IUCN Management Category I (Strict Nature Reserve)

Biogeographical Province 4.16.13 (Seychelles and Amirantes Islands)

Geographical Location A small island on the shallow Seychelles Bank, 2.35km west-south-west of Miller's Point on Praslin Island. 4°19'S, 55°39'E

Date and History of Establishment Designated as a special reserve by the Seychelles Government in 1975 by the National Parks and Nature Conservancy (Designation of Special Reserve) (Cousin Island) Order. However, administered as a bird sanctuary since 1968 under the Wild Animals and Birds Protection Ordinance 1966.

Area 27ha land area, extends 400m offshore from the high water mark (the former bird sanctuary only included the island down to high water mark).

Land Tenure Purchased by the International Council for Bird Preservation, British Section in 1968. Responsibility has recently been transferred to ICBP International.

Altitude Below sea level to 69m

Physical Features The island is approximately rectangular in shape with a group of rocks (Roche Cannon) located some 200-300m off the north-west point, linked with the main island by a natural stony causeway which is exposed at low tide. About 80% of the island comprises a flat, coastal plain of phosphate sandstone on the northern and eastern flanks of the granite hill, which rises to 69m. The southern and western slopes are rocky and barren, right down to the shore, while the northern and eastern slopes support dense stands of trees. The north-west, north, and north-east shores are characterised by beaches of fine white sand, making up some 80% of the shoreline. The seasonal change in wind direction (north-west/south-east) leads to the constant movement of sand between the east and north coasts, which affects the strand line vegetation and littoral beach organisms, as well as the marine turtle nesting grounds. During the north-west monsoon the North Beach is eroded out, exposing banks of beach rock, while the East Beach develops a wide beach platform; the south-east monsoon reverses this and North Beach develops a supralittoral beach flat, up to 100m wide. There is also a fringing coral reef surrounding the island which extends, on average, some 200m out from the high water mark. The only running fresh water on the island is a small, seasonal rivulet carrying run-off from the hill down the northern slope to the depression near some wells. The climate is humid and tropical, with a mean annual rainfall of 1,620mm. The highest monthly rainfall occurs between December and February (north-west monsoon), while May to July is the driest season. Monthly temperatures range from 24°C to 26°C, being lowest from April to October/November when the south-east trade winds are at their strongest.

Climate No information

Vegetation The island supports a variety of vegetation types: coastal herb communities maintained by wind-blown salt-spray, characterised by Boerhavia repens, Passiflora suberosa and Stenotaphrum dimidiatum; mature Pisonia grandis forest; regenerated Pisonia/Morinda citrifolia woodland emerging under the abandoned coconut Cocos nucifera plantations on the coastal plain; Panicum maximus, Cyperus polyphyllus and Fimbrystylis/Bulbostylis communities on the north and east hillside; Cyperus ligularis and the halophyte Portulaca oleracea on the south and west hill slopes; dense Euphorbia pyrifolia and Pandanus balfouri thickets and open sedge/herb communities on the granite slopes; substantial areas of mangrove Avicennia marina swamp in the shallow depression, flooded by high spring tides, between Anse Fregate and Ilot (SW), and a small freshwater marsh. Other notable species include the halophytes Carica papaya and Scaevola taccata found on the beach crests, Casuarina equisitifolia fringing the beaches, Pandanus multispicatus, Guettarda speciosa, Ficus mantarum, Ficus avi-avis and Lagresia madagascariensis (previously thought confined to Roche Cannon, but now recorded on the main island). More than 125 plant species have been recorded, over half of which are believed to be introduced (Fosberg, 1970), such as paw paw Carica papaya and castor oil Ricinus communis. By restricting the clearing of undergrowth, ICBP is hoping to re-establish the original island vegetation, which was thought to comprise forests of tall Pisonia grandis on the plateau; thickets of Scaevola taccada and Suriana maritima along the coast, backed by a dense hedge of Cordia subcordata, Guettarta speciosa and Morinda citrifolia; and dense woods of Morinda and Ficus spp. (Fosberg, 1970).

Fauna Cousin was acquired mainly because it was the home of three threatened endemic land birds namely: Seychelles brush warbler, Acrocephalus seychellensis (formerly Bebrornis) (R), Seychelles fody Foudia sechellarum (R), and Seychelles turtle dove Streptopelia picturata rostrata (E). This latter endemic race is believed to be extinct through hybridisation with the introduced race. By far the largest biomass is represented by large seabird colonies, including what is probably the largest breeding colony of the white fairy tern Gygis alba (10,000 in 1980) in the Seychelles, together with Audubon shearwate0 Puffinus therminiera (1,000 in 1980), wedge-tail shearwater P. pacificus (35,000 in 1980), white-tailed tropic birds Phaethon lepturus (1,000 in 1980), and bridled terns Sterna anaethetus nesting on the hill, while black noddy Anous tenuirostris (200,000 in 1980) and common noddy A. stolidus (3,000 in 1980) prefer the coastal plain for their nest sites. In all, some 52 species of bird have been recorded from Cousin. Other notable species not already listed are, Madagascar fody Foudia madagascariensis, barn owl Tyto alba, and Indian mynah Acridotheres tristis (introduced species), Seychelles sunbird Nectarina dussumieri (endemic), great frigate bird Fregata minor (regular visitor), lesser frigate bird F. ariel, and European hobby Falco subbuteo (migrant). The only residential mammal is the hare Lepus nigricollis, which was introduced from India in the 1920s, but fruit bat Pteropus seychellensis commute from neighbouring Praslin to feed on ripe fruit. All domestic animals surviving from the days when the island was inhabited have been eliminated. There is an abundance of the skinks Mabuya wrightii, and Scelotes gardineri, and brown "loose skin" gecko Ailuronyx sechellensis are also fairly common. Cousin is acknowledged as having one of the largest populations of breeding hawksbill turtle Eretmochelys imbricata (E) in Seychelles and green turtle Chelonia mydas (E) also breed here occasionally. Other reptiles are: Seychelles terrapin Pelusios subniger, small green gecko Phelsuma astriata a small number of reintroduced giant tortoise Geochelone gigantea (R), Mabuya sechellensis, at least one species of Caecilian and Phyllodactylus inexpectatus. Over 230 fish species have so far been identified from the reefs (checklist in Frazier and Polunih, 1973). The most conspicuous invertebrates are the crabs, with three species of ghost crab Ocypode spp., and hermit crabs Coenobita spp.. Interesting terrestrial invertebrates include: the giant millipede Scaphiostreptus madcassus, scorpion Isometrus maculatus, an uncommon species of tail-less whip scorpion Amblypygi which is confined to Cousin, Cousine and Aride islands, and the Madagascar termite Nasutitermes migricans. Butterflies are extremly scarce with only six species recorded including painted lady Cynthia cardui and Parallelia torrida. The coral reefs were surveyed in detail by Frazier and Polunin (1973) (includes species checklists of reef fish and corals) and UNEP/IUCN (in prep.) contains a summary of the reef structure and coral communities found encircling the island. The Acropora assemblage is most common, other characteristic coral species are: Millepora platyphylla and M. dichotoma in exposed areas, Pocillopora and Stylophora, Porites at the base of reef slopes.

Cultural Heritage No information

Local Human Population No information

Visitors and Visitor Facilities Tourism is restricted to daytime visitors, who are ferried during the daytime from nearby islands in staff boats, not more than 20 at a time and only on three specified days a week. There is no overnight accommodation.

Scientific Research and Facilities A fairly intensive research effort covering most of the flora and fauna has been carried out by the successive scientific administrators and is still being continued. Special attention has been given to the ecology, behaviour and population size of the brush warbler. Various ringing programmes have been carried out. Another long-term study has been the tagging of female hawksbill turtles; the hawksbill turtle population is probably the most studied in the world. F.R. Fosberg surveyed the vegetation in 1971. However, the full potential for research on the island has not yet been realised an few of the research priorities identified in the management plans (Diamond, 1975; 1980) have been achieved.

A fully-equipped research station with room for two or three visiting scientists was built from a donation by Ciba-Geigy.

Conservation Value No information

Conservation Management The Cousin Island Special Reserve Regulations (S.I. No. 93) were gazetted in 1979. The marine turtles are further protected under The Turtle Act, which lists Cousin as a protected breeding site. No turtles to be caught, killed, etc., within 1,000m of the high water mark. The collection of sea shells is prohibited under the protection of seashells Ordinance (Cap.138) of 1965.

ICBP manages the island as a nature reserve, integrating the interests of conservation, scientific research and limited tourism. The management objectives defined in the revised management plan (Diamond, 1980) are as follows (in order of priority): maintain the maximum possible number of the three endemic land birds; within this framework to restore the original habitat of the island, except when this conflicts with the primary objective; maintain the maximum possible population of hawksbill turtle on and around the island; maintain the maximum possible populations of seabirds breeding on the island; and make full use of the island's educational and research potential. The staff live on the island and buildings include the main house, three stores, three labourers' cottages and two boatsheds. The staff are in radio contact with nearby Praslin Nature Park and have three boats for transport. Undergrowth is no longer cleared in the coconut plantation to allow the natural regeneration of native vegetation. All domestic animal species have been eliminated and a strict ban on their import is maintained. The numbers of such introduced species as the Indian mynah and barn owl are controlled to avoid competition and predation with the indigenous species. There are regular beach patrols by reserve staff (reinforced by the Curieuse Patrol and Praslin Police) organised to protect the nests and breeding females of hawksbill turtle from poaching. In 1972, I. Robertson briefly surveyed the island.

There are certain very dense bird colony sites where the visitor access is prohibited; apart from this the island is too small for proper zoning.

Management Constraints Its past history as a well-maintained coconut plantation means that it is only now that the native vegetation is making a comeback. Many exotic species, such as papaya, castor oil and cotton, were introduced in the past. A patch of rangoon creeper is a persistent problem as it continually grows back vigorously despite repeated pruning and applications of weed killers. In an effort to encourage the return of native vegetation all coconuts that fall down are collected and shipped to Praslin. Occasional visits by the introduced African barn owl have to be watched as they prey on the fairy terns and have been responsible for the decline in their numbers on other islands in the Seychelles. Before 1968, the reefs were exploited for shells. Some of the Praslin fishermen have persisted in poaching hawksbill turtles, though numbers taken within the protected area are lower than outside the boundaries (Mortimer, 1981).

Staff Formerly one expatriate scientific administrator plus five Seychellois workers. In 1982, the staff structure was reorganized, replace the post of scientific administrator by the posts of warden and research officer.

Budget 1981 - expenditure 161,133.44 Rs. (|4,632.02); income 115,110.85 Rs (|5,497.07). The maintainance costs have over the years come from the original capital raised to by the island, grants from WWF and the Fauna and Flora Preservation Society, and income from landing fees and the sale of coconuts. In 1985, funds were becoming harder to raise, possibly at the expense of conservation priorities (Diamond, 1985).

Local Addresses

Chairman Cousin Island Local Management Committee, c/o Plaisance, Mahé.

References

Anon. (1980). Cousin - the small island with a big conservation success. Nation 4(96). Friday 25 April

Bathe, G.M. and Bathe, H.V. (1982). Territory size and habitat requirements of the Seychelles brush warbler Acrocephalus (Brebornis) sechellensis. Cousin Island Technical Report.

Diamond, A.W. (1975). Cousin Island Syechelles 1975-9. ICBP Report.

Diamond, A.W. (1985). Cousin Island Nature Reserve Management Plan revision 1980-1984. ICBP (British Section), London.

Diamond, A.W. (1985). Multiple use of Cousin Island Nature Reserve, Seychelles. ICBP Technical Publication No.3.

Fosberg, F.R. (1970). Cousin Island Report. ICBP internal report.

Frazier, J.G. and Polunin, N.V.C. (1973). Report on the coral reefs of Cousin Island, Seychelles. Manuscript. WWF library reference: 696-551.351.5

Garnett, M.C. (1979). The breeding biology of hawksbill turtles (Enetmochelys imbricata) on Cousin Island, Seychelles. Mimeographed. ICBP, London.

Mortimer, J.A. (1981). IUCN/WWF Project 1809 - Seychelles marine turtles. WWF Monthly Report February 1981.

Percy, R. (1970). Cousin Island Nature Reserve in the Seychelles, Indian Ocean. Biological Conservation 2: 225-227 (bought by ICBP in 1968; an account of its possibilities, with recommendations).

Phillips, J. (1981-1983) Report of the scientific administrator of Cousin Island, Seychelles No.44-49. ICBP (British Section)

Republic of Seychelles (1978). Praslin 2. 1:10,000 scale map prepared by the British Government's Ministry of Overseas Development (Directorate of Overseas Surveys. Series Y851 (D.O.S 204).

Ripley, S.D. (1973). Promotion of bird preservation in the Seychelles. Outline IUCN/WWF Project 1083.

Stoddart, D.R. (Ed.) (1984). Biogeography and Ecology of the Seychelles Islands. Dr. W. Junk Publishers. The Hague.

UNEP/IUCN (in prep.). Directory of Coral Reefs of International Importance. Volume 2. Indian Ocean.

Date June 1983