Black Storm-Petrel

How to find it

The Puntarenas to Paquera ferry is an easy, short way to see sea birds. The crossing lasts about an hour, and the deepest water, about half an hour out, is where storm-petrels have been seen. Bring binoculars, as the birds can stay distant. From the point at Puntarenas, storm-petrels often feed where the inner Gulf of Nicoya meets the outer gulf, and Black Storm-Petrels have been seen there from shore. For open water, a boat trip off the central Pacific coast between Quepos and Jaco, organized by a local guide, produced five on a 10-hour outing.

How to recognise it

This is a small seabird, about 23 cm long, with a wingspan of 46 to 51 cm. Its wings are long and angular. Its tail is long and moderately forked.

In the Gulf of Nicoya, one local birder compares its size to a Black Tern. Small birds flying low over the water at Puntarenas can look like Black Terns from a distance, but some turn out to be storm-petrels, so check them carefully.

Range-wide, it looks very much like Markham's Storm-Petrel in shape and size. The pale bar on the upperwing is the main difference: in the Black Storm-Petrel it stops before the wing's leading edge, while in Markham's it reaches it.

Behaviour and diet

It spends the day at sea and returns to its breeding colony only after dark. It usually forages alone, and feeds mostly on small planktonic crustaceans, especially spiny lobster larvae. It also takes small fish.

On a Pacific day trip off Costa Rica, Black Storm-Petrels flew low over the waves and were the most common storm-petrel of the day. On the Puntarenas to Paquera ferry, a few were seen zipping over the waves fairly close, alongside Wedge-rumped Storm-Petrels.

Where it lives

Away from its breeding islands, this is a bird of the open ocean, and it comes ashore only to breed. It breeds on islands off southern California, Baja California and the Gulf of California, not in Costa Rica.

Outside the breeding season it ranges over eastern Pacific coastal waters, from central California south to northern Peru, and that range includes Costa Rica's Pacific waters. In Costa Rica a photo was taken off Puntarenas, and a boat trip between Quepos and Jaco, more than 25 miles offshore, also found it.

When to see it

A study of seabirds off Costa Rica's Pacific coast says its authors saw this storm-petrel nearly all year. Single boat reports exist from September 2014 and November 2010.

Similar birds

In the Gulf of Nicoya the two likeliest storm-petrels are Black and Least. Least is smaller than the terns and flies with quick, snappy wingbeats. Markham's Storm-Petrel is the close lookalike range-wide, separated by how far the pale upperwing bar reaches.

Names and lore in Costa Rica

The Costa Rican official bird list gives the Spanish name as Paiño Negro. Elsewhere in its range it is also logged as Paiño Oscuro and Paíño de Patas Largas.

Status and conservation

The official Costa Rican bird list gives it the status M, a migrant, and range-wide it is common, with millions of pairs, and not considered threatened.

Photography tips

Birds on the ferry can stay distant, so binoculars help more than a short lens. Morning and late afternoon light at the Puntarenas point suits scanning, and the birds fly low over the waves.