Markham's Storm-Petrel

How to find it

Plan around a sea crossing, since it is almost never seen from shore. The organised expeditions from Puntarenas to Isla del Coco are where birders meet it. A paper on the island's seabirds lists it among storm-petrels and shearwaters that can be common along the ship route, either all year or in certain periods. Sea-based birdwatching in Costa Rica is recent, and pelagic outings also run from a few coastal boat guides, for example at Cabuya and Cabo Blanco, Bahía Herradura, and Drake and Isla del Caño. Watch for a dusky bird gliding a metre or more above the swell.

How to recognise it

Markham's is an all dusky storm-petrel, and its plumage runs from black to sooty brown. It is large and slender, with a wingspan of about 49 to 54 cm.

Look for these marks:

A pale diagonal bar across the upper wing, made by grayish brown coverts.

Pale bars that run almost to the carpal joint, the bend at the front of the wing.

Nearly black flight feathers.

A deeply forked tail.

Against the Black Storm-Petrel, the pale wing bands are bolder and the feet are smaller. The wings also look slightly shorter and broader, and the feet do not reach past the tail tip. An old note on the species points to a much shorter tarsus as the main difference.

Behaviour and diet

At sea it is usually seen alone or in small flocks, sometimes with other storm-petrel species. It is almost never seen from shore.

Its flight is leisurely, with shallow wingbeats and long glides, similar to Leach's Storm-Petrel. It typically flies more than a metre above the sea surface rather than skimming the waves.

Outside the breeding season, adults stay closer to the coast, while younger birds go farther out to sea.

Where it lives

This is an ocean bird of the Humboldt Current, and it prefers warm waters far offshore. In Costa Rica the place to look is the open Pacific, on the crossing to Isla del Coco.

Away from the breeding season it ranges over the eastern Pacific, reaching the coasts of southern Mexico. A genetic and distribution study puts the species mainly between 5 degrees north and about 30 degrees south, so Costa Rica lies north of its core band, which fits an edge-of-range visitor.

When to see it

No Costa Rican source gives months. Off South America it is in the cooler Peru Current from January to July, and from July to September it has been recorded in warm equatorial waters.

Similar birds

The Black Storm-Petrel is the main look-alike, and it is a migrant in Costa Rica too. Its pale wing bars are shorter, its wingbeats are deeper with less gliding, and its big feet often hang down. Markham's has bolder pale bands, shallower wingbeats and a more leisurely glide.

Names and lore in Costa Rica

Costa Rica's bird list uses the Spanish name Paiño de Markham. Other Spanish names for the species are golondrina de mar negra and paíño ahumado.

Status and conservation

The official Costa Rican list classes it as M, a migrant, and the IUCN rates the species Near Threatened.