Gola's Flora & Fauna

Much of the most interesting and spectacular wildlife to be found in Sierra Leone and indeed west Africa can be found in the Gola Forest. The Gola Programme partners have been carefully studying the Forest for over 5 years now and we continue to add to the impressive diversity of this forest all the time.

The Birds

White-necked picathartes - Guy Shorrock/RSPB

The project area is listed as an Important Bird Area (Fishpool & Evans 2001) and holds a high proportion of the threatened and endemic species of the region and a good representation of Guinea-Congolian forest biome species. Many of these species are also present in the community forests of the project zone (Demey 2011). Recent bird surveys (Klop et al 2010, Demey 2011) recorded 294 species in the project zone bringing the total to 327, which is amongst the highest of the Upper Guinean Forests. The birds that occur in the project zone include flagship species such as White-necked Picathartes, Rufous Fishing-Owl, White-breasted Guinea fowl and Gola Malimbe. Besides the high species diversity, several threatened species occur in good numbers. The threatened species of birds that occur in the project zone are listed on the 'Threatened Species Fact Sheet' page.

Nearly 80 of the bird species in the project zone are mostly restricted to forest habitats, although some may occasionally occur at the ecotone of forest and more open habitats. Another approximately 100 species occur in forest but are also frequently found in other habitats such as forest edges or clearings inside the forest. Nine species appear to be restricted to primary forest: Lemon Dove, Black-collared Lovebird, Shelley’s Eagle-owl, Brown-chested Alethe, Nimba Flycatcher, Dusky Crested Flycatcher, Yellow-bellied Wattle-eye, Lagden’s Bush-shrike and Gola Malimbe. In addition, the Lyre-tailed Honeyguide was nearly restricted to primary forest, with only a few records from tall secondary forest. Most of these species are rare or uncommon; only the honeyguide and the wattle-eye were more common. Evidently the conservation of these species depends entirely on the preservation of large tracts of undisturbed closed-canopy forest, and the project area can be considered essential to the survival of these species in Sierra Leone.

Although some of the true forest specialists are missing from the community lands in the buffer area of the project zone, the areas surrounding the project area hold good numbers and diversity of birds (Demey 2011). Many of these species are restricted to forest edges, open country and farmbush. Around 80 species of the project zone do not normally occur inside forest, although some were found in large clearings inside the forest. The species in the community lands comprise a gradient from ‘forest-oriented’ to ‘farmbush-oriented’ species. Species that are normally found close to, or sometimes in, forest are e.g. Violet-backed Hyliota, Dusky-blue Flycatcher, Capuchin Babbler and Splendid Starling. A number of species did not enter forest and were restricted to open farmbush. These species included Double-spurred Francolin, Common Bulbul and Pied Crow. Around 25 species were regularly recorded in all habitats. These habitat generalists include Palmnut vulture, Western nicator and Velvet-mantled drongo. Most of the farmbush species and habitat generalists are common and widespread throughout (West) Africa, and not currently threatened or likely to become so in the near future. The exception was Hooded Vulture which has recently been uplisted to Endangered.

The mammals

An overview of the mammals in the project zone is given by Lindsell et al (2011). 49 species of large mammal are known to occur, of which 9 species are currently considered to be threatened (Table X). Four species are listed as Endangered and five species as Vulnerable. Several species of ungulates that are known to occur in the project zone are endemic to the Upper Guinea forests. These include Jentink’s Duiker and Zebra Duiker, and Brooke’s Duiker if this subspecies of Ogilby’s Duiker is raised to full species status. Pygmy Hippopotamus is also endemic, (if the isolated population in Nigeria is extinct, as it is thought to be (IUCN 2011)). Black Duiker and Maxwell’s Duiker are both near-endemic to the Upper Guinea forests.

Despite 11 years of civil war in Sierra Leone, it appears that the mammal fauna of the project zone has survived relatively intact and that the project zone continues to be an important site for the conservation of threatened Upper Guinea forest wildlife, and the most important site for these species in Sierra Leone. No large mammal species was extirpated during the war and previously unrecorded species have been discovered in recent years. Some of the most threatened species continue to have healthy populations in the forest, especially primates, and showed little or no sign of reduced abundance. However, the population of African forest elephants has collapsed during the war, with only a few individuals remaining from approximately 110 in the mid-1980s (Lindsell et al 2011).

Eleven primates are known to occur in the project zone, including one ape and three prosimians. The Endangered Western red colobus is common but is mostly restricted to the less disturbed areas of the central and northern parts of the project area. The Vulnerable Diana monkey, Sooty mangabey and Western pied colobus are abundant and widespread but the only Near-threatened primate, Olive colobus seems to be rare (Klop et al, 2008).

The Endangered Chimpanzee is relatively widespread throughout the project zone. Based on transect sampling of nest counts in 2009, an average population density of 0.27 chimps per km² was estimated (Ganas 2009), with highest densities occurring in the northern part of the project area. These figures compare favourably to other West African forests. When extrapolated over the entire forest this density gives a total population of 303 in the project zone (Ganas 2009).

The Endangered Pygmy hippopotamus occurs in a many areas, most notably along the Mano/ Moro River. This area consists of a mix of floodplains dominated by herbaceous vegetation and patches of riverine forest. There is very little information on the ecology of this species so it is hard to make inferences about likely population sizes. Most of the riverine forest is in the leakage belt of the project zone and so floodplain areas in the community forest may be essential for the conservation of this species in Sierra Leone (Hillers and Muana 2011).

Small mammals

A rapid assessment of small terrestrial mammals in Gola identified 26 species of shrews and rodents (Anadu 2008). Three of these species, Crocidura jouvenetae, Crocidura obscurior and Malacomys cansdalei, are Upper Guinea endemics. Two species, Large-headed Forest Shrew (Crocidura grandiceps) and Buettikofer’s Shrew (C. buettikoferi), are restricted to the Gulf of Guinea and are classified as Near-threatened (Mondajem 2011).

The project zone is also an important stronghold for bats; 34 species have been identified so far, 2 of which are Vulnerable (Rhinolophus hillorum and Hipposideros marisae) (Weber and Fahr 2009).

See 'Threatened Species Fact Sheet' page.

Reptiles & Amphibians

Survey work by Hillers (2009) identified a total of 43 amphibian and 13 reptile species in the project zone. Most of the recorded frogs and reptiles were typical forest species that are restricted to the Upper Guinea Forest zone. One third of the encountered amphibians are listed as threatened or near threatened on the IUCN Red List, (see Table X; 1 CR, 2 EN, 1 VU, 10 NT). The majority of species were closely related to forest habitats (19 frog species, 44%; 9 reptile species, 69%). Additionally, 13 amphibian (30%) and one reptile (8%) species were also related to forests, but they are tolerant of farmbush habitats. The remaining 11 amphibians and three reptiles comprised of purely savanna, grassland and farmbush species. None of these species is currently considered to be threatened, although IUCN classification is incomplete.

Genetic analyses identified two specimens of the genus Phrynobatrachus as a cryptic species new to science. This species probably is endemic to the area and therefore is likely to be threatened based on its small distribution range. The spectacular finding of the Critically Endangered forest Tai toad Amietophrynus taiensis, that so far was thought to be endemic to the Taï National Park in Côte d’Ivoire, furthermore highlights the extremely high potential of the project zone for conservation (Hillers 2009). More research is likely to discover further surprises, including more species new to Sierra Leone or to science in general. Very high species richness, similar to the most diverse forests in south-western Côte d’Ivoire and south-eastern Guinea is not unlikely. The project area is therefore crucial in protecting its important forest habitat diversity and for guaranteeing the persistence of the regional biodiversity of the Upper Guinean forests.

The four amphibian species that are currently considered threatened are listed here. In addition, one reptile (African dwarf crocodile Osteolaemus tetraspis) is listed as Vulnerable. 'Threatened Species Fact Sheet' page

Freshwater Fish

The rivers of the project zone largely comprise the tributaries of the Moro, Mano, Mahoi and Moa Rivers within the Moro-Mano, Mahoi and Moa River basins. The waters of these basins are relatively demineralised, poorly buffered and hence vulnerable to change. Sampling in the Mahoi and Koye Rivers (Payne 2009) produced 31 fish species. With 35% of these species being regional endemics confined to the Sierra Leone/Liberia Upper Guinean ecoregion, the distinctiveness of the fish communities is remarkable. This further emphasises, in global terms, the distinctive nature of the Upper Guinean region of which the project zone is part. Many of the fish species found are scarcely known to science and must be regarded as data deficient or unevaluated in IUCN conservation terms. Of particular note are the headwater swamps and streams which have distinctive communities of smaller species.

Dragonflies

One hundred and forty species of dragonflies and damselflies (Odonata) are known to occur in the project zone (Dijkstra 2011), representing 80% of the species found in all of Sierra Leone. Odonate species can be used as indicators of the quality of freshwater ecosystems and forest habitats (e.g. Catling 2005). This dependency can contribute to raising public awareness of the importance of conserving forests and aquatic habitats. Twenty-two species are considered regionally endemic or threatened, rare and insufficiently known (and thus potentially threatened) (Dijkstra 2011). Six species found in the project zone in 2011 are new to science.

Butterflies

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Butterfly - Jim Wardell/RSPB

The importance of the project zone in the overall butterfly biodiversity of Sierra Leone can hardly be overestimated. Recent surveys have indicated that the project zone holds an extremely high diversity of butterflies, probably well in excess of 600 species or 80% of all the 750 species known from Sierra Leone. A significant proportion of the rarest and most interesting species in Sierra Leone are almost limited to the project zone, the great majority of which are forest-dependent (Safian 2009), two recently encountered butterflies are new to science (Safian 2011). Because of the incomplete IUCN assessment of invertebrates, the conservation status of many of these species is not clear. An overview of noteworthy species is given by Larsen & Belcastro (2008) and Safian (2011). Four recent descriptions of species new to science are based, at least in part, on material collected in the project zone.

Plants

Information on the vegetation types is described in section G1.2. 899 species of plant are known to occur in the project zone of which 232 are tree species; the most common family is identified as Leguminosae, with common species such as Cynometra leonensis and Brachystegia leonensis. However, the most dominant tree species is Heritiera utilis (Sterculiaceae) (Klop et al 2008).

IUCN classification for plants is incomplete. Nonetheless, at least 21 threatened species listed by IUCN have been recorded recently including one, Tieghemella heckelii, that is classified as Endangered and 20 classified as Vulnerable (IUCN 2012). Poorter et al. (2004) classified 278 woody plants in the Upper Guinea forests as rare or threatened based on extent of distribution and threats from human exploitation. Of these, 67 have been recorded in the project zone.