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Location South Africa, Western Cape
Central coordinates 19o 25.00' East  34o 41.00' South
IBA criteria A1, A4i, A4ii, A4iii
Area 20 ha
Altitude 0 - 9m
Year of IBA assessment 2001

BirdLife South Africa



Summary Dyer Island is one of two low-lying islands situated 4.7 km southeast of Danger Point; the nearest harbour is at Kleinbaai/Franskraal, just south of Gansbaai. This flat, low- lying island does not exceed 9 m above sea level.

Site description Dyer Island is one of two low-lying islands situated 4.7 km south-east of Danger Point. The nearest harbour is at Kleinbaai/Franskraal, just south of Gansbaai. The coastline is rugged with some low rocky areas spreading inland. The island is flat and low-lying, with a pebbly surface. The vegetation consists primarily of Mesembryanthemaceae and non-native weeds (including conspicuous stands of Lavatera). In the south-eastern part of the island are several buildings that house the island staff, boats and stores.

Key Biodiversity See Box for key species. The discovery of Oceanodroma leucorhoa in several of the stone walls on the island in October 1995 was the first evidence of a procellariiform bird breeding in southern Africa. In November 1996 it was estimated that 8–9 pairs were breeding. In 1996, after an absence of some 25 years, Sterna dougallii, which breed regularly only at two other islands in southern Africa (Bird and St Croix islands in Algoa Bay; IBA ZA074), attempted to breed again at Dyer Island. The breeding attempt failed owing to suspected human disturbance. The population of Spheniscus demersus at Dyer Island is in rapid decline, and although the island supported some 72,500 birds in 1976, it is thought that the population may have fallen below 3,000 pairs in 1997.

Many other species breed on this island, including large numbers of Phalacrocorax capensis and small numbers of P. carbo, P. neglectus and P. coronatus. Several large colonies of Larus hartlaubii and Sterna bergii breed at the island. Sterna sandvicensis, S. hirundo, S. paradisaea and S. vittata form large, mixed tern roosts with the breeding S. bergii. Dyer Island is estimated to hold over 1% of the world population of Haematopus moquini.

Non-bird biodiversity: The waters around the island hold a large population of the shark Carcharodon carcharias (VU).

Populations of IBA trigger species

Species Season Period Population estimate Quality of estimate IBA Criteria IUCN Category
African Penguin Spheniscus demersus resident  3,050 breeding pairs  A1, A4ii  Endangered 
African Penguin Spheniscus demersus winter  9,000 individuals  A1, A4ii  Endangered 
Cape Cormorant Phalacrocorax capensis resident  35,580 breeding pairs  A1, A4i  Endangered 
Cape Cormorant Phalacrocorax capensis winter  100,000 individuals  A1, A4i  Endangered 
Bank Cormorant Phalacrocorax neglectus breeding  uncommon  A1  Endangered 
Crowned Cormorant Microcarbo coronatus resident  60-238 breeding pairs  A1, A4i  Near Threatened 
Crowned Cormorant Microcarbo coronatus winter  150-500 individuals  A1, A4i  Near Threatened 
African Oystercatcher Haematopus moquini resident  2000  27-67 breeding pairs  unknown  A1, A4i  Near Threatened 
African Oystercatcher Haematopus moquini winter  160 individuals  A1, A4i  Near Threatened 
Kelp Gull Larus dominicanus breeding  88-130 breeding pairs  A4i  Least Concern 
Kelp Gull Larus dominicanus winter  200-500 individuals  A4i  Least Concern 
Hartlaub's Gull Larus hartlaubii breeding  110 breeding pairs  A4i  Least Concern 
Hartlaub's Gull Larus hartlaubii winter  280 individuals  A4i  Least Concern 
Greater Crested Tern Thalasseus bergii breeding  300 breeding pairs  A4i  Least Concern 
Greater Crested Tern Thalasseus bergii winter  750 individuals  A4i  Least Concern 
A4iii Species group - seabirds resident  100,000-499,999 individuals  unknown  A4iii   

IBA Monitoring

2014 high near favourable high
Habitat
Medium - based upon reliable but incomplete / partially representative data

Biological resource use fishing & harvesting aquatic resources - unintentional effects: large scale happening now small area/few individuals (<10%) no or imperceptible deterioration low
Biological resource use fishing & harvesting aquatic resources - unintentional effects: subsistence/small scale happening now some of area/population (10-49%) no or imperceptible deterioration low
Climate change and severe weather storms and floods likely in short term (within 4 years) some of area/population (10-49%) moderate to rapid deterioration medium
Human intrusions and disturbance recreational activities happening now some of area/population (10-49%) no or imperceptible deterioration low
Human intrusions and disturbance work and other activities happening now small area/few individuals (<10%) no or imperceptible deterioration low
Invasive & other problematic species, genes & diseases invasive non-native/alien species/diseases - named species happening now some of area/population (10-49%) no or imperceptible deterioration low
Invasive & other problematic species, genes & diseases problematic native species/diseases - named species happening now some of area/population (10-49%) moderate to rapid deterioration high
Pollution garbage & solid waste happening now some of area/population (10-49%) slow but significant deterioration medium
Pollution industrial & military effluents - oil spills happening now some of area/population (10-49%) slow but significant deterioration medium
Residential and commercial development housing and urban areas happening now small area/few individuals (<10%) no or imperceptible deterioration low
Residential and commercial development tourism and recreation areas happening now small area/few individuals (<10%) no or imperceptible deterioration low

Rocky areas Scree, boulders & bare rock  0 0 moderate (70-90%) good (> 90%) near favourable

Whole area of site (>90%) covered by appropriate conservation designation  A comprehensive and appropriate management plan exists that aims to maintain or improve the populations of qualifying bird species  The conservation measures needed for the site are being comprehensively and effectively implemented  high 

Local conservation groups The local conservation group below is working to support conservation at this IBA.

Name Year formed
Dyer Island Conservation Trust 0

Habitats

IUCN habitat Habitat detail Extent (% of site)
Unknown   -
Coastline   major
Other   major
Rocky areas Scree, boulders & bare rock  -

Land use

Land-use Extent (% of site)
nature conservation and research 100%
tourism/recreation -
urban/industrial/transport -

References Adams (1991), Branch (1991), Brooke and Prins (1986), Cooper (1981), Cooper and Berruti (1989), Cooper and Brooke (1986), Cooper et al. (1983, 1984), Crawford (1995), Crawford and Dyer (1995), Crawford and Shelton (1978, 1981), Crawford et al. (1982a,b, 1983, 1989, 1990, 1994, 1995c), Frost et al. (1976), Furness and Cooper (1982), Hockey (1983), Hockey and Hallinan (1981), Morant et al. (1981), Rand (1963), Randall and Randall (1980), Randall et al. (1980), Shelton et al. (1982), Siegfried (1982), Summers and Cooper (1977), Whittington (1996), Whittington and Dyer (1995), Whittington et al. (1998), Williams et al. (1990), Wilson et al. (1988).

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Recommended citation  BirdLife International (2015) Important Bird Areas factsheet: Dyer Island Nature Reserve. Downloaded from http://www.birdlife.org on 30/06/2015

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