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Table of contents
Biodiversity (non-avian)
Back to Ecosystems and Biodiversity

Biodiversity (non-avian)

The biodiversity of an ecosystem is a telling indicator of the state of the environment or the ecosystem’s health. Next to birds the whole range of species – from mammals to invertebrates – is relevant in that respect. Information on biodiversity is scarce however; here we summarise the available information on vulnerable species.

Water-bound ecosystems are generally very rich in biodiversity. For example, the gallery forests and other forests in the headwaters of the Niger are home to thousands of species ranging from amphibians, birds to an array of mammal species. The species richness is described in several studies (for example Mallon et al. 2015), but dedicated data on distribution and numbers are almost unavailable, only from species groups that have received a lot of attention as birds and large mammals. Information from the headwaters of the Niger in Guinea is extremely scarce, and is summarized by Klop et al (2019). For the Inner Niger Delta much information is known about fish, especially fisheries, and birds, but other species groups are much less known, either because they have largely disappeared (mammals) or because little study has been done on them (invertebrates).


Mammals

Today the large mammals of the Upper Niger Basin and Inner Niger Delta are only a poor reflection of the rich fauna of the past. The African manatee and the Common hippopotamus are nowadays two of the large mammals that remain present in small numbers in the UNB and IND. Both are listed as Vulnerable according to the IUCN Red List version 2016-3. A small population of African Elephants still lives east of the Inner Delta, these animals migrate between Burkina Faso and south-eastern Mali (information on the most recent distribution).

Carnivores
Various species of mammalian carnivores occur in the UNB, including several smaller species like mongooses and genets, and a few larger species like cats, jackals and possibly otters. Several of these species are common and widespread, but some are threatened. The biggest carnivore in the region is the Lion (Panthera leo), of which the West African population has become severely fragmented and is currently classified as Critically Endangered according to the IUCN Red List. Less than 500 Lions remain in West Africa, mostly restricted to the W-Arly-Pendjari (WAP) complex on the borders of Benin, Burkina Faso and Niger. Smaller populations still exist in Senegal, Nigeria and northern Cameroon. There are no confirmed records of Lions within our study area, although rumours persist about presence in the Parc National Haut Niger and Réserve partielle de Faune de Kankan. Lion is considered absent in Boucle de Baoulé and in Bafing-Faleme (information on the most recent distribution).

Within the UNB the Leopard (Panthera pardus) is only known to occur in Guinea. The Leopard has a broad geographic range, found from Africa through Asia. It is listed as vulnerable according to the IUCN Red List version 2016-3. An extant population is present within Parc National Haut Niger and a possibly as well along the border with Sierra Leone near the Niger source. The populations near the origins of the Milo and the Niandan are possibly extinct. The African golden cat (Caracal aurata), which is listed as Vulnerable, is an inhabitant of the moist forests of the Guineo-Congolian zone. At the fringes of its range, it might penetrate into the gallery forests in the forest-savanna mosaic, possibly including the Guinean highlands in the south of the UNB. This is a very secretive species and exact data on the distribution or numbers are lacking.

Primates
Many species of primates occur in West Africa, though most species are restricted to the forest zone. Besides the true monkeys, some other primate species occur within the Upper Niger Basin (Senegal Galago, Demidoff’s galago, possibly West African Potto). There are a few threatened species, as well as several more widespread primate species that occur in the savannas (Guinea baboon, Green monkey, Patas monkey) or forests (Sooty mangabey, Campbell’s monkey, Lesser spot-nosed monkey) in or close to the UNB.

The West African subspecies of Chimpanzee (Pan troglodytes verus) is listed as Critically endangered by the IUCN. It occurs in 3 of the 5 protected areas in Guinea and occur in suitable habitat in a wider area of Guinea. High densities occur in the Mafou forest of the Haut Niger National Park. Chimpanzees are mostly a forest species and within the Guinea savanna zone they occur in gallery forests and dense woodlands (information on the most recent distribution).

The range of the Western pied colobus (or King colobus, Colobus polykomos) stretches along the West African coast from southern Senegal to the Sassandra River in Côte d’Ivoire. The species prefers dense rainforests and gallery forests, but is sometimes found in secondary forests as well. Within the UNB, the species range covers the most southern part, around the origins of the Niger, Niandan, Mafou, Milo and Sankarani. The IUCN Red List Status (2016-3) is Vulnerable. The Upper Guinea red colobus (Piliocolobus badius) is listed as Endangered; it is restricted to the forest zone and might just occur within the limits of the UNB near the border with Sierra Leone.

Ungulates
The savannas and forests of West Africa are home to many species of ungulates, ranging in size from the diminutive Royal antelope (<3 kg) to the massive Giant eland (>500 kg) and some of the well-known megaherbivores like African elephant and Hippopotamus. In Mali and Guinea some globally endangered ungulate species are present. These are: Jentink’s duiker (Cephalophus jentinki)(EN), Zebra duiker (Cephalophus zebra) (VU), Pygmy hippopotamus (Choeropsis liberiensis) (EN); Common hippopotamus (Hippopotamus amphibious) (VU); African savanna elephant (Loxodonta africana) (VU); Forest elephant (Loxodonta cylotis) (VU) and the Western Giant eland (Tragelaphus derbianus derbianus) (CR). The first three species, as well as Forest elephant, are restricted to the rainforests of the south, and do not occur within our study area.

The distribution of the Common hippopotamus in West and Central Africa is quite fragmented. Within the UNB, they are mainly present along the floodplains of the Sankarani, Dion, Milo, Tinkisso and the Guinean part of the Niger. In 2001 river censuses were carried out in the Haut Niger National Park by Brugière et al. (2006) in Guinea. They surveyed the Niger and Mafou Rivers within the park boundaries in both the dry and wet season. A total of 93 hippos in 28 groups were counted in the dry season, mostly in the section of the Niger River bordering Mafou Forest. In the wet season, 77 hippos in 23 groups were found, mostly along the Mafou River in the southeast of the park (Brugière et al. 2006). These results indicate a population in 2001 of at least 100 individuals in Haut Niger N.P.

Within Mali, the distribution of Common hippos is mainly restricted to the Inner Niger Delta, where they have become rare. Pygmy hippos do not occur within our study area. The Western Giant eland is the West African subspecies of the Giant eland (Tragelaphus derbianus) and occurs mainly in south-eastern Senegal; its range might just overlap with the UNB near the Tinkisso river in Guinee. The eastern subspecies is not threatened and occurs in the woodland savannas of northern Cameroon and the Central African Republic.

2541_109a_mammals IND_web.jpg

Other species
African manatees (Trichechus senegalensis) occur along the coast from Angola up to Senegal, but also more inland in the larger rivers. In the Niger River, Manatees are reported up to the Upper Niger Basin, amongst others within the Tinkisso Ramsar-site and within the Parc National Haut Niger. Isolation of manatee population has become a major issue due to the construction of dams, particularly in the Niger and Senegal rivers. The manatees also suffered hunting and severe droughts. There are no accurate estimates of abundance. In addition, the impact of hunting and habitat destruction are not sufficiently documented.


Reptiles and amphibians

To our knowledge, no data are available on amphibians within the Upper Niger Basin or the Inner Niger Delta. However, the results of a RAP (Rapid Assessment Program) survey in Guinea’s Boké Préfecture might be translated to our study area. This RAP yielded 26 amphibian species and 11 reptile species. According to the habitat preference and the geographical distribution 13 amphibian species might also occur in the Upper Niger Basin. Most of these species are connected to savanna or farmbush habitat and have a distribution area that exceeds the Upper Guinean forest block or even West Africa. Only a few species are typical forest specialists. Further research is needed to comment on the herpetological diversity in Upper Niger Basin.

As for the amphibians, knowledge on the species diversity and distribution of reptiles within the UNB or IND is incomplete. The forests of the Fouta Djalon are home to for example Forest cobra, Rhinoceros viper, Nile monitor and African dwarf crocodile. These species may well occur within the UNB. Some of the, in the RAP survey encountered reptile species, are protected by CITES (Convention on International Trade in Endangered Species of Wild Flora and Fauna): Varanus niloticus, Chamaleo gracilis and Python regius.

In Africa, three species of crocodiles occur. The most widespread is Nile crocodile (Crocodylus niloticus) which occurs in suitable savanna habitat throughout the continent. Slender-snouted crocodile (Crocodylus cataphractus) is a Critically endangered species which is restricted to forested rivers in West and Central Africa. It may now be extinct in most parts of West Africa. The smallest species is the African dwarf crocodile (Osteolaemus tetraspis), which is listed as Vulnerable. It occurs in densely shaded swamps and streams in closed-canopy rainforest. It is uncertain whether this species occurs in the remaining forests of the Fouta Djalon within our study area.

The vast floodplains and river basin in the Inner Niger Delta provide habitat for Nile Crocodile, Nile Monitor lizard (Varanus niloticus) and African Rock Python (Python sebae). Crocodiles were once common in rivers and some of the lakes of the Delta, but have also declined considerably and are on the edge of extinction nowadays, as have populations of aquatic turtles (Trionyx, Pelusios). Nile monitor and Rock python are facing heavy human pressure.


Fish

The rich fish fauna specialized to live in the rapidly flowing streams in the upper reaches of the Niger is one of the distinguishing elements of the aquatic biodiversity of the UNB. The UNB hosts to about 150 species of fish, of which eight are endemics and one, the cyprinid Garra waterloti, is found only in this ecoregion. This has been one of the arguments to designate several Ramsar sites in this region. The majority of this ecoregion’s fish species are shared with the other ecoregions within the Niger River basin (www.feow.org).

Fish species

A rich fish fauna of 130 different species is found in the Inner Niger Delta, but few species are endemic because the Niger River was linked to the Chad and Nile systems at various times. Two of the near-endemic fish found here are Synodontis gobroni and a cichlid, Gobiocichla wonderi. Many species migrate upriver and downriver as well as laterally out on to the floodplain as the water rises. When the waters recede the fish move upriver, otherwise the risk becoming trapped in small, isolated ponds. Some fish species can survive in these dwindling pools by aestivating or by breathing air.

Fish migrations include both lateral movements onto floodplains and long-distance, longitudinal movements. There is anecdotal evidence of several fish moving as much as 440-640 km up the Niger River into the inner delta with the onset of floods. One of the African tetras, Bycinus leuciscus, has been observed moving 50 km from the river mainstream to the edge of the floodplain and may move 125-400 km upstream from the inner delta to the Markala dam as floods subside. Most migratory fish have a high fecundity and a breeding period synchronized with the rising flood, which promotes genetic mixing among fish that gather in a limited number of spawning sites from widely dispersed areas of the river.

Overfishing and poaching are also of concern. Ninety percent of Mali's freshwater fish catch comes from the Inner Delta; yet the size of the catch has declined considerably since 1969, as has the average size of landed fish. Prior to 1960, traditional management determined fishing practices for the delta. Two ethnic groups, the Bozos and the Somonos, were the primary fishermen in the Inner Delta. The change from traditional management to governmental regulation in 1960 opened fishery access to all citizens. This resulted in an increase in fishermen, as other ethnic groups became users of the fishery. The number of fishermen in the delta doubled from 1977 to 1997. This increase combined with the use of more sophisticated fishing equipment (such as nylon nets) has led to the decline in the catch of certain species, including the economically valuable Polypterus senegalus and Gymnarchus niloticus.


Sources and more information

  • Brugiere, D. & R. Kormos 2009. Review of the protected area network in Guinea, West Africa, and recommendations for new sites for biodiversity conservation. Biodiversity and Conservation 18: 847-868.
  • Mallon, D.P., Hoffmann, M., Grainger, M.J., Hibert, F., van Vliet, N. and McGowan, P.J.K. (2015). An IUCN situation analysis of terrestrial and freshwater fauna in West and Central Africa. Occasional Paper of the IUCN Species Survival Commission No. 54. Gland, Switzerland and Cambridge, UK: IUCN. x + 162pp.
  • Klop, E., M. Sikkema, M. Diawara, A. Gado 2019. Ecological hotspots and land use patterns in the Upper Niger Basin, Guinea. A&W-report 2501. Altenburg & Wymenga ecologisch onderzoek, Feanwâlden / Wetlands International, Bamako.