Come identificare Common Tern

Per identificare correttamente Common Tern (Sterna hirundo), controlla ciascuna di queste caratteristiche. Gli uccelli possono essere complicati da riconoscere, perché comportamento, habitat e canto spesso confermano ciò che una sola foto non può.

Dimensioni a colpo d'occhio

Lunghezza

31-35 cm (including tail streamers)

Apertura alare

72-82 cm

Peso

90-170 g

Caratteristiche fisiche da controllare

1. 1

   Piumaggio

   Colorazione e disegno generale del piumaggio.

   Adult breeding plumage features a black cap, white underparts, and pale grey upperparts. The primary flight feathers have dark tips, forming a dark trailing edge to the wing. Non-breeding adults have a reduced black cap, often streaked with white, and a dark carpal bar on the underwing. Juveniles are mottled brown and grey on the back, with a dark carpal bar and a less defined black cap.

2. 2

   Forma del becco

   Forma e colore del becco, un segno di campo chiave.

   Slender, pointed bill. In breeding adults, it is bright red with a black tip. In non-breeding adults and juveniles, it is typically black or dark red with a black tip.

3. 3

   Colore degli occhi

   Colore dell'iride e segni distintivi sugli occhi.

   Dark brown

4. 4

   Colore delle zampe

   Colore di zampe e piedi.

   Bright red in breeding adults, duller red or blackish in non-breeding adults and juveniles.

5. 5

   Caratteristiche distintive

   Tratti distintivi che separano questa specie.

   Long, deeply forked tail streamers (especially in breeding plumage), slender body, buoyant flight, and characteristic plunge-diving. The red bill with a black tip in breeding adults is a key feature.

6. 6

   Aspetto giovanile

   Come i giovani si differenziano dagli adulti.

   Juveniles have a scaly, mottled brown and grey back, a dark carpal bar on the upperwing, and a less extensive black cap that is often streaked with white. Their bill is dark, and legs are duller.

7. 7

   Cambiamenti stagionali

   Variazione del piumaggio tra stagione riproduttiva e non.

   Breeding adults develop a full black cap, bright red bill with a black tip, and bright red legs. Non-breeding adults lose the full black cap, which becomes streaked with white, the bill darkens (often entirely black or dark red with a black tip), and legs become duller red or blackish. The dark carpal bar on the underwing becomes more prominent in non-breeding plumage.

8. 8

   Dimorfismo sessuale

   Differenze tra maschi e femmine.

   Males and females are generally monomorphic in plumage, though males may be slightly larger on average. No obvious visual differences in the field.

Segni di campo chiave

• Size and Shape. Medium-sized tern, slender body, long pointed wings, and a deeply forked tail with long streamers, especially in breeding plumage.
• Plumage (Breeding Adult). Look for the solid black cap, white underparts, pale grey back, and the bright red bill with a distinct black tip. The dark trailing edge on the primaries is also a good indicator.
• Plumage (Non-breeding Adult/Juvenile). Note the streaky black and white cap, darker bill (often all black or dark red with black tip), and duller legs. Juveniles have a mottled brown back and a prominent dark carpal bar on the upperwing.
• Bill and Leg Color. The red bill with a black tip and red legs in breeding adults are key. Arctic Terns have an all-red bill, and Roseate Terns have a mostly black bill.
• Flight Style. Observe its graceful, buoyant flight, often hovering before plunge-diving for fish. This behavior is characteristic of many terns but helps distinguish them from gulls.
• Vocalizations. Listen for the sharp, screaming 'kee-arr' or 'kier-ick' call, which is a reliable identification cue, especially in colonies.

Esplora Common Tern