AYE-AYE

Daubentonia madagascariensis (Gmelin, 1788)

Order PRIMATES

Family DAUBENTONIIDAE

SUMMARY

The Aye-aye is probably widely but sparsely distributed in the forests of the east, north and north-west of Madagascar. Population numbers are unknown. It may be that this species is not as rare as previously thought, it is possibly merely very elusive. It is however, threatened by habitat destruction and is frequently killed by local people. Very little is known about its ecology and social organisation. It is nocturnal and mostly solitary. Its diet is reported to consist of fruit, especially coconuts, and insect larvae. Some short studies have been undertaken and an 18 month study began in July 1989. There are ten individuals in captivity, but none has been born there. Daubentonia madagascariensis is reported present in ten protected areas. Listed in Appendix 1 of CITES, in Class A of the African Convention and is protected by law in Madagascar.

DISTRIBUTION

The Aye-aye is probably still widely, but apparently very sparsely, distributed throughout the eastern rain forests. It is also in the north, in the north-west in the Sambirano Region and occurs as far south as Bemaraha Nature Reserve. Within the past five years, its presence or signs of it have been reported in Andohahela Nature Reserve (O'Connor et al, 1986), in Manomba Special Reserve (Nicoll and Langrand, 1989), near Ranomafana (P. Wright, pers. comm.), in Analamazaotra (Ganzhorn, 1986), in Zahamena Nature Reserve (Pollock, 1984), near Mananara and Maroantsetra (Albignac, 1987), on the Masoala Peninsula (Nicoll and Langrand, 1989, reported present), in Marojejy Nature Reserve (Safford et al, 1989 signs seen), in Analamera and Ankarana Special Reserves (Hawkins et al, in press), in Montagne d'Ambre National Park (Nicoll and Langrand, 1989), just south of both Ambilobe and Ambanja (J. Andrews pers. comm.), in Manongarivo Special Reserve (Raxworthy and Rakotondraparany, l988, reported by local people; Nicoll and Langrand, 1989) and in Bemaraha Nature Reserve (Petter and Andriatsarafara, 1987). Iwano (in litt) reported that natives had killed and eaten individuals from two sites in northern Madagascar, one about latitude 16°S and the other just west and north of Befandriana Nord.

POPULATION

Numbers are not known, but there are probably more Aye-aye than was thought (Ganzhorn and Rabesoa, 1986). It appears to be very elusive rather than very rare. It is, however, unlikely that it is found, or was ever found, in very high densities (Tattersall 1982). In Analamazaotra, it took 60 to 70 hours of intensive night work to find one animal (Ganzhorn, 1986). Population numbers are almost certainly declining (Sussman et al, 1985).

HABITAT AND ECOLOGY

The Aye-aye appears to be very adaptable in its choice of habitat. It is, or was, found in areas of primary rain forest, deciduous forest, secondary growth, cultivation (particularly coconut groves) and possibly even in mangrove swamps and dry scrub forest (Tattersall, 1982). It has been seen in an area of open brush and low trees several miles from any real forest (Rand, 1935).

Daubentonia is a nocturnal species. It spends the day in a nest, which it usually builds in a fork of a tree or in a dense tangle of lianas at a height of between 10 and 15 m (Petter and Peyrieras, 1970; Petter, 1977). At night, it is usually seen singly, though three were seen within about 50 m of each other in the forests of Mahambo (Petter et al, 1977), two adults were together in Analamazaotra (E. Stirling, pers. comm.) and three individuals were observed within 10 m of each other on Nosy Mangabe, one of these was an adult male (Iwano and Iwakawa, 1988).

The Aye-aye's diet is reported to consist of fruit, especially coconuts, and insect larvae (Petter, 1977). They have been seen eating lychees and mangoes (Petter, 1977). The larvae are extracted from dead branches and from the nuts in Terminalia fruits (Petter and Petter-Rousseaux, 1967, Petter, 1977). Pollock et al (1985) record an adult male Aye-aye on Nosy Mangabe feeding on gall-like protuberances on an Afzelia bijuga tree. The Aye-aye appeared to consume the fibrous bark of the tree, the clay-like tissue beneath the galls, the insects and, perhaps, vertebrates located within the galls' crevices. There were elaterid larvae in the galls and a frog was found there. Though Petter (1977; Petter et al, 1977) notes that Aye-ayes do not feed on adult insects, Pollock et al (1985) suggest that they are eaten. The D. madagascariensis observed on Nosy Mangabe also fed briefly on the shoots of the large variegated bamboo species, Bambusa striata (Pollock et al, 1985). Iwano and Iwakawa (1988) observed an Aye-aye on Nosy Mangabe feeding on "ramy" fruits (Canarium madagascariensis). It scraped off the outer pulp, gnawed into the hard nut then extracted and ate its contents.

It has been reported that Aye-aye may give birth only once in two or three years (Petter and Peyrieras, 1970; Petter, 1977). However, it is unclear why this is suggested. Singletons are said to be born in October and November (Petter and Peyrieras, 1970; Petter, 1977), but Albignac (1987) reports finding a three week old infant at the end of March.

THREATS

The main threat to the Aye-aye is the destruction of its habitat. It is not known if it can survive in degraded areas; it is suggested that it, at least, needs large trees in which to build its nests (Petter, 1977; Iwano and Iwakawa, 1988). In some areas of Madagascar it is killed on sight as it is regarded as a harbinger of misfortune. It is also reported to be killed when raiding crops (Albignac, 1987). It appears to be unafraid of humans and it is easy to capture (Petter, 1977). Two of the tree species which D. madagascariensis appears to use as a food source (Afzelia bijuga and Canarium madagascariensis) occur throughout the eastern rain forest, but they are frequently cut down as their wood is used in the construction of boats, houses and coffins (Pollock et al, 1985; Iwano and Iwakawa, 1988).

CONSERVATION MEASURES

The Aye-aye has been reported in Montagne d'Ambre National Park, in Andohahela, Bemaraha, Marojejy and Zahamena Nature Reserves and in Analamazaotra, Manomba, Manongarivo, Analamera and Ankarana Special Reserves, it was introduced to Nosy Mangabe Special Reserve (Nicoll and Langrand, 1989; Ganzhorn, 1986; Pollock, 1984; Safford et al, 1989; Hawkins et al, in press; Raxworthy and Rakotondraparany, 1988; Petter and Andriatsarafara, 1987; O'Connor et al, 1986). It is also found, or is reported to occur, in three of the areas in the east that have been proposed as protected areas. These are Ranomafana, Mananara and Masoala (Nicoll and Langrand 1989; Wright, 1988; Albignac, 1987). Most of these areas need better protection. In addition, conservation/education and development programmes are needed for the local people. The laws against killing Aye-ayes (or any other lemurs) require better enforcement, but local people should be compensated for any damage done to their crops by Aye-ayes (Albignac, 1987).

An Aye-aye conservation programme, funded by WWF, was set up by the Department of Water and Forests, the Museum of Natural History in Paris and IUCN (Constable et al, 1985). This programme included the release of nine Aye-aye in 1966/67 on to Nosy Mangabe, a 520 ha island off the east coast of Madagascar in the Bay of Antogil. This island was set up as a Special Reserve in December 1966 (Petter and Peyrieras, 1977; Constable et al, 1985). The number of animals on the island now are not known, but some are certainly still present (Constable et al, 1985; H. Simons, E. Sterling, pers. comm.).

E. Sterling (Anthropology Department, Yale University) began an eighteen month study of the Aye-aye on Nosy Mangabe in the summer of 1989 and T. Iwano intends to return for several months to continue his work. It is hoped that these studies will help ascertain the habitat requirements of the Aye-aye and its ability to adapt to environments modified by humans. Extensive surveys are needed to determine the extent of the present range of D. madagascariensis, its true population numbers and, thereby, its actual conservation status.

Participants at the St Catherine's Lemur Workshop held in Georgia in 1986 suggested that 10-20 individuals of this species be brought into captivity as they "should breed well". They regarded the Aye-aye as probably the single highest breeding priority for Malagasy lemurs.

Daubentoniidae is listed in Appendix 1 of the 1973 Convention on International Trade in Endangered Species of Wild Fauna and Flora. Trade in it, or its products, is subject to strict regulation and may not be carried out for primarily commercial purposes.

All Lemuroidea are listed in Class A of the African Convention, 1969. They may not, therefore, be hunted, killed, captured or collected without the authorization of the highest competent authority, and then only if required in the national interest or for scientific purposes.

Malagasy law prohibits the killing or unauthorised capture of any lemurs. This is, however, evidently impossible to enforce.

CAPTIVE BREEDING

Outside Madagascar, there are only seven individuals in captivity, two of each sex in Duke Primate Center, which were acquired in December 1987 and August 1988, and three at Paris Zoo which were taken there in 1986 (ISIS, June 1989; Albignac, 1987; Winn, 1989; A. Katz, J.-J. Petter, in litt.). In Madagascar, two Aye-ayes were reported to have been taken to Ivoloina in February 1989 but these became ill and had died by early 1990 (E. Simons, pers. comm.); there is a single animal in Parc Tsimbazaza (A. Katz, M. Pidgeon, G. Rakotoarisoa, in litt.). No Aye-ayes, however, have yet bred successfully in captivity. A pair were held for four years at Analamazaotra and they had two infants but these were eaten by the mother (Petter et al, 1977). Duke Primate Center intends to coordinate a breeding programme for animals of this species being held both inside and outside Madagascar (E. Simons, pers. comm.).

REMARKS

The Aye-aye is the only living representative of its family. It was originally classified as a squirrel and it was not until 1800 that it was recognised as a primate (see Jenkins, 1987). Long, coarse blackish-brown guard hairs overlay a dense layer of relatively short white hair, giving the overall impression of dark brown pelage suffused with white. The tail is bushy, ears are large, naked and mobile; incisors are long and continually growing, digits are elongated, particularly the middle finger, and most are clawed. D. madagascariensis weighs about 3 kg (Tattersall, 1982 Winn, 1989). See Petter (1977), Petter et al (1977), Jenkins (1987) and Tattersall (1982) for more details. Malagasy names for the species are hay-hay, ahay and aiay (Tattersall, 1982).