and less distinct supercilium of the Pectorals. Also note the extension of the supercilium of the Sharp-tailed into a distinct white 'blaze' behind the eye.

Breast
Pectoral Sandpipers have dark, heavily streaked breastplates, sharply demarcated from their white belly and this is often the feature most emphasized for separating the species from Sharp-tailed Sandpiper, which typically has a less prominent breastplate. The Pectoral's breastplate also meets at a point in the centre, although this feature is not always conspicuous. Pectoral Sandpipers are typically described as having cleaner white underparts below the breast cut-off compared to Sharp-taileds; however this is not always reliable. Obvious dark chevron markings on the flanks (retained from breeding plumage), however, are a good indicator of Sharp-tailed Sandpiper.

Pectoral Sandpiper with Sharp-tailed Sandpipers at Forrestdale Lake, showing the darker, more heavily streaked breastplate of the Pectoral.

Jizz
The Pectoral Sandpiper 'jizz' is not unique, but can be helpful in locating them in large flocks of Sharpies. In particular, their noticeably longer neck combined with their smaller, rounder, higher-crowned head often gives them a 'crane-like' jizz when alert to an approaching birder.

A relatively dark Pectoral Sandpiper at Quindalup Lagoon (Dunsborough), showing the typical 'crane-like' jizz created by the long, thin neck and small, ball-like head.

Finally, a note of caution. There is often significant individual variation shown by both Pectoral and Sharp-tailed Sandpipers so, as always, it's best to use a combination of features to clinch an ID, rather than relying solely on any single feature. The relative darkness, streaking, and sharp cut-off of a Pectoral Sandpiper's breastplate is close to diagnostic (cf. Sharp-tailed Sandpiper), but beware Sharpies with relatively dark breastplates - see http://www.feathersandphotos.com.au/forum/showthread.php?1339-It-s-the-wader-game!&highlight=wader for an example of a Sharp-tailed Sandpiper with a relatively dark breastplate, but note that while dark, the breastplate is not as cleanly cut off as a Pectoral's and lacks the distinctive streaking. Additionally, note the bill shape, which is also strongly indicative of Sharp-tailed Sandpiper. Below is an example of a Pectoral Sandpiper with a relatively subdued pale bill base (likely at least partially an artefact of the light), but note the dark, streaked breastplate and other features which confirm that it is a Pec.

Pectoral Sandpiper with a (apparently) relatively dark bill base at Thomsons Lake.

Further Reading
Hayman P., Marchant J. & Prater T. (1986) Shorebirds: An identification guide to the waders of the world. Houghton Mifflin Company, Boston. (see pages 200-201 & 375-377)

O'Brien M., Crossley R. & Karlson K. (2006) The Shorebird Guide. Houghton Mifflin Company, Boston. (see pages 169-172 & 416-417)

Van Duivendijk N. (2010) Advanced Bird ID Guide: The Western Palearctic. New Holland Publishers, London. (see page 103).

Pectoral Sandpiper at Nambeelup

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