California Gull

How to find it

Treat any sighting as a lucky bonus, not a goal. Gull flocks along the Pacific coast are the sensible place to look, since the Costa Rican record came from a Pacific beach. Long coastlines, shrimp ponds and other gull spots get little birding coverage, so careful checks could turn up rarities. Check the birds one at a time rather than as a flock. Note the back colour first, since the darker grey is a useful clue. Then look for a red spot and a black mark on the bill, not a neat black ring. Pay special attention to young gulls.

How to recognise it

Adults are medium-sized gulls with a rounded head. Look for these marks:

- A grey back, a little darker than a Ring-billed or Herring Gull.

- A white body, yellow bill and yellow legs, though one source describes the legs as greenish.

- A black ring and a red spot near the bill tip.

- Dark eyes.

- In flight, black wingtips with large white spots.

Young birds look very different. They are dark brown at first, with a thinner bill that is sharply pink at the base. This matters here, because every first country record in Central America involved a young bird. Costa Rica's was a first-winter gull, and Panama's first was a second-winter bird.

What it sounds like

Recording: truthseqr, CC0 1.0, source, read 4 Nov 2026.

Behaviour and diet

These are habits of the species in general, not observations from Costa Rica. It eats insects, fish, and the eggs and young of other birds, especially ducklings. It feeds in flight, or picks food up while swimming, walking or wading. It also scavenges at garbage dumps, marinas and docks. On coasts it feeds on dead fish and garbage, so a gull working the tideline or a dock is behaving as the species normally does.

Where it lives

The species breeds on inland lakes and marshes in western North America. It nests in colonies, sometimes very large and mixed with Ring-billed Gulls, in a shallow scrape on the ground near a lake or marsh, often on an island. Most birds then move to the Pacific coast for the winter.

It normally winters along the Pacific coast from Canada to Nayarit, Mexico. It sometimes wanders beyond that range, with records as far south as Ecuador. In Costa Rica the first record came from the Pacific coast, on the beach at Tárcoles in Puntarenas.

When to see it

The first Costa Rican California Gull was recorded in March 2013, which is the only dated Costa Rican record we have.

Similar birds

This is a hard gull for beginners to pick out. It is bigger than a Ring-billed Gull and smaller than a Herring Gull, though sizes can overlap. Next to an adult Herring Gull it has a darker grey back, dark eyes and black and red marks on the bill tip. In a mixed flock its call is lower and rougher than a Ring-billed Gull's, and its bill shows a red spot and a black mark, not a neat black ring.

Names and lore in Costa Rica

The Spanish name on the official Costa Rican list is Gaviota Californiana. Some sources also write it as Gaviota de California.

Status and conservation

The official Costa Rican list, in its 2025-2026 edition, gives it status A, accidental: a rare vagrant, not a resident or endemic.

Photography tips

The record at Tárcoles was accepted with photos as evidence, so clear images of the back colour, bill marks and leg colour are what count. Photograph young birds too, as they are the likeliest to turn up.