Newton 1958 Mauritius Cuckooshrike

Date since cut over for timber) which was still acceptable habitat for many endemic birds. Large areas south of Curepipe disappeared to pine (Edgerley 1962), and in the Midlands region also to tea (anon. 1961, Tilbrook 1968, Roy 1969). In the 1970s a job-creation programme (Travail Pour Tous) operated by the Development Works Corporation (anon. 1971c) and funded by the World Bank (Temple 1976b, Procter & Salm 1975) extended and accelerated clearances for exotic plantations into key habitat areas such as the remnants of the Kanaka and Grand Bassin forests and Les Mares. The latter low marshy forest was partly cut over in the 1890s (Koenig 1895), but was still of largely native composition and an important habitat for the Pink Pigeon Nesoenas mayeri - the 'Pigeon des Mares', named after this area (Temple 1976b; Chapter 5). Fortunately international interest in the by now precarious position of the surviving endemic birds has helped stabilise the situation (Temple 1976b, Jones 1980). More clearances will surely occur, but for the fauna to survive must stop well before the limit of the 2-2.5% of the island currently in nature reserves (4018 ha/9930 acres, Owadally 1981b). However, no more species have so far become extinct, though the parakeet Psit-tacula echo appears doomed (Jones 1980c, Chapter 5).

Most of the surviving endemic vertebrates have failed to adjust to the secondary habitats on Mauritius. Only the Phelsuma geckos (Vinson 1976b), the Grey White-eye Zosterops borbonicus (Staub 1976) and the two aerial feeders (Chapter 5) are widespread in or over man-made or secondary woodland, though the flycatcher Terpsiphone bourbonnensis has accommodated well in limited areas (Staub 1976, Chapter 4). Several other native passerines, namely the Merle Hypsipetes olivaceus, the Cuckoo-shrike Coracina typica, the Fody Foudia rubra and the Olive White-eye Z. chloronothos, would probably adapt to man-modified vegetation if the right mix of evergreen broad-leaved fruit and nectar-bearing trees were provided (Cheke 1978«, Chapter 4), as also no doubt would the hill forest race, rosagularis, of the gecko Phelsuma guim-beaui. The Pink Pigeon and native parakeet appear to require native vegetation for feeding (Chapter 5), though the Pigeon has catholic feeding habits in captivity and may prove capable of adapting to the right kind of replacement vegetation (Jones 1980a) . The endemic kestrel, feeding as it does largely on day-geckos (Chapter 5), would appear capable of living in most areas provided it was not persecuted, but is nevertheless at present confined to areas of native forest. Temple (1974a, c, 1976b, 1977«) and Newton (1958«, b) assumed that kestrels need native vegetation, but it has long seemed to me more probable (Pasquier 1980) that the catastrophic post-war decline to near extinction is attributable to the use of DDT and BHC during the successful campaign to eliminate human malaria on the island. A very intensive spraying programme started in 1948 had largely eradicated malaria and the main vector Anopheles funestus by 1952 (Toussaint 1972, Bruce-Chwatt 1974) but DDT and BHC formulations were used on a large scale until 1965 to control A. gambiae and thereafter at a much reduced intensity until the island was declared malaria-free in 1973 (Bruce-Chwatt 1974, Mamet 1979), and DDT was also widely used in agriculture for a time (C. M. Courtois in litt.) until restricted by the Pesticide Control Act of 1970 (Ricaud 1975). Since kestrels occurred on the Moka range near Port Louis in the 1950s (Jones 1980«, Chapter 5), I believe their restriction to the unpopulated forests around the Black River Gorges was due to this being the one area of the island not sprayed with DDT. However, even there it seems that fertility must have been reduced sufficiently for prédation by monkeys to become a serious threat to survival; high levels of pesticides have been found in recent eggs in captivity (Chapter 5). In the Seychelles Falco araea, another small forest-adapted kestrel that eats lizards and birds, remains fairly common (Watson 1984) despite habitat changes, and even nests on buildings (Feare et al. 1974). The Seychelles have always been free of malaria and its vector (Lionnet 1972, High 1976), and insecticides have not been widely used.

Reunion

The history of man's destruction of the native vegetation on Réunion roughly parallels that on Mauritius, but was somewhat constrained by the very rugged topography which made access to many parts of the interior difficult. As a result a proportionately much larger area of native forest survives uncut, but nearly all of this is at an altitude of over 500 m, and most over 1000 m (Cadet 1977).

Defos du Rau (1960) mapped and discussed the progressive occupation of the land in Réunion. As forest was not cleared independently of settlement, I have taken his stages of settlement to be equivalent to those of forest destruction.

Unlike Mauritius where the original Dutch colonisation was expressly to exploit ebony, Réunion was occupied for the purely political reason that King Louis XIV wanted a French presence in the Indian Ocean (Toussaint 1972). The main political object was Madagascar, and Réunion was originally little more than a bolt-hole from there. The embryo colony was persistently forgotten by France, and the few hundred inhabitants had to fend for themselves, often not seeing a visiting ship for 5 years at a time (Toussaint 1972). Hence the settlement pattern was an agricultural one from the start, needing land clearance on a fairly large scale (Defos du Rau 1960).

Settlement began at St.-Paul with a second focus at St.-Denis. By 1715 (ibid.) the northern and northwestern coastal zone from St.-Gilles round to Bras Panon was occupied, up to 500 m in altitude above St. -Gilles-St.-Paul but mostly under 200 m elsewhere. The dry west coast palm savannah would have been about half-destroyed, together with an important section of the western lowland dry forest and the northeastern part of the lowland wet forest (interpretation from maps in Cadet 1977).

The next phase, 1715-89, was critical for the wildlife. With the introduction of coffee in 1715 the colony suddenly became potentially important, though it was not until about 1725 that cultivation gave economic returns and the population began to rise dramatically (Toussaint 1972). By 1788 there were 45 800 people, spread round the entire coast except by the volcano in the south-east; the palm savannah and the dry forest ("forêt mégatherme semi-xérophile" of Cadet 1977) and the lowland wet forest (south and east) were all but gone. Bory (1804) described the sorry state of these zones, and noted that wood-fired limekilns were a particular feature of the west coast. Gruchet (1977) also stressed the effects of fires in this dry zone and the long period of overgrazing by the numerous feral goats. The centre of the island was populated only by small roving bands of fugitive slaves, fewer than in Mauritius (Pingré 1763, Bory 1804, Bulpin 1958) though enough for La Nux (1772) to consider them a danger to flying-fox populations. The beginning of this period saw the extinction of the Solitaire and oiseau bleu, and later, of the three native parrots. The first two, as indicated above, were probably victims of,feral cats, but the parrots may have been dependent on the lowland habitats. Evidence is conflicting but the flying-fox Pteropus niger and most of the tortoises probably also disappeared during this period (Cheke & Dahl 1981, and below).

The next period, 1789-1848, was largely one of consolidation in already settled areas, though in the latter part of the period the cirques, three huge caldera-like valleys surrounded by cliff walls up to 2000 m high, were colonised for the first time (Defos du Rau 1960). By 1850 Salazie, the first cirque to be settled, was devastated (Scherer 1965). As in Mauritius sugar cane was developed as a crop in the first half of the nineteenth century, but here it appears to have spread until about 1851 on land already cleared for other purposes (Defos du Rau 1960). The limited forest damage is reflected in the lack of extinctions during this period, though the last captive Mascarinus parrots, and with them the species, died out (see species account).

In Réunion, as in Mauritius, the emancipation of slaves (1848 here) brought a new wave of forest destruction. By 1852 over 30 000 ex-slaves had established smallholdings in montane forest areas, and a large number of poor whites, whose holdings became uneconomical after they lost their slaves, left the lowlands to settle higher up, usually in much more remote areas than the slaves (gorge bottoms, cirques, the Plaine des Palmistes and part of the Plaine des Cafres: Defos du Rau 1960, Toussaint 1972). These refugees from the coast largely practised shifting cultivation, thus destroying far more forest, and causing more erosion, than their population might suggest (ibid.). By 1880 little remained of the original vegetation below 1000 m in the west and 500 m in the east, though forest survived to below 200 m between Le Baril and Bois Blanc around the base of Le Volcan. Although in the mid-1860s the islands' naturalists were still optimistically claiming that huppes Fregilupus varius, black parrots Coracopsis sp. (introduced) and the last of the flying-foxes Pteropus subniger were still to be found in the forests of the cirques (Maillard 1862, Schlegel & Pollen 1868), it appears the naturalists had not visited the cirques themselves. Salazie had been deforested by 1850 and the other two laid waste by 1868 (Defos du Rau 1960), Mafatte in just 6 years (1862-8: Miguet 1973); all three species were probably extinct before 1860 (see below).

Although there was some attempt to limit déboisement in 1874, the authorities were unable or unwilling to prevent the next major wave of forest clearance that swept the western parts of the island between 1900 and 1925. This was due to the development of the Scented Geranium Pelargonium graveolens as a major cash crop amongst the shifting cultivators in the highlands (Defos du Rau I960, Lauret 1978b). This crop exhausts the soil very fast, and in addition the distillation of the geranium oil requires large amounts of fuel wood (ibid.). The rest of the Plaine des Cafres was cleared by 1913, and the culture spread along the west coast massif, the foresters managing to hold the clearances at the 1500 m contour above St.-Leu (ibid.), north to Trois Bassins, and rather lower further north (pers. obs.; anon. 1962 and other recent maps). This wave of destruction swept to the Dos d'Ane, then jumped to the Moka area east of St.-Denis, where it stopped around 1924-5 but restarted with a massive rise in the price of geranium oil after 1945 (Defos du Rau 1960, Lauret 1978b); Rivals (1952) published photographs of virgin forest freshly cleared for geranium at Moka in the 1940s. Further areas were cut for timber during the 1939-45 war (Miguet 1973).

Since the war a policy of replacing 'uneconomic' native forest by productive plantations (Miguet 1980) has resulted in some of the finest remaining areas of mid-altitude forest being lost (e.g. the Bélouve plateau above Salazie) and also the destruction of the last remnants of mature lowland forest, apart from one ludicrously small (c. 20 ha) nature reserve near St.-Philippe in the south-east (Gruchet 1973, Cadet 1977).

The Office National des Forêts has recently cut back on some of its plans for extending the replacement of native forest (ed. note in Info-Nature 15: 38 (1977); Cadet 1977) and further nature reserves are planned (Cadet 1977), though implementation is still awaited (Barré & Barau 1982). This has to a large extent removed the immediate threat to the habitat of Réunion's only remaining endangered bird species, the cuckoo-shrike Coracina newtoni (Cheke 1976,1978a, Chapter 6).

The depauperate vertebrate fauna that survives on Réunion has adapted rather better to changed conditions than has its counterpart on Mauritius. The Grey White-eye, Paradise Flycatcher and stonechat Saxícola tectes are widespread in exotic vegetation (Barré & Barau 1982, Barré 1983, Chapter 6), as is the Harrier Circus maillardi where not persecuted (Clouet 1978, Chapter 6). The Merle Hypsipetes borbonicus and the Olive White-eye Zosterops olivaceus are also commonly seen in secondary forest, but may require native forest intact at higher elevations at certain seasons (Barré 1983, Chapter 6). The cuckoo-shrike is extremely limited in its distribution for reasons as yet not understood (Cheke 1976, Chapter 6). As in Mauritius the Phelsuma geckos have adapted to exotic vegetation, but P. ornata inexpectata is restricted to a very small area near Manapany-Les-Bains in the south-west (Vinson & Vinson 1969, Cheke 1978a, 1979a, Bour & Moutou 1982, Moutou 1983c, 1984), "the zone where the dry forest originally reached the coast" (Cadet 1977). Reintroduction of species that still survive on Mauritius (kestrel, Pink Pigeon, Echo Parakeet, flying-fox) has been proposed (Cheke 1974b, 1978a, Temple 1981, Moutou 1983d) and a trial release of Mauritius Fodies was made in 1975 (Cheke 1975a, 1979a, Chapter 4).

Rodrigues

For some time after its discovery Rodrigues remained well wooded (Leguat 1708, Tafforet 1726, Pingré 1763). Pingré (1763) did, however, report a large area deforested by fire west of Baie aux Huitres and also remarked that he had seen no regenerating Latanias or palmistes (Dictyosperma album, Mascarena verschaffeltii), though Pandanus seedlings were everywhere. This suggests that the abundant rats were eating the seeds and preventing reproduction, as happens today on Gunner's Quoin off Mauritius (Bullock et al. 1983) (pers. obs. of chewed seeds); no doubt the goats ate any that did sprout. As late as the end of the eighteenth century the forests were still "thick and difficult to penetrate" over much of the island (Marra-gon 1795, Dupon 1969). By this time all but one of the birds which Rodrigues was destined to lose had vanished, the tortoises were reduced to a handful and the big gecko Phelsuma gigas confined to offshore islets - all victims of predators combined with hunting, rather than habitat loss.

By 1825 the cumulative effects of feral livestock and shifting cultivation since the beginning of permanent settlement in the early 1790s had reduced the vegetation in much of the island to a savannah with scattered trees (Hoart 1825, North-Coombes 1971). Corby's description (1845; North-Coombes 1971 in part) is of an island largely deforested with pockets of woodland here and there, the only well-wooded part he saw being around what is now La Ferme. Traces of fire were widespread and he encountered large numbers of feral cattle and pigs. It is clear that by then the feral animals and fires had prevented regeneration for a long time. Thorough exploration in 1874 (Balfour 1879a, b) did reveal forested valleys missed by Corby, but these were a tiny proportion of the area. Balfour wrote that the island was "now ... a bare parched volcanic pile with deep stream courses for the most part dry, in place of the verdant well-watered island of 200 years ago". He also noted the invasive spread of the exotics Leucena glauca and Eugenia (= Syzygium) jambos, apparently introduced since Corby's visit. Around this time the parakeet Psittacula exsul and the last mainland geckos Phelsuma edwardnewtonii disappeared, the habitat, and with it their numbers, too far reduced to withstand prédation and cyclones (see below). The remnants of native vegetation have progressively shrunk (Koenig 1914b, Wiehé 1949, Cadet 1975, Cheke 1974a, 1978b, Tirvengadum 1980, Strahm 1983), so that today only a few hectares survive, and these are mostly heavily overgrazed with no regeneration. Many of the endemic plant species are extinct or gravely threatened (Friedmann & Guého 1977, Tirvengadum 1980, Strahm 1983). The two surviving native birds have adapted to exotic vegetation (Cheke 1974a, 1978a, 1979a, Chapter 8). Plantations of the mixed evergreen species they favour were initiated following Koenig's recommendations in 1914 (North-Coombes 1971), but nearly destroyed again by the prevailing land-use policy during 1955-68 (Cheke & Dahl 1981: 219, Chapter 8).

Disease and pollution

Both introduced micro-organisms and contamination of the environment by man-made chemicals may have had their part to play in the extinction and rarefaction of endemic Mascarene vertebrates. We have, however, no direct evidence of either, though there are certain indications.

The remarkably rapid disappearance of the Réunion Starling Fregilupus varius, from abundance to extinction in 10 years (see below), led to the suggestion that a disease may have been responsible (Brasil 1912). The introduction of avian malaria and avian pox and their vectors to the Hawaiian islands has had disastrous effects on endemic birds there (Warner 1968), though Atkinson (1977) has claimed for the Ship Rat Rattus rattus a greater responsibility for extinctions. A number of avian parasites have been introduced to the Mascarenes (two spp. of Leucocytozoon, Haemoproteus columbae, Plasmodium spp. incl. relictum: Peirce et al. 1977, Peirce 1979), but others appear to be native (Leucocytozoon zosteropis, a Plasmodium and two species of Trypanosoma at least: ibid.); we know nothing of their pathogenicity. There is some suggestion in the distribution of avian malaria in native birds in Mauritius that birds in little-frequented upland forests are not infected, unlike those in disturbed forests and in the lowlands (Chapter 4). This distribution corresponds with the habits of the introduced vector Culex pipiens quinquefasciatus (=fatigans) (Peirce et al. 1977). Some native birds which are less widespread than one might expect from their habits (Olive White-eye, Fody) occur where the vector is least abundant; malaria may be a restricting factor in their distribution, though clearly not as dramatically so as in Hawaii (Warner 1968).

The usual gamut of pathogens and endopara-sites exists in domestic poultry and pigeons, at least in Réunion (Pourquier 1963); some were no doubt introduced at an early date and may well have infected native species, though helminths are rare in wild birds (Barré 1982).

Mammal diseases are better known because of their implications for man and livestock. However, little work has been done on wild species apart from Moutou's (1980) study on rats and leptospirosis, and a survey of helminth parasites (Barré & Moutou 1982). The only native mammals potentially at risk would have been bats, whose contact with introduced animals must always have been minimal, apart from interactions between rats and Tadarida acetabulosus, which often roosts in roofs (Moutou 1979, 1982b, Cheke & Dahl 1981). No work has been done on parasites or diseases of native bats.

Reptilian pathogens may have been brought in with introduced species. The mysterious nineteenth-century disappearance of Scelotes bojerii on both Réunion and Mauritius could have had such a cause, likewise the decline of Phelsuma borbonica in Réunion (see below), though this last was attributed by Vinson (1868) to the introduction of snakes. Native reptiles were not covered in the only parasite survey so far conducted (Barré 1982).

Temple (1976a) reported 14.7 ppm dry weight of DDE in seven addled eggs of the Trindade Petrel Pterodroma arminjoniana collected on Round Is. in 1974. He tentatively related this to pollution of the waters round Mauritius by DDT used in agriculture and mosquito control. It is difficult to know the significance of this observation as Bourne et al. (1977) found only relatively minute quantities of DDE in two other oceanic feeders (Puffinus pacificus, Sterna fuscata) from on or near Round Is. in 1975. The possible role of DDT in the decline of the Mauritius Kestrel has already been discussed under 'Destruction of habitat'. On Réunion, heavily treated with DDT against malarial mosquitos during 1949-67 (Defos du Rau I960, Gerard & Picot 1975), there was a severe post-war decline of the endemic harrier Circus maillardi, which led to special protection in 1966 (Gruchet 1975). The harrier has since increased considerably (Chapter 6), though whether this is due to reduced persecution or the cessation of DDT spraying is not known. Other possible victims of DDT are insectivorous bats, which during 1973-5 were noticeably commoner in Réunion than in Mauritius where DDT was widely used until 1973 (see above). Since then, observations by Jones (1980a) suggest an increase at least in one species, Tadarida acetabulosus. As the islands are free of heavy industry there appear to be no other widespread serious pollutants.

Wildlife protection in the islands

Mauritius

Although there had been sporadic attempts by the Dutch to protect tortoises and game (Pitot 1905), the first comprehensive game law was proclaimed in October 1767. This restricted hunting of ungulates, protected game birds and their eggs during the breeding season and gave the Common Mynah Acridotheres tristis special protection as it was expected to save the islands from a grasshopper plague (Rouillard 1866-9, Ly-Tio-Fane 1968). Other recently introduced granivorous birds had become such agricultural pests that in 1770 it became compulsory for landowners to produce each year a minimum of ten birds' heads per slave owned, the largest contributor getting a prize (ibid.); this law was still in effect in 1825 (Oustalet 1897). Mynahs (again!), Merles, doves and 'mesanges' (?) were protected in 1792 (d'Unienville 1982). The eighteenth century game laws were apparently not revised until the Game Ordinance of 1869, subsequently variously amended (Vinson 1956), including adding the protection of tenrecs in 1900 (Lane 1946 and later eds.). There was a provision for the governor to prohibit killing of any wild bird or animal by proclamation (Vinson 1946, Lane 1946) and it was under this regulation that Edward Newton first gave complete protection to kestrels and parakeets, and protection during the breeding season to a further three endemic species (E. Newton 1878«, b). By 1910 all the endemic birds were fully protected (Meinertzhagen 1912). Vinson (1956«) discussed the development of legislation to that date, and proposed revisions, which were largely followed by the 1957 proclamation (given in full by Newton 1958b), renewed in 1967 (Staub 1976). These rules allowed game birds and various introduced pests to be freely killed (though the game birds were covered elsewhere in the Game Ordinance: Lane 1946), and certain common introduced species to be kept as cage birds. Up to this time the proclamations all lapsed after a period and had to be renewed, but a new law in 1977 has given permanent protection to the native birds (Staub 1980). The endemic reptiles were protected in 1973 (Procter & Salm 1975), but the flying-fox remained outside conservation laws until the 1983 Wildlife Act (Act 33 of 1983), which consolidated and extended previous game and wildlife legislation.

An Ancient Monuments and National Reserves Ordnance was promulgated in 1944 (Carver 1945, Brouard 1963, Vaughan 1968) and the first nature reserves established in 1951 (anon. 1961). These were chosen on purely botanical considerations (Vaughan 1968), and included little of the best bird habitat (Procter & Salm 1975), and almost no bats. Round Is. was added in 1957 (Vaughan 1968), but it was only in 1974 that Bel Ombre and Macabé were linked by the intervening land to provide a reserve of sufficient size and diversity for birds (Procter & Salm 1975, Owadally 1976b, Staub 1980). A list of the reserves and their sizes was given by Owadally (1981b).

Réunion

Lougnon (1957) mentioned many of the early attempts at tortoise and game protection through legislation in Réunion. Killing of bird pests was made compulsory around 1760 (Pingré 1763). In 1767 the twin colonies of Mauritius and Réunion were ceded to the French Crown, and ruled jointly from Mauritius under the same laws until 1810 (Toussaint 1972; see above). In 1820 new stricter bird-pest legislation banned the import of any granivorous bird, and even required seed-eating cage-birds to be killed (various finches, ploceids and estrildines were specified); at the same time mynahs, doves and stonechats Saxicola tectes were specifically excluded from the provisions (Decary 1962). In 1946 the island became an overseas département of France and thus subject to metropolitan French laws (Defos du Rau 1960, Toussaint 1972). The endemic harrier Circus maillardi was listed as a pest species until 1966 (Gruchet 1975)! All birds are fully protected under current legislation (Servat 1974, Staub 1976), except three introduced pests, and the endemic bulbul Hypsipetes borbonicus which is considered as game, and may be shot during a 3-month season (Barré & Barau 1982). The only declared nature reserves are tiny botanical ones (Cadet 1977), but a network of larger reserves has been proposed (Bosser 1982), including one specifically for the endangered cuckoo-shrike Coracina newtoni (Cheke 1976).

Rodrigues

The first wildlife legislation in Rodrigues was the Rodrigues Game Regulations of 1883, under which hunters required a licence and the Magistrate (the island's chief executive) was empowered to impose close seasons for any species he defined as game (Lane 1946). Around the same time (Reg. no. 6 of 1882) Mountain and River Reserves were established to protect watersheds (Koenig 1914b), so incidentally preserving some suitable habitat for the endemic birds and bats. Subsidiary regulations in 1923, protecting a number of non-game birds (Lane 1946), were most memorable for their failure to cover the two endemic species (Cheke 1974a). This anomaly was not removed until the 1983 Wildlife Act, which, inter alia, protected the two endemic birds and the flying-fox and repealed the 1923 regulations. Two nature reserves for breeding seabirds were declared in 1981 (Owadally 1984), but the best remaining areas of native vegetation and the bird and bat habitat are covered only by ordinary forest legislation, although many proposals have been made for reserves (Staub 1973b, Cheke 1974a, 1978b, Lesouef 1975, Strahm 1983 etc.).

EXTINCTIONS AND INTRODUCTIONS: SPECIES ACCOUNTS

In this section the history of mammals, birds and reptiles in the islands is given in detail. Extinctions and introductions are documented where possible, and the subsequent history of introduced animals followed. Least emphasis is given to the surviving native fauna, which is considered in detail elsewhere (Staub 1976, Jones 1980a, Cheke & Dahl 1981, Chapters 4-8). The accounts are by taxonomic group, subdivided into separate island histories where appropriate. Although they are marine, I have included sea-cows and turtles in the accounts as they form a coherent part of the pattern, and like seabirds require land or its close proximity for feeding and for breeding.

The native fauna

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