|Location||Falkland Islands (Malvinas)|
|Central coordinates||60o 26.00' West 51o 37.00' South|
|IBA criteria||A1, A4i|
|Altitude||0 - 191m|
|Year of IBA assessment||2006|
Site description Hummock Island is the largest island in the group, stretching to nearly 2.5 miles (4 km) long and running in a north-west to south-east direction. The highest point is a very distinctive peak of 190 m looming like a gigantic breaking wave towards the north-east. Much of the coastline is cliffs, often reaching over 60 m in height. In the mid-20th century, it was used as an extension of the New Island sheep farm and a high level of grazing has led to much of the coastal Tussac being eaten out and replaced by bare ‘black ground’. Considerable Boxwood Hebe elliptica grows on the cliffs and there is a varied flora across the central oceanic heathland. Rabbit Island is 2.8 miles (4.5 km) north-west of Hummock Island and about 3.5 miles (5.5 km) west of Roy Cove. It is roughly rectangular, about 0.77 miles (2 km) square with a long promontory extending south-eastwards. The island slopes gently to the east and has very steep slopes up to 61 m facing north and west, with highest points of about 91 m. It has been heavily grazed by sheep in the past, though probably not since about 1986. An old shanty in a valley is in bad condition. The presence of rats was confirmed in 2000/01. Middle Island is a small, conical island reaching to around 120 m in height, with dense, thick coastal Tussac. There is no beach as such, but flat stone slabs and low cliffs form the shoreline. It is believed to have been grazed for a short period prior to 1930, however since then the island has been ungrazed. It is also free of introduced predators. The Tussac thins out and is replaced by short spongy grasses further inland. The island was struck by lightning and badly burnt in the late 1960s and again in the 1980s. It was declared a wild animal and bird sanctuary by the Falkland Islands Government, with the consent of the owner, in July 1966 and was retained by the Government when the estate was sold in the 1980s. Green Island is the smallest of the group, only 0.6 miles (1 km) offshore and extending to just 4 ha. The vegetation is apparently limited to dense Tussac. Little information exists about the birds present, although 10 species were recorded during a short offshore observation period in November 1997, including Tussacbirds. Gid’s Island is almost round and reaches approximately 60 m towards the north-western coast. Tall and healthy Tussac grass extends from the coastal fringe almost to the top of the slopes, although there are patches of black and eroded ground present. The island is thought to be free of introduced predators and has been grazed only intermittently in the past. No livestock are currently present.
Key Biodiversity These islands were visited during the Striated Caracara Survey in 1997; Hummock was revisited in 2001. Canary-winged/ Black-throated Finches, Falkland Steamer Ducks and Tussacbirds are present, but numbers are not known and therefore do not qualify the site. On Hummock Island, 28 bird species were found, including all native passerines except Falkland Pipits, but the visit was short and a thorough examination of the island was not possible. A total of 14 species were recorded on Middle Island, of which probably 12 were breeding. On Rabbit Island, there was a 32% increase in Rockhopper Penguins’ nests from 1995 to 2000. A total of 20 species was recorded in November 1997; 18 were breeding or probably breeding; only two individual Tussacbirds were seen and no Cobb’s Wrens, Canary-winged/Black-throated Finches nor Ruddyheaded Geese. Magellanic Penguins were breeding but counts are required. Gid’s Island held 17 species and 15 were probably breeding. At Green Island, in a very brief landing and circumnavigation, only 10 species were seen, of which nine were probably breeding. Thin-billed Prions and Common Diving Petrels may be present on some of these islands, but no surveys have been possible.
Non-bird biodiversity: More than 50 Southern Sea Lion pups were born on Gid’s Island in an earlier season and 29 were found in the 2003 census. The other islands are used as haul-out sites for a few non-breeding seals. In two visits, 53 flowering plant species were recorded on Hummock Island, including the largest known population of an unidentified purslane (Calandrinia), possibly a new endemic plant. These plants were growing on the north-west-facing slopes below the peak at a height of about 46 m. Five endemic species were found: Lady’s Slipper Calceolaria fothergillii, Woolly Ragwort Senecio littoralis, Coastal Nassauvia Nassauvia gaudichaudii, Falkland Rock Cress Phlebolobium maclovianum and Vanilla Daisy Leucheria suaveolens. One interesting and rare introduced species, Jersey Cudweed Gnaphalium luteoalbum, was found in very small numbers. On Rabbit Island, 45 species were identified, of which four were endemic and six introduced.
|Species||Season||Period||Population estimate||Quality of estimate||IBA Criteria||IUCN Category|
|Eudyptes chrysocome||breeding||2000-2001||1,664 breeding pairs||unknown||A1||Not Recognised|
|Phalacrocorax atriceps||breeding||2000-2001||5,000 breeding pairs||unknown||A4i||Not Recognised|
|Cobb's Wren Troglodytes cobbi||breeding||2005||unknown||-||A1||Vulnerable|
|Protected area||Designation||Area (ha)||Relationship with IBA||Overlap with IBA (ha)|
|Gid's Island||Nature Reserve||30||protected area contained by site||30|
|Middle Island||Sanctuary||155||protected area contained by site||155|
|IUCN habitat||Habitat detail||Extent (% of site)|
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Recommended citation BirdLife International (2015) Important Bird and Biodiversity Area factsheet: Hummock Island Group. Downloaded from http://www.birdlife.org on 26/11/2015
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