ZOBODAT - www.zobodat.at Zoologisch-Botanische Datenbank/Zoological-Botanical Database Digitale Literatur/Digital Literature Zeitschrift/Journal: Verhandlungen der Ornithologischen Gesellschaft in Bayern Jahr/Year: 1988 Band/Volume: 24_6_1988 Autor(en)/Author(s): Gatter Wulf Artikel/Article: The Birds of Liberia (West Africa) A Preliminary List with Status and Open Questions 689-723 G a t t e r : The Birds of Liberia© Ornithologische Gesellschaft Bayern, download unter www.biologiezentrum.at 689 Verh. orn. Ges. Bayern 24, 1988: 689—723 The Birds of Liberia (West Africa) A Preliminary List with Status and Open Questions By Wulf Gatter* The first important investigation of Liberia’s avifauna was carried out byBüttikofer (1890, etc) at the end of the last Century.In 1926, an expedition from Harvard Univer- sity visited Liberia for several months.A llen (1930) analyzed their results and combi- ned them with previously published findings into a list of “The Birds of Liberia” With additions from Bouet (1931) and Rand (1951), the list reached 310 known species of birds in Liberia. The investigations at Mt. Nimba (C olston & C urry -Lindahl 1985) where Guinea savanna and rain forest meet, with a further important mountain com- ponent, came up with a list of 385 species. Fig. 1 Map of Liberia with important observation points. - Karte von Liberia mit wichtigen Beobach­ tungsorten. * Mit einem Druckkostenzuschuß des Verfassers 690 [Verh. orn. Ges. Bayern 24, Heft 6, 1988] Together with the results of the rain forest region of South-East Liberia (390 spe­ cies) and the Monrovia© Ornithologische region Gesellschaft (408 Bayern, species) download by unter the www.biologiezentrum.at author and others, three sub-regions of the country were explored for the first time using modern methods of investigation. Since then the exploration of the unknown north-west after 1983 has produced a large number of new findings and closed the most important gap in our knowledge. Since 1981 efforts have been made to carry through nationwide investigations and to coordinate activities of observers, the numbers of whom remain low to this day. An accurate account of the state of knowledge at the present time is much needed by the authorities of the country, as well as by the increasing number of interested persons. Foliowing the initial project of drawing up an extensive annotated checklist of the birds of Liberia, the necessity of starting off with a short list with information on sta- tus and unanswered questions became apparent. Liberia is the only country along the Southern coast of West Africa which was re- stricted originally to a single Vegetation zone along its north-south extension — the lowland rain forest. Taking this into account, its record of 590 species shows a very rieh avifauna compared to other countries that have been extensively explored since colonial times and which have Vegetation zones ranging from evergreen rain forest through to the Sudan zone (e. g. Ivory coast with 683 species[T hiollay] 1985) or Ghana with 721 species [G rimes 1987]). Between 122 and 127 of Liberia’s bird species (22%) originate from the Palaearctic region. Topography, climate and main Vegetation zones The coastal lowland (up to 30 m above sea level) extends forty kilometres inland. It is followed by a beit of rolling hills at an elevation of some 300 m and mountain ranges reaching 600 m. The northern highlands are table lands at over 500 m and mountain ranges reaching 1385 m at Mt. Nimba and 1350 m in the Wologizi Range (S chulze 1973). C lim ate Liberia’s position near the equator between 4°20'N and 8°30'N places the country within the so-called “inner wet tropics” with a steady, warm temperature throughout the year. There is a rainy season from April to November and a “dry season” from December to March, with a short mid-dry in coastal and Southern parts of the country for not lon- ger than 3 weeks in July/August. Along the coast the annual rainfall ranges from 3 000 mm in the east (Harper) to 4800 mm in the west (Robertsport) climbing above 5 000 mm on the nearby Cape Mount. In the interior from Zwedru (South-East) to Ganta and Zorzor (North-West) it de- creases to about 2 000 mm and increases again to more than 3 000 mm in the northern highlands of the Nimba and Lofa region. The annual mean temperature of the coastal areas (25°-26°C) compares with the in­ terior (27°C) near Zwedru and Salala, and decreases in the northern highlands to 23.8°C at Kolahun and 19.6°C at Mt. Nimba. © Ornithologische Gesellschaft Bayern, download unter www.biologiezentrum.at G a t t e r : The Birds of Liberia 691 Vegetation zones Coastal savanna and mangrove: The man-made savanna extends as a beit along the coast up to 25 km into the country and is marked by various types of grassland-forest mosaic, the remains of gallery forests, local patches of primary swamp forest and va­ rious types of secondary forest. Along the coast and river estuaries mangrove Vegeta­ tion covers altogether about 310 sq. km. Numerous lagoons are located along the coast, generally behind the beach sand bar. Depending on their development, there are different types of salt- and freshwater lagoons with different Vegetation types (H asselmann 1979, G atter 1988). Tropical rain forest zone: Tropical rain forest once covered all of Liberia except for a few rock outcrops, some sandy areas along the coast and the mangrove swamps (G atter & M attes 1987). The most recent survey (1979 — 1982) of forested areas in Liberia reveals that 38% (42,000 sq. km.) of Liberia’s 111,369 sq. km. was still covered by primary and very old secondary forest. Of this percentage, all except Sapo National Park had been leased to timber cropping concessions by 1987. The annual destruction of primary forest by farmers, who have been enabled through the road construction by logging concessions, to set up their farms in the Cen­ ter of primary forest areas, was estimated at the beginning of the 1980’s to be 1 %, i. e. 400 sq. km. In the meantime it has increased, in particular in Western Liberia, and risen prob- ably to 500 sq. km per year and more. The rain forest beit can be divided into the evergreen rain forest zone in the south with more than 2 000 mm annual rainfall and a semideciduous forest zone in the north with less rain* and a transition zone between these two zones. Another 40% of the country is covered by secondary forest, which is slashed and burned within the farming system of shifting cultivation, with 7-25 year or even lon- ger fallow periods. The remaining areas are covered by plantations (mainly rubber), intensively used farmland and the following successions, and man-made savannas re- sulting from repeated shifting cultivation (G atter 1984). Southern Guinea zone: Along the northern edge of the forest zone there is a forest grassland mosaic adja- cent to the Mt. Nimba region. In the most northern sector of Lofa County it forms an interrupted beit of bare rock, farmland with conspicuous stands of oil palm, patches of grass savanna and forest. Nearly all of this area was covered with forest and rieh farmland some eighty years ago, but today is strongly degraded by the dense human population. Presentation of Data The families appearing in the systematic list follow earlier checklists on Gambian birds (G ore 1981), Nigerian birds (E lgood 1982) and Ghanaian birds (G rimes 1987). Within these taxa, genera and species are in alphabetic sequence. Beside this the na- mes used in the list usually follows those used in G rimes (1987). 692 [Verh. orn. Ges. Bayern 24, Heft 6, 1988] The status of each species is summarized by the following abbreviations: © Ornithologische Gesellschaft Bayern, download unter www.biologiezentrum.at RB resident breeder R(B) resident, but breeding unproven (RB) resident and breeding status unproven. Species may leave during the rains. PM Palaearctic migrant •NM Nearctic migrant, Neotropical migrant AfM migrates within Liberia and neighbouring areas AfM/B migrates to and from Liberia to breed in Liberia AfM/NB migrates to and from Liberia to spend the non-breeding season in Liberia. V vagrant ? indicates doubt about the status immediately preceding the question mark, but not of occurrence Where there is uncertainty about the occurrence of a species, it is placed in square brackets. Most of these species should occur in Liberia, but records have not been def- initely confirmed or it is believed that the species has been overlooked. This column is followed by information on abundance: a abundant c common u uncommon r rare u-c means the species is not uncommon, or is locally uncommon and locally common uScN uncommon in south, common in north etc. The next column deals with open questions (in brackets) (Ec) ecology, habitat, habits (Ph) phenology, migrations, migration direction, annual cycles such as breeding and moult, numbers (ZG) zoogeography, origin, distribution (Sy) systematics (Dy) population dynamics (short term and long term) (*) all possible further information needed The last column behind the brackets gives an indication of habitats, distribution, re- stricted areas such as the name of a town. N only north (of the forest zone) S south E restricted to East Liberia W restricted to West Liberia L local GS moist Guinea Savanna in the north CS coastal beit with savanna, mangrove and littoral PF primary forest and related formations F all forests, secondary forest, woodland M mountainous areas or higher elevations © Ornithologische Gesellschaft Bayern, download unter www.biologiezentrum.at SYSTEMATIC LIST NON-PASSERES PODICIPEDIDAE Podiceps ruficollis Dabchick RB, AfM u (Ph) PROCELLARIIDAE Bulweria bulwerii Bulwer’s Petrel V (Ph, *) Calonectris diomedea Cory’s Shearwater PM u (Ph) Procellaria grisea Sooty Shearwater V (*) Pterodroma mollis Soft-plumaged Petrel V (*) Antarct.