Ethiopian Wetlands and Bird Biodiversity

Yilma Dellelegn Abebe

Ethiopia’s diverse landform from high montane habitats to lowland landscapes is a reason to believe that there is a diverse wetland ecosystem in the country. A quick survey of major wetland types shows that there are lacustrine, palustrine, riverine wetlands including mires bogs and tarns at high altitude. The greatest problem that we face is the lack of information on these ecosystems and the biodiversity they harbour.

Wetlands, only next to tropical forests, are considered to be the most productive ecosystems in the world. They are homes to a multitude array of life forms from one celled organisms to large long-lived trees. They form the basis for intricate food webs that includes insects, amphibians, reptiles, birds, mammals and man himself.

The Ethiopian Wildlife and Natural History Society organises annual census of waterfowl that assists in monitoring the numbers of birds as well the wetlands they live in. The Environmental Protection Authority has recently completed an inventory of major Ethiopian wetlands with a report pending publication.

While it would be difficult to present a detailed examination of the biodiversity of Ethiopia's wetlands, a brief overview of the water birds is outlined in this presentation. Ethiopia has more than 200 species of birds that can be classified as water birds. Out of these 200 birds 128 of them are regularly counted in annual waterfowl census work in several wetlands throughout the country. These birds are found in a various types of wetlands and they can either be resident, Palaearctic migrants or African migrants. Most of these birds also show a congregatory affinity but others are also found in smaller family groups.

What are wetlands?

Wetlands are areas that are characterised by the presence of water and land at the same time.

Wetland is also a collective term that is used to describe areas associated with aquatic ecosystems.

A wide range of ecosystems including inland freshwater, coastal and marine habitats.

The edges of deep lakes and large rivers are considered as wetlands, if they contain rooted vegetation. The vegetation can be either submerged or emergent and the level of the water should not be more than six meters.

A wetland is an area where excess of water is the dominant factor. The presence of water determines the type of soil, plant and animal life.

Wetlands also include areas with seasonal flooding where the ground could be exposed for some time.

The Ramsar Convention defines them as “areas of marsh, fen, peatland or water, whether natural or artificial, permanent or temporary, with water that is static or flowing, fresh, brackish or salty, including areas of marine water the depth of which at low tide does not exceed six meters”.

Wetland Values

Flood Control Groundwater Replenishment Storm Protection Sediment and Nutrient Retention Climate Change Mitigation Water Purification Wetland Products Recreation/Tourism Cultural Value Reservoirs of Biodiversity

Reservoirs of Biodiversity

Freshwater ecosystems cover only 1% of the earth’s surface but hold more than 40% of the world’s species and 12% of all animal species.

Coral Reefs in marine ecosystems are biologically diverse and they rival tropical rainforests. Coral Reefs cover only 0.2% of the ocean floor but contain 25% of all marine species.

Productivity in wetlands is high for both plants and animals. Wetland products including fish and plants are relatively higher than any other biome in the world.

Commercial fisheries are totally dependent on the well being of wetlands for their continued business. About 1 billion people around the world feed on fish protein and two thirds of fish consumed are dependent on coastal wetlands.

Wetlands and the biodiversity they harbour are not well known in Ethiopia.

In Ethiopia, wetland biodiversity in terms of birds, fish and plants has better coverage than other biodiversity. Wetland plant studies may need to be more specific and distinctive by carrying out an inventory on wetland dependent species alone.

Most of the current studies are largely listings and monitoring work. Little work has been done on long-term ecological work for the groups.

Little or virtually nothing is known about other aspects of biodiversity including amphibians, reptiles and insects.

What is a Waterbird?

According to Ramsar, “waterbirds are birds that are ecologically dependent on wetlands”.

Ecological dependency is related to the species behaviour where it spends a large proportion of its time using wetland habitats for breeding, feeding, roosting and/or moulting.

More specifically waterbirds are defined in 33 bird families of which 23 are represented in Ethiopia.

Waterbirds: Global, Regional and National Aspects

A total of 2,271 biogeographic populations are recognised in the world. Total number of populations of species represented in Africa are 611.

The best known populations of waterbirds occur in Europe (97%) followed by Africa (91%), North America (81%), Asia (79%), Oceania (66%) and the Neotropics (59%).

Globally, waterbirds are represented by 808 species. From 1600 to the present, 60 species populations have been extinct.

Africa has a total of 492 waterbird species, which make up for 22% of all species. Africa has a total of about 2236 species of birds.

Ethiopia has a total of at least 212 waterbird species. This is 43% of the total for Africa (492 species).

Eighty-eight of the 212 species are migrants from the north. The rest 124 species are resident with a few other African migrants.

Annual waterbird counts regularly record 128-130 species out of the 212 species.

Where do you find Waterbirds in Ethiopia?

Waterbirds are associated with all sorts of wetland habitats including small seasonal pools and grassland inundation.

Amongst 23 sites that are annually censused, Lake Awassa is relatively the richest in diversity (74 species) and total number of waterbirds (12 000 – 12 500).

Abijatta has highest number of birds (30 000 – 30 500) with fewer species (about 46 species) than Awassa.

Other important sites include Nabega plains, Ashenge, Chelekleka and Wagtera.

What is the status of Waterbirds in Ethiopia?

From the 23 wetland samples annually counted the highest frequencies of occurrence have been recorded for the following species:

Egyptian Goose (23 sites) Spur-winged Plover (22 sites) Sacred Ibis (22 sites) Wood Sandpiper (20 sites) migrant Northern Shoveler (20 sites) migrant Cattle Egret (19 sites) Squacco Heron (18 sites) Black-winged Stilt (18 sites) Ruff (18 sites) migrant Common Sandpiper (16 sites) migrant

What kind of habitats do waterbirds prefer?

Ethiopian wetland classification is non-existent.

Ethiopia relative to its diverse landscape would have a wide range of wetland habitats.

Wetland types include lacustrine (lakes), palustrine (swamps, marshs, springs etc) and riverine systems.

While wetlands can be found across the breadth of the country (especially represented by riverine systems) significant wetland resources are found in the Southwest, Western, Northern and Rift Valley areas of the country.

Urban and Brown (1971), have classified bird habitats in Ethiopia into 5 types. They are Montane, Forest, Grassland and Savannahs, Arid and Aquatic habitats.

Out of these 5 habitats, wetland formations usually occur in 4, namely montane, forest, grassland and aquatic.

Wetlands associated with Montane habitat 3200–4000m (alpine meadows, moorland, heath, hypericum and bamboo).

Wetlands associated with Forest habitat 300 – 2900m (lowland riverine, glades, hagenia and juniper formations).

Wetlands associated with Grasslands and Savannahs 500-2750m (mostly highland grasslands but can also include lowland riverine systems, floodplains, seasonal rivers and plains where waterlogged conditions occur).

Wetlands associated with Aquatic systems (includes edges of large freshwater, alkaline lakes, highland streams and rivers).

Artificial or man-made conditions also attract waterbirds including dams, impoundments, sewage spills, pools and garbage dumps.

Importance of Waterbirds

Organisms associated to certain ecosystems can be useful bioindicators.

Some species can show trends and therefore act as bioindicators or early warning systems.

Regular and consistent monitoring will show changes that can be countered with proper measures in time.

Gaps in our Knowledge

We have information only on 23 sites upto now. We need to increase survey sites. Increase in sites requires capacity in terms of human and financial resources.

We have 13 years of census data on 128 species of waterbirds. That is only 60% of the total waterbird species (212 species) in Ethiopia.

Information collected can show us some kind of trend but not enough to describe population estimates and overall trends at a national level.

Waterbird monitoring can be fruitful if more people take part. Need to train persons at regional level.

The wetlands of Ethiopia need more attention in terms of knowing what they are and where they are found. There is a need to do basic research at a national level.