Climate and the restricted range of the Ethiopian Bush-crow

Distribution of the 4,455 1-km cells predicted to contain suitable land cover (dark blue) within 

the envelope of 6.001 1-km cells with optimal climate suitalility (light and dark blue) in southern Ethiopia. 

In a study, published in 2012 in the Journal of Ornithology*, we attempt to describe and explain the peculiarly restricted distribution of the globally threatened Ethiopian Bush-crow Zavattariornis stresemanni. At a regional scale, models containing only correlates of land cover suggested a far wider distribution of suitable habitat in north-east Africa than the area actually occupied. However, models including only climate variables predicted the known distribution almost perfectly, and suggested that the species’ area of occupancy is delimited by a pocket of climate that is cooler, dryer and more seasonal than surrounding areas. The predicted probability of occurrence was low outside a narrow range of mean annual temperatures of 17.5–20°C. Within the area predicted to be climatically most suitable, records of Bush-crows were concentrated in 1-km cells of marginally but significantly lower normalised difference vegetation index (NDVI), indicating a preference for areas of lower photosynthetic activity.  At a finer spatial scale within a 10-km2 intensive study site in the core of the species’ range, nests were located in 30-m cells of higher NDVI but always close to areas of lower NDVI. These areas of lower NDVI comprise open grassland, which standardised observations of individual birds showed to be the main foraging habitat. However, taller vegetation is also necessary for nesting and roosting; the average height of nests from the ground was nearly 5 m. Therefore, the species’ range appears to be defined primarily by a unique climate pocket within which it shows a preference for park-like habitats of grassland interspersed with taller vegetation, largely the result of clearance of vegetation by people and their associated grazers. The diet appeared unspecialised and a wide range of feeding methods was observed. Models estimate the species’ optimal climatic range to cover around 6,000 km2, of which perhaps 4,500 km2 has suitable land cover. We tentatively estimate the global population to be at least 9,000 breeding pairs, with a potentially larger additional population of non-breeding birds, particularly nest-helpers. Several climate models predict increases in both temperature and  precipitation in the southern highlands of Ethiopia. The species’ narrow climatic range suggests that global climate change may therefore pose a serious threat to its long-term survival.

* Donald, P. F., Gedeon, K., Collar N. J., Spottiswoode, C. N., Wondafrash, M. & Buchanan, G. M. 2012: The restricted range of the Ethiopian Bush-crow Zavattariornis stresemanni is a consequence of high reliance on modified habitats within narrow climatic limits. Journal of Ornithology 153: 1031-1044.

Francolinus (castaneicollis) atrifrons

Francolinus (castaneicollis) atrifrons

Here are some of our pictures of Francolinus (castaneicollis) atrifrons we took in May 2012 in Mega, Southern Ethiopia. The photos are from three birds the villagers had caught. .

Note the differences in head coloration: atrifrons males have a distinctive orange patch behind the eye, markedly different from other subspecies in the castaneicollis complex - and probably not visible on a specimen. At least in this regard the illustration in the Horn of Africa field guide  is not very appropriate. Also, the Mega birds appear much grayer than in the book.

The habitat is also different from other populations of F. canstanicolis. We found the species in densely vegetated, usually rocky areas at higher altitudes, but not in "juniper forest". One reason may be that these forests are now nearly disappeared around Mega. The mountain habitats are in pitiable condition. Added to this is an obviously strong pressure of hunting by snares.

Francolinus atrifrons was described by Conover in 1930 as a separate species. The "downgrading" to F.castaneicollis atrifrons goes back to Benson 1945. But B. P. Hall, in his francolin study of 1963 seemed inclined to regard atrifrons as separate species.

Töpfer, T. & Gedeon, K. (2013): Auf der Suche nach dem Schwarzstirn-Frankolin in Süd- Äthiopien. WPA-Rundbrief 121: 10-13.

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.

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.