Why share Ethiopian Bush-crow and White-tailed Swallow an identical range in spite of a very different history of colonization?

Distribution map of the three Hirundo species

There are two endemic bird species in southern Ethiopia which live in almost an identical range: Ethiopian Bush-crow and White-tailed Swallow. But apparently their respective ancestors come from very different parts of the world. The closet relatives of Zavattariornis - ground jays of the Genus Podoces - live in Central Asia, whereas the relatives of Hirundo megaensis are all from Africa. Dor et al (2010) describe the relationship of the swallows as follow:

"...the ‘Pearl-breasted Swallow’ clade, is comprised of the Pearl-breasted (Hirundo dimidiata), White-tailed (H. megaensis) and Pied-winged swallows (H. leucosoma). ... Phylogenetic relationships of the White-tailed Swallow, a species endemic to a small region in southern Ethiopia, have not been previously examined, but based on plumage traits it was expected to be close to the Pearl-breasted Swallow  (Sibley and Monroe, 1990; Turner and Rose, 1989), and our analysis confirmed this affinity. Indeed, the genetic divergence between H. megaensis and H. dimidiata (0.7%) is by far the smallest existing among species in the genus (otherwise, range = 2.0–11.6%) and is equivalent to the divergence among populations of the polytypic H. rustica (range 0.25–1.6%). H. megaensis and H. dimidiata inhabit similar habitats, but are separated by a range disjunction of about 1,500 km..."

It remains one interesting question: Why share Zavattariornis stresemanni and Hirundo megaensis a nearly identical tiny range in spite of a very different history of colonization?

Masked Lark records 2011 in southern Ethiopia

Singing Bush-lark (Miafra cantillans) in Sarrite, Southern Ethiopa 

According to Ash et al. (2009) there have been only 5 Masked Lark Spizocorys personata records (altogether 18 birds) in Ethiopia in more than 110 years. In Kenya only 3 sites are known. That's worldwide only 9 known locations with four subspecies. The range is said to be 73,300 km², but probably much smaller and fragmented. Nevertheless, the BirdLife model map shows a nearly coherent and widespread distribution, which does probably not exist in this way. There is a need for research, not least because the future outlook for this species seems to be very critical due to climate change.

In southern Ethiopia the subspecies Spizocorys personata yavelloensis has been scientifically described around 70 years ago. Since then apparently no other reliable data exist on the presence of this subspecies near the place of origin.  A search in June 2011 provided, however, positive results. An encouraging large number of Masked Larks were found in an area about 80 km west of Yabello. The area is also habitat for Grevy's Zebras and intended to be part of a prospective National Park. The most common lark in the area, however, is the Singing Bush-lark (figure).

Avifauna of Ethiopia: A new approach in conservation

Harenna Forest (Bale Mountains, Oromia Regional State)

In Ethiopia, there are currently seven national parks, wildlife sanctuaries as well as several other protected areas. The conservation status is unsatisfactory in most of these sites. There are several reasons, but one of the challenges is without question the tremendous population pressure. For example, large parts of the Harenna Forest (Bale National Park) is used today by settlers. The decline in dense forests 1973-2000 was 15% between 1973 and 2000. About 4% of the forest disappeared completely (Pinard et al, no date).  After restrictive protection measures and bans have failed in recent years, one focuses on a more collaborative approach that incorporates the interests and knowledge of the local population.

This corresponds in principle to the efforts of IUCN to establish so-called "Indigenous and community Conserved Areas" (ICCA) - a so far unconventional reserve category (Kothari 2009). It remains to be seen whether and to what extent this concept is successful. For the Borana territory in southern Ethiopia Bassi and Tache (2011) have demonstrated the possibilities, but also the limitations of such an approach. Practical obstacles existed, especially in the massive immigration of settlers from other areas, political marginalization of pastoralists, and a de facto privatization of formerly communal land.

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).

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).

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. 

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).

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.