Ethiopian Bush-crow and thermal adaptation

Ethiopian Bush-crow: Naked skin area could serve thermoregulation

The Ethiopian Bush-crow Zavattariornis stresemanni is an extremely range-restricted Ethiopian endemic that is confined to dry and relatively cool south Ethiopian acacia savannah habitats. It has been assumed that the specific temperature conditions in these areas might reflect a temperature optimum to which these birds have adapted. With non-tropical magpies Pica and ground-jays Podoces being among their closest relatives, bush-crows might have developed particular adaptive traits to persist under the tropical conditions of the south Ethiopian plains. However, this thermal adaptation hypothesis has not been tested so far. Using an infrared thermography system we investigated if bush-crows are able to regulate their body temperature by emitting heat.

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Rediscovery of the Black-fronted Francolin in Southern Ethiopia

In May 2012 and in May 2013 we searched for the Black-fronted Francolin Pternistis (castaneicollis) atrifrons in the Mega area in southern Ethiopia. Since most of the scarcely published records date back about seven decades, our objectives were (1) to confirm its presence at the type locality, (2) to explore other potentially suitable areas, (3) to collect information on morphology and field characteristics, behaviour

and habitat, (4) to conclude on its taxonomic position, and (5) to make a preliminary assessment of threats to the birds and their habitat. We recorded at least 12 different Black-fronted Francolin individuals on five sites around the town of Mega (04°03′28″ N 38°19′16″ E). The birds inhabited semi-open woodland between 1,480 and 2,223 m asl, where the original juniper forest has almost vanished because of heavy utilisation pressure, primarily by the expansion of agriculture, grazing and harvesting of firewood and timber. A typical external feature of the males is a clearly visible bald yellow patch behind the eye. While no other P. castaneicollis subspecies seems to have this spot, other francolin species have. Additionally, our molecular and bioacoustic data support the separate taxonomic status of atrifrons. Taking together all characters, assigning species status for the Black-fronted Francolin is justified. Based on our survey, we estimate the current population to be very small, rendering the Black-fronted Francolin the most endangered galliform bird of Africa. Also, we assume its range to be much smaller and more fragmented than previously thought, making the local populations crucially endangered.

Download the full article VERTEBRATE ZOOLOGY 64(2) 261-271

Vultures in Ethiopia

Griffon Vulture (Gyps fulvus). Robe. Ethiopia. 10 May 2013

Since there is little information on abundance of vultures in Ethiopia, the following information may be of interest.

On a long 2.988 km route from Awash to Moyale and back to Addis Ababa in May 2013 we recorded the following vulture species and numbers. The low density of almost all species in central and southern Ethiopia - compared to previous years - was striking. Only the Hooded Vulture is still abundant in some areas. In Filtu, 5°6’58”N 40°39’31’’E, we counted at least 70 individuals roosting on a radio antenna tower (12 May 2013).

Species: records/individuals 

Lammergeier Gypaetus barbatus: 1/1

Egyptian Vulture Neophron percnopterus: 7/12

Hooded Vulture Necrosyrtes monachus : 60/412

White-headed Vulture Trigonoceps occipitalis: 3/6

Lappet-faced Vulture Torgos tracheliotus: 2/5

White-backed & Rüppell’s Vulture Gyps africanus & Gyps ruepelli: 19/107.

The records of White-backed and Rüppell’s Vulture were summarized here because of some uncertain identifications of immature individuals.

In addition a Griffon Vulture Gyps fulvus was recorded on 10 May 2013, E of Robe, Bale area, 7°23’9’’N 40°8’26’’E. It seems to be the southernmost record in Ethiopia, according to the distribution map in Ash & Atkins (2009). Only 12 Ethiopian records up to 2009 in the northern part of the country.

More Ethiopian bird records: Gedeon, K. & Töpfer, T. (2013) Selected Bird Records Ethiopia 2013. Travel report. 

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.

Construction and thermal insulation of Ethiopian Bush-crow nests

The main function of bird nests is to provide shelter for eggs and nestlings in order to support optimal offspring development. While this basic condition applies to all nests, an enormous constructional variety in nests has evolved. Regarding its thermal properties, the avian nest construction generally represents a compromise between heat conservation,heat dissipation, and protection from external heat.

The Ethiopian Bush-crow is an endemic Ethiopian bird species which has a very small and climatically distinct range that is cooler, dryer and more seasonal than the surrounding areas. Bush-crows build large domed nests made of thorny twigs with comparatively thick walls and a soil-lined bottom. In a preliminary study* we studied the thermal properties of a bush-crow nest with the aid of IR thermography. Our results show that there was no heat emission in the early morning and that nest surface temperatures clearly corresponded to the temperature changes during the day. Therefore we hypothesise that the nest construction provides substantial thermal insulation during the night time and presumably also delays temperature increase in the internal nesting chamber during the day time. We suggest that the bush-crow’s specific nest construction may have contributed to its persistence in the climatically unique south Ethiopian conditions.

* Töpfer, T. & K. Gedeon 2012: The construction and thermal insulation of Ethiopian Bush-crow (Zavattariornis stresemanni) nests: a prelimary study. Avian Biology Research 5 (4): 198-202.

Thermographic image of a bush-crow nest just before sunrise (a) and at noon (b).

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.

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).