The Pectoral Sandpiper is a medium-sized shorebird, larger than the "peeps" like Least Sandpipers but typically smaller than a Dunlin. In Oregon, they are primarily seen as migrants, with the largest numbers occurring during fall migration (July-October), especially juveniles. They are often found in wet grassy areas, edges of marshes, and wet pastures rather than open mudflats, where they forage by peering over vegetation.

Overall Characteristics of Pectoral Sandpipers:
Size & Shape: Stout, medium-sized shorebird with a somewhat "chunky" or "top-heavy" appearance due to their broad breast. They have a moderately long, fairly thick-based bill that is often slightly decurved (drooping) at the tip, and often has a paler base. Their legs are yellowish, pale yellow-green, or sometimes pale orange. Their wings are long and extend beyond the tail when at rest.
Distinctive Breast Pattern: This is their most notable feature. They have a heavily streaked brown breast that forms a very sharp, distinct line, often V-shaped, where it abruptly meets the clean white belly. This contrast is a key identification mark.
Flight: In flight, they show very little to no wing stripe. The tail is brownish with white on the sides, bisected by a dark central line on the rump.
Voice: A low, raspy, often described as a "churrt" or "jrrff" call.

Plumage - Similar for Male and Female, but varies by age/season:
1. Breeding (Alternate) Plumage (less commonly seen in Oregon, primarily during spring migration):
Upperparts: Mottled with rich brown, gold, and black, often with a somewhat scaly or spangled appearance due to pale feather edges.
Underparts: White belly, with the striking, heavily streaked brown breast that forms a sharp cutoff.
Head: Dark crown with a noticeable pale supercilium (eyebrow) above the eye.

2. Non-breeding (Basic) Plumage (seen during late fall migration and winter, though most move further south):
Overall: Duller and grayer-brown above compared to breeding plumage. The streaking on the breast is still prominent and sharply demarcated but may appear a bit more diffuse or less intense.
Upperparts: Grayish-brown with paler feather margins and dark centers.

3. Juvenile Plumage (most common in Oregon during fall migration, late July-October):
Overall: Very crisp and fresh-looking. Similar to breeding adults but with more distinct, neat, and often rufous or buffy-edged feathers on the back and wings, giving a strongly "scaly" or "spangled" appearance.
Breast: The breast streaking is often finely defined and forms a very sharp border with the white belly.
Back: Often shows two parallel "V" marks on the back created by the pale margins of their scapular feathers.

**Distinguishing Male from Female:**

While Pectoral Sandpipers are generally similar in plumage between sexes, there is a **noticeable size difference** that can sometimes be used for identification, especially when birds are seen together:

Males are generally **considerably larger and heavier** than females, sometimes up to 50% heavier and with wings about 10% longer.
This size difference is particularly exaggerated on the breeding grounds where males put on extra weight and have inflatable air sacs in their breasts (the "pectoral" reference) used for their elaborate courtship displays. While these sacs are not visible during migration in Oregon, the underlying size difference persists.

You'll primarily identify Pectoral Sandpipers by their distinctive heavily streaked breast with the sharp cutoff, yellowish legs, and somewhat decurved bill.
If you see a group of Pectoral Sandpipers, you might notice some individuals are distinctly larger than others – these larger birds are more likely to be males, and the smaller ones females. However, individual variation always exists, so this is a general guideline rather than a definitive rule for every single bird.