The Western Sandpiper is one of the most abundant shorebirds in Oregon, particularly along the coast in estuaries and on beaches during migration. It's one of the "peep" sandpipers, generally slightly larger than a Least Sandpiper but smaller than a Dunlin.

Overall Characteristics of Western Sandpipers:
Size & Shape: A small, portly shorebird, typically 5.5-6.7 inches long. It has a relatively long, thin bill with a distinctive feature: a **slightly curved or decurved tip**, often described as having a "pinched" look just before a slightly broader "blob" at the end. Their legs are **black**. They have long, pointed wings that extend beyond the tail.
Habitat in Oregon: Most abundant along coastal mudflats and sandy beaches, foraging at the edge of the receding or advancing tide. They are also found inland at suitable wetlands.
Behavior: They walk slowly, pecking or probing in the mud and sand for tiny invertebrate prey. Often seen in large, coordinated flocks, especially during migration, performing impressive aerial maneuvers.

Plumage - Similar for Male and Female, but varies by age/season:
1. Breeding (Alternate) Plumage (seen in Oregon during spring migration, less commonly by late summer):
Upperparts: Rich rufous-chestnut on the back, scapulars (shoulder feathers), and often extending to the cheeks and crown. The scapulars have dark centers with rufous-chestnut edges, creating a "scaly" or "spangled" pattern.
Underparts: White, with extensive dark, arrow-shaped streaks or chevrons on the throat, breast, and flanks.
Head: Rufous crown and ear patch are often prominent.

2. Non-breeding (Basic) Plumage (most commonly seen in Oregon from late fall through spring):
Overall: Much duller, appearing pale gray above and whitish below. The rufous tones are lost.
Upperparts: Pale gray with darker feather shafts.
Underparts: Clean white, with little to no streaking on the breast or flanks.

3. Juvenile Plumage (most commonly seen in Oregon during fall migration, August-October):
Overall: Fresh and neat appearance, similar to non-breeding adults but with more vivid coloration on the upperparts.
Upperparts: Black-centered feathers with crisp, broad edges of gold or rufous, giving a strong "scaly" or "spangled" look. The rufous is particularly noticeable on the scapulars (shoulder feathers).
Underparts: Clean white with faint or no streaking on the breast.
Bill: May appear less strongly decurved than adult bills initially.

Distinguishing Male from Female:
While male and female Western Sandpipers share very similar plumage patterns, there are **subtle but often discernible differences in size and, more reliably, bill length**:
Females are generally **slightly larger** than males.
Females typically have noticeably longer bills than males, and their bills tend to be more distinctly decurved at the tip. This is often the most useful field mark for differentiating the sexes.

In the field in Oregon:
When observing Western Sandpipers, especially in flocks, you might notice a range of bill lengths. Birds with very long, distinctly decurved bills are almost certainly females. Birds with shorter, straighter bills are more likely to be males.
This distinction is most helpful when you can compare multiple individuals side-by-side. Individual variation means that a single bird's bill length alone might not be definitively diagnostic without comparison.
Their black legs are a key feature to distinguish them from Least Sandpipers (which have yellowish-green legs) in all plumages.