Ascension Island, 07° 56’ S 14° 22’ W
What can you do in 18 hours on Ascension Island? This question was on my mind at dawn as we approached the east end of Ascension. Arrival here was like a homecoming. For 18 months, between October 2001 and March 2003, I called Ascension Island home while employed as Conservation Officer. Little did I think at that stage that I would re-visit the island with the Endeavour.
The familiar dramatic volcanic landscape gradually emerged out of the gloom as the sun came up and illuminated lava flows and towering cliffs and birds – thousands of them. Ascension is the most important location for breeding seabirds in the tropical Atlantic. This importance remains despite the depredations of rats and cats, introduced accidentally and deliberately by humans. Once home to millions of seabirds, as evidenced by the guano deposits of the deserted ‘ghost colonies,’ today the populations number about 200,000 pairs of eleven species, confined mostly to predator-free offshore stacks.
Our first stop was at the most important of these stacks – the guano covered edifice of Boatswainbird Island, named for the tropicbirds that inhabit the 100 metre high cliffs, whose piercing calls reminded early mariners of a bosun’s whistle. A pre-breakfast Zodiac cruise below this seabird city offered great views of the multitude of seabirds that inhabits this refuge. Separated from the mainland by a mere 400 metres of sea, Boatswainbird Island has never been reached by the introduced rats and cats that arrived with humans on Ascension. Today, it is the only place in the world where the Ascension frigatebird breeds – the entire world population crammed into the limited space on the plateau of the island. Clouds of frigatebirds soared overhead, together with three species of booby, two species of noddy, tropicbirds sporting elongated central tail feathers and elegant fairy terns.
On arrival on the Pierhead at Georgetown we were greeted by my former colleagues, who were to act as our guides for the day (one of my roles in my previous existence here). First of many stops on our tour of the island was at the Wideawake Fairs. Wideawake is the local name for the sooty tern (pictured) – an onomatopoeic rendition of their trisyllabic call. With a population of about 130,000 pairs this season, these seabirds have managed to survive on the mainland despite the predation by cats for two reasons. During their unusual 38 week breeding cycle there is a post-breeding period when they are absent from the island while they moult and regain condition. In this 10 week period, cat numbers cannot be sustained and decline. Then, when the birds do return to the island, they swamp their predators by sheer weight of numbers.
Ascension Island has recently been the subject of an ambitious seabird restoration programme. With the eradication of feral cats, it is hoped that seabirds will recolonize their former mainland colonies. In addition, those birds already breeding on the mainland such as the wideawakes, will benefit from not losing thousands of adult and chicks to cat predation each season. The early results are very encouraging - to date about 80 pairs of five species of seabird have recolonized the mainland!
In the evening, many of us returned to shore to witness the spectacle of green turtles breeding on the white sand of Long Beach, but that is another story. The experience of 18 hours cannot compare with 18 months, but can be filled with extraordinary riches.
What can you do in 18 hours on Ascension Island? This question was on my mind at dawn as we approached the east end of Ascension. Arrival here was like a homecoming. For 18 months, between October 2001 and March 2003, I called Ascension Island home while employed as Conservation Officer. Little did I think at that stage that I would re-visit the island with the Endeavour.
The familiar dramatic volcanic landscape gradually emerged out of the gloom as the sun came up and illuminated lava flows and towering cliffs and birds – thousands of them. Ascension is the most important location for breeding seabirds in the tropical Atlantic. This importance remains despite the depredations of rats and cats, introduced accidentally and deliberately by humans. Once home to millions of seabirds, as evidenced by the guano deposits of the deserted ‘ghost colonies,’ today the populations number about 200,000 pairs of eleven species, confined mostly to predator-free offshore stacks.
Our first stop was at the most important of these stacks – the guano covered edifice of Boatswainbird Island, named for the tropicbirds that inhabit the 100 metre high cliffs, whose piercing calls reminded early mariners of a bosun’s whistle. A pre-breakfast Zodiac cruise below this seabird city offered great views of the multitude of seabirds that inhabits this refuge. Separated from the mainland by a mere 400 metres of sea, Boatswainbird Island has never been reached by the introduced rats and cats that arrived with humans on Ascension. Today, it is the only place in the world where the Ascension frigatebird breeds – the entire world population crammed into the limited space on the plateau of the island. Clouds of frigatebirds soared overhead, together with three species of booby, two species of noddy, tropicbirds sporting elongated central tail feathers and elegant fairy terns.
On arrival on the Pierhead at Georgetown we were greeted by my former colleagues, who were to act as our guides for the day (one of my roles in my previous existence here). First of many stops on our tour of the island was at the Wideawake Fairs. Wideawake is the local name for the sooty tern (pictured) – an onomatopoeic rendition of their trisyllabic call. With a population of about 130,000 pairs this season, these seabirds have managed to survive on the mainland despite the predation by cats for two reasons. During their unusual 38 week breeding cycle there is a post-breeding period when they are absent from the island while they moult and regain condition. In this 10 week period, cat numbers cannot be sustained and decline. Then, when the birds do return to the island, they swamp their predators by sheer weight of numbers.
Ascension Island has recently been the subject of an ambitious seabird restoration programme. With the eradication of feral cats, it is hoped that seabirds will recolonize their former mainland colonies. In addition, those birds already breeding on the mainland such as the wideawakes, will benefit from not losing thousands of adult and chicks to cat predation each season. The early results are very encouraging - to date about 80 pairs of five species of seabird have recolonized the mainland!
In the evening, many of us returned to shore to witness the spectacle of green turtles breeding on the white sand of Long Beach, but that is another story. The experience of 18 hours cannot compare with 18 months, but can be filled with extraordinary riches.
