Elephant Diet Research Articles

Group composition and diet of forest elephants, Loxodonta africana cyclotis Matschie 1900, in the Lopé Reserve, Gabon

SummaryForest elephants (Loxodonta africana cyclotis Matschie 1900) were observed opportunistically over a period of seven years between 1984 and 1991 in lowland rain forest in the Lopé Reserve, Gabon. Details of their group structure and diet are reported. Adult females were generally encountered accompanied by one or more offspring, and adult males were generally solitary. Mean group size was 2.8 individuals, and the mean size of a ‘Family Unit’ was 3.5 individuals. Associations of more than eight elephants were exceptional. Group sizes of elephants at Lopé were smaller than those recorded for savanna elephants in east Africa and those of Asian elephants living in Malaysian rain forest. The diet of elephants at Lopé was diverse, including a minimum of 307 items. The bulk of the diet, in terms of number of species and quantities eaten, came from leaves and bark (70% of all items recorded). Trees represented 73% of the species fed upon. In contrast to savanna‐living populations, fruit was an important part of the diet. Fruit of at least 72 species is eaten and the remains of at least one species of fruit was found in 82% of 311 fresh dung piles searched over a one‐year period.RésuméLes éléphants de forêt (Loxodonta africana cyclotis Matschie 1900) furent observés de façon opportuniste durant une période de sept ans entre 1984 et 1991 dans la forêt de basse altitude de la Réserve de la Lopé au Gabon. On rapporte des détails sur leur structure sociale et leur régime alimentaire. Les femelles adultes sont généralement rencontrées avec un ou plusieurs jeunes tandis que les mâles adultes sont généralement solitaires. La taille moyenne d'un groupe est de 2,8 individus et la taille moyenne d'une “Unité Familiale” est de 3,5 individus. Des associations de plus de huit éléphants sont exceptionnelles. Les tailles des groupes d‘éléphants à la Lopé sont plus petites que ceux des éléphants de savane observés en Afrique de l'est et que ceux des éléphants d'Asie vivant dans la forêt humide de Malaisie. Le régime alimentaire des éléphants à la Lopé est varié et comprend un minimum de 307 éléments. La majeure partie du régime alimentaire, en terme de nombre d'espèces et de quantité ingérée, provient de feuilles et d’écorce (70% de tous les éléments observés). Les arbres représentent 73% des espèces ingérées. Contrairement aux populations vivant en savane, les fruits représentent une portion importante du régime. Des fruits d'au moins 72 espèces sont mangés et les restes d'au moins une espèce de fruit fut trouvé dans 82% des 311 crotins frais examinés au cours d'une période d'un an.

Carbon isotopes as indicators of elephant diets and African environments

SummaryStable carbon isotope ratios have been successfully used to assess modern animal diets and to reconstruct prehistoric diets of animals and humans (Vogel & van der Merwe, 1977; van der Merwe & Vogel, 1978; Burleigh & Brothwell, 1978; Vogel, 1978a; DeNiro & Epstein, 1978; Tieszen et al., 1979; Tieszen & Imbamba, 1980; Chisholm, Nelson & Schwarcz, 1982; Tauber, 1981). We have used 13C/12C ratio measurements of bone collagen to study the diets of African elephants in twelve wildlife refuges. These represent most of the habitats in which elephants live, including such diverse plant communities as primary rain forest, savanna woodland and desert. The δ13C values were found to have a simple linear relationship with tree density in most cases. When translated into relative amounts of dietary browse (C3 plants) and graze (C4 plants), the grass content is seen to be systematically under‐represented, presumably due to inefficient metabolism. This does not affect the relationship between elephant diet and tree density, which has implications for the study of elephant‐woodland interactions, and for reconstructions of past African environments.

Notes on Seeds in Elephant Dung from Bia National Park, Ghana

Seeds were collected from elephant dung in Bia National Park, Western Region, Ghana during a 3-mo period prior to the major wet season, and were brought to the laboratory for counting, identification, and germination trials. We report here the quantities of seeds, characteristics of fruits and seeds of the species encountered, and the results of germination trials comparing fresh seeds (from ripe fruits) and ingested seeds (from dung). Altogether 449 seeds representing 11 species were enumerated, the most important of these being Panda oleosa, Balanites wilsoniana, Strychnos aculeata, and Parinari excelsa. For three of the species tested, the germination percentage was significantly higher for ingested seeds than for fresh seeds; for two species, there was no difference. ELEPHANTS FEED UPON FRUITS AND DISPERSE SEEDS (Ridley 1930, Aubreville 1958, Buss 1961, Depierre 1967, Guillaumet 1967, Wing & Buss 1970, Laws et al. 1975, Alexandre 1978, Brahmachary 1980, Short 1981, Martin 1982, Gautier-Hion et al. 1985). We report here our observations on species composition and quantities of seeds in elephant dung from one locality in Ghana and the results of germination trials with the most abundant seed species. Although elephant diets in the area have been studied (Short 1981, Martin 1982), this paper offers the first quantitative information on germination of seeds dispersed by elephants in Ghana.

Analysis of Bark Eating in a Tropical Squirrel

Although bark eating is quite common among mammals, few species include it as a major item in their diet. The diet of the small squirrel Sundasciurus lowii on Siberut Island, Indonesia, consists mainly of bark. Physical characteristics, nutrient concentrations, and the presence of defense compounds were investigated in bark from 711, 13, and 57 food and nonfood trees, respectively. The results suggest that the squirrels select bark on large, smooth-barked trees with low levels of hydrolysable tannins, whereas concentrations of fat, crude protein, crude fibre, carbohydrate, and calorific value examined in a set of bark samples had no detectable influence on food tree selection. FEEDING ON BARK IS WIDESPREAD AMONG MAMMALS although none has been reported to consume bark to the exclusion of more nutritious items like fruit, herbs, seeds, or grasses. Bark has been recorded as an item in the diet of orangutans (Rijksen 1978), elephants (Hubback 1941, Olivier 1978), rhinoceros (Hubback 1939, Strien 1974), rabbits (Thompson & Worden 1956), squirrels (MacKinnon 1978, Payne 1979, Farentinos et al. 1981), and many species of deer. In the majority of cases, however, no attempt has been made to analyze the physical or chemical features important in bark selection. A study of the ecological separation of three species of diurnal squirrels on Siberut Island, Indonesia (J. Whitten 1981), found that a major food type in the diet of one small species, Sundasciurus lowii (total length, 23 cm), was bark (an average 49% of stomach contents and over 90% of food trees). It was never observed to eat fruit, and stomach analyses revealed that animal remains occupied an average of only 39 percent of the stomachs' volume. S. lowii does not strip bark from large areas in the same way as do common red and grey squirrels, but removes only small flakes, even from trees whose bark would easily strip. Bark is not carried away from the tree and used in nest building, nor has any evidence been found that this behavior is associated with intraspecific aggression. None of the food trees (either trees on which we saw S. lowii feeding or those whose bark showed clear signs of squirrel feeding) produced sap, and no evidence pointed to squirrels' seeking exudates to feed upon (cf. I Received 7 November 1984, revision received 12 December 1985, accepted 8 January 1986. 2 Present address: School for Resource and Environmental Studies, Dalhousie University, Halifax, Nova Scotia, Canada. Lacher et al. 1984). Thus, all bark removal seems to be associated with feeding. This paper describes an analysis of bark and bark eating by S. lowii. METHODS AND MATERIALS Diurnal squirrels were studied on Siberut Island, 100 km west of West Sumatra, for a total of 12 mo during 1976 and 1977. The study area has been described by J. Whitten (1981) and A. Whitten (1982a, b), and the general methods of squirrel observation have been described by J. Whitten (1981). In order to investigate the selection of bark food trees by S. lowii, the following data were recorded from all trees of at least 5 cm DBH in four 0.25ha plots and from all known food trees: species, girth, tree height, canopy height (distance from lowest major bough to topmost leaves), canopy width, bark roughness on a scale of 1 (smooth) to 7 (very rough), thicknesses of the outer bark (that which could be split away from the inner bark) and of inner bark, and ease with which the outer bark could be split away from the inner bark (easy or difficult). In addition, signs of feeding on bark (Fig. 1) and presence of moss, lichen, and climbers were estimated on a scale of 0 (none present) to 3 (very abundant). Similarly, the ease of access for a squirrel from the surrounding vegetation was judged on a scale of 0 (impossible without coming to the ground) to 3 (possible with great ease). Bark samples were dried initially in an oven over an oil lamp for 2 days, after which the samples were taken to the mainland to be dried in an open gas oven for 2 more days. Although we assumed that all signs of bark feeding were made by S. lowii, other species may have contributed. BIOTROPICA 19(2): 107-115 1987 107 This content downloaded from 157.55.39.247 on Wed, 27 Apr 2016 06:49:50 UTC All use subject to http://about.jstor.org/terms

Elephants, Ivory, and Charcoal: An Ecological Perspective

Using ecological data on elephant diet and habitat can shed some light on the appearance of elephant herds in north Syria during the late second and early first millennia B. C. A period of reduced ...

The savanna ecology of Kidepo Valley National Park

Summary(1) Food habits of elephant and giraffe were recorded in short sample periods over several years using the feeding minutes technique. (2) Twelve species of common plants were collected on these occasions, separated into their main parts and analysed chemically. (3) Damage to trees was also recorded at intervals. (4) Fifty‐nine species of plant were eaten by elephant. During wet months their diet was predominantly grass but during dry months woody vegetation became more important. Giraffe were observed eating from thirty‐nine species of plant which were almost entirely browse throughout the year. At least eighteen of these species were also eaten by elephant. (5) Three of the browse species most important to giraffe were also important to elephant in dry seasons. In the driest month the species eaten by giraffe formed more than two‐thirds of the observed diet of elephants. (6) Chemical analyses of plants show that browse leaves had a higher level of protein, fat and minerals than most other plants. (7) The trunk of an elephant and the tongue of a giraffe are highly sensitive organs which permit food selection. Elephant in particular appeared to alter their food habits seasonally and it is suggested that this may be an attempt to obtain a balanced intake of nutrients. (8) Due to the effect of elephant and other agencies there is an accelerating decline in Acacia gerrardii woodlands. Browsing and fire are independently preventing their regeneration. (9) The extensive overlap of food requirements on preferred but diminishing browse resources implies potential if not already existing competition between elephant and giraffe. (See Part III.)

ELEPHANT ECOLOGY IN THE QUEEN ELIZABETH NATIONAL PARK, UGANDA

Summary1. Aerial and ground counts in the Queen Elizabeth National Park from 1963 to 1969 indicate that the number of elephants has more than doubled. The increase appears to be the result of immigration rather than reproduction.2. Elephant food habits were studied for 10 months in two areas of the Park. In the short‐grass/thicket area, browse intake rose markedly whenever the rainfall fell below 50 mm/month. In the tall‐grass area without thicket, herbs were eaten frequently during the rains and Cymbopogon grass bases in the dry season.3. Food availability had an important influence on the diet of elephants. Sometimes, however, elephant were very selective, e.g. for Panicum maximum, Azima tetracantha, Securinega virosa, and Tribulus terrestris. Certain grass inflorescences were selected during the rains, and bases in the dry season.4. Most browse was consumed in the thicket area during the dry season and most grass was eaten in the tall‐grass area of the Park.5. Stomach and faecal samples gave a similar result and indicated that the diet in the tall‐grass area was comparable to that of elephant in Murchison Falls National Park.6. Analyses of important plant species showed that, in general, tall‐grass had a lower crude protein content than short‐grass, herbs and browse. Browse leaves had a relatively high crude‐protein content in the dry season. Differences were less marked in the rains.7. Ether extract, or fat content, was high in browse leaves and in Cymbopogon, in particular its bases. These may have been selected in the dry season for this reason.8. Grass and browse stems were very fibrous and this may have contributed to their being avoided.9. High carbohydrate levels probably enhanced the palatability of grass bases and browse leaves.10. Grasses were very siliceous, in particular their bases when contaminated with soil. Elephant took considerable trouble to remove soil. Browse leaves had little silica but were rich in other minerals, and this may have contributed to their greater palatability.11. Studies of woodland dynamics show a decline in large trees which corresponds to the increase in elephants. In some cases trees have been almost eliminated. Damage to trees indicates that a most important factor in their decline is the elephant. There is some evidence that the trees are eliminated selectively.12. In the tall‐grass area there has been an increase of 46.3% in elephant numbers, but a decline of 80.3 % in buffalo, over the past 15 years. An overall decline in combined biomass of 36.9 % is calculated. Estimates of energy utilization of the annual vegetation production by elephant and buffalo indicates a decline from 6.1 % to 3.9% over this period.

Growth and diet of young elephants in captivity

Growth and diet of young elephants in captivity