Olrog's Gull
Larus atlanticus
Large, dark-backed gull with a broad black band on a white tail. Breeding adults have mostly clean white bodies with black backs and wings. In the nonbreeding season, adults have a black hood and a broken white eye-ring. Immatures are very distinctive, with mottled gray-brown backs and brown breasts and heads with a white patch around the bill. Usually seen on the immediate coast, where it mostly eats crabs. During the austral winter, some migrate farther north.
Identification
Olrog's gull is a large gull with a white head, neck, rump, breast, and belly. The back and wings are black except for a white trailing edge to the wings. The tail is white with a broad black band at the back. The beak is yellow with a black band and red tip. The eyes are brown with a red orbital ring and the legs and feet are dull yellow. The length of this gull is 50 to 60 cm (20 to 24 in) and it has a wingspan of 130 to 140 cm (51 to 55 in). Males are a little larger than females. Juveniles have black heads and brownish plumage.
Taxonomy
- Scientific name
- Larus atlanticus
- Authority
- Olrog, 1958
- Order
- Charadriiformes
- Family
- Laridae
- Genus
- Larus
Range and habitat
Olrog's gull is native to the Atlantic coast of Argentina, Uruguay, and southern Brazil. It breeds at a very limited number of colonies between 38.49° and 45.11°S, about two-thirds of which are in the estuary of the Bahia Blanca River. It nests on the ground just above high-water mark, on low islands and islets. At other times, it is to be seen on rocky coasts, harbours, beaches, coastal lagoons, brackish water, and estuaries.
- Breeding range
- SA : coastal s Buenos Aires and Chubut provinces (ne, ec Argentina)
- Non-breeding range
- some move to coasts of se Brazil
- Migration
- Complete migrants
Behavior
During the breeding season, Olrog's gull feeds largely on crabs, which are picked up from the exposed shore or the seabed while walking or swimming, or dipping under the surface of shallow water. This particular diet gives the gull its name in its native range: gaviota cangrejera, or crab-eater gull.<p>At other times of year, it supplements its crab diet with bivalve molluscs and polychaete worms. Other prey items include insects, gastropod molluscs, fish, and fish waste, and the birds sometimes visit sewage outlets and refuse dumps.<p>Breeding starts in September and October. Olrog's gull is monogamous and nests in dense colonies. The nest is on rock, sand, or shingle and is usually lined with vegetation, but sometimes with seaweed, feathers, shells or bones. Two or three olive-brown eggs with brown splotches are laid and the incubation period is about 30 days. Fledging takes place between November and January according to the location of the colony.
Conservation
- Population trend
- stable
Photos
Distribution
Bird Calls
Other Birds
Dark-throated Seedeater
Sporophila ruficollis
A small finchlike bird with a short and stubby bill. Males are a striking combination of gray, black and a rich cinnamon color. Males have a black breast and cheeks, a cinnamon belly, and a gray helmet that becomes brownish towards the back. Male “melanops” morphs have a black hood and are olive-brown above and pale below. Females are olive-brown above and buff below. Both sexes have a white wing spot that is not found in the “melanops” morph. Inhabits mature grasslands, usually near water, where it is often seen in flocks with others seedeaters during migration.
Red Kite
Milvus milvus
Distinctive large, graceful raptor with a fairly long, forked, rusty-orange tail. Flies with easy languid wingbeats and lazy glides, circling gracefully over fields and roadsides. Can be confused with Black Kite; note overall more reddish coloration, paler face, larger white patches on the underwings, and more deeply forked tail. Inhabits varied semiopen habitats, from woodland to farmland and moorland with hedges and wooded patches; locally in urban areas. Often scavenges with crows.
Long-tailed Meadowlark
Leistes loyca
Handsome and eye-catching bird that is fairly common in grassland, steppe, matorral, farmland, and even town parks with grassy areas. Feeds mainly on the ground, at times in small groups, but male sings from prominent perches and in flight. Male has a bright red breast, long pointed bill, and white eyebrow. Female has much less red below, but note size and shape, and pale eyebrow. No similar species in its Chilean range, but in Argentina compare with Pampas Meadowlark.
Start Your Bird Watching Journey
Identify a bird outdoors and keep the field guide close for your next observation.