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The diet of the Desert Eagle Owl, Bubo bubo ascalaphus, in the Eastern Desert of Jordan
Journal of Arid Environments (2000) 44: 369–372 doi:10.1006/jare.1999.0601, available online at http://www.idealibrary.com on
The diet of the Desert Eagle Owl, Bubo bubo ascalaphus, in the Eastern Desert of Jordan
Lina B. Rifai, Walid N. Al-Melhim, Burhan M. Gharaibeh & Zuhair S. Amr* Department of Biology, Jordan University of Science & Technology, Irbid, Jordan (Received 26 June 1998, accepted 16 September 1999) One hundred and seventy-four pellets regurgitated by one individual of the Desert race of the Eagle Owl (Bubo bubo ascalaphus) yielded 765 individuals representing five mammals (four rodents and one insectivore), undetermined snakes and lizards, at least three birds, three and two confirmed scorpions and beetles respectively, and unidentified solpugida and beetles species. By frequency, arthropods constituted 50)8% of the diet, mammals 36)8%, reptiles 9)1% and birds 3)3%. The results suggest that the Eagle Owl is an opportunistic hunter and feeds on a wide range of animals. 2000 Academic Press Keywords: Bubo bubo; Jordan; diet; Eagle Owl
Introduction Several papers have discussed the diet of the Eurasian race of the Eagle Owl in Europe (Cramp, 1985). Comparatively, few have focused on the diet of the Desert race, Bubo bubo ascalaphus. In North Africa, Boukhamza et al. (1994) found that the Eagle Owl in Algeria fed mainly on mammals (94)5%) representing at least 13 species of rodents, a hare, and two shrews, while at the Kharga Oasis in Egypt, Goodmann (1990) reported five mammalian species, including the trident bat, Asellia tridens. The Desert race of the Eagle Owl is distributed throughout North Africa and into the southern Middle East (Cramp, 1985). In Jordan, B. b. ascalaphus, is a resident owl in desert habitats, and seems to be restricted to extreme dry deserts. The Northern race (Bubo bubo interpositus) is found in vegetated areas near Jarash and the highlands. Bates & Harrison (1989) found that the Northern race fed on the lesser-white toothed shrew (Crocidura suaveolens), the long-eared hedgehog (Hemiechinus auritus), and other rodents. In a preliminary study on the Eagle Owl in the Azraq Oasis, Jordan, Amr et al. (1997) recovered the remains of two insectivores (Paraechinus aethiopicus and C. suaveolens), three rodents (M. crassus, J. jaculus and Mus musculus) and Passer domesticus. About 20 races of the Eagle Owl are known to occur across the Palearctic, where a smaller Southern race, ascalaphus, breeds in the Jordanian deserts (Andrews, 1995; Porter et al., 1996). The eastern desert of Jordan is unique in many aspects; its geological *Please address all correspondence to: Dr Zuhair S. Amr, Department of Biology, Jordan University of Science & Technology, P.O. Box 3030, Irbid, Jordan. E-mail: [email protected] 0140}1963/00/030369#04 $35.00/0
2000 Academic Press
L. B. RIFAI ET AL.
370
formation and habitats, as well as animal communities, are distinct from those in North Africa. The present study reports on the diet of the Desert race of the Eagle Owl in the Eastern Desert of Jordan, based on a large number of pellet series. Materials and methods During the summer of 1997, a total of 174 pellets were collected from Faydat ad Dahikiyah (31333 N, 37310 E). This area is located near the Jordanian-Saudi Arabian borders. It consists of a series of sharp mountains and cliffs, void of vegetation. On the periphery of the study site, several small and medium sized caves are scattered and the Eagle Owl was spotted and positively identified in a small cave. Each pellet was placed in a Petri dish, soaked in water for 15 min, then all bones and arthropod remains were removed. The contents of each pellet were separated. To determine the number of individuals per pellet, lower jaws of reptiles and mammals, bird’s bills, and arthropod remains (Chelicera, telsons, and elytras) were matched when possible. Results A total of 174 pellets regurgitated by the Eagle Owl were analysed (Table 1). A total of 765 individuals representing five mammals (four rodents and one insectivore), undetermined snakes and lizards, at least three birds, three and two confirmed scorpions and beetles respectively, and unidentified solpugida and beetles species were found. By
Table 1. Frequency of species recovered from 174 pellets of the Desert Eagle Owl ( Bubo bubo ascalaphus) in Jordan
Total Lizards Snakes Reptiles Birds
%
Range
67 3 70 25
8)7 0)4 9'1 3'3
0+3
Mammals Cricetulus migratoris Gerbillus dasyurus Jaculus jaculus Meriones crassus Paraechinus athioicus
1 3 130 144 4
0)1 0)4 17)0 18)8 0)5
0–1 0–1 0–4 0–4 0–1
Arthropods Androctonus crassicauda Compsobuthus werneri Scorpio maurus palmatus
3 113 59
0)4 14)8 7)7
0–1 0–6 0–4
Solifugids Scarabaeus sacer Phyllognathus excavatus Unidentified beetles
153 4 2 54
20 0)5 0)3 7)1
0–6 0–1 0–1 0–8
Total
765
100
0–4 0–1
DIET OF THE DESERT EAGLE OWL
371
frequency, arthropods constituted 50)8% of the total prey identified, mammals 36)8%, reptiles 9)1% and birds 3)3%. The number of ingested items per pellet ranged from 1–23 individuals (average 4)4). For example, one pellet contained the remains of one Jaculus jaculus, while another included the remains of one Meriones crassus, four lizards, six scorpions, two solpugids, and 10 beetles. However, from the biomass point of view, mammals comprised the highest percentage in comparison to arthropods. The remains of 282 mammals representing five species belonging to two orders were found in the pellets (Table 1). The Sundevall’s jird, M. crassus, was by far the most common prey (144 individuals), followed by the three-toad jerboa, J. jaculus (130 individuals). The number of rodent skulls ranged from 0–4 per pellet (average 1)6). Apparently, the Eagle Owl preyed on both M. crassus and J. jaculus adults. This was established because individuals with a mandibular length of 19–24)9 and 16–24)9 mm constituted the largest portion of ingested Sundevall’s jird (48 out of 71) and three-toad jerboa (36 out of 44), respectively. A total of 70 reptilian remains were recovered representing 67 lizards and 3 snakes. In the study area, three lizards (Acanthodactylus schmidti, A. boskianus and A. opheodurus) and one snake (Psammophis schokari) were collected. Twenty-five bills of at least three species of birds were found in the pellets. The number of bills ranged from 0–3. The Crested Lark (Galerida cristata) and the Hoopoe Lark (Alaemon alaudipes) were found to occur in the study site. Three scorpion species (Scorpio maurus palmatus, Compsobuthus werneri and Androctonus crassicauda) were identified. Compsobuthus werneri was the most consumed scorpion (113 individuals), followed by S. m. palmatus (59 individuals). Solifugids were the most common Arachnids in the pellets (20%). Other beetles include the Sacred Scarab (Scarabaeus sacer) and the Unicorn Beetle (Phyllognathus excavatus), and other unidentified beetles constituted 7)9% of the total items consumed by the owl. Discussion It seems that B. b. ascalaphus utilizes a wide range of prey items in respect to its habitat. In Algeria, 13 and 3 species of mammals and birds, respectively, were consumed, where Meriones shawi and three species of the genus Gerbillus were the most consumed species (Boukhamza et al.,1994). On the other hand, the house mouse, Mus musculus, was the most preyed vertebrate (67)5%). As for birds, our results are similar to those obtained by Goodman (1990), who reported that 10)4% of the total vertebrates were birds. In contrast Boukhamza et al. (1994) stated that birds constituted only 1)1% of the total. The hunting range for the Eagle Owl is about 5 km. It seeks its prey at night and in the early morning hours. The owl lands on the ground and relies on its hearing to locate the prey (Richard Porter, pers. comm.). In Faydat ad Dahikiyah, the Golden Eagle, Aquila chrysaetos, and the Little Owl, Athene noctua, were found to share the same habitat with the Eagle Owl. However, the first two species are diurnal, thus avoiding competition with B. b. ascalaphus. Goodman (1990) indicated that mammals constituted 85)5% of the total percent of vertebrates, while representing 70)9% of the total weight consumed by the Eagle Owl desert race in the Kharga oasis, Egypt. By contrast, Boukhamza et al. (1994) found that mammals taken by this owl in Algeria comprised 95)4% and 99)5% in frequency and biomass, respectively. The number of arthropods per pellet varied (1–18) with an average of 2)3 arthropods per pellet. Both S. m. palmatus and C. werneri have soft bodies compared to the stout and heavily sceletized and poisonous A. crassicauda. Indeed, 14)8% and 7)7% of the total diet consisted of C. werneri and S. m. palmatus, while only three A. crassicauda individuals (0)4%) were recovered.
372
L. B. RIFAI ET AL.
Despite the presence of Gerbillus dasyurus in the study area, fragments of only three individuals were found. This view was shared on the limited pellets analysed by Evans & Bates (1993). Perhaps the activity pattern of G. dasyurus does not coincide with that of the Eagle Owl. Reptilian remains accounted for 9)1% of the total prey remains. They included 67 lizards and 3 snakes. Boukhamza et al. (1994) did not report any reptiles in their study, however, Goodman (1990) found that reptiles constituted 4)3% of the total vertebrates consumed by the owl. Resorting to this type of diet appears to be related to their relative abundance and perhaps to the low number of other mammalian species. Similarly, Al-Melhim et al. (1997) showed that the Little Owl, Athene noctua, occurring in the Safawi area, eastern Jordan, fed mainly on reptiles (35)5%). Arthropods comprised the major proportion of the owl’s diet (388 individuals, 50)8%). Papgeorgiou et al. (1993) implied that insects and arthropods play a more significant role in the European race of the Eagle Owl diet in southern Europe than in northern Europe, based on their relative abundance in southern Europe. Scorpions and solifugids are very common in arid environments and appear to provide an important source of energy. Further studies are needed to elaborate on bioenergetics and energy conversion following prey intake, and the seasonal fluctuation of the diet of the Eagle Owl in arid habitats as a function of the relative abundance of the prey species in the environment. This work was supported in part by the Higher Council of Science and Technology/Badia Development and Research Project (Animal Biodiversity). We are grateful for the continuous support of Mr. Mohamed Shahbaz, Director of the Badia Development and Research Project.
References Al-Melhim, W., Amr, Z.S., Disi, A. & Katbeh-Bader, A. (1997). On the diet of Little Owl, Athene noctua, from Safawi area. Zoology in the Middle East, 15: 19–28. Amr, Z., Al-Melhim, W. & Yousef, M.A. (1997). Mammal remains from pellets of the Eagle Owl, Bubo bubo, from Azraq Nature Reserve. Zoology in the Middle East, 14: 5–10. Andrews, I.J. (1995). The Birds of the Hashemite Kingdom of Jordan. Musselburgh. 185 pp. Bates, P.J.J. & Harrison, D.L. (1989). New records of small mammals from Jordan. Bonner Zoologishe Beitrage, 40: 223–226. Boukhamza, M., Hamdine, W. & Thevenot, M. (1994). Donnees sur le reH gime allmentaire du Grand-duc ascalaphe Bubo bubo ascalaphus en milieu steppique (Ain Ouessera, Algerie). Alauda, 62(2): 150–152. Cramp, S. (1985). The Birds of the Western Palearctic, Vol. 4. Oxford: Oxford University Press. 960 pp. Evans, M. & Bates, P. (1993). Diet of the Desert Eagle Owl in Harrat al Harrah reserve, northern Saudi Arabia. Ornithological Society of the Middle East Bulletin, 30: 26. Goodman, S.M. (1990). The food habits of the Eagle Owl (Bubo bubo ascalaphus) in Kharga Oasis, Egyptian Western Desert. Journal of Arid Environments, 18: 217–220. Papageorgiou, N.K., Vlachos, C.G. & Balkaloudis, D.E. (1993). Diet and nest site characteristics of Eagle Owl (Bubo bubo) breeding in two different habitats in north-eastern Greece. Avocetta, 17: 49–54. Porter, R.F., Christensen, S. & Schiermacker}Hansen, P. (1996). Field Guide to the Birds of the Middle East. London: T & AD Pyser. 460 pp.
The diet of the Desert Eagle Owl, Bubo bubo ascalaphus, in the Eastern Desert of Jordan
Lina B. Rifai, Walid N. Al-Melhim, Burhan M. Gharaibeh & Zuhair S. Amr* Department of Biology, Jordan University of Science & Technology, Irbid, Jordan (Received 26 June 1998, accepted 16 September 1999) One hundred and seventy-four pellets regurgitated by one individual of the Desert race of the Eagle Owl (Bubo bubo ascalaphus) yielded 765 individuals representing five mammals (four rodents and one insectivore), undetermined snakes and lizards, at least three birds, three and two confirmed scorpions and beetles respectively, and unidentified solpugida and beetles species. By frequency, arthropods constituted 50)8% of the diet, mammals 36)8%, reptiles 9)1% and birds 3)3%. The results suggest that the Eagle Owl is an opportunistic hunter and feeds on a wide range of animals. 2000 Academic Press Keywords: Bubo bubo; Jordan; diet; Eagle Owl
Introduction Several papers have discussed the diet of the Eurasian race of the Eagle Owl in Europe (Cramp, 1985). Comparatively, few have focused on the diet of the Desert race, Bubo bubo ascalaphus. In North Africa, Boukhamza et al. (1994) found that the Eagle Owl in Algeria fed mainly on mammals (94)5%) representing at least 13 species of rodents, a hare, and two shrews, while at the Kharga Oasis in Egypt, Goodmann (1990) reported five mammalian species, including the trident bat, Asellia tridens. The Desert race of the Eagle Owl is distributed throughout North Africa and into the southern Middle East (Cramp, 1985). In Jordan, B. b. ascalaphus, is a resident owl in desert habitats, and seems to be restricted to extreme dry deserts. The Northern race (Bubo bubo interpositus) is found in vegetated areas near Jarash and the highlands. Bates & Harrison (1989) found that the Northern race fed on the lesser-white toothed shrew (Crocidura suaveolens), the long-eared hedgehog (Hemiechinus auritus), and other rodents. In a preliminary study on the Eagle Owl in the Azraq Oasis, Jordan, Amr et al. (1997) recovered the remains of two insectivores (Paraechinus aethiopicus and C. suaveolens), three rodents (M. crassus, J. jaculus and Mus musculus) and Passer domesticus. About 20 races of the Eagle Owl are known to occur across the Palearctic, where a smaller Southern race, ascalaphus, breeds in the Jordanian deserts (Andrews, 1995; Porter et al., 1996). The eastern desert of Jordan is unique in many aspects; its geological *Please address all correspondence to: Dr Zuhair S. Amr, Department of Biology, Jordan University of Science & Technology, P.O. Box 3030, Irbid, Jordan. E-mail: [email protected] 0140}1963/00/030369#04 $35.00/0
2000 Academic Press
L. B. RIFAI ET AL.
370
formation and habitats, as well as animal communities, are distinct from those in North Africa. The present study reports on the diet of the Desert race of the Eagle Owl in the Eastern Desert of Jordan, based on a large number of pellet series. Materials and methods During the summer of 1997, a total of 174 pellets were collected from Faydat ad Dahikiyah (31333 N, 37310 E). This area is located near the Jordanian-Saudi Arabian borders. It consists of a series of sharp mountains and cliffs, void of vegetation. On the periphery of the study site, several small and medium sized caves are scattered and the Eagle Owl was spotted and positively identified in a small cave. Each pellet was placed in a Petri dish, soaked in water for 15 min, then all bones and arthropod remains were removed. The contents of each pellet were separated. To determine the number of individuals per pellet, lower jaws of reptiles and mammals, bird’s bills, and arthropod remains (Chelicera, telsons, and elytras) were matched when possible. Results A total of 174 pellets regurgitated by the Eagle Owl were analysed (Table 1). A total of 765 individuals representing five mammals (four rodents and one insectivore), undetermined snakes and lizards, at least three birds, three and two confirmed scorpions and beetles respectively, and unidentified solpugida and beetles species were found. By
Table 1. Frequency of species recovered from 174 pellets of the Desert Eagle Owl ( Bubo bubo ascalaphus) in Jordan
Total Lizards Snakes Reptiles Birds
%
Range
67 3 70 25
8)7 0)4 9'1 3'3
0+3
Mammals Cricetulus migratoris Gerbillus dasyurus Jaculus jaculus Meriones crassus Paraechinus athioicus
1 3 130 144 4
0)1 0)4 17)0 18)8 0)5
0–1 0–1 0–4 0–4 0–1
Arthropods Androctonus crassicauda Compsobuthus werneri Scorpio maurus palmatus
3 113 59
0)4 14)8 7)7
0–1 0–6 0–4
Solifugids Scarabaeus sacer Phyllognathus excavatus Unidentified beetles
153 4 2 54
20 0)5 0)3 7)1
0–6 0–1 0–1 0–8
Total
765
100
0–4 0–1
DIET OF THE DESERT EAGLE OWL
371
frequency, arthropods constituted 50)8% of the total prey identified, mammals 36)8%, reptiles 9)1% and birds 3)3%. The number of ingested items per pellet ranged from 1–23 individuals (average 4)4). For example, one pellet contained the remains of one Jaculus jaculus, while another included the remains of one Meriones crassus, four lizards, six scorpions, two solpugids, and 10 beetles. However, from the biomass point of view, mammals comprised the highest percentage in comparison to arthropods. The remains of 282 mammals representing five species belonging to two orders were found in the pellets (Table 1). The Sundevall’s jird, M. crassus, was by far the most common prey (144 individuals), followed by the three-toad jerboa, J. jaculus (130 individuals). The number of rodent skulls ranged from 0–4 per pellet (average 1)6). Apparently, the Eagle Owl preyed on both M. crassus and J. jaculus adults. This was established because individuals with a mandibular length of 19–24)9 and 16–24)9 mm constituted the largest portion of ingested Sundevall’s jird (48 out of 71) and three-toad jerboa (36 out of 44), respectively. A total of 70 reptilian remains were recovered representing 67 lizards and 3 snakes. In the study area, three lizards (Acanthodactylus schmidti, A. boskianus and A. opheodurus) and one snake (Psammophis schokari) were collected. Twenty-five bills of at least three species of birds were found in the pellets. The number of bills ranged from 0–3. The Crested Lark (Galerida cristata) and the Hoopoe Lark (Alaemon alaudipes) were found to occur in the study site. Three scorpion species (Scorpio maurus palmatus, Compsobuthus werneri and Androctonus crassicauda) were identified. Compsobuthus werneri was the most consumed scorpion (113 individuals), followed by S. m. palmatus (59 individuals). Solifugids were the most common Arachnids in the pellets (20%). Other beetles include the Sacred Scarab (Scarabaeus sacer) and the Unicorn Beetle (Phyllognathus excavatus), and other unidentified beetles constituted 7)9% of the total items consumed by the owl. Discussion It seems that B. b. ascalaphus utilizes a wide range of prey items in respect to its habitat. In Algeria, 13 and 3 species of mammals and birds, respectively, were consumed, where Meriones shawi and three species of the genus Gerbillus were the most consumed species (Boukhamza et al.,1994). On the other hand, the house mouse, Mus musculus, was the most preyed vertebrate (67)5%). As for birds, our results are similar to those obtained by Goodman (1990), who reported that 10)4% of the total vertebrates were birds. In contrast Boukhamza et al. (1994) stated that birds constituted only 1)1% of the total. The hunting range for the Eagle Owl is about 5 km. It seeks its prey at night and in the early morning hours. The owl lands on the ground and relies on its hearing to locate the prey (Richard Porter, pers. comm.). In Faydat ad Dahikiyah, the Golden Eagle, Aquila chrysaetos, and the Little Owl, Athene noctua, were found to share the same habitat with the Eagle Owl. However, the first two species are diurnal, thus avoiding competition with B. b. ascalaphus. Goodman (1990) indicated that mammals constituted 85)5% of the total percent of vertebrates, while representing 70)9% of the total weight consumed by the Eagle Owl desert race in the Kharga oasis, Egypt. By contrast, Boukhamza et al. (1994) found that mammals taken by this owl in Algeria comprised 95)4% and 99)5% in frequency and biomass, respectively. The number of arthropods per pellet varied (1–18) with an average of 2)3 arthropods per pellet. Both S. m. palmatus and C. werneri have soft bodies compared to the stout and heavily sceletized and poisonous A. crassicauda. Indeed, 14)8% and 7)7% of the total diet consisted of C. werneri and S. m. palmatus, while only three A. crassicauda individuals (0)4%) were recovered.
372
L. B. RIFAI ET AL.
Despite the presence of Gerbillus dasyurus in the study area, fragments of only three individuals were found. This view was shared on the limited pellets analysed by Evans & Bates (1993). Perhaps the activity pattern of G. dasyurus does not coincide with that of the Eagle Owl. Reptilian remains accounted for 9)1% of the total prey remains. They included 67 lizards and 3 snakes. Boukhamza et al. (1994) did not report any reptiles in their study, however, Goodman (1990) found that reptiles constituted 4)3% of the total vertebrates consumed by the owl. Resorting to this type of diet appears to be related to their relative abundance and perhaps to the low number of other mammalian species. Similarly, Al-Melhim et al. (1997) showed that the Little Owl, Athene noctua, occurring in the Safawi area, eastern Jordan, fed mainly on reptiles (35)5%). Arthropods comprised the major proportion of the owl’s diet (388 individuals, 50)8%). Papgeorgiou et al. (1993) implied that insects and arthropods play a more significant role in the European race of the Eagle Owl diet in southern Europe than in northern Europe, based on their relative abundance in southern Europe. Scorpions and solifugids are very common in arid environments and appear to provide an important source of energy. Further studies are needed to elaborate on bioenergetics and energy conversion following prey intake, and the seasonal fluctuation of the diet of the Eagle Owl in arid habitats as a function of the relative abundance of the prey species in the environment. This work was supported in part by the Higher Council of Science and Technology/Badia Development and Research Project (Animal Biodiversity). We are grateful for the continuous support of Mr. Mohamed Shahbaz, Director of the Badia Development and Research Project.
References Al-Melhim, W., Amr, Z.S., Disi, A. & Katbeh-Bader, A. (1997). On the diet of Little Owl, Athene noctua, from Safawi area. Zoology in the Middle East, 15: 19–28. Amr, Z., Al-Melhim, W. & Yousef, M.A. (1997). Mammal remains from pellets of the Eagle Owl, Bubo bubo, from Azraq Nature Reserve. Zoology in the Middle East, 14: 5–10. Andrews, I.J. (1995). The Birds of the Hashemite Kingdom of Jordan. Musselburgh. 185 pp. Bates, P.J.J. & Harrison, D.L. (1989). New records of small mammals from Jordan. Bonner Zoologishe Beitrage, 40: 223–226. Boukhamza, M., Hamdine, W. & Thevenot, M. (1994). Donnees sur le reH gime allmentaire du Grand-duc ascalaphe Bubo bubo ascalaphus en milieu steppique (Ain Ouessera, Algerie). Alauda, 62(2): 150–152. Cramp, S. (1985). The Birds of the Western Palearctic, Vol. 4. Oxford: Oxford University Press. 960 pp. Evans, M. & Bates, P. (1993). Diet of the Desert Eagle Owl in Harrat al Harrah reserve, northern Saudi Arabia. Ornithological Society of the Middle East Bulletin, 30: 26. Goodman, S.M. (1990). The food habits of the Eagle Owl (Bubo bubo ascalaphus) in Kharga Oasis, Egyptian Western Desert. Journal of Arid Environments, 18: 217–220. Papageorgiou, N.K., Vlachos, C.G. & Balkaloudis, D.E. (1993). Diet and nest site characteristics of Eagle Owl (Bubo bubo) breeding in two different habitats in north-eastern Greece. Avocetta, 17: 49–54. Porter, R.F., Christensen, S. & Schiermacker}Hansen, P. (1996). Field Guide to the Birds of the Middle East. London: T & AD Pyser. 460 pp.