Black-legged Kittiwake

Informazioni

The Black-legged Kittiwake is a medium-sized gull, primarily pelagic outside the breeding season, known for its distinctive short, black legs and relatively small, unmarked yellow bill. It is a highly colonial breeder, forming dense colonies on steep coastal cliffs.

Dimensioni e longevità

Lunghezza

37-41 cm

Apertura alare

91-105 cm

Peso

300-525 g

Longevità

Up to 20 years in the wild, typically 10-15 years

Dieta

Carnivore (primarily piscivorous)

Caratteristiche fisiche

Piumaggio

Adult breeding plumage features a white head, neck, and underparts, with a grey mantle and upperwings. The wingtips are solid black, lacking the white 'mirrors' found in many other gulls. The tail is white and slightly forked. Non-breeding adults have a dusky grey smudge behind the eye and on the nape.

Forma del becco

Relatively small, unmarked yellow bill, slightly decurved at the tip.

Colore degli occhi

Dark brown eyes, surrounded by a thin red orbital ring in breeding adults.

Colore delle zampe

Short, black legs and feet. The hind toe is vestigial or absent, giving rise to the 'tridactyla' (three-toed) name.

Caratteristiche distintive

Solid black wingtips without white mirrors, short black legs, and a plain yellow bill are key identifiers. The slightly forked tail is also characteristic.

Aspetto giovanile

Juveniles have a distinctive 'W' pattern across their upperwings formed by black primary tips and a black bar on the secondary coverts. They also have a black hind-neck collar, a black bar on the tail, and a dark bill. Their legs are blackish-grey.

Cambiamenti stagionali

Adults in non-breeding plumage develop a dusky grey smudge behind the eye and on the nape, and the red orbital ring becomes less prominent or absent. The bill remains yellow.

Dimorfismo sessuale

Males and females are morphologically similar in plumage and size.

Come identificare

1. 1

   Wingtips

   Look for solid black wingtips without any white 'mirrors' or spots. This is a key distinguishing feature from most other gulls.

2. 2

   Legs

   Observe the legs; they are short and black. The lack of a prominent hind toe is also characteristic, though difficult to see in the field.

3. 3

   Bill

   Note the plain, unmarked yellow bill, which is relatively small and slightly decurved.

4. 4

   Tail

   The tail is white and slightly forked, especially noticeable in flight.

5. 5

   Juvenile Plumage

   In juveniles, look for the distinctive black 'W' pattern across the upperwings, a black hind-neck collar, and a black tail band.

6. 6

   Vocalization

   Listen for the characteristic 'kitti-waak' call, especially near breeding colonies.

Habitat e areale

Biomi

Marine, coastal, pelagic

Areale geografico

Circumpolar in the Northern Hemisphere. Breeds on coasts of the North Atlantic and North Pacific, including Greenland, Iceland, Svalbard, northern Europe, Siberia, Alaska, and Canada. Winters widely across the North Atlantic and North Pacific, often far offshore.

Fascia altitudinale

Sea level to coastal cliff tops (up to several hundred meters for nesting sites).

Ambienti preferiti

Steep coastal cliffs, sea stacks, and offshore islands for breeding. Pelagic waters, often over continental shelves, during the non-breeding season.

Comportamento

Periodo di attività

Diurnal, though they may feed at night during periods of high prey availability or under moonlight.

Abitudini alimentari

Primarily surface feeders, snatching small fish (e.g., sandeels, capelin, herring, cod fry) and marine invertebrates (e.g., crustaceans, squid) from the water's surface. They often feed in large flocks, sometimes associated with cetaceans or fishing vessels. They do not typically plunge-dive from great heights like terns, but may make shallow dives.

Comportamento sociale

Highly colonial breeders, forming dense, noisy colonies on cliffs. Outside the breeding season, they are gregarious, often found in large flocks at sea.

Tipo di volo

Graceful and buoyant flight, often with shallow wingbeats. They are highly adapted to oceanic conditions, capable of sustained flight over open water.

Migrazione

Migratory. After breeding, they disperse widely across the North Atlantic and North Pacific, spending the non-breeding season far out at sea, often hundreds of kilometers from land. Return to breeding colonies in early spring.

Territorialità

Highly territorial within the breeding colony, defending a small nest site. Less territorial outside the breeding season.

Riproduzione

Stagione riproduttiva

Typically May to August, with peak egg-laying in late May to early June.

Abitudini di nidificazione

Nests are built on narrow ledges of steep coastal cliffs, often in very dense colonies. Nests are cup-shaped, constructed from mud, grass, seaweed, and guano, cemented together to form a sturdy structure that can withstand strong winds.

Dimensione della covata

1-3 eggs

Descrizione dell'uovo

Typically 1-3 eggs (most commonly 2), olive-buff to pale blue-green, variably marked with dark brown or black spots and blotches.

Periodo di incubazione

24-28 days, incubated by both parents.

Periodo di involo

35-49 days. Young remain at the nest site until they are capable of flight.

Cure parentali

Both parents share incubation duties and feed the chicks. Chicks are fed regurgitated fish and invertebrates.

Dove trovarlo

Consigli sul campo

1. Visit Breeding Colonies. The easiest way to see Black-legged Kittiwakes is to visit known breeding colonies during the summer months. They are very numerous and vocal at these sites.
2. Pelagic Trips. For observations during the non-breeding season, consider joining organized pelagic birding trips that venture far offshore into their oceanic wintering grounds.
3. Scan for Flocks. At sea, look for large flocks of birds feeding, often associated with schools of fish or marine mammals. Kittiwakes are often part of these mixed feeding frenzies.
4. Learn Calls. Familiarize yourself with their distinctive 'kitti-waak' call, which can help locate them, especially in noisy colonies.

Specie simili

Fatti rapidi

Distinctive Feature:

Solid black wingtips without white mirrors

Leg Color:

Black

Bill Color:

Plain yellow

Breeding Habitat:

Steep coastal cliffs

Wintering Habitat:

Open ocean (pelagic)

Conservation Status:

Vulnerable

Curiosità

• The name 'Kittiwake' is an onomatopoeic representation of its distinctive call, 'kitti-waak'.
• Unlike most gulls, Black-legged Kittiwakes rarely scavenge on land or visit urban areas, preferring a strictly marine diet and habitat.
• Their short legs and vestigial hind toe are adaptations for their cliff-nesting lifestyle, making them less agile on flat ground but well-suited for perching on narrow ledges.
• They are one of the most numerous seabirds in the North Atlantic, though populations have been declining in many areas, leading to their 'Vulnerable' status.
• Kittiwakes often nest in incredibly dense colonies, with nests sometimes just inches apart, creating a bustling and noisy environment.

Classificazione scientifica

Regno

Animalia

Phylum

Chordata

Classe

Aves

Ordine

Charadriiformes

Famiglia

Laridae

Genere

Rissa

Specie

Rissa tridactyla

Esplora Black-legged Kittiwake