Falkland Islands - Commemorative

NEW ISSUE - Release date - 8 July 2010

Petrels and Shearwaters

The oceans which surround the Falkland Islands are particularly rich in petrels and shearwaters (Procellaridae) which are among the most successful of all the world’s bird families. The word Procellaridae derives from the Latin word procella (violent wind) and idae (family). All 80 species in this family are adapted to fly in wind and tend to be more concentrated in the windier latitudes. This issue features the four largest Procellarids which are known to breed in the Islands.

Apart from the Giant Petrels, all Procellarids hunt exclusively in the open ocean, feeding on fish, squid and crustacae, with many species also taking fisheries discards and carrion. Most food is taken on the surface but the shearwaters, in particular, are also accomplished divers. All species are both long-distance foragers, and able to withstand periods without food. Many undertake long trans-equatorial migrations. All have a characteristic tubular nasal passage which is used for olfaction and helps to locate both patchily distributed prey at sea and also nesting colonies.

Procellarids tend to be colonial nesters, mostly breeding on remote predator-free islands. They are monogamous and form long-term pair bonds, returning to the same nesting site over many years. Many dig burrows in which a single and relatively large egg is laid in spring. Burrowing species mostly attend their nests nocturnally in order to reduce predation. Both parents participate in incubation and chick rearing. Incubation times and fledgling periods are long compared to other birds and once a chick has fledged there is no further parental care.

Sooty Shearwater Puffinus griseus

The smallest of the four featured species, the Sooty Shearwater is 40-46 cm long with a wingspan of around a metre. It has the typically "shearing" flight of the genus, dipping from side to side on stiff wings with few wing beats and wingtips almost touching the water. Using both wings and feet for propulsion, Puffinus griseus can dive to an astonishing depth of 67 metres in pursuit of fish and squid although more commonly they take surface food.

“Sooties” return from the northern hemisphere to traditional colonies in mid-September. They are known to breed on several smaller islands and at least at one mainland location on East Falkland. The total Falklands’ breeding population is estimated at 10,000-20,000 pairs.

At dusk large numbers assemble offshore in floating “rafts”, close to colonies. They arrive and depart the land nocturnally. A single white egg is laid within a burrow in October/November and incubated for 54 days. Raising the chick generally takes between 86 and 109 days. Colonies are deserted by early May.

Sooty Shearwaters also breed on islands around both Cape Horn and along Chile’s south-western seaboard. Elsewhere they breed in huge numbers on islands in southern Australasia where they are known as “mutton birds”. Their overall world population is estimated to be in the millions.

“Sooties” are spectacular long-distance migrants, following a circular route, travelling north up the western side of the Pacific and Atlantic Oceans at the end of the nesting season in March-May, reaching sub Arctic waters in June-July where they cross from west to east, then returning south down the eastern side of the oceans in September-October, reaching their breeding colonies by October/November. Falkland birds are known to fly as far north as Norway.

White-chinned Petrel   Procellaria a aequinoctialis

The White-chinned Petrel is a large and heavily-built shearwater-like species with a body length of 55cm and wings spanning almost 1.5 metres. In strong sunlight the plumage appears dark brown. Most birds have a small white patch beneath the bill. Flight is powerful and deliberate, with slow wing beats and frequent long glides. At sea it is easily confused with the larger Giant Petrel as well as the similar Westland and Black Petrels.

“Cobblers” are present in Falkland waters throughout the year and are known to breed in a couple of locations in the Islands, most notably on Kidney Island in the Berkeley Sound where there are an estimated 1000 pairs. They feed on squid, crustaceans and fish, taken either by shallow diving or from the surface and often scavenge around ships and follow trawlers. Adults return to the colonies in late September. Courtship is noisy and involves copious trilling. Their knicknames of “cobbler” and “shoemaker” derive from this noise which resembles that of rapid hammering. The single egg is laid in an often lengthy burrow, late in October. It takes nearly six months to complete the breeding cycle with the last chick vacating the colonies in late April. Young Falkland birds disperse rapidly northwards to southern Brazil, not returning to their colony to breed for 7-10 years. Their pelagic range is circumpolar in the Southern Oceans and extends from the subtropics in the north to the Antarctic pack-ice in the south.

South Georgia has the largest population of White-chinned Petrels with an estimated two million pairs. The total global population is estimated at around 7 million.

Southern Giant Petrel Macronectes giganteus

Whichever way you look at it, the Giant Petrel is an impressive creature. The size of a small albatross and by far the largest of all the petrels, its bulky, hump-backed body measures up to a metre in length and its wingspan is double that. “Stinkers”, as they are popularly known, can weigh as much as an oven-ready turkey.

Familiar in Falkland waters throughout the year; “Stinkers” are both scavengers and predators. They are equipped with a massive bill for tearing into flesh and will tackle anything from the hide of a stranded whale to tiny krill. They are the only Procellarid  to walk well on land and it is not unusual to find them onshore attacking cast sheep, moulting geese and fledgling penguins. They are long-lived and highly intelligent, and possess both a good memory and an acute sense of smell.

Loosely-knit breeding colonies are found on bare or grassy ground, often close to seal or penguin colonies. The breeding cycle takes 6 months to complete. The single, large egg is laid during October in a nest of stones and incubated for 7-8 weeks. Chicks are ready to leave the nest by late March.

After fledging, juvenile birds spend their first two or three years of life at sea on an extensive migration, during which they circumnavigate the Southern Ocean. Although this species may begin to breed at four years, most individuals do not begin until they are between six and ten years of age.

There are two colour forms of this species. The dark form is that featured in the illustration. The white form lives further south and is only occasionally seen in Falkland waters.

Greater Shearwater Puffinus gravis

Greater Shearwaters are one of the most common Atlantic seabirds with a body length of 50cm and a wingspan of over a metre.Their flight is powerful and direct with straight, stiff wings dipping from side to side almost touching the water. They feed on fish, squid, and crustaceans taken both from the surface and by making shallow dives.

Only a handful nest in a single location in the Falklands making them the least common of the local species featured in this issue. This is the only known breeding site outside of the Tristan da Cunha and Gough Island group where huge and tightly-knit subterranean colonies contain an estimated total of 6-9 million pairs.