Short-tailed Shearwater

How to find it

Any search happens at sea rather than from shore. A boat trip well off the Pacific coast is the only realistic way to look for it. Ecotourism pelagic trips are where its lookalike, the Sooty Shearwater, is increasingly recorded, so those are the outings where a dark shearwater might be studied. The Sooty occurs off the Pacific coast between May and October, which is a lookalike's season and not given for the Short-tailed. Look at the bill, head shape and forehead, and note the trailing grey feet and any white in the centre of the underwing. A clear photo matters here, because a photo is exactly what the missing voucher would need.

How to recognise it

These marks describe the species across its range, not Costa Rican birds specifically.

Adults are completely dark brown. The tail is rounded. In flight the dark grey feet trail a little behind the tail. The underwing sometimes shows a bit of white in the centre.

It looks much like the Sooty Shearwater and often cannot be told apart. Compared with Sooty, it tends to have a shorter bill, a rounder head and a steeper forehead. Both are medium-sized dark shearwaters with variable pale underwings, so the shape of the head and the manner of flight matter more than colour.

What it sounds like

Recording: Paul J. Morris, CC BY-SA 4.0, source, read 4 Nov 2026.

Behaviour and diet

It is sociable at sea, gregarious both over the ocean and at its nesting islands, so birds are often in groups rather than alone. It feeds mainly by diving underwater, down to about 70 m, after small fish, crustaceans and cephalopods.

In flight it moves in a more rapid, frantic, erratic way than the Sooty Shearwater, whose flight is smoother, more repetitive and direct. These habits are described for the species in general, not from Costa Rican observations.

Where it lives

Range wide, it lives in open ocean and coastal waters, not on land, except at its breeding islands. Those islands lie off southern and eastern Australia.

In Costa Rica, seabird work has mostly covered the coasts and Isla del Coco National Park, and records remain poorly studied. The single dated record comes from open Pacific water about 40 miles offshore, not from land or a named park.

When to see it

No Costa Rican source gives months for this shearwater, and the one dated record is from July 1978. Range wide, it spends the northern summer in the North Pacific, from about late April to mid September, then heads south from August on an eastern route.

Similar birds

The Sooty Shearwater (Pardela Sombría, a migrant) is the closest lookalike, and the two often cannot be told apart. Costa Rica's other dark shearwater on the official list is the Wedge-tailed Shearwater (Pardela Colicuña, also a migrant). The Short-tailed tends to show a shorter bill, a rounder head and a steeper forehead than Sooty, and a more frantic, erratic flight.

Names and lore in Costa Rica

The Spanish name on the Costa Rican list is Pardela Colicorta. Elsewhere the species is also called Pardela de Tasmania and Pardela de Pico Fino. In Australia, where it breeds, it is known as the muttonbird, and its chicks are licensed for harvest, but that is not a Costa Rican name.

Status and conservation

The official Costa Rican list marks it M?-SC, a probable migrant with no voucher, while its global status is Least Concern.

Photography tips

Photos are the point here, because a confirmed photo is what the missing voucher needs. From a boat, aim to capture the bill, head shape and forehead, the trailing dark grey feet and the underwing centre, since these are the marks that separate it from the Sooty Shearwater.