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Decline of the Golden Eagle (Aquila chrysaetos) in Ethiopia
Author(s): Michel Clouet and Claude Barrau
Source: Journal of Raptor Research, 49(2):222-226.
Published By: The Raptor Research Foundation
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J. Raptor Res. 49(2):222–226
E 2015 The Raptor Research Foundation, Inc.
DECLINE OF THE GOLDEN EAGLE (AQUILA CHRYSAETOS) IN ETHIOPIA
MICHEL CLOUET AND CLAUDE BARRAU
AROMP Museum d’Histoire Naturelle, 35 Alle´es Jules Guesde, 31000 Toulouse, France
KEY WORDS: Golden Eagle; Aquila chrysaetos; Afro-alpine;
Ethiopia; relict population.
Ethiopia harbors a small and isolated population of
Golden Eagles located in the Bale Mountains, southern highlands, east of the Rift valley, the only known population in tropical Africa (Clouet and Barrau 1993, Ash and
Atkins 2009; Fig. 1). The Ethiopian highlands, where the
Afro-alpine community is the largest on the continent, are remarkable for their endemic and range-restricted flora and fauna. The Bale Mountains National Park (BMNP) was created to protect part of this Afro-alpine ecosystem and initially to safeguard their two charismatic mammals, the mountain nyala (Tragelaphus buxtoni) and the Ethiopian wolf (Canis simensis; Brown 1969, Hillman 1986).
We previously studied a sample of this population of
Golden Eagles over 5 yr from 1993 to 1997 in the BMNP, reporting a number of unusual characteristics: relatively small home range, low diet diversity, low productivity, and strong interspecific interactions with Verreaux’s Eagles (Aquila verreauxii; Clouet et al. 1999). This sample, which numbered seven occupied territories, possibly represented the entire population of Golden Eagles of the
BMNP and even of Ethiopia (Ash and Atkins 2009).
Since the 1990s, the BMNP has been under increasing pressure from an ever-growing human population, resulting in a strong negative effect on the habitats and the fauna (Stephens et al. 2001, Gower et al. 2013). In this context, we thus revisited this population of Golden Eagles, and we here report on its status two decades later.
Study Area. The study was conducted in the upper Web valley between 3200 and 4000 masl, and focused on the same seven sites, in an area of 200 km2, as previously investigated in the 1993–1997 study. The upper Web valley, which is the only known breeding range of the Golden
Eagle in tropical Africa, represents the typical Afro-alpine steppe, with its endemic rodent community (mainly the giant mole-rat [Tachyoryctes macrocephalus] and two species of murine rodents [Arvicanthis blicki and Lophuromys melanonyx]), which make up the majority of the prey of the
Ethiopian wolf (Sillero-Zubiri and Gottelli 1995) and of a rich raptor assemblage (Clouet et al. 2000). The upper
Web valley harbors the highest biomass of rodents of any area studied within the BMNP (Sillero-Zubiri et al. 1995,
Tallents et al. 2012) and formerly held a high density of the endemic Starck’s hare (Lepus starcki), the main prey of the Golden Eagles (Clouet et al. 1999).
Survey Method. Our study was conducted during the breeding season of 2014 (22 February–4 March). Observers (one to four) walked the same standardized transects in the Web valley as in our previous study (2–6 km in length; n 5 21, three surveys in each eagle territory) through known territories of Golden Eagles, recording presence and activities of the birds. Transects were supplemented by periods of continuous observations of 2–5 hr (for a total observation time of 52 hr), during which all bird sightings were recorded. We also conducted complementary transects in the Web valley (n 5 6) and on the
Sanetti plateau (n 5 6), the other large region of Afroalpine habitat in the BMNP, to search for other sites occupied by Golden Eagles.
On all transects (n 5 33), we recorded other raptor species and hares (as potential prey for the eagles). Data on presence of livestock (species, number) and settlements were also collected during the survey.
Among the seven territories monitored in 1993–1997, only three, located in the uppermost part of the valley, were occupied by pairs of adult Golden Eagles in 2014 (i.e., birds perching, soaring, and displaying with undulating flights). Except for an immature female near one of these occupied territories, no other eagles were observed in the Web valley nor on the Sanetti plateau.
Conversely, other raptor species did not show any decrease in numbers compared to the results of our previous study (Clouet et al. 2000; Table 1). All seven of the Verreaux’s Eagles’ territories previously found within the sampling area and contiguous with those of Golden Eagles were occupied by breeding pairs (Fig. 2). These Verreaux’s Eagles now moved through the vacant nesting areas of Golden Eagles. Breeding Augur Buzzards (Buteo augur) numbered three pairs in each of the vacant Golden
Eagle nesting areas, where previously there were none when the sites were occupied by the eagles. Numbers of1 Email address: firstname.lastname@example.org 222 breeding Bearded Vultures (Gypaetus barbatus), Lanner Falcons (Falco biarmicus) and Eurasian Kestrels (F. tinnunculus) remained stable, as did counts of migrating Steppe