Jan Stevens

Conservation status and vocal and morphological description of the Grand Comoro Scops Owl Otus pauliani Benson 1960

The Grand Comoro Scops Owl Otus pauliani , confined to forest on Mount Karthala on Grand Comoro, Indian Ocean, is a distinct species based on the evidence of its plumage and voice. In November 1989 studies of territorial calling birds at night revealed its presence between 1,000 and 1,900 m on the north, west and south flanks of the volcano, on which there exists some 10,000 ha of suitable habitat. As territory sizes may be only 5 ha, the population could well be over 1,000 pairs but, although this is encouraging, there remains a long-term threat from forest loss through habitat fragmentation (fires, logging) and the spread of the Indian Myna Acridotheres tristis .

Conserving the endemic birds on the Comoro Islands, I: general considerations on survival prospects

The status of the Comoro endemic birds is briefly reviewed. Field data were gathered during expeditions in 1981, 1983, 1985 and 1989. Some native birds (Cyanolanius madagascarinus, Dicrurus fuscipennis on Ngazidja, Treron australis on Mwali, Accipiter francesae, Otus rutilus, Leptosomus discolor on Ndzuani, Dicrurus waldenii on Maore) are so rare that they are certainly highly endangered. The altitudinal stenotopy of a few other species makes them also very vulnerable, e.g. Zosterops mouroniensis in the tree-heath zone on Mount Karthala above 1,750 m. A preliminary analysis of habitat preference on Ngazidja suggests a relatively large flexibility of most forest species between different types of forest, including those with altered vegetation structure, but demonstrated their absence in plantations without large trees and/or natural shrubs. Comparison of density of species in Ngazidja and Mwali and an overview of the avifaunal composition on all four islands are the basis for a discussion on colonization history (with possible extinctions), historical change in avifaunal composition, the suitability of each island for the different species and the completeness of their avifauna. The results are checked for possible threats and necessary actions for conservation. Competition by introduced species does not yet seem to be a problem. But importation of foreign animals must be banned and hunting must be regulated (especially for pigeons). Habitat loss (overexploitation of the forest) will soon become a serious problem for the stenotopie forest birds. A suggestion is made for delimiting a national park on Ngazidja and Mwali. Most controversial is the development of tourism. For long-lasting results, education of local people is necessary, together with full liaison with the authorities.

Conserving the endemic birds on the Comoro Islands, II: population fluctuations on Ngazidja

JAN STEVENS, MARC HERREMANS and MICHEL LOUETTESummaryLand bird abundance on Ngazidjas , Comoro Islands by poin, obtainet count indsSeptember 198 an5d November-December 1989 are compared. The overall abundance o fmost specie dis d not differ significantly. Most difference can b interpretee s d as normalwithin-year fluctuations. Some important change are identifies d and attributed to short-

COMPARISON OF FOREST BIRD COMMUNITIES ON NGAZIDJA and MWALI (COMORO ISLANDS)

Summary Louette, M., Bijnens, L., Stevens, J. & Janssens, L. 1989. Comparison of forest bird communities on Ngazidja and Mwali (Comoro Islands). Ostrich suppl. 14: 33–37 Ngazidja (21 forest bird super-species) has a coastal vegetation zone, a forest zone and a supraforest (heath) zone; the latter is lacking on Mwali (17 forest bird super-species). Point-counts of birds during the prebreeding season of 1985 at different altitudes of Ngazidja (17 stations) and Mwali (3 stations) were used as indications of relative density. Most forest species occur in the same relative density on both islands, although there are some minor differences in guild composition. Six forest species, peculiar to Ngazidja, make up only a small part of the total bird community; five of them are absent from Mwali by altitudinal restriction. At least two species, limited to high altitude on Ngazidja, do occur on Mwali. The absence of two other forest species (occuring on Mwali) from Ngazidja is remarkable as is also the higher density...

Biology of Frances's Sparrowhawk, Accipiter francesiae, on the Comoro Islands

Throughout their range on Madagascar and in the Comoros Francess Sparrowhawks, Accipiter francesiae, breed from October to December, in the late dry/early wet season, resulting in young leaving the nest before or when the heavy rains start in January/February. In contrast to Madagascar, nests on Mayotte (Comoros) are placed in exposed positions, and are maintained and enlarged after the young fledge, possibly as a form of territorial advertisement. On average, two young fledged per successful nest, and 1.5 fledged per nesting attempt. During the breeding season, sparrowhawks on Mayotte consume more reptiles than do those on Madagascar. On Mayotte, second-year birds can be recognized by plumage type. Recruitment into the breeding population does not occur during the first year, but possibly only from the third year. Francess Sparrowhawks are unevenly distributed on Mayotte and post-breeding dispersal may take place from the wettest zone, where the highest breeding densities occur, to the drier southeastern parts.

Fragmented distribution and genetic differentiation of the Forest Fody, Foudia eminentissima algondae, on the island of Mayotte (Comoros)

Most of the species in the genus Foudia (Passeriformes, Ploceidae), endemic to the Malagasy region, are endangered and one is already extinct. We studied the distribution of the Forest Fody, Foudio eminentissima algondae, on Mayotte (Comoros) during two surveys (October 1993, February 1995), and reviewed all other available data. The field surveys showed that 1) the distribution of the Forest Fody population on Mayotte is very patchy; 2) the size of the Mayotte population is larger than anticipated, probably several thousands of individuals, distributed in six different subgroups; 3) there is no evidence for a decrease in population size nor in population range over the last decade, perhaps even to the contrary; 4) the species occupies a wide range of open habitats, mainly along the coast (we never observed it in forested areas). Although sample sizes were small, bandsharing analyses on multilocus DNA-fingerprints of 44 blood samples (four different subgroups) suggested a rather high degree of isolation between subgroups, even though maximum distances did not exceed 30 km. The rather strong isolation effects over short distances, together with differences in habitat occupation between the subgroups, may be important topics for further study and for future conservation measures.

Abundance and habitat choice as an indication of colonisation history in Comoro Land birds

Louette, M., Stevens, J. & Neri, F. 2000. Abundance and habitat choice as an indication of colonisation history in Comoro Land birds. Ostrich 71 (1 & 2): 345–346. We measured bird abundance and habitat parameters by point transect counts. Bird abundance is different for a number of species among the four Comoro islands (Louette, M. et al. 1993. Oiseau 63: 115–126), and among sites on a given island (especially in the case of forest birds, such as on Grand Comoro, an island with great variation in habitat).

The status of the Forest Fody on Mayotte (Comores)

Adriaensen, F., Louette, M., Stevens, J., Plompen, W. & Verheyen, G. 2000. The status of the Forest Fody on Mayotte (Comoros). Ostrich 71 (1 & 2): 330–331. Once, every group of islands in the Malagasy region had its own species of Foudia (Passeriformes, Ploceidae), but in recent years things have changed profoundly. Except for the widespread Madagascar Fody E madagascariences, most of the species are more or less endangered. This paper reports on two surveys of the island of Mayotte (Comores) on the presence of the Forest Fody in October 1993 and March 1995. All other available observations are discussed in view of these results. Currently the population is subdivided in 6 sub-groups. Total population size must be several thousands of birds. The species occupies a wide variety of habitats, but it is remarkable that areas with very similar habitat where not occupied in other parts of the island, even when adjacent to another sub-group. On Mayotte, in sharp contrast with most of the other islands, Forest Fodies live in rather open areas and surely not in evergreen forest. Also in 1993, blood samples were collected to analyse the population genetic structure of the supposedly isolated sub-populations, using band-sharing coefficients from multilocus DNA-fingerprinting. Band-sharing analyses showed that all four subgroups studied showed an increased level of band-sharing compared to open populations of various other songbirds. The between-subgroup band-sharing is lower than the within-sub-group band-sharing suggesting a rather high degree of isolation between the subgroups tested. The apparently low dispersal activity together with the patchy habitat occupation in the different subgroups, are important factors to watch when considering conservation measures for the species.