How to identify the Blue-gray Gnatcatcher

To correctly identify the Blue-gray Gnatcatcher (Polioptila caerulea), 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

10-13 cm (4-5 inches)

Wingspan

15-16 cm (6-6.5 inches)

Weight

5-7 g (0.18-0.25 oz)

Physical features to check

1. 1

   Plumage

   Overall feather coloration and pattern.

   Adults are primarily blue-gray on the upperparts, with white underparts. They have a prominent white eye-ring and a long, slender black tail edged with white. The wings are dusky with narrow white edgings on the flight feathers. The undertail coverts are white.

2. 2

   Beak shape

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

   Small, thin, and pointed, adapted for gleaning small insects. Color is black.

3. 3

   Eye color

   Iris color and any distinctive eye markings.

   Dark brown.

4. 4

   Leg color

   Leg and foot color.

   Dark gray to black.

5. 5

   Distinguishing features

   Standout features that separate this species.

   Its small size, constant flicking of its long, black-and-white tail, and distinctive white eye-ring are key features. The overall blue-gray and white coloration is also characteristic.

6. 6

   Juvenile appearance

   How young birds differ from adults.

   Juveniles resemble adult females but are duller, with a brownish-gray wash on the upperparts and a less distinct white eye-ring. Their tails may be shorter and less distinctly patterned.

7. 7

   Seasonal changes

   Plumage variation between breeding and non-breeding seasons.

   Males exhibit a more pronounced black headband during the breeding season (spring and early summer). Outside of the breeding season, this headband becomes less distinct or disappears, making them more similar to females.

8. 8

   Sexual dimorphism

   How males and females differ.

   Males in breeding plumage have a distinct black eyebrow or 'headband' that extends from the bill to just behind the eye. This headband is absent or very faint in females and non-breeding males. Females and non-breeding males have a less intense blue-gray coloration and a more prominent white eye-ring.

Key field marks

• Size and Shape. Look for a very small, slender bird with a relatively long tail that is often cocked or flicked.
• Coloration. Observe the overall blue-gray upperparts and clean white underparts. Note the dusky wings.
• Head Markings. Identify the distinct white eye-ring. In breeding males, look for the thin black 'headband' above the eye.
• Tail Pattern. Pay attention to the long, black tail with prominent white outer tail feathers, which are often fanned or flicked.
• Behavior. Watch for its hyperactive foraging style, constantly flitting through foliage and gleaning insects. The tail-flicking behavior is a strong clue.
• Vocalization. Listen for its distinctive, thin, reedy, and often buzzy 'pzzzz' call or its jumbled, high-pitched song.

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