August 22, 2011

Avifauna of Ethiopia: Some risk aspects


Threatened animal species in Africa (WCM/IUCN 1998) 
Many of the endemic species in the Horn of Africa live in very narrowly defined areas. 30 of 67 species in the Endemic Breeding Bird table inhabit areas of less than 20,000 square km, eight of them even in areas of 200 square km or less. Therefore, the risk potential of these species must be assessed as high. Regional and even local changes in land use or climate conditions can have serious consequences for the development and survival of small populations.

According to IUCN, 17 of the 67 endemic bird species are considered as "endangered", three of them as "critical endangered": Ochre-brested Francolin (Francolinus ochropectus), Archers's Lark (Heteromirafra archeri) and Liben Lark (Heteromirafra sidamoensis). The latter exists only in an approximately 30-acre area in southern Ethiopia. The total population size is estimated to be less than 250 individuals (Donald et al. 2010). If no protection measures are implemented in the near future, we will probably witness its extinction. Encouraging are recent observations from May 2011, after which the species occurs in another small area in north eastern Ethiopia (Nigel Collar, oral information). Genetic studies should also clarify whether H. archeri and H. sidamoensis are actually different taxa.

Looking at the birds of the African continent as a whole, the avifauna of Eastern Africa (including Horn of Africa and offshore islands) is particularly at risk. Back in the nineteen nineties, 107 bird species in that area were threatened according to IUCN criteria (critical endangered, endagered or vulnerable ). That's more than 50% of then 207 threatened bird species in Africa (WCM / IUCN 1998).

August 15, 2011

Avifauna of Ethiopia: Some unsolved taxonomic questions

Ethiopian Boubou (Laniarius aethiopicus)
Numerous taxonomic questions of birdlife in the Horn of Africa region will require further clarification or have been investigated only recently.

This concerns at least eight of the taxa listed in the Endemic Breeding Bird table. The Socotra Buzzard (Buteo socotraensis) is according to genetic findings closest related to Buteo bannermanni, who lives on the Cape Verde islands. Valid nomenclatural description was not done until recently (Jennings 2010, Porter and Kirwan 2010). Buteo archeri, living in Somalia, is often regarded as a subspecies of Buteo augur. Further studies to define the populations are lacking. Otus socotranus (described 1899) is seen again as a separate species after long lumped with O. senegalensis (Jennings, l.c.). The re-separation of Laniarius erlangeri (described 1905) of L. aethiopicus was only recently (Nguembock et al. 2008). In this context the Bulo Burti Boubou (L. liberatus), described in 1991 by Smith et al., was recognized as a morph and the species status withdrawn. Calandrella erlangeri (described 1905) was long regarded as subspecies of Calandrella blanfordi. Dowsett and Forbes-Watson (1993) united C. somalica, C. athensis and C. erlangeri to C. somalica. However, Clements (2000) regarded C. erlangeri again as separate species. While Redman et al. (2009) follow the suggestion, Ash and Atkins (2009) treat erlangeri again as a subspecies of C. blanfordi. A final clarification seems open. The Degodi Lark is no longer a valid species (Collar et al. 2009).

August 12, 2011

The range of the Ethiopian Bush-crow in southern Ethiopia


Ethiopian Bush-Crow (Zavattariornis stresemanni)
In July 2010 we made a survey on the endemic Ethiopian Bush-crow Zavattariornis stresemanni in southern Ethiopia (Oromia Regional State, Borana zone). Along a 2,500 km-long track about 500 GPS-based records on birds and nest sites were collected. We counted a total of 2,600 birds or nests. Previous studies on the range of the Ethiopian Bush-crow were largely limited to countings along the paved roads and on random observations. With the data now available, it is possible to estimate the range of the species more reliably. We found birds or nests in 81 grids (5x5 minutes fields). This corresponds to an area of ​​approximately 7,000 sq. km. Thus, the range of the species is larger than thought. Previous estimates were 4,600 sq. km (BirdLife International species factsheed, July 2011). The results can be found in the following maps.

Map of the track and records
Distribution map (grid map, with a grid size of 5 minutes)
Map of the main breeding areas
Density map 

We are currently working on a model that explains the limited range of the species based on data on climate and vegetation. A publication is being prepared. I am grateful to Deutsche Ornithologen-Gesellschaft (DO-G) and Gesellschaft für Tropenornithologie (GTO) for funding. 

August 5, 2011

Early explorers of the birds of Ethiopia

Christian Gottfried Ehrenberg *1795 +1876
A brief but fascinating insight into the scientific discovery of the birdlife of Ethiopia and Eritrea give Ash and Atkins (2009). Only one special aspect is to be discussed here in more detail: the role of German scientists and travelers. German researchers have discovered and described 29 of the 67 taxa listed in the Endemic Breeding Birds table, that is about 45% of the Horn of Africa endemic bird species.

The earliest description of an Ethiopia/Eritrea endemic species, still recognized today, was written by Johann Friedrich Gmelin (1789). It concerned the Dark-headed Oriole (Oriolus monacha) and goes back to an entry in the famous book "Histoire naturelle des oiseaux," written by the Frenchman Buffon. But in this book, the binary nomenclature has not been used. Thus, the Göttingen scholar had the honor of having described the first Horn of Africa endemic species according to scientific standards.

The first German field researchers on the Red Sea coast and hinterland were Christian Gottfried Ehrenberg and Friedrich Wilhelm Hemprich. After extensive research travels in the Middle East and North Africa, another expedition led them to Southern Arabia and finally 1824/25 to Ethiopia (Eritrea).

August 4, 2011

Endemic Birds on the Horn of Africa

Ethiopia is characterized by a great topographic and landscape diversity. The height profile varies from 125 meters below sea level in the Danakil desert to the 4,533 m high summit of Ras Dejen in the Simien mountains. With an area of 1,127 million km² Ethiopia is something three times as large as Germany, with a comparable population of currently around 85 million. The peculiarity of the Ethiopian avifauna can be judged better when viewed in a somewhat wider context. As a spatial reference point should serve the "Horn of Africa", in addition to Ethiopia including its neighbors Eritrea, Djibouti and Somalia, as well as the Socotra Archipelago (short Socotra), lying off the Somali coast, but politically belonging to Yemen.

In this region more than 1,000 nesting and migratory bird species were noted. In the Endemic Breeding Birds table overall 67 species or taxonomic units are listed, which may be awarded the status of "endemic" on the Horn of Africa. Such a list is always provisional and can not offer more than a basis for discussion. This is due to the fact that a number of taxonomic and nomenclatural issues are still unclear. New findings inevitably lead to other perspectives and revised figures. Secondly, there is always a certain discretion whether to record a species with very small area units (or occasional occurrence) in neighboring countries in such a list or not. The table includes the IUCN Red List category, population size and trend for each species.