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Natural diet of the Arabian Rheem gazelle, Gazella subgutturosa marica
Journal ofArid Environments (1991) 20: 371-374
Natural diet of the Arabian Rheem gazelle, Gazella
subgutturosa marica
S. A. Mohamed, J. Abbas & M. Saleh* Department ofBiology, University of Bahrain, P.O. Box 32038, [sa Town, Bahrain (Received 23 February 1990, accepted 9 Aprii1990) The natural diet of the Arabian Rheem gazelle was determined by using the faecal analysis method. Eleven different species of plants were identified as food items. Heliotropium crispum and Helianthemum lippii was frequently present in the gazelle's diet. Nutritional values were determined for most food items. Although Zygophyllum quatarense is the most abundant plant in the area, and contains a high percentage of water in its tissues, it was not included in the gazelle's diet.
Introduction The Arabian Rheem gazelle, Gazellasubgutturosa marica, is present in the western region of the Arabian Gulf, including the island of Bahrain (Harrison, 1981). Although considered an endangered species (Anon., 1986), very little is known about its biology, ecology, diet and feeding behaviour. Various methods have been adopted to study the natural diet of herbivores: (1) direct observation and pasture analysis before and after grazing (e.g. Stoddard, 1952; Lamprey, 1963; Abdel-Razik etal., 1988); (2) stomach contents analysis (e.g. Norris, 1943; Baharav, 1982);and (3) faecal analysis (e.g. Storr, 1961; Stewart, 1967). The last method has proved reliable for the recognition of most plants eaten by herbivores (Croker, 1959; Hercus, 1960). The present study examines the natural diet of a wild population of G. subgutturosa by the technique offaecal analysis and attempts to investigate the basis for food selection.
Materials and methods An area about 10 krrr', located in the southern region of Bahrain island (Fig. 1) and inhabited by a herd of 20 G. subgutturosa, was selected for study. The ecology and vegetation of the area are described elsewhere (Saleh et al., in prep.). The faecal analysis method, described by Bhadresa (1986), was adopted for examining food items. Samples of plants present in the area were collected and identified. A reference collection of epidermal tissue from different parts of all plants collected during the period was prepared. Thirty different samples of gazelle faeces were collected and prepared for microscopic examination as described by Bhadresa (1986). These samples were collected before the first rain * Present address: Department of Zoology, Faculty of Science, Al Azhar University, Nasr City, Cairo, Egypt. 0140-1963/911030371
+ 04 $03'00/0
© 1991 Academic Press
Limited
S. A. MOHAMED ET AL.
372 50° 30'
Bahrain
o
26°
Study area
--5 km
Figure 1. The study area.
came when only perennial plants were available to gazelles. Five slides were prepared of each faecal sample and were examined microscopically to identify the plants eaten. Direct observations of gazelles feeding in this area were also used to verify the selection of certain plants. The plants eaten and other abundant species were analysed for nutritional values. Caloric value was obtained by using a bomb calorimeter, and protein was measured according to the method of Lowry et al. (1951). Water content was determined by keeping the specimens in the oven at 110°C for 48 h, and inorganic content was obtained by burning the specimens in a furnace at 500°C. Results Faecal analysis revealed that Arabian Rheem gazelles in the wild feed on a variety of plants. Eleven species were identified in faecal samples, and the percentage of their occurrence in
NATURAL DIET OF THE ARABIAN RHEEM GAZELLE
373
100 90 "e 0
., 0
c
~
:::J
0 0
0
'0
>0
80 70 60 50
.,c
40
0-
30
..
:::J
u:
20 10
A
B
K
C
Figure 2. Various food items included in the diet of the Rheem gazelle analysed by the percentage of occurrence. A, Helianthemum lippii; B, Heliotropium crispum; C, Sporobolus arabicus; D, Pennisetum
divisum; E, Cyperus conglomeratus; F, Calligonum polygonoides; G, Panicum turgidum; H, Aeluropus lagopoides; I, Asphodelus tenuifolius; J, Cutandia memphitica; K, Leptadenia pyrotechnica.
gazelle faeces is shown in Fig. 2. Remains of Heliotropium crispum and Helianthemum lippii were found most frequently in the faeces, and appeared to comprise the major part of the diet. Sporobolus arabicus, Pennisetum divisum and Cyperus conglomeratus were also represented in the diet, but occurred less frequently. Table 1 shows the caloric value, protein, water and inorganic contents of plants included in the gazelle's diet as well as of Zygophyllum quatarense which was abundant in the area but not included in their diet. Caloric values varied according to plant species. The lowest was for Z. quatarense (2'260 K cal g-I) and the highest for Panicum turgidum (4'407 K cal g-I). Calligonum polygonoides contained the highest amount of protein (13'68 mg g dry weighC I) while the figure was only 0'6 mg g dry weight-I for Leptadenia pyrotechnica. Water and inorganic content were highest in Z. quatarense where they reached 81% and 9'4%, respectively. Discussion For a wild population of Rheem gazelle, direct observation proved to be difficult. It is not acceptable to examine the gut contents of an endangered species of gazelle but the faecal Table 1. Caloric value,protein, waterand inorganic contents ofeightvarious plants available to G. subgutturosa marica Plant species
Caloric value K cal g-I
mg protein g dry weighC I
Zygophyllum quatarense Panicum turgidum Helianthemum lippii S'porobolus arabicus Leptadenia pyrotechnica Calligonum polygonoides Cyperus conglomeratus Heliotropium crispum
2'260 4·407 3·507 3·960 3'696 2'805 3'726 3·507
4·27 1·71 8·55 3'42 0'6 13'68 6'0 5·13
Water content
Inorganic content
%
%
81·0 57·0 49·45 52'5 70·4 60·3 70·0 72·5
9'4 2·9 4·45 5·5 2·1 9'7 3'6 6·6
374
S. A. MOHAMED ET AL.
analysis technique adopted has been reported to be reliable for identifying plants eaten by herbivores (Croker, 1959; Hercus, 1960; Bhadresa, 1986). Examination of the faeces showed that the Rheem gazelle included in their diet 11 species of the plants which were available in the area. However, only two of them, H. crispurn and H. lippii, represent the most important food items in their diet. Both H. lippii and H. crispurn are abundant in the area, with the latter forming an important community (Saleh et al., in prep.). These contain in excess of 72% water, but have a low protein content. On the other hand, H. lippii, with less than 50% water content, contained considerable amounts of protein (Table 1). These two abundant plant species form the major diet of gazelles in the area, at least during the non-rainy season, which lasts for most of the year. Such a combination would provide a good source of water as well as protein. Although Z. quatarense is the most abundant plant in the area and contains large amounts of water in its tissues (81%), there was no sign of its inclusion in the gazelle's diet. This may be due to the presence of deterrent chemicals in its tissues. A bitter chemical called 'zygophyllin' has been reported in another species: Z. coccineurn by Rizk (1986). Further investigations of the chemistry of Z. quatarense will be necessary to determine the reasons for its exclusion. We would like to thank the administrative staff of EI Areen Wildlife Reserve for providing us with access to the study area. We also thank Dr J. Ahmad for helping in calorimetry, MrsB. Alrufaei, Ms N. Fulaifel and Ms S. A. Hussein for protein analyses.
References Abdel-Razik, M., Ayyad, M. & Heneidy, S. (1988). Preference of grazing mammals for forage species and their nutritive value in a Mediterranean desert ecosystem (Egypt). Journal of Arid Environments, 15: 297-305. Anon. (1986). 1986 Red List of Threatened Animals. Cambridge, U.K.: mCN Conservation Monitoring Centre. Baharav, D. (1982). Desert habitat partitioning by the dorcas gazelle. Journal ofArid Environments, 5: 323-335. Bhadresa, R. (1986). Faecal analysis and exclosure studies. In: Moore, P. D. & Chapman, S. B. (Eds), Methods in Plant Ecology. pp. 61-67. Oxford: Blackwell Scientific Publications. 589 pp. Croker, B. H. (1959). A method of estimating the botanical composition ofthe diet of sheep. New ZealandJournal ofAgriculture Research, 2: 72-85. Harrison, D. H. (1981). Mammals oftheArabian Gulf. London: George Allen and Unwin. 92 pp. Hercus, B. H. (1960). Plant cuticle as an aid to determining the diet of grazing animals. Proceedings ofthe8th International Grassland Congress, pp. 443-447. Lamprey, H. F. (1963). Ecological separation ofthe large mammal species in the Tarangire Game Reserve, Tanganyika. East African WildlifeJournal, 1: 63-92. Lowry, O. H., Rosebrough, N. J., Farr, A. & Randall, R. J. (1951). Protein measurement with the Folin phenol reagent. Journal ofBiological Chemistry, 193: 265. Norris, J. J. (1943). Botanical analysis of stomach contents as a method of determining forage consumption of range sheep. Ecology, 24: 244-251. Rizk, A. M. (1986). The Phytochemistry oftheFloraofQatar. Richmond: King Print. 582 pp. Stewart, D. R. M. (1967). Analysis of plant epidermis in faeces, a technique for studying the food preferences of grazing herbivores. Journal ofApplied Ecology, 4: 83-111. Stoddard, L. A. (1952). Problems in estimating grazing capacity of ranges. Proceedings of the 6th International Grassland Congress, pp, 1367-1373. Storr, G. M. (1961). Microscopic analysis of faeces, a technique for ascertaining the diet of herbivorous mammals. Australian Journal ofBiological Science, 14: 157-164.
Natural diet of the Arabian Rheem gazelle, Gazella
subgutturosa marica
S. A. Mohamed, J. Abbas & M. Saleh* Department ofBiology, University of Bahrain, P.O. Box 32038, [sa Town, Bahrain (Received 23 February 1990, accepted 9 Aprii1990) The natural diet of the Arabian Rheem gazelle was determined by using the faecal analysis method. Eleven different species of plants were identified as food items. Heliotropium crispum and Helianthemum lippii was frequently present in the gazelle's diet. Nutritional values were determined for most food items. Although Zygophyllum quatarense is the most abundant plant in the area, and contains a high percentage of water in its tissues, it was not included in the gazelle's diet.
Introduction The Arabian Rheem gazelle, Gazellasubgutturosa marica, is present in the western region of the Arabian Gulf, including the island of Bahrain (Harrison, 1981). Although considered an endangered species (Anon., 1986), very little is known about its biology, ecology, diet and feeding behaviour. Various methods have been adopted to study the natural diet of herbivores: (1) direct observation and pasture analysis before and after grazing (e.g. Stoddard, 1952; Lamprey, 1963; Abdel-Razik etal., 1988); (2) stomach contents analysis (e.g. Norris, 1943; Baharav, 1982);and (3) faecal analysis (e.g. Storr, 1961; Stewart, 1967). The last method has proved reliable for the recognition of most plants eaten by herbivores (Croker, 1959; Hercus, 1960). The present study examines the natural diet of a wild population of G. subgutturosa by the technique offaecal analysis and attempts to investigate the basis for food selection.
Materials and methods An area about 10 krrr', located in the southern region of Bahrain island (Fig. 1) and inhabited by a herd of 20 G. subgutturosa, was selected for study. The ecology and vegetation of the area are described elsewhere (Saleh et al., in prep.). The faecal analysis method, described by Bhadresa (1986), was adopted for examining food items. Samples of plants present in the area were collected and identified. A reference collection of epidermal tissue from different parts of all plants collected during the period was prepared. Thirty different samples of gazelle faeces were collected and prepared for microscopic examination as described by Bhadresa (1986). These samples were collected before the first rain * Present address: Department of Zoology, Faculty of Science, Al Azhar University, Nasr City, Cairo, Egypt. 0140-1963/911030371
+ 04 $03'00/0
© 1991 Academic Press
Limited
S. A. MOHAMED ET AL.
372 50° 30'
Bahrain
o
26°
Study area
--5 km
Figure 1. The study area.
came when only perennial plants were available to gazelles. Five slides were prepared of each faecal sample and were examined microscopically to identify the plants eaten. Direct observations of gazelles feeding in this area were also used to verify the selection of certain plants. The plants eaten and other abundant species were analysed for nutritional values. Caloric value was obtained by using a bomb calorimeter, and protein was measured according to the method of Lowry et al. (1951). Water content was determined by keeping the specimens in the oven at 110°C for 48 h, and inorganic content was obtained by burning the specimens in a furnace at 500°C. Results Faecal analysis revealed that Arabian Rheem gazelles in the wild feed on a variety of plants. Eleven species were identified in faecal samples, and the percentage of their occurrence in
NATURAL DIET OF THE ARABIAN RHEEM GAZELLE
373
100 90 "e 0
., 0
c
~
:::J
0 0
0
'0
>0
80 70 60 50
.,c
40
0-
30
..
:::J
u:
20 10
A
B
K
C
Figure 2. Various food items included in the diet of the Rheem gazelle analysed by the percentage of occurrence. A, Helianthemum lippii; B, Heliotropium crispum; C, Sporobolus arabicus; D, Pennisetum
divisum; E, Cyperus conglomeratus; F, Calligonum polygonoides; G, Panicum turgidum; H, Aeluropus lagopoides; I, Asphodelus tenuifolius; J, Cutandia memphitica; K, Leptadenia pyrotechnica.
gazelle faeces is shown in Fig. 2. Remains of Heliotropium crispum and Helianthemum lippii were found most frequently in the faeces, and appeared to comprise the major part of the diet. Sporobolus arabicus, Pennisetum divisum and Cyperus conglomeratus were also represented in the diet, but occurred less frequently. Table 1 shows the caloric value, protein, water and inorganic contents of plants included in the gazelle's diet as well as of Zygophyllum quatarense which was abundant in the area but not included in their diet. Caloric values varied according to plant species. The lowest was for Z. quatarense (2'260 K cal g-I) and the highest for Panicum turgidum (4'407 K cal g-I). Calligonum polygonoides contained the highest amount of protein (13'68 mg g dry weighC I) while the figure was only 0'6 mg g dry weight-I for Leptadenia pyrotechnica. Water and inorganic content were highest in Z. quatarense where they reached 81% and 9'4%, respectively. Discussion For a wild population of Rheem gazelle, direct observation proved to be difficult. It is not acceptable to examine the gut contents of an endangered species of gazelle but the faecal Table 1. Caloric value,protein, waterand inorganic contents ofeightvarious plants available to G. subgutturosa marica Plant species
Caloric value K cal g-I
mg protein g dry weighC I
Zygophyllum quatarense Panicum turgidum Helianthemum lippii S'porobolus arabicus Leptadenia pyrotechnica Calligonum polygonoides Cyperus conglomeratus Heliotropium crispum
2'260 4·407 3·507 3·960 3'696 2'805 3'726 3·507
4·27 1·71 8·55 3'42 0'6 13'68 6'0 5·13
Water content
Inorganic content
%
%
81·0 57·0 49·45 52'5 70·4 60·3 70·0 72·5
9'4 2·9 4·45 5·5 2·1 9'7 3'6 6·6
374
S. A. MOHAMED ET AL.
analysis technique adopted has been reported to be reliable for identifying plants eaten by herbivores (Croker, 1959; Hercus, 1960; Bhadresa, 1986). Examination of the faeces showed that the Rheem gazelle included in their diet 11 species of the plants which were available in the area. However, only two of them, H. crispurn and H. lippii, represent the most important food items in their diet. Both H. lippii and H. crispurn are abundant in the area, with the latter forming an important community (Saleh et al., in prep.). These contain in excess of 72% water, but have a low protein content. On the other hand, H. lippii, with less than 50% water content, contained considerable amounts of protein (Table 1). These two abundant plant species form the major diet of gazelles in the area, at least during the non-rainy season, which lasts for most of the year. Such a combination would provide a good source of water as well as protein. Although Z. quatarense is the most abundant plant in the area and contains large amounts of water in its tissues (81%), there was no sign of its inclusion in the gazelle's diet. This may be due to the presence of deterrent chemicals in its tissues. A bitter chemical called 'zygophyllin' has been reported in another species: Z. coccineurn by Rizk (1986). Further investigations of the chemistry of Z. quatarense will be necessary to determine the reasons for its exclusion. We would like to thank the administrative staff of EI Areen Wildlife Reserve for providing us with access to the study area. We also thank Dr J. Ahmad for helping in calorimetry, MrsB. Alrufaei, Ms N. Fulaifel and Ms S. A. Hussein for protein analyses.
References Abdel-Razik, M., Ayyad, M. & Heneidy, S. (1988). Preference of grazing mammals for forage species and their nutritive value in a Mediterranean desert ecosystem (Egypt). Journal of Arid Environments, 15: 297-305. Anon. (1986). 1986 Red List of Threatened Animals. Cambridge, U.K.: mCN Conservation Monitoring Centre. Baharav, D. (1982). Desert habitat partitioning by the dorcas gazelle. Journal ofArid Environments, 5: 323-335. Bhadresa, R. (1986). Faecal analysis and exclosure studies. In: Moore, P. D. & Chapman, S. B. (Eds), Methods in Plant Ecology. pp. 61-67. Oxford: Blackwell Scientific Publications. 589 pp. Croker, B. H. (1959). A method of estimating the botanical composition ofthe diet of sheep. New ZealandJournal ofAgriculture Research, 2: 72-85. Harrison, D. H. (1981). Mammals oftheArabian Gulf. London: George Allen and Unwin. 92 pp. Hercus, B. H. (1960). Plant cuticle as an aid to determining the diet of grazing animals. Proceedings ofthe8th International Grassland Congress, pp. 443-447. Lamprey, H. F. (1963). Ecological separation ofthe large mammal species in the Tarangire Game Reserve, Tanganyika. East African WildlifeJournal, 1: 63-92. Lowry, O. H., Rosebrough, N. J., Farr, A. & Randall, R. J. (1951). Protein measurement with the Folin phenol reagent. Journal ofBiological Chemistry, 193: 265. Norris, J. J. (1943). Botanical analysis of stomach contents as a method of determining forage consumption of range sheep. Ecology, 24: 244-251. Rizk, A. M. (1986). The Phytochemistry oftheFloraofQatar. Richmond: King Print. 582 pp. Stewart, D. R. M. (1967). Analysis of plant epidermis in faeces, a technique for studying the food preferences of grazing herbivores. Journal ofApplied Ecology, 4: 83-111. Stoddard, L. A. (1952). Problems in estimating grazing capacity of ranges. Proceedings of the 6th International Grassland Congress, pp, 1367-1373. Storr, G. M. (1961). Microscopic analysis of faeces, a technique for ascertaining the diet of herbivorous mammals. Australian Journal ofBiological Science, 14: 157-164.