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Falklands Conservation |
Outer Island 48.2 acres (43.2 acres Tussac)
Outer and Double Islands were purchased as nature reserves by Falklands Conservation in early 1998, largely with donations from members. On 30th October 1998 they were visited by Michael Morrison and Robin Woods as part of the second season's work on the Johnny Rook Survey. Robin Woods reports here on what they found.
Outer Island lies only 250m to the west of the westward-projecting reef of Double Island. It covers approximately 20ha and carried some taller and more dense tussac than Double Island. The tussac in the centre of the Island had been flattened and well-used by sea lions in many places, though only four young ones were seen on the eastern shore. An ancient cow's skull was found suggesting former usage for fattening beef (a common use of tussac islands in the past). Twenty four bird species were recorded here. In addition to those on Double Island, a single Gentoo Penguin was seen preening on the beach rocks, a colony of about 200 pairs of Rock Shags were discovered on the north-western cliffs, a Crested Caracara was heard calling at the southern point, and a Falkland Thrush singing on the east-facing slope.
These two Islands carry good stands of mature and in places, very dense tussac grass. Sea lions use both Islands, with apparently far more on Outer Island. Outer Island had a larger and less disturbed flora than Double Island. The endemic Falkland Cudweed was found growing here and ten of the 16 species identified were native plants. The extreme shortage of songbirds however, with no Black-throated Finches, Cobb's Wrens, Long-tailed Meadowlarks or Tussacbirds on either island was most noticeable. Unfortunately, both islands are heavily infested with rats. Many droppings were found beneath overhanging tussac skirts. The remains of a dead rat are now at the Natural History Museum, Tring, awaiting identification. Whilst Falklands Conservation as owners can protect these Islands from grazing by herbivores, their conservation status would be greatly enhanced if the rats could be eradicated. How we can undertake a project to do this is now being investigated.
The most striking feature about Outer island is the Tussac Grass, which is denser and taller than that found even on Kidney Island. On Kidney Island it is quite possible to walk through the Tussac (albeit with some difficulty), because the pedestals are sufficiently spaced to allow channels between them: this was not the case on Outer Island. The majority of Outer Island has Tussac Grass which is completely impenetrable, and therefore the only means of crossing such areas is to climb to the top of the pedestals, and jump from pedestal to pedestal. The height of the Tussac is approaching 3m in these areas. It has almost certainly never been stocked, and can therefore be considered pristine in terms of tussac. Blue Grass was common on the island.
The only areas where the Tussac Grass has been eroded are on the south-east corner of the island, where large numbers of Sea Lion have worn highways into the tussac from the shore. The value of the island in terms of its Sea Lion population is confirmed by the Falklands Conservation Sea Lion Survey of 1995, which showed that the island held over 1% of the Falkland's breeding population of Sea Lion.
Other species breeding on the island are: Rock Shag (140 nests), Flightless Steamer Duck, Crested Duck, Night Herons, Blackish Oystercatchers, Pied Oystercatchers, Turkey Vultures and Ground Tyrants. Also present were about 300 King Shags, about 40 Snowy Sheathbills and around 30 Johnny Rooks. A few of the Johnny Rooks were adults, and there is a possibility that one or two pairs may breed on the island.
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Patron: HRH The Duke of York CVO ADC Member of the International Union for Conservation of Nature | BirdLife International Representative |