The Vallée De Mai palm forest is a remarkable remnant of the prehistoric forests which existed when the Seychelles islands were still part of Gondwanaland, the huge land mass which included what is now Africa, Madagascar and India. Millions of years of isolation enabled a unique community of plants and animals to develop in the Vallée De Mai and some species are found nowhere else.
Coco de Mer
The Coco de Mer palm is surrounded by myth and legends. This is partly because the strange bi-lobed nuts were discovered long before the palm itself and partly because of the suggestive shapes of both male and female structures which occur on separate Coco de Mer palms. As the most renowned and flagship species for Vallée de Mai, and as the subject of conservation revenue through nut harvesting and sale, this palm merits special consideration. Seychelles Islands Foundation, with responsibility for Vallée de Mai, is entrusted with 25% of the total world population of Coco de Mer palms.
The canopy within Vallée de Mai reaches up to 30m, although the majority of trees are still juvenile. The tree grows best in the deeper, richer soils of the lower slopes, but also extends to the high ridges at a lower density. In Vallée de Mai, leaves of young Coco de Mer palms can reach a length of 14m or more. There are male and female Coco de Mer palms. Male palms grow to about 30m high, female palms to about 24m high.
The tree is renowned for its unusual biology, including the production of the largest seed which is thought to weigh as much as 20kg. The first leaf appears about one year after germination. Existing data suggests that a trunk first appears after about 15 years, and the tree reaches maturity after 20-40 years, although such figures are doubtless a generalisation and trees on higher, drier slopes will be slower growing. Female trees may carry very heavy loads of nuts. Coco de Mer palms probably live for between 200 and 400 years.
The flowers attract insects, geckos and slugs but there is no firm evidence about whether the flowers are animal or wind pollinated. Generally 3-5 fruits develop on each inflorescence, although a tree may bear over 25 fruits at a time.
Time to maturation of the nut is 6-7 years, although the nut reaches full size after only 9 months. When immature, the fruit contains a translucent jelly that was previously used for making desserts. On maturation the fruit falls to the ground where, if not collected, it will germinate within 3-6 months.
Seychelles Black Parrot
The Seychelles Black Parrot (Coracopsis nigra barklyi) is the national bird of Seychelles. It is an endemic species or subspecies and merits special consideration.
Coracopsis is a well-defined genus endemic to western Indian Ocean. There is some uncertainty as to the precise taxonomy of the group. Birds of Seychelles and Comoros (race sibilans) are very similar in size and plumage and differ substantially from the nominate race. Seychelles Black Parrot shows grey in the outer webs of primaries (unlike sibilans) and undertail-coverts are sometimes paler than the rest of the body (sibilans is always concolorous). Both Seychelles and Comoros birds have been generally regarded as subspecies of the Lesser Vasa Parrot C. nigra of Madagascar. However, the latter averages 35cm, (about 17% bigger) and Seychelles/Comoros birds are grey-brown whereas birds of Madagascar are dark brown, lacking any grey tones. It has sometimes been claimed it was introduced to Seychelles from Comoros but this is probably incorrect. "Coffee-coloured parrots," evidently this species, were recorded by the Marion Dufresne expedition of 1768, two years prior to any human settlement.
The Seychelles Black Parrot has only been recorded as breeding from Praslin, though possibly it once occurred throughout the Praslin group. In 1976, 65% of birds counted were in the Vallée de Mai region, but since then there has been a spread into lowland areas, at least for feeding. Since 1988 it has been regularly seen feeding on Curieuse, but there is no evidence of breeding.
There are specimens in Paris from Marianne (collected 1875 by de l'Isle) and at the American Museum of Natural History from Aride (collected 1907). The first estimate in 1964-65 suggested a population of 30-50 birds. Annual surveys by V. Laboudallon from 1982, suggest an increase in population of c. 40% between 1985 and 1996, and by 2001 the population probably numbered 200-400 birds.
Possibly the greatest threat is introduced rats, common on Praslin. Nest boxes protected by rat guards have been erected in Vallée de Mai, but in other natural sites most nests are predated when chicks begin to call at three days old. In one study, 72 rats were trapped in the vicinity of a single nest box during the period when chicks were vulnerable (V. Laboudallon pers. comm.). Habitat destruction outside Vallée de Mai and a growing human population on Praslin may also put pressure on the species. Bush fires are frequently recorded on Praslin and have sometimes destroyed both breeding sites and food plants.
Annual population surveys have been carried out since 1982, building on work carried out by Evans (1979). Enough is known about the ecology and current status to be confident that Vallée de Mai provides critical breeding sites. More research is probably not a priority. Numbers may ultimately be limited by a shortage of nest sites, dead trees often being cleared away, and only in Praslin National Park are these generally left to provide nest sites.
The bird is particularly fond of fruits of the endemic palm Latannyen Lat and the introduced Bilenbi. Diet also includes fruits, buds and flowers of introduced plants such as Guava and Pawpaw and endemic plants such as Bwa Rouz, Bwa Dou, Bwa Kalou, Palmis and Coco de Mer (flowers).
Other key species
There are a number of significant animal species associated with Coco de Mer forest, in particular, the molluscs Vaginula, Stylodonta, Pachnodus, as well as invertebrates associated with palm and Pandanus leaf bases. Other insects and also green geckos of the genus Phelsuma may have a significant role in pollination of Coco de Mer. There are also three species of the genus Aeluronyx present in Vallée de Mai. Freshwater organisms are well represented. Among plants, Vallée de Mai may represent a significant refuge for populations of several endangered and vulnerable species of flowering plants, and also of ferns and epiphytes, which have been less well studied.