Pebble Island is the third largest offshore island in the archipelago, stretching about 18.5 miles (30 km) from east to west, but it is only about 4.3 miles (7 km) at its widest point. There are three peaks west of the settlement: First Mountain reaches 277 m, Middle Mountain 214 m and the western Marble Mountain 237 m. The land to the east is generally low lying with many large lakes and ponds, which provide important waterfowl and wader habitat. The coastline is deeply indented and Elephant Bay, north-east of the settlement, has a spectacular 3 mile-long (5 km) white sand beach. Pebble Island is one of the most visited tourist sites in the Falklands, with a lodge and self-catering cottage accommodation in the centrally located settlement and a cottage near Marble Mountain on the far western point. The largest of the associated islets, Pebble Islet is low lying, reaching no more than 20 m at the western point. The northern coast has shelf rock and there are extensive kelp beds off the northern and western coasts, extending to Government Islet. There are a few large ponds and the island has been heavily grazed by sheep and horses. The vegetation is open and sparse, with only about 14 ha of Tussac cover at the eastern point. Government Islet is almost entirely covered by dense Tussac but was grazed by up to 10 bullocks in the early 1960s. There are cliffs up to 15 m on the western and north-eastern coasts, and large sheltered bays towards the east. White Island is a low rocky stack with thick Tussac on the southern slopes and in the centre, but less vegetation towards the east and west. It has probably not been grazed. Keppel Islet is a low, domed island with a boulder beach on the north-east coast and low cliffs to the south-east. It is densely covered in Tussac, which appears to be in good condition, although it was used for fattening bullocks, probably between 1960 and 1970.
In 1995, 39 species were found breeding on Pebble Island, with another four possibly breeding. A total of 23 of the 25 species of waterfowl and wading birds (as defined under the Ramsar Convention) breeding in the Falklands are found in the large wetland area on Pebble Island East, and more than 1,000 pairs of Imperial Shags breed near Cape Tamar. There are also colonies of Rockhopper and Gentoo Penguins. The Gentoo population doubled in the five years between 1995 and 2000, while the Rockhopper population remained more or less stable. The very small number of breeding Macaroni Penguins is associated with a large colony of Rockhopper Penguins north of Marble Mountain. The status of some of the species that could be breeding needs clarification and the entire group warrants further study since the previous (partial) surveys took place in 1995 and 1998. During the summer of 2000/01 the first pair of Coscoroba Swans – known to breed successfully in the Falklands since 1860 – was recorded on the eastern wetlands. Sightings of rare visitors or breeders such as Red Shovelers and Cinnamon Teals make the site a favourite haunt for birdwatchers. This part of the island probably supports the largest concentration of Blacknecked Swans in the Falklands, with at least 15 pairs nesting in 1995/96. The Cobb’s Wren is absent from Pebble Island, and probably Pebble Islet, as it cannot co-exist with rats. Members of the Royal Air Force Ornithological Society carried out a complete coastal survey of Pebble Island in 1995. A total of 16 species was noted during a brief visit to the south-eastern part of Government Islet in December 2001. Cobb’s Wrens, Tussacbirds and other species were numerous, suggesting that the islet is apparently free of introduced predators. However, an old bleached rat skull was found in a clearing among Tussac and a piece of orange expanded polystyrene on the beach had been chewed. These items may have been carried by a bird, perhaps a Striated Caracara. Keppel Islet was examined briefly from a passing boat in December 2001; 11 species were noted, including Tussacbirds near a colony of Rock Shags. This suggests that the islet is free of rats. Endemic sub-species known to be present in the Pebble Group include the White-tufted/Rolland’s Grebe, Black-crowned Night-heron, Upland Goose, Kelp Goose, Short-eared Owl, Dark-faced Ground-tyrant, Falkland Pipit, Falkland Grass Wren, Falkland Thrush and the Long-tailed Meadowlark.
Non-bird biodiversity: About 40 immature Southern Elephant Seals and several Southern Sea Lions used the south-western beach of Government Islet in December 2001. White Island is also a traditional site for Southern Sea Lions. The flowering plants of Pebble Island have been well surveyed (133 species recorded up to 2001). The following eight endemics have been recorded: Clubmoss Cudweed Chevreulia lycopodioides, Antarctic Cudweed Gamochaeta antarctica, Vanilla Daisy Leucheria suaveolens, Hairy Daisy Erigeron incertus, Coastal Nassauvia Nassauvia gaudichaudii, Woolly Falkland Ragwort Senecio littoralis, Smooth Falkland Ragwort Senecio vaginatus and Lady’s Slipper Calceolaria fothergillii. Other species of note include Yellow Lady’s Slipper Calceolaria biflora and the ‘local and scarce’ Shoreweed Littoralis australis.
BirdLife International (2019) Important Bird Areas factsheet: Pebble Island Group. Downloaded from http://www.birdlife.org on 18/06/2019.