Kelp Gull

How to find it

Check river mouths and estuaries on a coastal day, since the mainland bird was at a river mouth near Quepos. Scan flocks of smaller gulls for a larger bird standing out among them. Look at the legs first: yellowish green points to Kelp Gull. Then check that the back is deep black rather than slate. Harbours are also worth a look, as the species gathers there elsewhere in its range. Listen for the harsh two-part call.

How to recognise it

Adults are bold black-backed gulls. Look for these marks:

A strong yellow bill with a clear red spot on the lower mandible.

A deep black back and wings against a white head, neck and underparts.

A head that stays fully white all year.

Yellowish green legs, also described as greenish or grey.

Only a small white wing-tip window.

In size it sits between Lesser Black-backed and Great Black-backed Gulls, which it resembles. Young birds are grey-brown with pale edging, dull legs and a black bill. They quickly gain a pale bill base and a mostly white head and underparts, and take about three or four years to become adult. Beside smaller local gulls its bulk stands out: at Barra del Colorado, one was the largest gull in a group of four Laughing Gulls.

What it sounds like

Recording: Richard Littauer, CC BY 4.0, source, read 4 Nov 2026.

Behaviour and diet

Kelp Gull is an opportunist that eats almost anything, and it often gathers at harbours and rubbish dumps. It uses both marine and land food sources.

It is bold and dominant, especially where gulls feed and rest, and it can act aggressively toward other birds. It may be alone, in pairs or in flocks.

Where it lives

Across its range it is mainly a coastal gull, found on beaches, rocky shores and islands. It also uses estuaries and harbours.

In Costa Rica the records come from Isla del Coco in the Pacific, from a river mouth on the Pacific coast near Quepos, and from the Colorado River mouth at Barra del Colorado on the Caribbean side. Ten gull species have been recorded in the country, most of them sporadic vagrants along the coast, and Kelp Gull is one of these strays with no known resident population.

When to see it

The dated Costa Rican sightings are 8 January 2013, 16 December 2013 and 26 January 2014. All fall in December and January, but no season is established for the species.

Similar birds

Great Black-backed Gull has pink legs, while Kelp Gull has yellow-green legs. Lesser Black-backed Gull is smaller and slimmer, with a paler slate-grey back. Both are also accidental in Costa Rica, so check legs and back colour. In the Costa Rican paper, Lesser Black-backed was ruled out for one bird because it has pinkish to yellowish legs at that age.

Names and lore in Costa Rica

The official Costa Rican Spanish name is Gaviota Cocinera. The first record notice also lists Gaviota Dominicana, a name that refers to the Dominican Order of friars, whose habits were black and white like the adult gull.

Status and conservation

The official list of the birds of Costa Rica marks Kelp Gull as status A, accidental, a very rare visitor.