Sea Lion Island is about 5 miles (8 km) from east to west and 1.2 miles (2 km) at its widest part. The island is a slightly inclined plateau with steep cliffs of about 30 m at the south-western point and long sandy bays to the east. Substantial parts of the coastline have dense Tussac, protected by fencing, while there is mature original Tussac at the eastern point. Red ash deposits visible below peat layers on the southern coast show that Tussac stands were burnt, probably in the 19th century. Habitat inland is largely open heath and grassland. The island was managed as a sheep farm from at least 1904 until about 1997 when it was cleared of all but a small flock of sheep. Western coasts show evidence of overgrazing and soil erosion. There are permanent ponds and boggy ground, which are attractive to a variety of waterbirds. The island was surveyed extensively in 1998 as part of the Ramsar designation process. Rum Islet, lying 0.6 miles (1 km) south of Sea Lion Island, is only about 750 m long. It is very low lying with a beach of large irregular boulders and rock slabs with considerable dead kelp, ideal for Cobb’s Wrens. The island is almost covered by Tussac up to 2 m tall, but it is easy to walk through because it has been opened up by Southern Sea Lions. Brandy Island is 1.2 miles (2 km) east of Sea Lion Island and is covered with tall, dense Tussac. Apart from sheer cliffs up to 15 m on the south-eastern coastline and shelf rocks at the southern point, the beach consists of large unstable boulders and it can be difficult to land. Whisky Island is only 400 m east of Brandy. It lies east to west with a boulder beach on the northern coast and extensive shelf rock below cliffs up to 15 m along the southern coast. Dense Tussac covers the ground above high water mark. Sea Lion Easterly lies about 5.6 miles (9 km) east of Sea Lion Island and reaches no more than 17 m at its highest southern and north-eastern points. Much of the central part of the island is boggy, with two permanent ponds, one near the northern point and one towards the south-western point. It has a dense belt of tall, coastal Tussac and a beach of large boulders.
Between 1983 and 1993, 53 species were recorded on Sea Lion Island during fieldwork for the Breeding Birds Survey. Of these, 43 were breeding or probably breeding, including eight of the nine resident songbirds and five species of penguins. The Macaroni Penguin occasionally breeds among the Rockhoppers but not in sufficient numbers to warrant site qualification. On Rum Islet, only 17 species were recorded in November 1998, including 15 probably breeding. Brandy Island had 26 species, of which 17 were breeding or probably breeding. These included Common Diving Petrels found incubating and the remains of a Sooty Shearwater. Whisky Island had 19 species, with 13 probably breeding, while Sea Lion Easterly had 24 species, of which 21 were breeding or probably breeding. The Grey-backed Storm-petrel is present but breeding needs to be confirmed. The predator-free status of all five islands in the Sea Lion group makes them important for small passerines and burrowing petrels. It is noticeable that Tussacbirds and Cobb’s Wrens are very numerous, particularly on the beaches of the four smaller islands. These islands all support at least one pair of Striated Caracaras but the Ruddy-headed Goose was found only on Sea Lion Island, where wetlands provide suitable habitat. An interesting feature of the bird community of the group is the current absence of the very conspicuous Long-tailed Meadowlark over the past 10 years, though it is present at Bull Point only 9 miles (15 km) away. However, it was recorded on Sea Lion Island in 1915 and again in 1987 and 1992. Endemic sub-species present include the White-tufted/ Rolland’s Grebe, Black-crowned Night-heron, Upland Goose, Short-eared Owl, Dark-faced Ground-tyrant, Falkland Pipit, Falkland Grass Wren and the Falkland Thrush.
Non-bird biodiversity: Experimental plantings of Tussac made in 1985 produced useful results when compared with similar plantings at Port Howard and Keppel Island. Sea Lion Island is of particular interest for the large colony of breeding Southern Elephant Seals, which produce around 200 pups per year. These are the subjects of a long-term study by Italian researchers from the University of Rome. Southern Sea Lions also breed on the coasts, with 40 pups in 2003. The other small islands are used as haul-out sites for Southern Sea Lions and many Southern Elephant Seals, although no breeding takes place there. Sea Lion Island is popular with tourists for its diverse bird and mammal life. Because of the steeply shelving coastline, it is also one of the best places in the Falklands to see Killer Whales hunting and feeding on penguins and seals just offshore. In November 1998, 56 species of flowering plants were recorded on Sea Lion Island. The most interesting is the Fuegian Violet Viola magellanica. In the Falklands, this plant has been found only on Sea Lion Island, growing with Tussac on sand north of the lodge. It is not known how the plant reached this remote island. At least 12 species were introduced agricultural weeds or grasses and only three were endemics. In contrast, only two to six species of flowering plants could be found on each of the four smaller islands, although 12 species have been recorded on Sea Lion Easterly in the past. All these sppecies are natives, except for Groundsel Senecio vulgaris found on Rum, which is immediately south of Sea Lion Island.
BirdLife International (2021) Important Bird Areas factsheet: Sea Lion Islands Group. Downloaded from http://www.birdlife.org on 12/04/2021.