The raptor community of Nias Island, Sumatra: Survey and conservation

During a short survey of the diurnal raptor community on the island of Nias in July 1992,I found. seven species of Falconiformes. Three of them were hawk-eagles: Spizaelus alboniger last confirmed in 1886, S. nanus, presumed to be extinct and S. cirrhatus, never cited for the island. These three eagles appeared to be highly endangered because of heavy deforestation but the future of the other raptor species seems more secur

Le peuplement avien. Essai d’étude quantitative

The avifauna of the Lamto area has been studied during a two year period. 263 species have been recorded and the habitat prefe rences, diet, breeding periodicity and fecundity of the major species studied. 43 % of the birds are forest species. Only very few of them are abundant, eight species accounting for half of the total numbers of birds counted. Migrants are numerous in the savanna ; one third of them are palearctic passerines, while local migrants are represented mainly by non-passerine families. 90 % of the species are more or less omnivorous, but all migrants show a distinct preference for insect food. Breeding occurs throughout the year : among the 124 commoner species, 62 % breed during the rains and 23 % during the dry season. Fecundity is low and the same female seldom reproduces twice during the year. Counts have been made regularly on a line-transect 12.5 km long and 40 m wide. Monthly variations of numbers and biomasses are given in tables V and VI. Contrary to the situation further North, seasonal variations are small in the forest-savanna mosaic. There are two peaks : the first one, from February to May, corres ponds to an intlux of northern migrants ; the second, from July to September, is attributable to the natural increase of sedentary species and an intlux of fruit-eaters. Minimum values are found in December, at the beginning of the dry season. The average yearly biomass of birds for the Lamto savanna is in the order of 1 kg/ha (fresh weight)

Habitat determinants of golden‐headed lion tamarin (Leontopithecus chrysomelas) occupancy of cacao agroforests: Gloomy conservation prospects for management intensification

Organismal distributions in human‐modified landscapes largely depend on the capacity of any given species to adapt to changes in habitat structure and quality. The golden‐headed lion tamarin (GHLT; Leontopithecus chrysomelas) is an Endangered primate from the Brazilian Atlantic Forest whose remaining populations occupy heterogeneous landscapes consisting primarily of shade cacao (Theobroma cacao) agroforestry, locally known as cabrucas. This cash crop can coexist with high densities of native tree species and holds a significant proportion of the native fauna, but its widely extolled wildlife‐friendly status is increasingly threatened by management intensification. Although this potentially threatens to reduce the distribution of GHLTs, the main determinants of tamarin's occupancy of cabrucas remain unknown, thereby limiting our ability to design and implement appropriate conservation practices. We surveyed 16 cabruca patches in southern Bahia, Brazil, and used occupancy modeling to identify the best predictors of GHLT patch occupancy. Key explanatory variables included vegetation structure, critical resources, landscape context, human disturbance, and predation pressure. We found a negative relationship between GHLT occupancy and the prevalence of jackfruit trees (Artocarpus heterophylus), which is likely associated with the low representation of other key food species for GHLTs. Conversely, cabrucas retaining large‐diameter canopy trees have a higher probability of GHLT occupancy, likely because these trees provide preferred sleeping sites. Thus, key large tree resources (food and shelter) are currently the main drivers of GHLT occupancy within cabruca agroecosystems. Since both factors can be directly affected by crop management practices, intensification of cabrucas may induce significant habitat impacts on GHLT populations over much of their remaining range‐wide distribution

Decline of Birds in a Human Modified Coastal Dune Forest Landscape in South Africa

Previous studies demonstrate that old-growth forest remnants and vegetation regenerating after anthropogenic disturbance provide habitat for birds in a human modified coastal dune forest landscape in northern KwaZulu-Natal, South Africa. However, occurrence does not ensure persistence. Based on a 13-year monitoring database we calculated population trends for 37 bird species and general trends in overall bird density in different vegetation types. We evaluated species' characteristics as covariates of population trend and assessed changes in rainfall and proportional area and survey coverage per vegetation type. 76% of species assessed have declined, 57% significantly so at an average rate of 13.9% per year. Overall, bird density has fallen at 12.2% per year across old-growth forest and woody regenerating vegetation types. Changes in proportional area and coverage per vegetation type may partly explain trends for a few species but are unlikely to account for most. Below average rainfall may have contributed to bird declines. However, other possibilities warrant further investigation. Species with larger range extents tended to decline more sharply than did others, and these species may be responding to environmental changes on a broader geographical scale. Our results cast doubt on the future persistence of birds in this human modified landscape. More research is needed to elucidate the mechanisms driving population decline in the study area and to investigate whether the declines identified here are more widespread across the region and perhaps the continent