Biological Inventory of Saba

KNAP project 96-10
november 1997
Carmabi Foundation
Postbus 2090
Curaçao, Nederlandse Antillen

According to the data of Stoffers (1962,1963, 1966, 1973,1979, 1980,1982 and 1984) and Howard (1979, 1988 and 1989), and based on personal field observations (1966) the flora of Saba consists of 520 wild plants: 59 ferns and related species (Pteridophyta) and 461 seed-plants (Spermatophyta) of which 110 are monocotyledons and 351 are dicotyledons (Appendix I and II). Of the 110 monocotyledons 65 belong to the Cyperaceae and Gramineae (Appendix II).

There are no known island-endemic species on Saba Stoffers mentions two species in his publication, but both turned out to be species with a wider distribution. However there are species with a limited geographical distribution area. Of the 520 species, 98 (18.8%) are limited to the West Indies (including the south of Florida in some cases) and from these, 24 species only occur on the Lesser Antilles (including the Virgin Islands). This last group consists of 4.6% of the total number of plant species. Six species are limited to only a few islands. Two of those only occur on Saba and on one of the Greater Antilles, the others are also found on some other Lesser Antilles islands. It concerns the following species:

In addition to these six species, a rare variety of the West Indies species Charianthus purpureus is found in Saba, i.e. crinitus. It does not grow anywhere else except in St. Kitts. In August 1996 it was found flowering on top of The Mountain (personal observation) (photo 5). It is remarkable that the smallest island of the Windward Islands in the Netherlands Antilles possesses almost as many species as the island of St. Maarten that is 6.6 times as big. This is connected to the wide variety in habitats, including the very diverse habitat of the (secondary) rainforest. Especially Pteridophyta are numerous (photo 6). The climatological circumstances on The Mountain are very favorable for this group. Of the 59 species at least 40 species are found in this area. Furthermore Saba's flora consists of species that are restricted to the unique mountain formations, completely absent or very limited in the other two Windward Islands, e.g. the Mountain Cabbage, Prestoea montana, and three different species of tree ferns. Many of these species are restricted to the Lesser Antilles with Saba the most northern island of thier range of distribution. Howard (1989) indicates the importance of the Mountain Mahogany (Freziera undulata) that grows on the top of Mt. Scenery. This tree, although it also grows in Jamaica and the other islands of the Lesser Antilles, is nevertheless much smaller there, and hardly ever dominates the vegetation like in Saba. Other plants in Saba that are unique for the Netherlands Antilles are, among others, the insect catching Utricularia alpina and the saprofyte Voyeria aphylla growing in the same area.

With regard to the Bryophyte flora in Saba, 48 species of leaf mosses are known (Wiersma, 1984) and 31 species of liverworts (Augustinus et al., 1985). Saba and St. Eustatius' leaf moss flora are characterized by a high percentage of neo-tropical species and an extremely low rate of endemism (Wiersma, 1984). The representation of bryo-geographical elements is very consistent with that of the Lesser Antilles as a whole, except with regard to endemism, which amounts to 12% in the Lesser Antilles as a whole and only 2% in Saba and St. Eustatius. However, endemism occurs only on the larger and older islands like Guadeloupe and Martinique. The very young and small islands Saba and St. Eustatius do not harbor endemic species. Only one endemic variety for the top of Saba has been described: Campylopus atratus var. sabaensis. Several species have a relatively small distribution range and all of them can be found above 600 meters altitude. Three species are called Caribbean species by Wiersma (West-Indies and the nearby coasts of Central and South America): Leucoloma albulum, Crossomitrium orbiculatum and Porotrichum insularum.

The following quotation from Stoffers' publication (1956) aptly describes Saba's pattern of vegetation: “The zoning of the plant societies can be perfectly demonstrated in high volcanic islands. Beards' classification starts with rainforest, occurring in places where 'the yearly aridity stops being effective, and where a year-round abundant supply of moisture exists'. The area below this zone is submitted to a relatively dry climate, which results in either a vegetation of dry evergreen forest or seasonal forest, while immediately along the coast a small and limited zone is influenced by the salt laden wind, which has a dehydrating effect and is mechanically destructive. This results in a dry evergreen forest-like vegetation. Although the rainfall keeps increasing and is always present above the rainforest level, the rainforest does not continue to the top of the mountain. A series of mountain formations results, in which growth progressively decreases again, both in shape and form. These mountain formations consist of lower mountain rain forest, mountain brushwood and elfin woodland, and their secondary or sub-climax communities”.

Edaphic communities are lacking on Saba. The climax and mountain formations only occur above about 400 meters altitude in Saba. There, the rain is sufficient to provide the plants enough water throughout the whole year. Mountain formations are found above 800 meters. Lack of sunlight, due to mist, lower temperature, and the influence of the wind play a key role here.

The following is a short characterization of the most important types of vegetation from high to low (figure 5), indicating the importance of each, and possible endangering factors.

Elfin woodland, belonging to the montane formations, covers the top of The Mountain between 825 and 870 meters altitude (Augustinus et al., 1985). The average temperature and light-intensity are low there compared to lower parts of the island and the relative humidity is high. The elfin woodland consists of only a few tree species (Stoffers, 1956). These trees are mostly low and gnarled, and often form an impenetrable vegetation of 6 meters high. On the leewardside of the mountain, just below the top however, this forest grows higher and Mountain Mahogany (Freziera undulata) trees of up to 15 meters tall were measured here (Van 't Hof, personal med., 1997). The branches of the trees and bushes are weighed down with mosses and other epiphytes (photo 7), mostly ferns, but orchids are also present. The Mountain Cabbage (Prestoea montana= Euterpe globosa) and tree ferns can be found, though in small numbers. Vines and creepers are numerous and epiphytes also grow terrestrial. Many trees are bush-like. The Mountain Mahogany and Myrsine coriacea (= Rapanea coriacea) are dominant. Among the shrubs Marila racemosa, Charianthus purpureus var.crinitus (= C. crinitus) and the White Bell (Hillia parasitica) often occur. Purple Heart (Phytolacca rivinoides) en Psychotria guadelupensis (= P. pendula in Stoffers, 1956) are present in small numbers. In the herb layer many ferns, Mountain Manna (Begonia retusa) and in some places Anthurium cordatum are found. The largest number of species consists of vines and epiphytes.

Leaf-mosses and liverworts play an important role in the vegetation types of Saba, both qualitatively and quantitatively (Augustinus et al., 1985). Under conditions of maximum humidity because of the continuous fog and rain showers, a remarkable development of bryophyte flora took place on the top of The Mountain. In contrast with the moss flora in (the remains of) the elfin woodland in St. Eustatius, the moss flora in the elfin woodland in Saba consists mainly of liverworts (photo 8). Leaf mosses are rare. The trunks and branches of the trees and even the aerial roots of the epiphytic bromeliads are covered with a thick layer of liverworts. The weight of these mosses on each well-developed tree is estimated at hundreds of kilograms. The abundance of liverworts in this vegetation is larger in quality and quantity than in all other vegetation types.

Even though elfin woodland is found all over the Caribbean on high summits and mountain ranges that are veiled in clouds almost permanently (Stoffers, 1956), Howard says the elfin woodland in Saba is unique. The Mountain Mahogany also occurs in elfin woodland in other islands, however, nowhere is it the dominant species. According to Howard this tree is bigger on Saba than on the other islands. In the elfin woodland of St. Eustatius the Mountain Mahogany is absent. Here the Wild Balsam (Clusia major) dominates.
In the past a small-scale disturbance took place through the planting of tannia- and banana, and also by the construction of the present trail to the top and the building of the radio mast, the latter being the major disturbance. Howard (1989) points out that the vegetation of the top forms a thick water absorbing layer, which slowly releases its water to the lower levels, perhaps even down to the areas where agriculture takes place, including Rendezvous and the villages of The Bottom, Windward Side and Hell's Gate. This “sponge” has already been broken by the construction of the transmitting mast, and the effects are visible in the form of a different kind of vegetation. Howard cautions that further removal of the vegetation for the benefit of more masts will deteriorate the situation. Besides, it will affect what is left of the unique vegetation on the top and may even impact the vegetation on all the slopes of Mount Scenery.

The palm brake lies below the elfin woodland between 775 and 825 meters altitude (Augustinus et al., 1985) and also belongs to the montane formations. This type of vegetation appears under the same climatological conditions as elfin woodland, but only on very steep slopes with loose substrate prone to sliding. Thus Beard (1949) considers this type of forest as a 'disturbance climax'. According to Romeijn (1987) in places where little stonewalls remain from former miniature cultivation plots the forest shows the same structure as in the adjacent areas, indicating a very fast regeneration capacity of the palm brake. In the palm brake the Mountain Cabbage (Prestoea montana= Euterpe globosa in Stoffers, 1956) is typical and dominant (Stoffers, 1956) (photo 9). The forest height is very variable (between 7 and 20 meters). There is no shrub layer, there is however, usually a very rich herb layer dominated by ferns. Here and there little groups of tree ferns are to be seen. Elsewhere in the Caribbean this type of vegetation is also found, and on several Lesser Antilles the Mountain Cabbage also is an important species. Because this type of vegetation is connected to steep slopes, anthropogenic disruption has been slight. Furthermore goats only penetrate the forest above the 600 meters (Romeijn, 1987) in times of severe aridity. This forest can be counted as one of the few original types of forest.

Below the palm brake lies the tree-fern brake. At an altitude of 575 meters there is a sudden change of secondary rain forest into this tree-fern forest (photo 10). The vegetation consists of up to 4-meter tall tree-ferns (Cyathea arborea en Cyathea antillana), standing very close together and making it too dark for a shrub or herb layer under the foliage. This vegetation is typical for secondary vegetation, which appears after the rainforest has disappeared because of human activities or a natural fire. The report of Augustinus et al. (1985) proposes that high humidity is essential to the development of this type of forest. The leaf moss flora of the tree-fern brake is much poorer than that of the secondary rain forest, but the liverwort flora is equally rich (Augustinus et al., 1985).
According to Romeijn (1987) the success of the tree-ferns can partly be explained by the fact that goats do not eat the leaves. Although goats occur mostly below the height of 300 meters, in arid times they can penetrate to above 600 meters. By doing so they influence the vegetation on the major part of the island.

True rainforest, as a climax formation such as known from the larger Antilles, does not exist on Saba (Stoffers, 1956). There is a type of vegetation however, that can be called ravine rainforest. It is found only in deep ravines, too steep or to inaccessible to be planted. Two locations are known: Down Gut (Van 't Hof, pers. comm., 1997) and a ravine at Island Gut (Stoffers, 1956). In this latter location Bird's Cherry (Myrcia citrifolia) is the most common species. This tree reaches a height of 8-10 m. Bird's Cherry is accompanied by Sloanea massoni (=S. truncata in Stoffers, 1956). Psychotria berteriana is abundant as an often-bushy 6 m tall tree. Tree ferns are numerous, but the Mountain Cabbage is only found in small numbers. The climbing Elephant Ears (Philodendron giganteum) and P. lingulatum are abundant, and Marcgravia umbellata is common. The brush layer is rather open. Ferns are abundant. In the herb layer scattered groups of Wild Banana (Heliconia bihai) can be seen. Only one epiphyte was collected: Tillandsia utriculata. Trunks and leaves are generally covered in liverworts. Leaves are of medium size and evergreen. Neither buttress roots nor prop roots are found. According to Stoffers (1956) this type of rainforest has not been described for any of the other islands of the Lesser Antilles or Virgin Islands.

Originally the major part of the zone between 420 and 650 m was covered in rainforest (Augustinus et al., 1985). Since the colonization of the island a large part was deforested for agriculture. The agricultural area gradually decreased during the twentieth century however. Only at Troy, Rendezvous, and Hell's Gate some small plots can still be found (photo 11). Nowadays mostly secondary rainforest(photo 12) is seen in this zone,in which many signs of past anthropogenic influence are still present,such as terraces with low walls and planted fruit trees such as Guava (Psidium guajava), Cacao (Theobroma cacao) and Avocado (Persea Americana).

Usually thickets of young trees are found here, quite variable in height from place to place (Stoffers, 1956). Some trees have aerial roots. Undergrowth is practically absent, save some areas with Anthurium cordatum. The strangling fig (Clusia major) is frequently seen. Several typical rainforest species are found such as Black Seet Wood (Nectandra krugii), Hairy Plum (Hirtella traindra), Blue Berry (Symplococcus martinicensis) and Sticking Berry (Cordia sulcata). They signal the development of a new rainforest. Ferns are often abundant. Ten different species of orchids are found here on the trees together with a number of Bromeliads mostly of the genus Tillandsia (Stoffers, 1960). The low stone walls are overgrown with lichens, Piperaceae and ferns. As the altitude increases conditions become gradually more humid. The forest is regularly veiled in mist, causing a decrease of average light intensity and temperature (Augustinus et al., 1985). Of all the vegetation types studied in Saba the moss flora present here is the richest. The number of species in this vegetation type increases with increasing altitude. Liverworts too are well represented.

In some places in the secondary rainforest the vegetation consits mainly of thickets of Miconia laevigata and Tetrazygia discolor, or of trees with a dense shrub layer, in which Piper reticulatum often occurs (Stoffers, 1956). The first type of vegetation is called Miconia thicket by Stoffers, and the last Piper dilatatum thicket. According to Stoffers the latter was much influenced by human activities, particularly by charcoal burning. At present however, charcoal burning no longer occurs (Van 't Hof, pers. med., 1997).

In the western part of the island between Parish Hill and Great Hill, and The Bottom and Torrents Point, and in the east below English Quarter (fig. 6) between 200 and 350/420 meters altitude (Augustinus et al., 1985), woodland derived from dry evergreen forest is found. In the west this vegetation covers the largest area. This area is located on the drier leeward side of The Mountain. The vegetation here is very dense, about 5 meters high and made up of species of the genus Guettarda, Eugenia, Myrcia, Citharexylum, Pithecellobium, Chiococca, Croton and Lantana. From this several higher trees emerge, such as the Wild Misple (Morisonia americana), the Tamarind (Tamarindus indica), the White Cedar (Tabebuia heterophylla= T.pallida) and Trema lamarckiana (= T.lima in Stoffers, 1956). In addition to the Tamarind other fruit trees from elsewhere are also found here and there, proving that these areas were formerly cultivated to some extent by Saba's inhabitants. In the ravines banana trees are usually growing at this altitude. According to Stoffers (1956) the vegetation below English Quarter in the east was severely impacted by human activity. As a result of all the past disturbances the vegetation, derived from dry evergreen forest, now shows a varied pattern. Notable is part of the area north-east of Middle Island and along the stairs to Ladder Bay, where Stoffers saw many young Mahogany trees (Swietenia mahagoni) (personal observation, 1996). These trees have now grown into full-grown specimens (personal observation, 1996). Howard remarked in 1989 that within a few decades, seedlings of these trees had grown into fruit bearing trees. He considers it possible to plant these trees for wood production.
The flora of the leaf mosses in this area includes nine species (Wiersma 1984), much less than in the secondary rain forest (23 species). The liverwort flora of this type of vegetation is called poor (Augustinus et al., 1985).

Between Rendezvous, The Level and Old Booby Hill a secondary woody vegetation, derived from seasonal forest, is found. In some parts there are many loose rocks and locally it is very steep. Partly it is used as grazing land. The vegetation shows no closed canopy. The density varies from very dense to rather open. Several taller shrubs and trees in this vegetation are Miconia laevigata, the Maho (Daphnopsis americana ssp.caribeae = D.caribaea in Stoffers, 1956), Sweet Wood (Nectandra coriacea) and Red Wood (Inga laurina). Grazing prevents progression in the succession series.

In lowest and driest parts of Saba Croton thickets are found (photo 13). Sometimes a few little trees or high shrubs are scattered in it, sometimes there is only Marrow (Croton flavens). Wild Sage (Lantana camara, L. involucrata) and several cactus species can often also be found. There are no leaf mosses here and only a few liverworts (Augustinus et al., 1985) The lower parts in the south and east are used for goat grazing, whereas in the northeast there are goats gone completely wild (Romeijn, 1987).

Even though Stoffers does not mention a coastal vegetation in his publication (1956), a small strip of Hippomane woody vegetation at Core Cut Bay can be reported (personal observation, 1996). Like in St. Maarten it was also in a bad condition (photo 14). Most trees were bare. Probably here too this is due to hurricane Luis.

Like in St. Eustatius the description of Saba's vegetation is incomplete. Stoffers did not consider the vegetation in the northern part of the island below roughly 500 meters. This area was visited however in August 1996.

It is a wild and pristine area of high scenic value (photo 15). The coast here is very steep and the vegetation in the coastal area is influenced by the strong trade winds. In several steep ravines the vegetation is very lush. There are several points where the visitor can enjoy the beautiful views (photo 16).

The elfin woodland is very important due to its regional rarity, the presence of unique species, and also because of its water retaining potential. The palm brake and the ravine rainforest are important especially because of their virginity, and the recovering secondary rainforest mainly because of its wealth in species, both of higher plants as well as of bryophytes. The secondary vegetations below the rainforest are mainly important in the control of erosion, and they also have scenic value, especially the parts between The Bottom and Well's Bay. With regard to the woodland derived from dry evergreen forest, it should be taken into account that dry tropical forests have internationally been severely impacted by human activity and have for instance practically disappeared in Central America and certain areas in South America (Janzen, 1998, Ceballos, 1995).

A total of five bat species were found at any time in Saba. (Appendix III). Husson (1960) only mentions one, the St. Vincent Fruit-eating Bat, however on the Knox Jones and Phillips (1970) list of bats of the Lesser Antilles, three species are mentioned. A fourth species was collected in August 1996 and a fifth species in April 1997. Four of the five species can also be found on St. Eustatius and St. Maarten, one only on Saba. None of the species is endemic for Saba.

The St.Vincent Fruit-eating Bat (Brachyphylla cavernarum) is a West Indian species that can be locally abundant (Petersen et al., 1996). It is apparently not very sensitive to the effects of huyrricanes because of its omnivorous diet (Petersen et al., 1996). This bat was collected in a small cave in 1949 and 1959, close to the coast at Landpoint (Husson, 1960). The name Landpoint is unknown on Saba. Surely Tentpoint was intended with Landpoint. Westermann and Kiel, (1961) mention the name Landpoint on their map of Saba instead of Tentpoint. Furthermore, Wagenaar Hummelinck (1979) mentions a cave on Saba not formed in limestone, supposedly called Bat Hole and situated on the coast west of Fort Bay. In this category of caves the same author mentions Chamber and Hall beneath the top of Great Hill. In August 1996 the cave at Tent Point was localized but could not be reached.

The Free-tailed Bat Tadarida brasiliensis antillularum and the Mastiff bat, Molossus molossus debilis are both small and insectivorous. They belong to the same families and resemble each other very much. The Free-tailed Bat is limited as sub-species to the West Indies and the Mastiff bat as sub-species to the northern Lesser Antilles (Knox Jones and Phillips, 1970). The Free-tailed Bat can be found in houses, in caves and in hollow trees. The Mastiff Bat is really a house bat. It prefers to live in attics. In Saba a Mastiff Bat was collected for the first time In August 1996. A resident of Saba (Mr. Don McGehee) found the animal in a swimming pool. Several Free-tailed Bats were netted nearby a swimming pool (Walsh-McGehee, personal comm., 1997).

The Mexican Funnel-eared Bat (Natalus stramineus stramineus) is a widely spread insect-eating American species. The sub-species however, is found only in the Lesser Antilles. In addition to Saba, this species was only seen in Antigua, Anguilla, Montserrat and Dominica.

The Jamaica Fruit-eating Bat (Artibeus jamaicensis), a large fruit-eater, is widespread on the American continent. It can easily cover the distance to these islands. Besides the small cave at Tent Point, where the St. Vincent Bat was found, no information was found in the literature about locations of diurnal roosts or foraging areas. In addition to the cave at Tent Point, informants only mention the sulphur mine at Pirate Cliff. A bat colony is supposedly roosting here. The sulphur mine was visited in August 1996, but no bats were found. The entrance of this mine caved in some time ago however, leaving only a small hole. Even though there are no other known caves in Saba, it is possible that there are holes in the numerous steep cliffs, which are used by bats. Furthermore buildings and hollow trees can serve as diurnal roosts.
Apparently there are no nectar-eating bats in Saba, which play an important role in pollination in many eco-systems. There are however fruit-eating bats, which are important for the spreading of seeds.

BIRDS

Differences between avifauna of the islands are caused by a combination of factors: the size of the island and the height above sea-level, variety in habitat, isolation and the influence of human and several imported animals (Evans, 1990). Saba being the smallest of the Windward Islands one would expect the smallest number of breeding birds. However, the number of breeding birds is the same as in St. Eustatius. Of course the size of the island limits the number of birds that can maintain themselves there, but this is partly compensated by the diversity and richness of the available habitats. Although coastal habitats are mostly lacking, there is large variety in terrestrial habitats, from dry Croton thickets to rainforest and elfin woodland. Especially the (secondary) rainforest offers optimum possibilities for birds. Although in the past a large part of this rainforest was cut down for farming, today many fields are deserted and the forest once again has the opportunity to develop. Also, several steep, densely overgrown ravines are inaccessible for people. In addition the population density is low, even lower than in the past, and large parts of the island are uninhabited. Furthermore the Mongoose is absent. These are all favorable conditions for the avifauna. In Saba inland bays and saliña's are completely absent, but there are two very small rocky islands in front of the coast, that accommodate breeding seabirds.

Saba's avifauna consists of 26 sedentary and breeding birds, and 36 migratory birds and visitors from elsewhere (Voous, 1983). There are17 seabirds, of which 5 species nest in Saba (Appendix III). None of the species is endemic to the island. However there are species or subspecies with a limited geographical range.
Most of Saba's breeding birds are West Indian species: 15 of the 26, of which 5 are endemic to the Lesser Antilles and the Virgin Islands. Of 4 species the subspecies are limited to the Lesser Antilles (Appendix III).

The following species are endemic to the Lesser Antilles and Virgin Islands at the species level:

The Green-throated Carib and the Antillean Crested Hummingbird exploit the wealth in flowering plants both in the forest as well as in the gardens and along the agriculture plots. They are common birds, but he Crested Hummingbird is not seen above the 400 meters (Voous, 1983). The Purple-throated Carib is more a bird of the humid forest and is rare on Saba. Usually it is only found in the lush vegetation at higher altitudes, especially in the tree-fern woods and in the banana plantings at the top of The Mountain (Voous, 1983). This bird was observed in the area of Sandy Cruz in August 1996. In the field it looks black and it flies like a small torpedo through the lower layers of the forest.

The Scaly-breasted Thrasher resembles the Pearly-eyed Thrasher (Margarops fuscatus) and lives in the same habitat, but in Saba it is more common (Voous, 1983). It is a shy bird that stays hidden in the dense foliage of the canopy layer. It feeds mainly on fruit. Sometimes both species are found in the same tree when they visit the fruit plantations. The Scaly-breasted Thrasher was observed only once in the forest of Troy in August 1996. The Pearly-eyed Trasher however, was seen at several sites and was notably numerous in the secondary evergreen forest between The Bottom and Well's Bay.

The trembler can be found in the humid cloud forests above 450 meters in Saba, where it moves between the vertical trunks of the tree-ferns and the lianas, looking for food among the bromeliads, orchids and other epiphytes (Voous, 1983). In general it is a quiet and inconspicuous bird, which can be easily missed (Evans, 1990). However in August 1996 it was observed and heard at Mount Scenery and Troy. This bird is limited within its range to mountain forests (Voous, 1983). On several islands it is an endangered species or may possibly be extinct already, like in Martinique. Saba's subspecies is limited to only a few islands: Saba, St. Eustatius, St. Kitts, Nevis, and Montserrat. Conservation of the vegetation of The Mountain above 450 meter is undoubtedly of major importance to the continued survival of this regionally rare species/sub-species.

The Lesser Antillean Bullfinch is one of the more common birds in the Lesser Antilles (Evans, 1990). On Saba it feels at home in the shrubs at sea-level as well as in the humid forest high on The Mountain, and in the gardens of the houses (Voous, 1983). Saba's subspecies lives only on the islands south of Saba down to Montserrat. In St. Martin another subspecies is found.

The Zenaida Dove and Common Dove are species that live in the dryer habitats, although the Zenaida Dove sometimes penetrates the rainforest (Evans, 1990). The range of the Zenaida Dove given for Saba in The Preliminary Data Atlas of ECNAMP (1980) only includes the lower slopes along the coast, but according to Voous (1983) the bird is typical for the montane forest just like the Pearly-eyed Trasher. In August 1996, it was observed in the area of Cow Pasture and at Lower Hell's Gate, while being especially numerous in low shrubs along the coast of Tent Bay. The Common Ground Dove is one of the most numerous species in inhabited areas in the other islands. However Voous reports it to be remarkably rare in Saba. The Preliminary Data Atlas only mentions Flat Point as the range of the Common Ground Dove, but this bird was observed at the same location as the Zenaida Dove at Tent Bay in August 1996. Both birds are mentioned in the ECNAMP-report as species that are hunted.

The Blue-crowned Euphonia mostly lives in the rainforest within its range, especially montane rainforest, but occasionally also in dry woody vegetation and secondary brushland (Evans, 1990). It is not common there and easier heard than seen. This beautiful bird was seen a few times on Saba, always in the lush overgrown ravines above 300 meters (Voous, 1983). Breeding has not been proven, and since 1952 several observers looked for it in vain. It was not seen in August 1996, and none of the informants had ever observed one either. The species must be rare, endangered of already extinct.

Two other larger dove species that are also hunted according to the ECNAMP report, are the Bridled Quail Dove (Geotrychon mystacea) and the Red-necked Pigeon (Columba squamosa).
Outside of the Lesser Antilles and the Virgin Islands, the Bridled Quail Dove is only found in Puerto Rico (Evans, 1990; Chipley, 1991), though it is rare there, except in a few locations (Rivera-Milán, 1992). This bird is most abundant in the larger Virgin Islands. There its numbers increased since the beginning of this century. Elsewhere however, the species has declined and according to Evans (1990) it should be considered highly endangered in the southern Antilles. In Dominica and Barbuda it is extinct already. The Bridled Quail Dove is Saba's only species mentioned in the ICBP/IUCN Red Data Book of 1992. It is listed as a nearly threatened species. On Saba this bird is rather common in the woody ravines and the cloudforest (Voous, 1983). It even visits the gardens in Windwardside at 400 meters high.
According to the Preliminary Data Atlas (1980) it is also found in the secondary dry evergreen forest. It also occupies this latter habitat in the island of Guana (one of the Virgin Islands), where it avoids areas with cactuses and thorny bushes (Chipley, 1991). In August 1996 the Bridled Quail Dove was observed in the area of Mary's Point.

The Red-necked pigeon is a much persecuted bird. Everywhere in its range it is hunted. For that reason probably, it has become rare in many locations (Evans, 1990). Its preferred habitat is the rainforest, but it is also observed in the dryer woodland vegetations. On Saba it is found all over the island (ECNAMP, 1980), though more in the higher than in the lower parts. A couple were observed in Cow Pasture in August 1996 at an altitude of about 200 meters, thus rather low. On the other side of the island near Pirate Cliff and rather low too, the bird was also observed. The Red-necked Pigeon is suspected to make trips over the sea (Voous, 1983). That would be the reason why it occurs only periodically.

The lower slopes in the east and southeast of the island are favorite hunting grounds of two species of bird of prey (Voous, 1983). The largest is the Red-tailed Hawk (Buteo jamicensis jamaicensis). Evans (1990) calls it a common species in the northern Caribbean, where it is widespread in a large number of habitats with a preference for mountains.
This bird nests in the Virgin Islands and in Saba (Evans, 1990) and according to Voous (1983) also on St. Eustatius. Five or six couples supposedly live in Saba (Voous, 1983). In contrast to St. Eustatius, the Red-tailed Hawk was observed in Saba on several locations in August 1996: Grey Hill, Sandy Cruz and Troy. Shortly before, four birds were observed together (Johnson, personal comm., 1996). These observations correspond with Voous' estimations. It is probable that these animals still nest in Saba. In St. Maarten has been hunted almost to extinction because it is supposed to be a chicken thief.

The American Kestrel (Falco sparverius caribaearum), a small bird of prey, is common in the northern Lesser Antilles and the Virgin Islands, however in the east of St. Lucia it is only an occasional visitor (Evans, 1990). It is listed on Appendix II of CITES. This bird can also be found in inhabited areas. In August 1996 it was seen flying above the road to Hell's Gate.

The other seven terrestrial breeding birds (Annex III) have an extensive geographical range. Most of them are common in Saba. However, two species, which in the other islands are numerous in the vicinity of houses, are scarce in Saba: the Bananaquit (Coereba flaveola bartholemica) and the Black-faced Grassquit (Tiaris bicolor omissa). The first lives in all kinds of habitats, but the latter inhabits only dry warm slopes with low shrubs (Voous, 1983).
Among the terrestrial breeding birds there is only one coastal bird: the Green Heron (Butorides striatus). Breeding in the island has not been proven however. Voous (1983) does not mention the Yellow-crowned Night Heron (Nyctanassa violacea bancrofti) as a breeding species. According to him it was observed only once. Mulder and Stam (1987) observed this bird several times in 1987. It is known to be a crab eating species. It might be possible that this bird nests on Saba.

Notwithstanding the lack of inland bays, marshlands and sandy beaches, five species of seabirds nest in the island. Important factors are the steep cliffs along the coast, and two rocks in the sea: Green Island on the northern coast and Diamond Rock on the northwest side of the island. Van Halewyn and Norton (1984) do not classify Saba as an important breeding area for seabirds; nevertheless several seabirds do nest here which according to these authors are considered possibly threatened or threatened.

Audubon's Shearwater (Puffinus lherminieri lherminieri) has the status of a threathened species, which should receive special attention with regard to conservation measures. The breeding grounds of these birds are almost exclusively restricted to the Caribbean region, with the islands of the Southern Lesser Antilles and Tobago as the main area (Haleweyn and Norton, 1984). The breeding habitat is quite varied. The birds nest in holes in the ground high in the hills, but also in natural hollows under cliffs, rocks and in limestone, sometimes only just above sea level. Both the birds and their eggs are subject to human exploitation. These birds are known to breed in sheltered places in the higher parts of the island (Voous, 1983). Nests were found above Hell's Gate at an altitude of 600 meters in 1928 and 1937. In the ECNAMP Preliminary Data Atlas a location on Great Hill is also indicated.

Two species of tropicbirds nest on Saba. The Red-billed Tropicbird (Phaeton aetherius mesonauta) is possibly threatened according to van Halewyn and Norton (1984). Its status should therefore be monitored. The Caribbean region is its main breeding ground. According to van Halewyn and Norton (1984) this species is most numerous in theVirgin Islands and Tobago. Voous (1983) estimated their numbers in Saba at 20 couples or less. In the Preliminary Data Atlas (ECNAMP, 1980) three locations are mentioned: Kelby's Ridge, Old Booby Hill and Fort Bay. Voous (1983) only mentions Booby Hill Cliffs, but he observed that there are undoubtedly many other breeding places. The results of counts of the Red-billed Tropicbirds in April 1997 all around the island (Walsh-McGehee, 1997) require an adjustment of the numbers Voous reports for Saba. The number of Red-billed Tropicbirds is estimated at 750 to 1000 pairs according to these counts, however these were counted outside the peak period (Walsh-McGehee, 1997). This makes Saba the island with the largest number of breeding pairs in the Caribbean Region. Red-billed Tropicbirds were seen at Cove bay, Tent Bay and Green Island in August 1996. A pair disappeared in a crack in the rocks opposite Green Island (Pirate Cliff) (photo 17).
According to van Haleweyn and Norton (1984) eggs of Red-billed Tropicbirds are occasionally gathered and birds are sometimes killed also, but these activities remain limited because the nesting places (holes in sea cliffs) are mostly inaccessible. In several locations the lack of sufficient nesting habitat may limit the population size. That would be why the Caribbean populations are small, but relatively stable according to van Halewyn and Norton (1984). Walsh-McGehee (1997) however, warns that coastal development, so common in West Indian islands, is causing enormous habitat losses.

The Yellow-billed Tropicbird (Phaeton lepturus catesbyi) also nests in Saba, however according to Voous (1983) only a few pairs are present. Walsh-McGehee (1997) reports that their numbers in Saba are much lower than of the Red-billed Tropicbirds, and their nests are less accessible. The Red-billed Tropicbird dominates the Yellow-billed in places where they compete for nesting sites (van Halewyn and Norton, 1984). Their breeding seasons overlap only partly however. The Yellow-billed Tropicbird nests in spring and in summer.
According to van Halewyn and Norton (1984), the conservation status of this species is not really worrying, but recent data suggests that the Caribbean breeding populations have decreased by half since the 1980s (Walsh-McGehee, pers. comm. 1997). Coastal development and loss of nesting sites are supposed to be the main cause for their decline. That is why Walsh-McGehee thinks Saba is so important for breeding Tropicbirds.
Nesting sites of the Yellow-billed Tropicbirds are known from Fort Bay to Flat Point (Voous, 1983), and from several locations on the northern and western coast (ACNAMP, 1980). The species was possibly not distinguished from the Red-billed Tropicbird in August 1996.

On the little rock island Diamond Rock (photo 18) the Bridled Tern (Sterna anaethetus recognita = S. anathetus melanoptera?) nests. This tern is widespread and a rather common breeding bird in the Caribbean region (van Halewyn and Norton, 1984). It is quite rare above the sea around Saba. In 1972 a breeding colony of at least 25 pairs was found at Diamond Rock (Voous, 1983). Van Halewyn and Norton (1984) report the number of 50 pairs.

The Brown Noddy (Anous stolidus stolidus) is second most numerous breeding seabird in the Caribbean region (van Halewyn and Norton, 1984). It nests in several habitats, but disturbance may force it to take refuge in less suitable breeding habitats. In summer it is quite common above the sea around Saba. It probably nests on Green Island (photo 19) but was also observed around Diamond Rock and Flat Point (Voous, 1983). Roughly 150 birds were seen around Green Island in August 1996.

Brown Boobies (Sula leucogaster) possibly nest on Diamond Rock and Green Island (Voous, 1983). These birds are regularly seen there (Voous, 1983 and Van 't Hof, personal med., 1996).

Other seabirds are observed above the sea around Saba, but do not breed on the island.
The Magnificent Frigatebird (Fregata magnificens) and Brown Pelican (Pelecanus occidentalis), that are considered endangered by Halewyn en Norton (1984), are regularly observed around the island. Frigatebirds were observed at Well's Bay and Cove Bay, and the Brown Pelican at Green Island among Brown Noddy's in August 1996.

Saba, like the other Antillean islands, is important for migratory birds and winter visitors from North America (Annex III). Mostly they are not numerous, but are easily missed in the dense vegetation (Voous, 1983). Voous (1955) mentions the visiting American Redstart (setophaga ruticilla) a bird typical for the montane forests.

The relative isolation of the island because of the relatively large distance to other islands is reflected in the island's herpetofauna: a few species, but there is one true island endemic. One amphibian and 10 reptiles are known from Saba: 5 species of lizards, one species of snake and 4 species of seaturtles. Of the 5 species of lizards, only two are active during the day, half as many as on St. Eustatius. One of these two is an endemic anolis: Anolis sabanus. Ground-lizards are totally absent. Of the other three lizards that are active during the night one has a limited geographical range. The snake species is limited to Saba and St. Eustatius.

Saba's only amphibian is the same as the one in St. Maarten and St. Eustatius: Eleutherodactylus johnstonei (Annex III). It is species of the Lesser Antilles. On most islands it is abundant in disturbed habitats and secondary forest, but on smaller islands it also occurs in primary forest due to the lack of other species of Eleutherodactylus, as is the case in Saba (Kaiser and Henderson, 1994). On some islands of the Lesser Antilles this species was imported and according to Schwartz (1967) possibly also in Saba from St. Eustatius. The animal adapts easily and is supposed be able to outcompete other, native species (Kaiser and Henderson, 1994). Although its size is small, the piping frog makes an impressive sound. This amphibian's singing is heard on Saba as soon as dark sets in and also during the day after a rain shower.

Anolis sabanus

Lazell (1972 calls it the harlequin among the anolises of the Lesser Antilles because of the dark spots that occur all over the body of the males (photo 20). The females are mostly paler and they have paler spots. Sometimes females have vague stripes on their back. This anolis is found from sea level to 870 meters high, however not on Diamond Rock and Green Island (Lazell, 1972). It is evenly distributed and numerous all over the island, except in the driest areas, where it occurs in small groups in the shade around shrubs. It is inconspicuous in its behavior and withdraws into holes and cracks when disturbed. This lizard was seen in different habitats in August 1996, from the rubble beach of Well's Bay to the top of Mount Scenery.

Saba's only snake, the Red-bellied Racer Alsophis rufiventris (photo 22) has a very limited geographic range. In additon to Saba, it is only found on St. Eustatius. The animal used to live on St. Kitts and Nevis, but has not been seen there since the 19^th century (Daltry et al., 1997). Its disappearance is related to the introduction to these islands of the Mongoose.
Because of the dramatic decline of its range (from 302 km² to 33 km²), the Red-bellied Racer is now listed as endangered on the IUCN's “Red List of Threatened Animals” of 1996. Within its present day range it appears to be still present in high densities, especially at higher altitudes. It was more often observed in Saba than in St. Eustatius (Daltry et al., 1997). According to the guide Johnson it is often sighted during field trips. In August 1996 a specimen was observed in the neighborhood of Mary's Point. Daltry et al., (1997) report that 55 % of the snakes had incomplete tails, which suggests that they are nevertheless seriously predated. The natural enemy of this snake is the American kestrel, Falco sparverius. Among the introduced preditors cats hunt snakes, and even chickens have snake on their menus. Rats eat snake eggs and on other islands are known to also attack the Racers. Moreover people on Saba persecute snakes believing them to be poisonous. Daltry et al., 1997 point out the danger of accidental introduction of the mongoose from other islands. The Red-bellied racer preys on Eleutherodactylus and lizards (Schwartz and Henderson, 1975). These prey are present in abundance, especially in the wooded habitats.

Three lizard-species of Saba belong to the geckos that are active at night. One of these species, Sphaerodactylus sabanus is only found on Saba, St. Eustatius, and St. Kitts and Nevis. Nothing is known about its habits and status. Two other geckos are widespread. They often occur in houses and were probably introduced by humans.

The Green Iguana is widely spread throughout the Antillean islands and the American continent (Annex III). Destruction of habitat endangers many populations in its range of distribution (Lazell, 1973). Almost everywhere it is hunted for food. It is listed on the Appendix II of CITES. On Saba too hunting endangers it. Its habitat extends from sealevel to about 500 meters high. Steep rockwalls are its preferred habitat. Informants particularly note the area around Spring Well's Bay to the road (Leysner and Johnson, personal comm., 1996). The inaccessibility of the Green Iguana's habitat is no obstruction for the hunters regrettably, who get their prey with rifles (Carmabi/Stinapa, annual report 1992). In August 1996 one animal was observed at the side of the road near English Quarter.

Four species of sea turtle are common in the sea around the island: the Green Turtle (Chelonia midas), the Hawksbill Turtle (Eretmochelys imbricata), the Loggerhead (Caretta caretta) and the Leatherback (Dermochelys coriacea). The first two are seen most often (Sybesma, 1992). All four species are listed on Appendix I of CITES as endangered species. Green, Hawksbill and Leatherback Turtle have in the past nested on Saba, however the nesting frequency must be very low because Saba only has temporary sandy beaches. In the past nesting was observed at Fort Bay, Well's Bay and Cave or Rum Bay (Barkau Maylan, 1983). Sea turtles enjoy a certain protection on Saba. There is an island regulation that limits their capture (Sybesma, 1992).

There are two species of land crabs found on Saba. The Red Shank (Gecarcinus lateralis) lives close to the sea (v.d. Hoeven and Walters, 1987). The Mountain Crab (Gecarcinus ruricola) lives on the ground in the higher regions. Both species are important as detritivores in the terrestrial ecosystem of the island. Since the early 80's The Mountain Crab was collected and shipped to St. Maarten. This caused a serious decline of the population. During the late 70's these crabs are supposed to have been present in large numbers on and besides the roads (v.d. Hoeven and Walters, 1988). Mulder and Stam (1988) also studied the Hermit Crab Coenobitus clypeatus on Saba, as well as the Mountain Crab.

14 species of terrestrial and fresh water snails (Vernhout, 1914; Haas, 1960 and 1962),
one species of scorpion, probably endemic (de Armas, 1983),
one species of mite (Kohls, 1969),
70 insect species (Weber, 1948; v.d.Kuyp, 1953 en 1954; Cobben, 1960; Drake & Cobben, 1960; Marcuzzi, 1962; Forrest Gilmour, 1963; v.Doesburg, 1970; Cobben & Wygodzinsky, 1975; Stusák & Cobben, 1975; Marcuzzi, 1977; Simonthomas, 1984),
including 27 species of diurnal butterflies (Smith et al., 1994; Miller and Miller, pers.comm., 1996).

In August 1996 eight species of diurnal butterflies were collected. The specimens were sent to butterfly expert Lee D. Miller for definitive identification. In addition five species of terrestrial and fresh water snails were collected. These were sent to snail expert Dr. A. Hovestadt for identification.

In the preceding text several threats to the biodiversity have already come forward. With the exception of hurricanes, humans are the source of all threats. Below are the most important ones:

Of the three Windward islands of the Netherlands Antilles Saba has without question received the most attention with regard to the conservation of its natural heritage. Even in 1957 Thijsse, studying possibilities to increase the level of prosperity in the Windward Islands and in Bonaire, concludes that conservation of certain nature areas is indispensable if one wants to activate the tourism potential. He notes that this will necessitate additional legislation in the area of nature conservation, conservation of monuments, agriculture and husbandry, planning, and construction. Winsemius (1962) was commissioned to study the planological results of tourism as a consequence of the imminent opening of the airport and the construction of the harbor. He speaks highly of the nature and scenery in this “dream island” and predicts that the attraction for tourists will be extremely great. Even then there was supposedly great interest for Saba in the US. Winsemius however, counsels steady development and protection of ”strategic” areas.

Stinapa already became involved in the new developments in Saba in 1968, and made concrete proposals for the establishment of nature reserves and the management of some of them (Westermann, 1969). Several important people supported these initiatives. Westermann (1969) for example stresses in his article that the remains of the woodlands in Saba should be managed as a nature reserve for the good of science and recreation. This would also safeguard the habitat of the Trembler, the Common Ground Dove and the Blue-crowned Euphonia. According to him there would be no objections to the construction of trails and even some tourist roads in the area to be preserved, but construction of houses and agriculture should be excluded. Westermann calls the volcano highly interesting, but does not feel the need for special protection of Saba's geological formations since it is unlikely that human activities would cause them to disappear or to be seriously affected. In the case of the stone crushing facility though, there is a definite alteration of the geological formations, and of the scenery. Mörzer Bruyns (1969) is of the opinion that Saba is such a beautiful and “rich” island, that the whole island should without hesitation be declared a 'national park', for practical reasons perhaps with the exclusion of the settlements and their immediate surroundings.
He points out that tourists take orchids as souvenirs, while tree ferns are cut to make flower boxes. Because Saba is completely dependent on the development of tourism, he recommends among other things, opening up of beautiful nature areas with walking trails, for research and educational purposes as well as for 'ordinary' tourism. Such development would of course need to go hand in hand with legislation to protect flora and fauna. Where necessary, particularly important areas should be designated as strict reserves.

Later plans of several oil companies to explore and develop suspected oil strata in the Saba bank, and the attending dangers to the island's integrity, caused several people, for instance Lichtveld and Henriquez, to devote themselves to the idea already proposed by Mörzer Bruyns, i.e. to designate all of Saba as a National Park. These persons set up an ad hoc committee for this. According to Henriquez (1977) the uninhabited northwest part of the island would meet the requirements for a National Park and the southeast part should then be declared to be a National Scenic Park. A scenic park features both nature areas and elements, as well as cultural areas valuable for their cultural historical and scenic values. Saba's administrative government was in complete agreement with these plans (Sticusa Journal, 1977). Supposedly since 1960 a committee has been working on a proposal for a regulation to make it easier to purchase undivided estates.

Voous (1979) who published a memorandum on nature conservation and management in the Netherlands Antilles, noted that in most of the Lesser Antilles the humid hill forests with their animal life are seriously threatened by deforestation and subsequent erosion, imparting more than local importance to Saba's top. He opposes expansion of farming and agriculture to the higher areas, favoring small-scale development. Such development would not be in conflict with the aspiration to establish Saba as a national park.

In spite of all ideas and plans and the willingness of the island's Executive Council at that time to establish a national park, the year report of Carmabi and Stinapa of 1982 notes that it was extremely difficult to get something off the ground, because people were insufficiently aware of the value of this wealth of nature with respect to education, but also from an economical point of view. The year report does note a clear change at that time however, especially in the younger generation, which now did recognize the importance of good nature management. Hence in 1982 the government requested Stinapa to prepare a management plan for a park with nature trails, with which the foundation immediately complied. The island government promised their cooperation, as did the department of Culture and Education in Curaçao. STICUSA was willing to finance part of the costs. Indeed several trails are constructed, using mainly historical footpaths. Route descriptions are also made (Romeijn, 1987). Construction of these trails is seen as a useful first step to establish one or more national parks. Romeijn (1987) also points out the unique function of the area for water management and erosion prevention. However the establishment of a land park is not attained. With respect to the sea developments are more favorable. The group in Saba promoting dive tourism also advocates management of the reef (Carmabi/Stinapa, 1982). In 1987 the island government passes an island ordinance establishing the underwater park of Saba (Carmabi/Stinapa, 1989). The Saba Conservation Foundation founded in 1987, is charged with the management.

After the building of a radio mast on top of The Mountain in the seventies, in 1989 the unique vegetation of the top was further threatened with destruction. Several telecommunication companies show an interest to build new masts on the top (Carmabi/Stinapa, 1989). The Saba Conservation Foundation asks Stinapa's assistance against these attacks on Saba's natural heritage. Stinapa again urges the island government to establish Mount Scenery as a national park. At the central government level a national framework ordinance for spatial planning is in place since 1976 (Zadelhoff, 1993). The Saba Conservation Foundation proposes to develop a zoning plan for Saba. Dr. Richard Howard is asked to advise in this. Howard (1989) warns agains further destruction of the elfin woodlands vegetation, and comes out with new arguments in the pursuit of having the top of The Mountain established as a national park. He also gives practical advice for the management. In addition he points out the uniqueness of Saba's terrace agriculture and recommends ethno-botanical research. Notwithstanding all these recommendations and advice there is still no terrestrial nature park on Saba nor a zoning plan.

It is to be hoped that shortly the legal framework for actual nature conservation and management will come into existence. In the implementation, a thorough knowledge of nature elements and processes is of greaty importance. In the past several studies were done that are useful for nature management. The present “Red-bellied Racer Conservation Project”, initiated by Fauna and Flora International, and Walsh-McGehee's study of the Red-billed Tropicbird are also important contributions to this. Nevertheless, further research is necessary. Dr. Richard Howard (1989 points out for instance that a complete inventory of plants growing on the top of Mount Scenery is desirable, as well as good satellite photos to determine where additional trails should be constructed and to localize plant populations. Furthermore he indicates that an ecological study of the elfin woodlands would make comparison with studies of elfin woodlands elsewhere possible. Stoffers' vegetation map (1956) shows an unclassified northern part of the island below about 450 meters. A vegetation analysis of this area should be made. In addition to the Red-bellied Racer and the Red-billed Tropicbird, Saba also posesses several other small populations of regionally rare or endangered vertebrates. In order to ensure their continued survival in Saba it is necessary to study these island populations also. About the status of the invertebrates nothing much can be said as yet. Here too is a wide unexplored field for study.

Based on the available literature, conversations with relevant people and personal observations in situ, the following areas are considered to have great natural value, and are recommended for conservation and management in order to preserve the biodiversity of Saba.

ACKNOWLEDGEMENTS

The project “Biological Inventory of the Windward Islands” was brought about at the initiative of Dr. A. Debrot of the Carmabi. He was also responsible for the supervision during the realization phase. I would like to thank him here for his initiative and support. I am grateful to the KNAP Fund for providing the necessary financing, making this project possible.

Photo 22. Guide James Johnson.

During my visit to Saba in August 1996 I received the cooperation of various people and authorities. Without their help this report would lack important recent information. I want to thank Tom van 't Hof of the Saba Conservation Foundation, the guide James Johnson (photo 22), and Brian Leysner of Carmabi for the invaluable information they provided me with.
In addition Tom van 't Hof also arranged for transport and lodging and for a guide. James Johnson was an excellent guide and I herewith thank him for his company and help in collecting butterflies and terrestrial snails. I want to thank Heleen Cornet for her thoughtfulness and hospitality. I also thank Don McGehee for providing the bat.

I thank Mandy Walsh-McGehee for her consent to include in this report the preliminary results of her census of Red-billed Tropicbirds and her remarks concerning bats.

Finally I thank L.D. Miller and J.Y Miller of the Allyn Museum of Entomology for providing me with their unpublished list of Saba's diurnal butterflies. This list was realized thanks to project financing from the National Geographic Society (# 4726-92).

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