How to identify the Dunlin

To correctly identify the Dunlin (Calidris alpina), check each of these features. Birds can be tricky: habit, habitat, and call often confirm a sighting that a single photo cannot.

Size at a glance

Length

16-22 cm (6.3-8.7 in)

Wingspan

32-39 cm (12.6-15.4 in)

Weight

30-80 g (1.1-2.8 oz)

Physical features to check

1. 1

   Plumage

   Overall feather coloration and pattern.

   Breeding plumage features a rufous back with black streaking, a white belly with a prominent black patch, and a white supercilium. Non-breeding plumage is duller, grayish-brown above, white below, with faint streaking on the breast. Juveniles resemble non-breeding adults but have more distinct streaking on the flanks and breast, and often a reddish wash on the back.

2. 2

   Beak shape

   Shape and color of the bill: a key field mark.

   Medium-length, slender, and slightly downcurved black bill.

3. 3

   Eye color

   Iris color and any distinctive eye markings.

   Dark brown

4. 4

   Leg color

   Leg and foot color.

   Black

5. 5

   Distinguishing features

   Standout features that separate this species.

   The slightly downcurved bill is a key feature in all plumages. The black belly patch in breeding adults is diagnostic. In non-breeding plumage, its overall grayish tone and bill shape help distinguish it from other small sandpipers.

6. 6

   Juvenile appearance

   How young birds differ from adults.

   Juveniles have a scaly-patterned rufous-brown back, a buffy wash on the breast with fine streaking, and often a faint blackish belly patch that is less defined than in adults. Their upperparts are often brighter and more patterned than non-breeding adults.

7. 7

   Seasonal changes

   Plumage variation between breeding and non-breeding seasons.

   Dramatic change between breeding and non-breeding plumages. Breeding plumage (late spring to late summer) is characterized by the rufous back and black belly patch. Non-breeding plumage (late summer to early spring) is a drabber gray-brown above and white below, lacking the distinctive black belly.

8. 8

   Sexual dimorphism

   How males and females differ.

   Males and females are generally similar in plumage, though females tend to be slightly larger and have a slightly longer bill on average. The black belly patch in breeding plumage can be slightly larger in females.

Key field marks

• Bill Shape. Look for the medium-length, slender bill that is distinctly, though subtly, downcurved at the tip. This is a consistent feature across all ages and plumages.
• Black Belly Patch (Breeding Plumage). In late spring and summer, the prominent black patch on the lower belly is unmistakable and diagnostic for adult Dunlins.
• Plumage Coloration. Breeding adults have a rich rufous back with black streaking. Non-breeding adults are uniformly grayish-brown above and white below, with faint streaking on the breast. Juveniles have a scaly back and often a buffy breast.
• Leg Color. Always black legs and feet.
• Behavior. Observe their feeding behavior – they often probe deeply into mud. Also, note their tendency to form large, cohesive flocks, especially during migration and winter.
• Call. Listen for the distinctive, reedy, slightly descending 'kreep' call, often given in flight.

Explore the Dunlin