Text and photographs by Phil Hockey

slands have always fascinat- because many occurred before this time, ed biologists. Charles Darwin’s visit to following the earliest colonisations by Ithe Galapagos­ Islands was instrumen- man. In the African regions, these extinc- tal in shaping his evolutionary (and, at tions are well documented for the endem- the time, revolutionary) thinking. Chance ic birds of St Helena. Prior to 1600, three colonisations of islands by plants and species of seabirds (as well as five non- animals, and their subsequent isolation, endemic species – a rail, crake, dove, have given rise to unique biological com- cuckoo and hoopoe) were driven to munities. Sometimes, as with the lemurs extinction by man and his introduced and vangas of Mada­gascar, spectacular animals. Today, all of the nine land-bird radiations occur, giving rise to high levels species breeding on the island are aliens of endemism. Following approximately and only one endemic, the St Helena 120 million years of isolation from Africa Plover, survives. The Hawai­ian Islands and India, all of Madagascar’s 50 primate and New Zealand have similar dismal taxa are unique to the island – as are 88 histories. per cent of the reptiles, 80 per cent of the Some of the post-1600 extinctions, plants, and 56 per cent of the resident such as those of the Great Auk Alca breeding birds. impennis of the north Atlantic and the Although isolation creates unique com- dodos and solitaires of the Mascarene munities, it brings with it a unique suite Islands, are fairly well known. Others of problems. Should conditions change, have been less well documented and, in species unable to adapt or disperse else- some instances, it is almost certain that where are doomed. Some changes are unrecorded extinctions have taken natural, such as the desertification of the place: the figure of 124 extinctions on eastern­ Canary Islands, but others are islands is therefore a minimum. This man-made, such as habitat alteration for article endeavours to summarise extinc- agriculture, the introduction of alien pre­ tions that have occurred on African dators and the introduction of disease. islands and to identify where possible Globally, approximately 136 species of their causes and the lessons they hold birds (and a further 90 locally endemic for the future. The serenity of tropical islands, such as the subspecies) dwindled to extinction in the I have defined ‘African islands’ as Seychelles, belies the looming extinctions 400 years from 1600 to 2000. One hun- being those lying to the east of the Mid- of many endemic birds. dred and twenty four of these post-1600 Atlantic Ridge, west of the Mid-Indian ex­tinc­tions (91 per cent) occurred on Ridge and north of 40˚S. This encom- islands. This figure is not representative passes islands from Madeira in the of the total number of extinctions, north-west to Tristan da Cunha in 

island extinctions 33 the south and Socotra in the north-east. quite clearly that local extinctions of An analysis of the chronology and geog- native land birds on many islands have raphy of extinc­tions, and the numbers frequently exceeded 50 per cent of the of currently endangered species, reveals original species’ complement. some very obvious patterns. • The average rate of extinction on • The number of extinctions has African islands to date has been one spe- de­creased progressively since 1600. cies every 11.5 years. Should 50 per cent There were 14 extinctions in the 17th of the 20 surviving critically endangered century, 12 in the 18th, six in the 19th species become extinct over the course of and three in the 20th. On the face of it the next 10 years, this rate would have this might appear to be encouraging, increased to one species every year. but bear in mind that as the number of (Critically endangered species are defined extinct species increases, fewer species by the IUCN as having a probability of remain to become extinct. By contrast, extinction greater than 50 per cent in the not one bird species has become extinct on the African mainland during the same period, although some local popu- Why should the Mascarenes lations have disappeared, such as the Moroccan guineafowl. have suffered so badly? • Overall, the islands that have the next 10 years.) most endangered species today are The widely introduced Madagascar Fody those that have experienced few or no Many early travellers waxed lyrical about competes with several Red Data Book spe- extinctions. This suggests that these the diversity and abundance of birds on cies for nest sites and food. islands may now face an imminent all three Mascarene islands, reporting extinction crisis. dodos and ducks, rails and herons, par- • The geography of extinctions is rots, pigeons and starlings. With pre- un­even. Of the 35 species lost, all except cious few exceptions, these species are A combination of felling and burning has five have been on the Mascarene Islands now consigned to history. Edible bird fragmented the forests of Madagascar­ into of Mauri­tius, Réunion and Rodrigues. species were hunted mercilessly – the almost treeless landscapes. However,­ the table on page 39 shows flightless ones soon succumbing to such

pressure. As early as 1613, Samuel Book (RDB). Idyllic tourist paradise... but cultivation Castleton wrote that on Réunion, 10 By 2000, the human population of and reclamation have totally transformed men armed with sticks and stones could Mauri­tius – a smaller and less rugged the lowland forests and mangrove swamps kill sufficient White Dodos to feed 40 island – had reached 1 179 500, an of Mahé, Seychelles. people – 160 years later, the White Dodo average density of almost 670 people per was no more. Over time, rats, mongoos- square kilometre. Ten of the Mauritian es, macaques and others (including en­de­mics are extinct, two are critically many alien birds) were also introduced endangered, three are endangered (20 per to the Mascarenes, where they continue cent chance of extinction in 20 years) and Translocations almost certainly saved the to cause immense harm to native birds. four are vulnerable. Today, the only sur- Seychelles Warbler from becoming extinct. Today, more than 60 per cent of the viving endemic bird on Mauritius that is land area of Mauritius is under inten-­ not included in the RDB is the Mauritius sive agriculture, and the few remaining Grey White-eye Zosterops mauritianus. patches of indigenous forest are heavily The story of the Masca­renes is a chilling infested with alien trees. The human col- parallel to that of the St Helena extinc- onisation of Réunion also tells a chilling tions – the only difference is that human story. The first permanent settlement of colonisation of St Helena happened the island took place in 1663 and by 1671 about 100 years earlier. the human population had reached 76. São Tomé and Principé, by contrast, In 1735 there were 8 150 residents, and have experienced no documented extinc­ 140 years later this had swelled to tions and between them have 26 en­­ 67 000. By this time, seven Réunion demic taxa, of which 12 are included in endemics had been driven to extinction. the RDB. These islands are far less isolated In July 2000, the human population had than the Mascarenes and the adaptations reached 730 000; of the four remaining of their birds may therefore be less endemic species, only the Réunion Bul­­ extreme. Additionally, the human popu- bul Hypsipetes borbonicus (whose specific lation density is only one quarter that of status is questionable) and the Réunion Mauritius and much primary forest Stonechat Saxicola tectes have escaped remains on Principé, although São Tomé’s inclusion in the International Red Data primary forest is reduced to two patch-  To page 38

34 island extinctions africa – birds & birding april/may 2001 ZANZIBAR and PEMBA Locations and approximate dates of global extinctions Extinct species on African islands, 1600–2000, and a comparison with No extinctions or endangered species species classified as ‘Critically Endangered’ or * COMORO ISLANDS ‘Endangered’ by BirdLife International in 2000 Extinct species critically endangered and endangered species No extinctions Anjouan Scops Owl Otus capnodes 1 Grand Comoro Scops Owl O. pauliani 1 Moheli Scops Owl O. moheliensis 1 Grand Comoro Flycatcher Humblotia flavirostris Grand Comoro Drongo Dicrurus fuscipennis Mayotte Drongo D. waldenii

SOCOTRA Extinct species No extinctions or endangered species madeira Extinct species SEYCHELLES (including ALDABRAS) No extinctions or endangered species Extinct species DATE OF loss critically endangered and endangered species White Mascarene Seychelles Parrot Psitticula wardi 1870-1881 Seychelles Scops Owl Otus insularis 1 Aldabra Warbler Nesillas aldabrensis 1986 Seychelles Magpie-Robin Copsychus sechellarum 1 Starling 1 CANARY ISLANDS Seychelles Paradise Flycatcher Terpsiphone corvina Seychelles White-eye Zosterops modestus 1 Extinct species Date of loss

MASCARENES (more than one island) Extinct species DATE OF LOSS Mascarene Coot Fulica newtoni 1693 Mascarene Parrot Mascarinus mascarinus 1834-1840 White Mascarene Starling Necropsar leguati 2 1840

MAURITIUS Extinct species DATE OF loss critically endangered and endangered species CAPE VERDE ISLANDS Mauritius Night Heron Nycticorax mauritianus Pre-1700 Mauritius Parakeet Psittacula echo 1 Extinct species critically endangered and endangered species Mauritian Duck Anas theodori 1696 Mauritius Fody Foudia rubra 1 1 Mauritian Red Rail Aphanapteryx bonasia 1693 Pink Pigeon Columba meyeri No extinctions Razo Lark Alauda razae Dodo Raphus cucullatus 1655 Mauritius Olive White-eye Zosterops chloronothos Cape Verde Warbler Acrocephalus brevipennis Dutch Pigeon Alectroenus nitidisima 1826-1835 Mauritius Grey Parrot Lophopsittacus bensoni 1765 Broad-billed Parrot L. mauritanus 1675-1680 Mauritian Barn Owl Tyto sauzieri 3 1700 Newton’s Barn Owl T. newtoni 3 1700 Dutch Pigeon Commerson’s Scops Owl Scops commersoni 1836-1850 SÃO TOMÉ and PRINCIPÉ Extinct species critically endangered and endangered species RODRIGUES No extinctions Dwarf Olive Ibis Bostrychia bocagei 1 Extinct species DATE OF loss critically endangered and endangered species São Tomé Fiscal Shrike Lanius newtoni 1 São Tomé Grosbeak Neospiza concolor 1 Unnamed petrel Pterodroma sp. 1726 Rodrigues Warbler Acrocephalus rodericanus Rodrigues Night Heron Nycticorax megacephalus 1761 Leguat’s Rail Aphanapteryx leguati 1700-1760 Rodrigues Solitaire Pezophaps solitarius 1765 Rodrigues Pigeon Columba rodericana 1726 Rodrigues Parrot Necropsittacus rodericanus 1761-1800 Rodrigues Ring-necked Parakeet Psittacula exsul 1876-1880 ASCENSION ISLAND Rodrigues Little Owl Athene murivora 1726 Extinct species Rodrigues Starling Necropsar rodericanus 1726 Unnamed bulbul Hypsipetes sp. 1600s No extinctions or endangered species

RÉunion Extinct species DATE OF loss critically endangered and endangered species Unnamed night heron Nycticorax sp. Pre-1700 Mascarene Black Petrel Pterodroma aterrima 1 ST HELENA Unnamed stork Ciconia sp. Pre-1674 Barau’s Petrel P. baraui Extinct species critically endangered and endangered species Réunion Flightless Ibis Borbonibis latipes 1773 Réunion Harrier Circus maillardi No extinctions St Helena Plover Charadrius sanctaehelenae Unnamed falcon Falco sp. Pre-1674 Réunion Cuckoo-shrike Coracina newtoni Réunion Dodo (Solitaire) Raphus solitarius 4 1710-1715 White Dodo Victoriornis imperialis 4 1770 Réunion Crested Starling Fregilupus varius 1850-1870 Unnamed fody Foudia sp. 1671

MADAGASCAR TRISTAN DA CUNHA GROUP Extinct species DATE OF loss critically endangered and endangered species * Extinct species critically endangered and endangered species Elephant Bird Aepyornis maximus 5 1650 Alaotra Grebe Tachybaptus rufolavatus [extinct?]1 BirdLife International. 2000. Threatened Birds of the 1 1 Snail-eating Coua Coua delelandei 1920-1930 Madagascar Pochard Aythya innotata [extinct?] No extinctions Spectacled Petrel Procellaria conspicillata World. Barcelona & Cambridge, U.K.: Lynx Edicions & Madagascar Fish Eagle Haliaeetus vociferoides 1 Tristan Albatross Diomedea dabbadena BirdLife International. 1 1 Madagascar Serpent-Eagle Eutriorchis astur Sakalava Rail Amaurornis olivieri 1 Critically endangered species. 2 Meller’s Duck Anas melleri Madagascar (Bernier’s) Teal A. bernieri Some authorities consider this to be the same species as Slender-billed Flufftail Sarothrura watersi Rodrigues Starling. 3 Madagascar Red Owl Tyto soumagnei Yellow-bellied (Sunbird-) Asity Neodrepanis hypoxantha 36 island extinctions Mascarene Parrot These two owls considered by some to be one species. Van Dam’s Vanga Xenopirostris damii 4 Some authorities do not distinguish between these two es. Similarly, the Comoro Islands (includ- the lists of extinct and endangered birds some seed dispersal failure and certain cores to dangerously low numbers. ing the French territory of Mayotte) have are combined (as an indication of the tree species important to the birds will This can readily be seen on several experienced no extinctions, and have 16 types of birds most under threat), small be lost from some forest patches. Should African islands. On La Digue in the endemics of which half are listed in the owls, pigeons and parrots seem to be at the ‘lost’ trees be critical fruit providers Seychelles, the woodland habitat of the RDB. Human popu­lation density here is a disproportionately high risk, especially at a certain time of year, patches will Seychelles Paradise Flycatcher was less than half that of Mauritius. on small islands. In broad terms these eventually become less and less suitable reduced from 51 hectares in 1988 to 41 The causes of some of the early can be classified as forest or woodland as feeding grounds for birds – and the hectares by 1992. Some of the birds Mascarene extinctions are not docu- birds (as are some of the other critically vicious spiral continues. Interestingly, responded by moving out of the wood- mented, although the flightless species endangered species, such as the São frugivorous bats of the African islands land into surrounding, marginal habi- (dodos, rails and the flightless ibis) were Tomé Grosbeak, Mauritius Fody and seem to have been less impacted, possi- tats, but there is no evidence that they undoubtedly hunted to extinction. Two Seychelles Paradise Flycatcher). The bly because their diets are less specialised can breed successfully in their ‘second- pigeons and four parrots had also disap- small owls prey mostly on large inverte- and they can eat large fruits that may be ary’ homes. Other examples of forest peared by the end of the 19th century. brates and small vertebrates, whereas unavailable to birds. birds being ‘squeezed’ in this way The Rodrigues Parrot was hunted, as fruit figures strongly in the diets of The second effect of forest fragmenta- include the three critically endangered probably were the pigeons, but the loss pigeons and parrots. tion is to change the light and moisture species of São Tomé (see page 36) and of these forest-dwelling fruit-eaters, All forest-dwelling species are likely to regimes within the surviving patches. the recently discovered Anjouan Scops along with four species of owls and three be affected directly by a loss of habitat, Forest edges are drier and brighter than Owl of the Comoros. Although only starlings, strongly suggests that the loss especially on small islands, but frugi- forest interiors and support different tree listed as vulnerable in the RDB, the São of lowland forests with the advent of vores seem to be particularly at risk. The species. As the forest patches become Tomé Short-tail Amaurocichla bocagii, agriculture had a devastating effect. reasons for this are probably twofold. smaller, the ratio of ‘edge’ to ‘core’ habi- like the grosbeak, fiscal shrike and ibis, Firstly, there is a mutualistic relationship tat increases, and those birds dependent is entirely confined to the remaining The abandonment and encroachment between fruit-eating birds and the fruit- on trees, invertebrates or micro-habitats primary rainforest and its RDB status of coconut plantations in Seychelles producing trees on which they depend. that are confined to forest interiors find may require revision. It is not only loss threaten the forest-dwelling Seychelles Direct and indirect Many of these trees rely on the birds to progressively less suitable habitat. This of forest area that can impact native spe- Magpie-Robin. effects of man disperse their seeds and, in particular, to habitat erosion can be seen in the forest cies, but also invasion of forest by alien transport those seeds between forest fragments of Madagascar where the fre- plants. For example, on Frégate Island in Major environmental change has The 20 critically endangered species patches. As the distance between forest quent burning of adjacent grasslands for the Sey­chelles, collapse of the copra occurred in the eastern Canary Islands, listed on pages 36 and 37 belong to dis- patches increases, journeys made by the agriculture gradually eats away at the for- trade led to abandonment of coconut but much of this has been as a result parate taxonomic groups, from grebes birds between forest remnants become est fringes. Forest contraction can rapidly plantations and their subsequent inva- of changing climate. and eagles to white-eyes and fodies. If less frequent. In time, this will result in reduce the bird populations of the forest sion into the indigenous woodland. This has reduced the availability of suit- able foraging habitat for the critically A comparison of extinction endangered Sey­chelles Magpie-Robin. rates (global and local com- Forest loss has had, and continues to bined) of native terrestrial bird have, the greatest impact on small islands. species present in 1600 and There has been substantial forest loss on existing numbers of introduced the huge island of Madagascar, but this (alien) species on the satellite was not responsible for the extinction of islands of Madagascar the giant elephant birds during the 17th century: these 400- to 500-kilogram ISLAND # in 1600 % extinct # introduced giants were hunted to extinction by MASCARENES Mauritius 22 50 20 man. The only other documented extinc- Réunion 19 53 9 tion on Madagascar was the Snail-eating Rodrigues 11 82 7 Coua. This bird was a forest-dweller, but SEYCHELLES was confined to the offshore island of Mahé 9 22 8 Praslin 10 40 6 Saint Marie where it was driven to extinc- La Digue 8 60 7 tion within the first 30 years of the 20th Silhouette 5 20 6 Curieuse 4 25 5 century by a combination of forest loss Frégate 5 0 6 and introduced rats. Marianne 6 50 5 Introduced animals pose particularly Felicité 5 40 5 Aride 6 33 4 severe threats to island bird populations Cousin 6 0 6 and, to date, are probably responsible Cousine 5 0 5 Bird Island 3 0 4 for the greatest number of extinctions. Aldabra Group 15 13 1 Unlike birds, land animals generally Astove 7 29 0 Assumption 4 50 4 have very poor dispersal abilities and Cosmoledo Group 7 43 0 rarely reach islands unassisted. Some Providence 1 100 1 Farquhar Group 1 100 2 land birds, evolving in the absence of Amirantes Group 2 100 5 predators, became flightless – although COMOROS all originated from flying ancestors. Grande Comore 33 0 10 Others have retained the ability to fly Moheli 27 0 10 Anjouan 25 0 9 but have lost the costly adaptations they Mayotte 20 0 12 once had for avoiding predators. The 

38 island extinctions africa – birds & birding april/may 2001 birds of St Helena and the Mascarenes Seychelles, the Madagascar Fody Foudia Aldabra, a trial translocation of the highly have paid a high price for these intro- madagascariensis may compete with the localised flightless rail is underway. ductions, as have birds on islands else- Seychelles White-eye for both food and In most instances, however, the long- where. For example, the Stephen Island nest sites. The fody also competes for term success of these programmes will Wren Xenicus lyalli was discovered in food with the endemic RDB fodies of depend on solving the root cause of the 1894: in the same year, over the space of Mauritius and Rodrigues. original problem. In the case of preda­­- about one month, it was driven to tors and alien trees on Mauritius, for extinction by the lighthouse keeper’s cat example, this is a daunting prospect, but (called Tibbles). Future prospects one that ultimately will have to be It is not only predators that cause addressed if the establishment of wild, problems. The ability of goats to trans- self-sustaining populations is to be form landscapes is legendary: on St Despite the islands’ torrid history, man’s achieved. The control of coconut palm Helena they were probably the most intervention has, at least temporarily, seedlings on Frégate Island in Seychelles, important agent of forest loss and habi- saved several species from almost certain by contrast, could be relatively easily tat transformation. As early as 1578, extinction. These include the Mauritius effected. What we can hope, however, is pigs, goats and ‘other four-footed beasts’ Kestrel, Pink Pigeon, Seychelles Magpie- that the losses of the past and the danger were reported to number ‘in the thou- Robin and Seychelles Warbler Acro­cephalus signals of the present will serve to help sands’ on this one island of only 410 sechellensis. Today, several of the critically us prevent further damage to the birds square kilometres. endangered species of the African islands and other wildlife of Africa’s fascinating Introduced birds have doubtless also are the focus of national and interna- but fragile island satellites.  affected indigenous species, although the tional conservation efforts. Many of these extent to which this is a problem is not bodies face an uphill task. Efforts on The illustrations of the White Mascarene Starling and the Mascarene Parrot on page 36 appear in Oiseaux de well understood (see page 39). Certainly, Mauritius depend heavily on captive La Réunion (N. Barré, A. Barau & C. Jouanin, 1996) there are many introduced species on the breeding to supplement populations ail- and are reproduced with kind permission of Les Editions islands: more alien bird species breed on ing from habitat degradation and intro- du Pacifique, Paris. The illustration of the Dutch Pigeon Mauritius than in the whole of sub-Saha- duced predators. In Seychelles,­ a supple- appears in Extinct Birds (E. Fuller, 1987) and is repro- duced with kind permission of Rainbird Publishing ran Africa! On Mauritius, introduced mentary feeding programme, provision Group Ltd, London. Ring-necked Parakeets Psittacula krameri of predator-proof nestboxes and inter- and Indian Mynas Acridotheres tristis island translocation helped save the Lowland forest clearance and intensive compete with the critically endangered Seychelles Magpie-Robin. Trans­lo­ca­tion agriculture contributed to the extinction Mauritius Parakeet for nest sites, and in saved the Seychelles Warbler and, on of many species on Mauritius.

40 island extinctions africa – birds & birding