Birds of Tristan da Cunha
Tristan da Cunha and Gough Island are home to several bird species that are found nowhere else, and are the main breeding sites for many other species. This stamp series celebrates a selection of Tristan’s amazing birdlife.
1p Atlantic Petrel
The Atlantic Petrel, Pterodroma incerta, is a large gadfly petrel that only breeds at the Tristan islands. As one of only three winter-breeding petrels on Tristan, large numbers were harvested for food in the 18th and early 19th centuries. As a result, most of the population of close to two million birds breeds on Gough Island, where they are threatened by predation by introduced House Mice. As a result, the species is listed as Endangered. At sea, Atlantic Petrels disperse widely throughout the temperate and sub-Antarctic waters of the South Atlantic, with most heading west towards South America rather than east towards Africa. They lay a single egg in a deep burrow in the ground, and only return to the islands at night to reduce the risk of predation by Brown Skuas.
5p Gough Finch
The Gough Finch, Rowettia goughensis, was once known as the Gough Bunting, but it is the largest member of the tanager-finch family from South America. As its name suggests, it is only found on Gough Island, where it is the only songbird. In the absence of a thrush, the Gough Finch has evolved a longer bill than the finches of the Tristan archipelago, and has a more catholic diet. The juveniles appear very different from the adult illustrated in the stamp, and were initially described as a second species. Pairs are quite territorial, and typically lay two eggs in a cup nest during spring. Once common throughout the island, they are now largely confined to coastal cliffs and the highlands, seemingly due to depredation by introduced House Mice. With a total population of only one to two thousand birds, the species is listed as Critically Endangered.
10p Gough Moorhen
The Gough Moorhen, Gallinula comeri, is a flightless species, closely related to the Common Moorhen. A similar flightless form on the main island of Tristan, G. nesiotis, went extinct in the late 19th century. Genetic evidence suggests that both evolved from vagrants from Africa rather than Asia, which makes them the only land birds to have colonised from the east. It was common on Gough in areas below 450 m, where the vegetation provides sufficient cover to protect them from Brown Skuas. However, most of the population was killed during the attempt to eradicate introduced House Mice from Gough Island in 2021. Fortunately, a handful of Gough Moorhens were introduced to Tristan in 1956, and the species is now found throughout the island in areas of fernbush vegetation. It is listed as Vulnerable to extinction.
45p Great Shearwater
The Great Shearwater, Ardenna gravis, is a large shearwater that is virtually confined as a breeding species to the Tristan islands; only a few tens of pairs breed in the Falklands. It is one of the most abundant breeding seabirds at Tristan, with several million pairs breeding at Inaccessible and Nightingale, and close to one million pairs at Gough. It presumably used to also breed at the main island of Tristan, but no longer does so. It is a trans-Equatorial migrant that arrives at the islands in September, lays eggs in November, and departs back to the North Atlantic in April. During the breeding season, adults forage throughout the South Atlantic, from Argentina to southern Africa. It is the only species on the stamp issue not listed as threatened or near-threatened globally.
55p Northern Rockhopper Penguin
The Northern Rockhopper Penguin, Eudyptes moseleyi, is the largest of the three species of rockhopper penguins, and is characterised by its luxuriant head tassels, extensive dark margins to the under flipper, and deeper call. As its name suggests, it breeds at more northerly locations than the other two rockhoppers, with over 95% of the population at the Tristan islands, and the remainder breeding on Amsterdam and St Paul islands in the central Indian Ocean. Its restricted range makes it one of the hardest penguins for people to see in the wild. It lays two eggs, but like all crested penguins, only raises at most one chick. The smaller, first-laid egg provides insurance in case the second-laid egg fails to hatch. Like all penguins, it is vulnerable to oil pollution, and many birds were killed after a bulk carrier ran aground on Nightingale Island in March 2011. Due to recent population decreases, it is listed as Endangered.
65p MacGillivray's Prion
The MacGillivray's Prion, Pachyptila macgillivrayi, is an enigmatic seabird known only from Gough Island and a tiny remnant population at St Paul Island in the central Indian Ocean. Its occurrence on Gough was overlooked for many years, because it closely resembles the Broad-billed Prion, that is abundant around the main landing sites on Gough. It was only in 2011, when researchers collected skulls of prions from across the island, that it was discovered that two species of prion breed in different areas of the island. MacGillivray’s Prion breed two months later than Broad-billed Prions, which helps to prevent hybridisation between the two species. Prior to the attempt to eradicate introduced House Mice from Gough Island in 2021, few if any chicks were raised by the prions. Immediately after the eradication, prion breeding success improved dramatically, but very sadly, a few mice survived, and their numbers soon recovered. The species is listed as Critically Endangered, although this would change should a second attempt to remove mice from Gough succeed.
95p Inaccessible Island Rail
The Inaccessible Island Rail, Laterallus rogersi, is the smallest flightless bird in the world. There were smaller flightless songbirds in New Zealand, but they all went extinct following the introduction of predators such as rats, mice, cats and stoats. As its name suggests, the Inaccessible Island Rail is only found on Inaccessible Island, where it is common throughout most of the island. However, it is more often heard than seen, as it remains in dense cover to avoid the unwanted attentions of Brown Skuas and Starchies. Pairs defend territories and lay two eggs in a well concealed nest in spring. The population is estimated at some 5,000 pairs, and there is no evidence that this has decreased in recent years, but the species is listed as Vulnerable to extinction because of the ongoing risk of an accidental introduction of rodents onto Inaccessible Island.
£1 Starchy (Tristan Thrush)
The Tristan Thrush or Starchy, Turdus eremita, is one of the more charismatic birds at Tristan. It is the only landbird that has survived on the main island of Tristan; both the native moorhen and finch went extinct after the island was colonised in the 19th century. Starchies occur on all islands in the northern archipelago, with different subspecies recognised from each of the three main islands in the group. However, they are much less common on Tristan than they are on the uninhabited islands, and a visitor to Tristan would be lucky to see one. They mainly occur on the lower slopes of the peak above 900 m, although some persist on the steep coastal cliffs and in the gulleys that cross the island ‘base’. The species is listed as near threatened globally.
£1.50 Spectacled Petrel (Ringeye)
The Spectacled Petrel or Ringeye, Procellaria conspicillata, is a large petrel that only breeds on the plateau of Inaccessible Island in the Tristan archipelago. It differs from the closely related White-chinned Petrel that breeds around the sub-Antarctic, by its distinctive white ‘spectacle’, blackish bill tip and lower-pitched calls. It breeds in summer in deep burrows, often with a muddy entrance moat. Non-breeding birds disperse throughout the temperate South Atlantic, with more heading west toward South America than east towards Africa. The species was on the brink of extinction in the early 20th century, but fortunately the introduced pigs on the island died out before they ate the last Spectacled Petrels. Since the 1930s, the petrel population has been increasing at around 7% per year, and there are currently more than 30,000 pairs. Despite this, the species remains listed as Vulnerable globally due to its restricted breeding range.
£2.50 Tristan Albatross
The Tristan Albatross, Diomedea dabbenena, is one of five distinct forms of the Wandering Albatross, renowned as the bird with the longest wingspan. Like other northern-breeding populations, the Tristan Albatross is slightly smaller and its plumage whitens more slowly than the ‘snowy’ Wandering Albatross. Tristan Albatrosses used to breed on the main island of Tristan, but were hunted to extinction there; currently almost all breed on Gough Island, with only a few pairs on Inaccessible Island. They lay a single egg in January, which hatches in March and the chicks fledge in November. The breeding season is so long that only a few pairs attempt to breed in the year following a successful breeding attempt. Because they breed through winter, when introduced House Mice are most desperate for food, many chicks are attacked and killed by mice. Fully grown birds are also at risk from being caught accidentally on fishing gear, and the species is listed as Critically Endangered.
£3 Wilkins' Finch
The Wilkins's Finch, Nesospiza wilkinsi, is confined to tiny Nightingale Island and is one of the naturally rarest birds in the world. It feeds on the fruit of the Island Tree Phylica arborea, and pairs defend breeding territories that contain at least some trees. A comprehensive survey estimated there were some 120 breeding pairs in 2017, but extensive storm damage to the woodlands north of the Ponds in 2019 reduced the number of pairs by roughly one third. As a result, the species was uplisted to Critically Endangered, but such events have occurred in the past, and the population probably fluctuates depending on the abundance and distribution of Island Trees. To help ensure the future of Wilkins’s Finch, Tristan’s conservation department is restoring Island Trees on the eastern lowlands of the island, where it was harvested historically for firewood.
£5 Atlantic Yellow-nosed Albatross
The Atlantic Yellow-nosed Albatross, Thalassarche chlororhynchos, only breeds at Tristan and Gough. At sea, it is largely confined to the South Atlantic Ocean and adjacent Indian Ocean, but a few individuals wander north of the Equator into the North Atlantic. It is one of the smallest albatrosses, and its agility in the air and on land allows it to breed among dense vegetation. Pairs build a cone-shaped nest from mud among fernbush and tussock grass up to 800 m elevation on Tristan, but only up to 450 m on Gough Island. The single egg is laid in September, chicks hatch in November-December and fledge in April. The relatively short breeding season allows pairs to breed each year. The population at Tristan was impacted by harvesting for food, but it has been protected since 1976. The main threat currently is from accidental capture on fishing gear at sea. Although this threat is now less severe, thanks to various measures introduced to reduce the risk of catching seabirds, the species remains listed as Endangered.
We acknowledge with thanks the help and assistance of Peter Ryan, University of Cape Town
High resolution images for this issue can be found below -
SetFirst Day Cover
