Wildlife on Soqotra

Soqotra has a high level of biodiversity and is rich in endemic animals and plants. On this site you can find an overview of birds, and of the terrestrial and marine life of the islands. Additional information linked to the texts has been provided by experts working in these fields.
Further, information on international Development programmes and institutions as well as links to Biodiversity networks are also provided.


Soqotra's Birds
Terrestrial life
Marine life
FaunaMAIN

Soqotra's Birds

By Richard Porter
BirdLife International

Birds are a group of warm blooded vertebrate animals that have two wings, two legs and a beak. Their bodies are covered in waterproof and insulating feathers and they lay eggs. Over 10,000 species are found in the world from the smallest, the hummingbirds (5 cms), to the largest, the ostrich (over 2.5 m tall).
On Socotra some birds are resident (breed and are present all year round) and others that are migratory, using the archipelago as a stop-over to rest and feed on their annual migrations.
Over 220 species of bird have now been recorded. Of these just 38 breed regularly, whilst over 180 are migrant visitors - stopping for a while during their long migrations from breeding areas in Europe and Asia to their wintering grounds in Africa. Many of these migrant birds are very rare (vagrants) and have only been recorded on Socotra a few times.
The most important birds are the eleven endemic species – birds that are not found anywhere else in the world, the 15 Globally Threatened or Near Threatened species that have occurred and the ten species of seabird that breed in internationally important numbers: Socotra has a special responsibility for the protection of all of these.
One endemic, the Socotra Golden-winged Grosbeak Rhynchostruthus socotranus, is Yemen’s national bird and the recently named Socotra Buzzard Buteo socotraensis appears in the Guiness Book of Records as the ‘newest bird of prey in the world‘!" Surveys have shown that the grosbeak has a widespread population on Socotra with over 16,000 individuals, whilst the buzzard is much rarer with less than 250 pairs and is assigned as globally Vulnerable in the IUCN/BirdLife Red List. The only globally endangered species the Egyptian Vulture Neophron percnopterus has the highest concentration in the world with an estimated 800 pairs.
Further information can be found at the homepage of the BirdLife International and in various publications listed in the Bibliography.

Checklist of the birds of the Soqotra Archipelago

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Terrestrial life

Flora

By Lisa Banfield
Al Ain Wildlife Park and Resort and the Centre of Middle Eastern Plants/Royal Botanic Garden Edinburgh

The Socotra Archipelago boasts a rich flora, remarkable endemic species and plants with a long history of traditional use. With a total of 835 vascular plant species, 308 (37%) are endemic such as Aloe perryi. There are also 74 bryophytes; one hornwort, 30 liverworts and 43 mosses, 6 of which are endemic.
Because of such high diversity and endemism in plants, the islands have been declared a WWF Global 200 Ecoregion, a Plantlife International Centre of Plant Diversity and are included in the Horn of Africa Biodiversity Hotspot. These are added to desig- nations of UNESCO World Natural Heritage and UNESCO Man and Biosphere Reserve.
The islands have a diverse geology and varying climate, creating a diversity of vegetation types. Dense evergreen and semi- evergreen woodland can be found in high altitude, wet and sheltered areas, but there are also drought-adapted plants surviving in desert-like landscapes.
Several aspects of the flora of Socotra are of special scientific interest to botanists but also to non-scientists. Probably the most famous is the “dragon’s blood tree”, Dracaena cinnabari. The sap has been used cosmetically and medicinally on Socotra and elsewhere since ancient times. Another group of trees with a long history of importance are the endemic species, which produce frankincense. Eight of the 24 species of are endemic to the Socotra Archipelago.
Several trees of Socotra have adapted a bloated trunk which stores water, helping them to survive the arid environment. Probably the most famous example is the desert rose, Adenium obesum subsp. sokotranum. Equally interesting is the cucumber tree, Dendrosicyos socotranus, the only arborescent member of the cucumber family and one of the tallest trees on Socotra. Another example is Dorstenia gigas.

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THREATS AND CONSERVATION
Although the Archipelago is in better condition than many other island ecosystems, the flora of the Socotra Archipelago does face some very real threats leading to a "critically endagered" status of plants such as Duvaliandra dioscoridis. Many tree species are suffering from a lack of regeneration. Climate change, overgrazing, or a combi- nation of both, are thought to be the most important factors causing this. Overgrazing is also leading to loss of vegetation cover and serious soil erosion in some areas.
Traditional land management practices are becoming less adhered to as the culture of the island changes, which could lead to overexploitation of some species. Illegal plant collecting threatens sought-after plant species, in particular rare succulents. Large-scale infrastructure projects, such as road building, are damaging habitats as well as the aesthetic beauty of the island.
Further information can be found on the homepage of the Royal Botanic Garden Edinburgh, in the book about the Ethnoflora and in various other publications listed in the Bibliography.

Fauna

By Wolfgang Wranik
Biological Department, University of Rostock
with additional templates provided by Rob Felix, Vladimir Hula, Josef Suchomel and Razetti et al. (2011)

The fauna of the archipelago is as fascinating as the flora, and has an exceptional number of endemics. However, because the terrestrial fauna is still poorly studied, no-one knows exactly how many terrestrial and freshwater animal species occur on the islands, though it can be assumed that the number exceeds the 1,000 or so species so far recorded. Many species are known only from single or very limited re-cords. Because much faunistic data dates back to expeditions which were carried out a hundred years ago, these records need confirmation and a critical taxonomic revision. In addition, many specimens collected recently still await identification and description.
Most diverse among Soqotra’s terrestrial fauna are the invertebrates, chiefly represented by arthropods and molluscs. As well as the birds, more than 600 species of insects, some 100 land and freshwater molluscs, around 80 arachnids, some dozen myriapods, four land- and fresh-water crabs, 30 reptiles and 14 mammals have been found to occur. All of the land snails, 90 % of the reptiles and about 60 % of the spiders are unique to the Soqotra Archipelago.
Surprisingly there is a paucity of mammals. Apart from four species of cave-dwelling bats and a Pigmy shrew - provisionally identified as Suncus etruscus - all other known mammals are either domesticated (goats, sheep, cattle, camels, donkeys) or introduced (Lesser Indian civet cat, domestic cats, rats, mice).
However, the islands support a diverse and interesting reptilian fauna. The geckoes represent some two thirds of the 30 species and are one of the groups which demonstrates a spectacular capacity for adaptive radiation throughout the different niches available. The seven species of the genus Pristurus are ground-, tree- and rock-dwelling, and they are unusual among geckoes in being active during the day-time rather than at night. Whereas nocturnal geckoes use calls to communicate, these geckoes communicate mainly through visual signals, such as body posture and tail movements. Nocturnal species are characterized by strongly dilated digits, each with rows of small, leaf-like lamellae underneath. They are represented with 11 species in the genera Hemidactylus and Haemodracon, with Haemodracon riebeckii, of a size up to 30 cm, being the “giant” of its group. Other creatures are the skinks, lizards, a chameleon, six snakes - among them four worm-like, blind snakes - and a worm lizard.

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The islands support a high number of arthropods, comparatively small in size, but diverse and spectacular in shape, adaptation and biology. The hairy tarantula, Monocentropus balfouri, for instance, the size of the palm of a hand; yellow, brown and dark-coloured scorpions; bizarrely shaped spiders; wind scorpions, tailless whipscorpions and the giant centipede, Scolopendra valida. Omnipresent among insects are various beetles, such as the flightless Darkling Beetles (some 38 species), the majority of which are considered endemic; the Ground and Dung Beetles; the Rhinoceros Beetle with a hornlike projection on the middle of the head; the Long-horn Beetle, Mallodon arabicum (up to 60 mm in size), and the colourful Jewel Beetle, Julodis clouei. There are approximately 50 species of grasshoppers and crickets, and locusts, many flightless or poor fliers, and more than half of which are endemic. The sound of cicadas is audible for a few weeks of the year, otherwise they spend the rest of the time as nymphs below ground. The conical, pitfall traps of antlion larvae can be found everywhere in suitably sandy habitats. There are some 15 species, the adults superficially resembling dragonflies. While these are usually seen at night in the light of lamps, the 18 or so species of dragonflies and damselflies can be seen during the day in the vicinity of streams, ponds and estuaries. Their nymphs too can be seen in these freshwater areas, together with aquatic bugs, various water beetles, six species of fresh-water snail and the unique, endemic fresh-water crab. There are colourful butterflies and numerous moths, wasps and bees, ants and termites, flies and mosquitoes, as well as woodlice and many other arthropods. Of special scientific interest are the 100 or so species of land snail, whose shells can be found all over the islands, usually empty, or, at times of year without sufficient moisture, with their inhabitants in an inactive state.
Further information can be found in various publications listed in the Bibliography.

Marine life

By Uwe Zajonz
BiK-Research centre, Senckenberg Institute Frankfurt a.M.

The coastal and marine ecosystems of the Soqotra Archipelago are complex and home to an astonishing biological diversity. At the same time they are very productive, providing sustenance and livelihoods to people on the coast, food to those of the island interior and increasingly also to people on the Yemeni mainland, as well as market opportunities for a number of economic players. The alternating seasons of the Indian monsoon and associated complex oceanographic setting, including the upwelling of cool, nutrient- rich cold water during the summer monsoon, and the reversing ocean current patterns which connect Soqotra the year round to all the neighbouring seas appear to be the main driving force lying behind these high levels of marine biodiversity and productivity.
The six main littoral habitat types (coastal, intertidal) cover an area of 284.93 km2 comprising sediments (37.24 km2), cobble beaches, bedrock (101.70 km2), salt marshes (0.01 km2); mangroves (2.94 km2), and khawrs (coastal lagoons) and wadis (165 km2), as well as terrestrial coastal vegetation (141.38 km2). These littoral habitats are made up of a range of different biotope types. The 20 or so temporarily open/closed estuaries (TOCEs) of Soqotra Island are important roosting and breeding sites for resident and migratory coastal birds. They are especially important as spawning sites and nurseries for > 30 economically important species of marine fish, and the food organisms thereof. Recent surveys have identified 64 species of fish from 12 TOCEs and more than 80 species can be expected to occur.
Sublittoral habitats, mapped to a depth of 20 m within a 5 km zone of 584.10 km2 around the island group (a fifth of the total area), are again composed of six main types, comprising more than 60 different biotope types: sediments (75.69 km2), cobbles (18.76 km2), small rock boulders (1.44 km2), large rock boulders (27.70 km2), bedrock (276.39 km2), and coral dominated habitats (184.12 km2).
Although coral habitats thus cover less than one-third of the known subtidal area, and biogenic reef frameworks in the classical sense even less than 2 km2, the diversity of so-called "reef-associated" organisms is high. Over the past 15 years the number of species recorded in the main marine organism groups has risen dramatically, and are, as follows: Macroalgae (~ 130 spp.), Hard Corals (> 250 spp.), Molluscs (~ 600 spp.), Decapod Crustaceans (> 300 spp.), Bryozoans (> 150 spp.), and Fishes (> 750 spp.). Levels of biodiversity generally increase in East- West and South-North direction across the Archipelago. In several taxonomic groups Soqotra hosts a greater wealth of diversity than, for example, the much larger Red Sea. In general, it is most probably the biologically richest and most productive area of any reasonably comparable marine biogeographical or eco-regional subunit in the Arabian region.
Soqotra is a major biodiversity hotspot not only in the terrestrial but also in the marine realm, and it is to be hoped that its status as a UNESCO World Natural Heritage Site will help to promote the conservation and sustai- nable use of its coastal and marine biotopes and biota. A lot more needs to be done in terms of studying the marine biodiversity and ecology in general, but certain habitats and organism groups remain particularly understudied such as, for example, all the non-coral-dominated sublittoral biotopes (e.g. the vast sea grass beds), the coastal lagoons, many of the invertebrate groups (e.g. sponges), the plankton communities and also the fishery resources.
Further information can be found on the homepages of the Biodiversity and Climate Research Centre (BiK-F) and the Senckenberg Research Institute and Natural History Museum, Frankfurt a.M., Germany, and in various publications listed in the Bibliography.

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fish fish © R. Klaus
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