Ivory gull

Pagophila eburnea

(Photo from Wikipedia)

Common name:
ivory gull (en); gaivota-marfim (pt); mouette blanche (fr); gaviota marfileña (es); elfenbeinmöwe (de)

Taxonomy:
Order Charadriiformes
Family Laridae

Range:
This species has a circumpolar distribution in the high-Arctic, being found as far south as the Bearing Strait, Alaska and northern Canada, northern Iceland, northern Scandinavia and northern Russia.

Size:
These birds are 40-48 cm long and have a wingspan of 105-120 cm. They weigh 450-700 g.

Habitat:
They breed in rocky islands or on the mainland, in steep and inaccessible cliffs near pack ice, on broken ice-fields or on bare, level shorelines with low rocks. Outside the breeding season they are found along the edges of pack ice or near drift ice.

Diet:
They feed on fish, shrimps, shellfish, algae, carrion such as seal placentas, offal and animal faeces. In winter they are known to swallow large pieces of frozen food.

Breeding:
Ivory gulls breed in June-August. They form small colonies of 5-150 pairs, each nesting in a mound of mosses, dry grass, driftwood, feathers, down, stalks, algae, seaweeds, lichen and dried mud. The nests are placed on cliff ledges, dry stony ridges within a few meters of the ice cap, gently-sloping boulder-strewn mounds, or gravel banks in small streams. The female lay 1-3 dark olive to pale brown eggs with dark spots and blotches, which are incubated by both parents for 24-26 days. The chicks fledge 4-7 weeks after hatching. They reach sexual maturity at 2 years of age.

Conservation:
IUCN status - NT (Near-Threatened)
This species has a large breeding range and a global population estimated at 12.000-18.000 individuals. Population trends are difficult to estimate as colony size fluctuates from year to year, but sustained declines of up to 80% in the last 3 decades have been recorded in Canada. The declining are believed to be due to changes in conditions on its staging or wintering grounds, such as more severe winters and changing sea-ice distribution and thickness, as well as illegal hunting, oiling at sea, disturbance of colonies due to escalating diamond exploration, increased nest predation, and toxic pollutants, such as mercury, PCB and DDT, that bioaccumulate at high trophic levels.

California gull

Larus californicus

(Photo from Les Animaux du Monde)

Common name:
California gull (en); gaivota-da-Califórnia (pt); goéland de Californie (fr); gaviota californiana (es); Kaliforniermöwe (de)

Taxonomy:
Order Charadriiformes
Family Laridae

Range:
This species breeds inland, from central Canada, in Alberta, Saskatchewan and the southern parts of the Northwest Territories, and through North Dakota, Wyoming and Idaho into Washington, Oregon, California and western Nevada, in the United States. With the exception of some resident populations in Washington, the California gull winters along the Pacific coast of North America from southern British Columbia, Canada, to Colima, Mexico.

Size:
These birds are 45-54 cm long and have a wingspan of 122-140 cm. They weigh 430-1.050 g.

Habitat:
The California gull breeds on rocky islands in freshwater and hypersaline inland lakes and rivers, as well as in marshes. Outside the breeding season they also use coastal waters, sandy beaches, estuaries, mudflats, pastures, agricultural fields and garbage dumps. they are present from sea level up to an altitude of 2.800 m.

Diet:
They have a very varied diet, including fish, insects, earthworms, small mammals such as gophers and mice, birds, aquatic invertebrates, grain, fruits and garbage.

Breeding:
California gulls breed in April-July. They nest in colonies and the pairs are monogamous. The nest is a scrape in sand or dirt, sometimes lined with vegetation, feathers and bones, where the female lays 2-5 buff to greenish eggs with dark spots, speckles and blotches. The eggs are incubated by both parents for 23-27 days. The chicks may leave the nest after a few days but remain in the immediate area. they are fed by both parents and fledge 47-54 days after hatching. They reach sexual maturity at 4 years of age.

Conservation:
IUCN status - LC (Least Concern)
This species has a large breeding range and the global population is estimated at 0,5-1 million individuals. The population is believed to be increasing.

Red-legged kittiwake

Rissa brevirostris

Photo by Doug Sonerholm (Flickr)

Common name:
red-legged kittiwake (en); gaivota-tridáctila-do-Pacífico (pt); mouette des brumes (fr); gaivota piquicorta (es); klippenmöwe (de)

Taxonomy:
Order Charadriiformes
Family Laridae

Range:
This species is found in the northern Pacific ocean, with breeding colonies around the Bearing sea, in the Pribilof, Bogoslof, Budir and Aleutians islands of the United States, and in the Commander islands of Russia. They wander in the Pacific between parallels 35º and 62º N.

Size:
This small gull is 35-40 cm long and has a wingspan of 84-92 cm. They weigh 325-510 g.

Habitat:
The red-legged kittiwake is a pelagic predator, foraging in the open ocean and breeding in vertical sea cliffs and rocky offshore islands.

Diet:
They feed on small fishes, namely lampfish and pollack, as well as squids, small crustaceans such as amphipods and carrion.

Breeding:
Red-legged kittiwakes breed in April-September. They breed in colonies, nesting in a shallow cup of mud, grass and kelp placed on a ledge in a vertical cliff. The female lays 1-2
grey to buff or greenish eggs with brown blotches, which are incubated by both parents for 23-32 days. The chicks are fed by both parents and fledge 38-48 days after hatching.

Conservation:
IUCN status - VU (Vulnerable)
This species has a relatively large breeding range and a global population estimated at 337.000-377.000 individuals. From the 1970s to the 1990s the population declined by 35 %, a trend which as since stabilized for a total decline of 30-50% over the last 4 decades. The reasons for the population decline remain unclear, but it has been attributed to a reduction in food supply resulting from excessive commercial fishing. Shifts in the distribution of prey fish species, resulting from climate change and rising sea temperatures, may also contribute to current and future declines, while climate change may also have a direct impact on this species which as a breeding range restricted to within 10º latitude from the polar edge. There may also be some impact of subsistence hunting in some islands. If rats reach the islands where they breed they could pose a further threat, so a rat prevention programme is underway in the Pribilof Islands

Black-tailed gull

Larus crassirostris

Photo by Tom Edelsten (Birds Korea)

Common name:
black-tailed gull (en); gaivota-do-Japão (pt); goéland à queue noire (fr); gaviota japonesa (es); Japanmöwe (de)

Taxonomy:
Order Charadriiformes
Family Laridae

Range:
This species breeds in northern Japan, extreme south-eastern Russia, Korea and north-eastern China. Some population migrate south to winter along the coasts of Japan and the East China Sea down to Hong Kong.

Size:
These birds are 46-48 cm long and have a wingspan of 118-124 cm. They weigh 440-640 g.

Habitat:
The black-tailed gull is found breeding in rocky offshore islands, sea cliffs and rocky shorelines, foraging on a variety of coastal habitats including rocky and sandy intertidal areas, tidal pools, kelp beds, seagrass beds, reefs, estuaries and also on the open sea.

Diet:
They feed on fishes, especially sand lance and Japanese anchovy, molluscs, polychaetes, crustaceans, insects and also carrion and human waste. They often follow fishing vessels in search of food and also steal food from other seabirds.

Breeding:
Black-tailed gulls breed in May-July. They form large breeding colonies and nest on sandy areas, or among rocks, in a shallow scrape that is usually lined with dry grasses. There the female lays 2-3 eggs, which are incubated for 24-27 days. The chicks fledge 35-40 days after hatching.

Conservation:
IUCN status - LC (Least Concern)
This species has a relatively large breeding range and the global population is estimated at 1,1 million individuals. The current population trend is unknown, but is suspected to be stable in the absence of evidence for any declines or substantial threats.

Franklin's gull

Larus pipixcan

Photo by Alan Vernon (Wikipedia)

Common name:
Franklin's gull (en); gaivota-de-Franklin (pt); mouette de Franklin (fr); gaviota de Franklin (es); präriemöwe (de)


Taxonomy:
Order Charadriiformes
Family Laridae


Range:
This species breeds in central North America, mostly in Alberta, Saskatchewan and Manitoba, Canada; and in Montana, North Dakota and South Dakota, United States. They migrate south to winter along the Pacific coast of South America, from Ecuador to Chile and further inland in northern Argentina.


Size:
These birds are 32-38 cm long and have a wingspan of 85-95 cm. They weigh 220-335 g.


Habitat:
The Franklin's gull breeds in marshes and inland lakes with emergent vegetation. Outside the breeding season they are found in coastal areas, lakes, marshes, cultivated fields and rubbish dumps.


Diet:
During the breeding season they mostly eat earthworms, chironomids and other aquatic insects, grasshoppers and sometimes also rodents and seeds. Outside the breeding season their diet includes a larger portion of fish, but also insects and other invertebrates, seeds and often also offal and refuse.


Breeding:
Franklin's gulls breed in May-August. They are highly gregarious, forming colonies of hundreads to over 10.000 pairs. The nest is a floating platform of vegetation, placed in thick reeds above water. The female lays 2-4 creamy-white, yellowish or greenish eggs with dark brown spots. The eggs are incubated by both parents for 23-26 days. The chicks are semi-precocial, but remain in the nest for around 3 weeks and receive food from both parents until fledging, 31-35 days after hatching.


Conservation:
IUCN status - LC (Least Concern)
This species has a very large breeding range and the global population is estimated at 470.000-1.500.000 individuals. The population has undergone a small increase over the last 4 decades.

Yellow-legged gull

Larus michahellis

Common name:

yellow-legged gull (en); gaivota-de-patas-amarelas (pt); goéland leucophée (fr); gaviota patiamarilla (es); mittelmeermöwe (de)

Taxonomy:

Order Charadriiformes

Family Laridae

Range:

This species is found throughout the Mediterranean and Black Sea, along the western coast of Iberia up to the Gulf of Biscay and in the Atlantic archipelagos of Madeira, Azores and Canary islands.

Size:

The yellow-legged gull is 52-68 cm long and has a wingspan of 120-155 cm. They weigh 800-1.500 g.

Habitat:

This species breeds in large colonies of thousands birds on coastal cliffs and rocky islands, but also inland, including urban areas. It also nests on rocky or sandy islands, beaches, and grassy islets with bushes on streams. Outside the breeding area they are mostly found in coastal areas, often following fishing boat, inside harbours and urban areas, but also along rivers and in agricultural fields.

Diet:

The yellow-legged gull feeds primarily on fish and crustaceans, and destroys the clutches of terns, petrels and shelducks. It also frequents rubbish dumps and consumes various other invertebrates, small mammals, molluscs and lizards.

Breeding:

These birds start breeding in March-April. They form large colonies, nesting on the ground, on and between rocks, on sand or pebbles. The nest is a cup-shaped scrape, lined with grass, twigs, algae and debris. There the female lays 2-3 eggs which are incubated for 26-31 days. The semi-precocial chicks are fed by both parents in and around the nest and fledge 40-48 days after hatching.

Conservation:

IUCN status - LC (Least concern)

This species has a very large breeding range. The global population size is unknown owing to recent taxonomic splits, but is estimated to be well above 200.000 individuals. Although this species is affected by factors like oil pollution, long-lining, habitat destruction and disturbance from tourism at breeding sites, the overall population trend is increasing and the species is even considered a pest in some areas.

Silver gull

Larus novaehollandiae

Photo by J.J. Harrison (Wikipedia)

Common name:

silver gull (en); gaivota-prateada (pt); mouette argentée (fr); gaviota plateada (es); silberkopfmöwe (de)

Taxonomy:

Order Charadriiformes

Family Laridae

Range:

The silver gull is found throughout Australia and tasmania, not only in coastal areas, but also inland. they are also present in New Zealand and New Caledonia.

Size:

This medium-sized gull is 40-45 cm long and has a wingspan of 91-96 cm. They weigh up to 350 g.

Habitat:

The silver gull is found at virtually any watered habitat, both coastal, insular and inland, but it is rarely seen far from land. They have also adapted well to urban environments and thrive around shopping centres and garbage dumps.

Diet:

Originally these birds would mostly feed on fish, plankton, worms, insects and crustaceans. However, they are now mostly scavengers of human garbage.

Breeding:

Silver gulls breed in August-December. The nest is built by both parents, a simple cup on the ground made of seaweed, roots and pant stems. Nests may be found in low scrubs, rocks and jetties. Each clutch consists of 1-3 pale eggs blotched with black and brown. The eggs are incubated by both parents for 21-27 days. The chicks are fed by both parents and become independent at 6 weeks of age. This species produces two clutches per season.

Conservation:

IUCN status - LC (Least Concern)

This species has a population of 100.000-1.000.000 individuals and a very large breeding range. The overall population trend is increasing, although some populations have unknown trends.