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The feeding ecology of wildebeest and zebra in Athi-Kapiti Plains
Abstract
Food habit studies on wildebeest (Connochaetes taurinus Burchell) and plains zebra (Equus burchelli Gray), using stomach contents analysis, were carried out between April 1972 and October 1973 in the Athi-Kaputei plains and Nguruman in Kajiado district. Both areas fall within the semi-arid region of Kenya and are grazed by both Masai stock and wildlife.
Wildebeest was highly selective for grass leaves, while zebra took more of the coarse plant materials, viz. sheath and stem. Zebra is more suited to coarse feeding, which enables it to survive the droughts better than wildebeest. The latter is usually hit harder at such times, as it cannot maintain itself on the fibrous materials which can constitute a maintenance diet for zebra.
... Herbivores select resources based on their morphology, digestive system and energy requirements which are species-specific. Ruminants select high-quality grass more consistently than non-ruminants, due to the different digestion mechanism, which allows non-ruminants to sustain themselves with high quantities of lowquality grass (Owaga, 1975). Because of the broader dietary tolerance, indeed non-ruminants can use a larger variety of resources; they also tend to have a wider distribution than ruminants, and are considered to be more generalist (Du Toit & Cumming, 1999). ...
... Zebra were found in areas with lower NDVI values than the average availability. This result was expected as zebra can forage on grass of low quality if quantity is not limiting (Owaga, 1975). Red hartebeest preferred areas with higher NDVI values than the average availability in the open grassland landscape, while preferring areas with lower NDVI values than the average in the wooded grassland landscape ( Table 2). ...
... Indeed, zebra was the only species preferring this area and blue wildebeest was the only ruminant species often found here. Zebra is a generalist non-ruminant which tolerates low-quality grass if available in large quantities (Owaga, 1975), while blue wildebeest appeared to behave as facultative specialist (Shipley, Forbey & Moore, 2009), able to tolerate lower grass quality if needed. On the other hand, both black wildebeest and red hartebeest acted as obligate specialist (Shipley et al., 2009), consistently selecting for high-quality grass at this spatial scale as well as at the feeding patch scale (Mariotti et al., submitted). ...
In fenced protected areas with limited opportunities to disperse, resources and constraints vary in space and time, affecting herbivore behaviour. The distribution, availability and quality of resources, burnt areas, and potential inter-specific competition all play a role in sustaining populations of large sympatric African herbivores. We investigated the role of resources, constraints and interspecific relationships on habitat use by three ruminants-black and blue wildebeest (Connochaetes gnou, C. taurinus) and red hartebeest (Alcelaphus buselaphus), and a non-ruminant, plains zebra (Equus quagga), across seasons and in different landscape types in a South African reserve. Black wildebeest, blue wildebeest and red hartebeest preferred the open grassland landscape, with homogeneous vegetation, while zebra favoured the wooded grassland landscape, with more heterogeneous vegetation. Burnt areas and vegetation greenness were important for all species, while elevation represented a constraint for black wildebeest only. The presence/absence of other species was important in shaping landscape use for black and blue wildebeest, and this suggests the possibility of competition. Our findings confirm the importance of heterogeneity and, in particular, the important role of a planned burning regime in maintaining such heterogeneity to sustain multi-species herbivore assemblages in small fenced nature reserves, where competition might arise between species using similar resources. Keywords: large herbivore habitat use, competition in a small fenced reserve, heterogeneity, NDVI, red hartebeest, zebra, black wildebeest, blue wildebeest.
... Thus, for example, ruminants select high quality grass more consistently than non-ruminants. This is due to the different digestion mechanism, which allows non-ruminants to sustain themselves with high quantity of grass with protein content that is too low to maintain ruminants (Owaga, 1975). ...
... Being non-ruminants, zebra are limited by grass quantity, while the quality of grass they can accept pag. 47 may vary widely (Jarman, 1974;Owaga, 1975). Zebra were thus expected to select areas regardless of the NDVI value. ...
... confirmed by several studies (Owaga, 1975;Helm, 2007;Hamunyela, 2017), red hartebeest selected grass taller than 11 cm, black wildebeest selected grass shorter than 10 cm and zebra did not select any height of grass in particular, but mostly fed on grass taller than 11 cm. ...
Ungulate resource use and distribution are shaped by resources and constraints present in the environment, which are in turn modified by herbivory. Knowing the relationships between ungulates and their environment is particularly critical when managing enclosed areas, which can contain only a limited amount and variety of resources. When resources are limited and used by many species, competition can arise with the result that some species decline in number and may eventually disappear. To investigate how ungulate landscape use varies in relation to resources and constraints in an enclosed area, four ungulate species, one generalist, plains zebra, and three specialists, black and blue wildebeest, and red hartebeest, were observed foraging over one year at Telperion and Ezemvelo nature reserves, a grassland-savanna transition zone in the eastern Highveld of South Africa. Distance between the species, elevation and forage characteristics such as grass greenness, biomass, height and distribution were compared at used and available locations at feeding patch and landscape scale across the East and West sections of the reserves. Red hartebeest and black wildebeest were mainly limited to the West section of the reserves, while blue wildebeest and zebra selected areas on both sections. Large burnt areas were selected by both wildebeest species at landscape scale while being avoided at feeding patch scale, confirming the importance of investigating different spatial scales. Changes in season triggered changes in grass selection in all species. In the dry season, red hartebeest and black wildebeest switched to feeding patches offering more biomass, blue wildebeest accepted taller grass and zebra used less green feeding patches than in other seasons. In addition, results suggest the presence of interspecific competition between black and blue wildebeest at both spatial scales, and an inability for both red hartebeest and black wildebeest to use the eastern half of the study area, probably due to lack of grass of adequate quality. Therefore, this study shows how resources and constraints interact to shaping ungulate distribution and resource use, underlining the importance of considering different spatial scales, and giving important insight for management.
... The two herbivores studied here (Burchell's zebra and blue wildebeest) are grazers with similar body weights (zebra ranges from 175 AE 250 kg for females to 220 AE 322 kg for males; wildebeest ranges from 141 AE 186 kg for females to 171 AE 242 kg for males) and very similar patterns of resource use (Owaga 1975;Estes 1991;Apps 2000;Redfern et al. 2003). These ecological similarities mean that there is a potential for interspecific competition for food resources between these herbivore species, although, like other equids, zebra are hind-gut fermenters and have been classified as non-selective grazers, while wildebeest are ruminants and are more selective grazers (Bell 1971;Sinclair & Griffiths 1982;Duncan et al. 1990;Hack et al. 2002). ...
... Previous studies have also reported the high nutritional value of the grasses selected and their preferential consumption by zebra and wildebeest (Owaga 1975;Ben-Shahar 1991;Ben-Shahar & Coe 1992;Bodenstein et al. 2000;Treydte et al. 2013); however, no nutrient analyses were conducted in the present study. Future studies should include these analyses to provide a better interpretation of feeding preferences in these herbivores. ...
... While I. cylindrica was consumed by both zebra and wildebeest in the MSR, particularly during the wet season, this species had not been recorded previously in studies of their diets (Owaga 1975;Ben-Shahar 1991;Ben-Shahar & Coe 1992;Bodenstein et al. 2000). This grass is of poor grazing value due to its hard, rough leaves (van Oudtshoorn 2014) and the consumption of the species, in the present study, appeared to be related to its greenness and its occurrence in low-lying wetlands. ...
Differences in the selection of habitat and specific dietary items support resource partitioning and coexistence of sympatric African grazing herbivores, such as zebra and wildebeest. In Maputo Special Reserve (MSR), southern Mozambique, these two species were extirpated during the civil war (1977–1992); since 2010, they have been reintroduced into the Reserve. Identifying the resource selection by reintroduced species and how these species coexist, while utilising the same resources, is both of ecological interest and important for the management of wildlife communities and parks. This is a key application of our research. Therefore, the present study investigated resource partitioning between Burchell's zebra (Equus burchelli, Smuts 1832) and blue wildebeest (Connochaetes taurinus, Burchell 1823) in the MSR. We conducted the study from July 2016 to June 2017. The data were collected by direct observation, driving the vehicle along the reserve's roads that covered the vegetation communities where zebras and wildebeest are known to commonly occur. The composition of the diet and specific features of the grass grazed by the two species, including greenness, height, and the number of stems, were assessed. The widely available grass, Aristida barbicollis, contributed most to the diet of both herbivores. The dietary overlap between the two herbivores was higher during the dry season (95%) than wet season (86%). Resources partitioning appears to be determined, principally, by the height and greenness of the grass, with the zebra grazing taller grass, which may facilitate the access of the wildebeest to the greener, lower proportion of the forage. That results follow the expectation that, among native herbivores, overlap in resource use is not expected based on evolutionary segregation.
... This activity makes the vegetation to be shorter and remove the older growth layer of lignified stems and seed heads to stimulate tender and nutritious new growth for selective grazers (Beekman and Prins, 1989). Thus, Burchell's zebra plays a great role in assisting the latter members of the succession within grazer community and enrich the variety and numbers of herbivores that could be sustained in the grassland ecosystem (Owaga ,1975). ...
... Second, this ability to subsist on low quality forage, when combined with relatively large body size and its concomitant lowering of transport costs, enables Burchell's zebra to undergo large migrations to track changing resources. Thirdly, Burchell's zebra typically move into a grassland ahead of other grazers and, by removing the older growth layer of lignified stems, sheaths, and seed heads, open it up to grazing by the more selective ruminants, such as wildebeest and Thompson's gazelle, which concentrate on the tender and nutritious new growth (Owaga, 1975). Thus, Burchell's zebra play a key role in initiating the pattern of succession within the grazer community, thereby enriching the variety and numbers of herbivores (Bell, 1971). ...
... Burchell's zebra is non-ruminant, non-selective and roughage grazer, which feeds on both short young shoot and long flowering grasses (Arsenault and Owen-Smith, 2002;Bell, 1970;Owaga, 1975). They eat the coarsest part of the grass, which is relatively low in protein (Moss, 1982). ...
... Its knobby long legs lack the agility of the impala, its bovine horns do not have the might of the Cape buffalo, and its emaciated frame pales to the sturdiness of the gemsbok or eland. But for all the oddities of its misshapen physique, the wildebeest thrives in its role as a primary consumer in a wealth of habitats in southern and Wildebeest are obligate grazers with little variation in diet between seasons (Knight 1991;Owaga 1975). Grass makes up at least 97 percent of their diet year-round, though the diversity of grass species eaten is relatively high (Knight 1991). ...
... Wildebeest do not show a major selection bias against browner grass in the dry season (Knight 1991), but they do strongly select for short grass leaves. The high protein/fiber ratio in the leaves allows the wildebeest to maintain their selective grazing for longer periods than would otherwise be possible during dry spells (Owaga 1975). However, even accounting for this selection, the protein intake of the Kalahari wildebeest falls below the necessary threshold of 6 percent during much of the dry season (Knight 1991). ...
... Zebras tend to associate with other ungulate species, particularly wildebeest, and both have diets consisting of over 90 percent grass (Grubb 1981). The zebra is a much less selective grazer, however, eating a high proportion of coarse plant parts (Owaga 1975). In the Serengeti, zebras eat mostly grass sheaths and leaves during the wet season, but switch to a diet of almost entirely stems and sheaths during the dry season. ...
... 2007). This grass has also been shown to be seldom selected by wild herbivores including zebra in such systems especially when mature (Owaga, 1975). ...
... However, we suspect that most of these effects were related to plains zebra, which was the most frequent wild herbivore species in the study plots (see Young et al., 2005). Zebras are known to feed almost entirely on grasses (Casebeer and Koss, 1970;Owaga, 1975;Voeten and Prins, 1999), and are likely to be primarily responsible for the observed reductions in grass cover. Eland, the second most frequent in the study site (Young et al., 2005), is largely a browser (Field, 1975;Buys, 1990;Codron et al., 2005) and was likely to contribute less to changes in grass cover. ...
We assessed whether prior foraging by wild herbivores affected foraging behaviour of cattle in Laikipia rangeland, Kenya, during February 2001, August 2001 and February 2002. The study compared cattle bite rate, step rate and bites per step in plots exclusively accessible to cattle and those accessible to cattle and large wild herbivores. During February 2001 when conditions were dry, cattle bite rate was 18–19% lower, step rate 25–26% higher, and bites per step 36% lower in plots shared by cattle and wildlife compared to those exclusively accessible to cattle. Differences in these measured foraging behaviour parameters were strongly correlated with reductions in herbage cover in plots accessible to wild herbivores. Plot differences in herbage cover and the measured foraging behaviour parameters were not significant in the subsequent trials when conditions were wet, suggesting that wild herbivore impacts reported here are short-term within season and dependent on weather conditions (and plant productivity). With reduced herbaceous plant cover in wildlife grazed realms in the dry season, cattle respond with increased travel and reductions in bite rate and bites per step, suggesting that wild herbivores can seasonally affect foraging behaviour of cattle. It remains to be demonstrated whether or not these altered behaviours of cattle affect weight gains or other measures of performance.
... 47 Figure S3). However, wildebeest have been reported to be mostly grazers, feeding on C 4 grass, [48][49][50] but have also been reported to supplement their diet with C 3 plants, 51 providing further support for the idea of a distributed lag time. ...
Rationale
Metabolism and diet quality play an important role in determining delay mechanisms between an animal ingesting an element and depositing the associated isotope signal in tissue. While many isotope mixing models assume instantaneous reflection of diet in an animal– tissue, this is rarely the case. Here we use data from wildebeest to measure the lag time between ingestion of ³⁴ S and its detection in tail hair.
Methods
We use time‐lagged regression analysis of δ ³⁴ S data from GPS‐collared blue wildebeest from the Serengeti ecosystem in combination with δ ³⁴ S isoscape data to estimate the lag time between an animal ingesting and depositing ³⁴ S in tail hair.
Results
The best fitting regression model of δ ³⁴ S in tail hair and an individual– position on the δ ³⁴ S isoscape is generated assuming an average time delay of 78 days between ingestion and detection in tail hair. This suggests that sulfur may undergo multiple metabolic transitions before being deposited in tissue.
Conclusion
Our findings help to unravel the underlying complexities associated with sulfur metabolism and are broadly consistent with results from other species. These findings will help to inform research aiming to apply the variation of δ ³⁴ S in inert biological material for geolocation or understanding dietary changes, especially for fast moving migratory ungulates such as wildebeest.
... This can help to reduce understory competition and therefore allow for a diverse regrowth of palatable forbs and or grasses. The presence of grasses such as Setaria spp, Digitaria macroblephara, Cynodon dactylon, Themeda triandra and Aristida spp which are foraged by zebra and wildebeest (Owaga, 1975) is an indication that they can survive in the area. Likewise, medium-sized antelopes such as Impala (Aepyceros melampus) can also be reintroduced in UDOM rewilding area to further rewild the site. ...
Backgroundand research aim
In the anthropogenic landscapes where historically wildlife existed, there can be a potential for rewilding to reverse extinction. However, there is limited literature providing approaches to achieve successful rewilding. The current study aimed at providing empirical based methodological procedures for successful rewilding of the University of Dodoma (UDOM) and nearby degraded landscape by assessing past and current vegetation and large mammal species’ occurrence.
Methodology
The past occurrence of mega-herbivores and their habitat was assessed using systematic literature survey, past vegetation maps and key informant interviews. EBSCOhost database and Google Scholar search engine were used for literature searching. A survey was conducted at UDOM area which is one of the remaining habitat patches in central Tanzania to examine present plant diversity.
Results
The baseline vegetation map of 1960 indicated that the study area was mainly Savanna woodland. Literature suggested that anthropogenic activities resulted into Land-Use Land-Cover Changes (LULCC) leading into wild animals’ extirpation leaving remnant populations in the surrounding protected areas. While the key informant interviews verified local loss of mega-herbivores, field data collected at UDOM campus in 2022 indicated the vegetation transformation to bushland dominated by Dichrostachys cinerea. The area’s past vegetation composition was 33% grasses, 29% herbs, 21% shrubs and 17% trees while the current was 18% grasses, 42% herbs, 30% shrubs and 10% trees.
Conclusion
The study revealed that central Tanzania hosted spectacular large mammal populations that interacted with the savanna which has recently been transformed to bushland. However, observed evidence on past existence of large mammals and recent elephants’ sightings at UDOM area indicate great potential for rewilding.
Implication for conservation
Reconstructing historical information of ecosystems is crucial for successful rewilding. Such information can guide conservation efforts aiming at reversing extinction and reestablishing connectivity of large herbivore population across ecosystems.
... specimens are also most similar to African bovid mixed-feeders and generalists in the discriminant function, African bovids are likely a lessappropriate comparative framework for interpreting equid diets. Notably, this discriminant function classi ed modern zebras as mixed feeders when they are known to have a more grass-dominated diet (McNaughton and Georgiadis, 19 ;Owaga, 1975). Thus, our direct comparisons to other s species (North Slope s sp. ...
In contrast to the modern Arctic, high-latitude ecosystems of the Late Pleistocene supported a diverse range of large mammalian herbivores, including abundant bison (Bison priscus) and horses (Equus sp.). This ‘mammoth steppe’ biome has no extant analog and modern tundra vegetation is likely incapable of supporting such a high density of large mammals. Compared to modern Arctic ecosystems, higher diversity and biomass of Late Pleistocene large mammal populations may have been sustained by more nutritious forage and/or dietary niche partitioning. We used dental microwear texture analysis and dental mesowear analysis of bison and horses (Bison priscus, Equus sp.) to characterize diet and assess the degree to which dietary differences supported co-existence of these dominant and likely competing herbivores on the mammoth steppe. Additionally, we compared microwear and mesowear of Late Pleistocene specimens to modern Alaska bison (reintroduced Bison bison athabascae and introduced Bison bison bison) and published microwear and mesowear data for extant bovids and equids. Our results demonstrate that Late Pleistocene bison and horses had less abrasive diets than modern obligate grazers, suggesting that these “grazers” of the mammoth steppe likely incorporated more forbs in their diets than modern grazers. Furthermore, Late Pleistocene bison and horses ate foods with similar textures, indicating that dietary niche partitioning alone cannot explain their co-occurrence. However, taphonomic differences between bison and horse specimens indicate potential spatial or temporal niche partitioning during the Late Pleistocene.
... These species provided the bulk of the rest of the diets of both zebra and wildebeest, and it seems likely that their contribution is related to their relative value as forage, and their general acceptability, digestibility, and nutritional value. Previous studies have also found that the grasses selected by both zebra and wildebeest have a high nutritional value and are consumed preferentially (Ben-Shahar & Coe, 1992;Owaga, 1975;Treydte et al., 2013), although the nutrient content of these species was not analyzed in the present study. Clearly, future studies should include the analysis of nutrients to support a more conclusive interpretation of the feeding preferences of these herbivores. ...
The reintroduction of wild animal species into conservations areas is widely used to restore populations of species endangered with extinction. The assessment of the quality of the diet and the nutritional status of the animals is crucial to the success of herbivore reintroduction programs, given that adequate nutrition is essential to ensure the survival and fertility of ungulates. Given this, the present study investigated the quality of the diet and nutritional status of Burchell’s zebra ( Equus burchelli, Smuts 1832) and blue wildebeest ( Connochaetes taurinus, Burchell 1823) reintroduced into Maputo Special Reserve (MSR), in southern Mozambique. The study was conducted between July 2016 and June 2017, and the data were collected through direct observation, by driving a vehicle along the roads within the reserve that pass through the vegetation cover where zebra and wildebeest are known to occur most frequently. The composition of the diet and specific feature of the grass grazed by the two species, such as greenness (an indication of food quality) were assessed. Crude fecal protein and phosphorus were determined to evaluate the nutritional status of the two herbivore species. Both herbivores were pure grazers, consuming a diet composed entirely (100%) of grass. Aristida barbicollis was the principal component of the diets of both zebra and wildebeest and both species grazed almost entirely on green grass (91–100% of greenness). However, wildebeest consumed significantly more green grass (which has a better nutrient content) than zebra, which tolerated a considerably larger proportion of browner grass in both seasons. The levels of crude protein and phosphorus in the zebra and wildebeest fecal samples were not below threshold of nutritional stress recommended for large southern African herbivores, which indicates that neither the zebra nor the wildebeest populations in MSR are undernourished at the present time and that the quality of the forage found in the study area is not a factor limiting the persistence of the reintroduced populations of either species.
... Ruminant selection for very green feeding patches is common among large herbivores (Bergman et al. 2001;Odadi et al. 2011). In the same way, selection of grass height by all species followed what would be predicted, based on their muzzle morphology (Owaga 1975;Janis and Ehrhardt 1988;Helm 2007;Arsenault and Owen-Smith 2008). Red hartebeest selected grass >11 cm, black wildebeest selected grass <10 cm and zebra did not select for any particular height of grass. ...
The coexistence of a large herbivore community depends on the degree of overlap in the resource used by the different species composing it. We investigated the role of grass greenness, height, biomass and feeding patch status on feeding patch selection by ruminant black and blue wildebeest (Connochaetes gnou, Connochaetes taurinus), red hartebeest (Alcelaphus buselaphus) and non-ruminant plains zebra (Equus quagga) in a protected grassland in South Africa. Selection by ruminants was associated with grass greenness and grass height, <10 cm for black and blue wildebeest, and >11 cm for red hartebeest. The non-ruminant zebra were more generalist, but selected for wetlands in all seasons, as did red hartebeest and blue wildebeest. Each species modified its behaviour during the late dry season by searching more for biomass or accepting grass that was less green or longer. The presence of burnt patches did not affect patch selection by any study species. Accordingly, large herbivore resource use showed strong seasonal adaptations, wetlands were important for sustaining sympatric species in the study area, and none of the species used the exact same combination of resources.
... The use of different parts of the plant may provide partitioning without significant dietary changes, allowing the species to coexist more effectively. The same pattern of partitioning has also been found between sympatric Wildebeests Connochaetes taurinus and Zebras Equus burchelli, who feed on different parts of plants to share limited food resources (Owaga 1975). ...
Pheasants (order Galliformes) are typical ground‐dwelling birds, having large body size and weak flight abilities. Sympatric pheasants are expected to share narrower niche space and face more extensive interspecific competition. However, little work has been undertaken to simultaneously investigate niche partitioning among sympatric pheasant species across multiple ecological dimensions. We compared microhabitat use, activity pattern and foraging strategy of sympatric Blood Pheasant Ithaginis cruentus, Buff‐throated Partridge Tetraophasis szechenyii and White Eared‐pheasant Crossoptilon crossoptilon on the Qinghai‐Tibet Plateau, China, to identify potential interspecific niche partitioning along different ecological dimensions in the breeding season. We found that the Buff‐throated Partridge significantly differed from the other two species in microhabitat use, while the three species showed different foraging strategies. It is likely that niche partitioning reduced potential interspecific competition, thus facilitating the species’ stable coexistence. Our study provides practical evidence of multidimensional niche theory within sympatric ground‐dwelling pheasant species, emphasizing that species interactions and coexistence within a guild is often not uni‐dimensional. Given global conservation concern for maintaining bird diversity, we recommend further restriction of yak grazing in these species’ habitat.
... In Kenya, however, zebra is ranked fourth as a problem wildlife species, after antelopes, elephants and primates (Naughton-Treves and Treves 2005). Similar to elephants, zebra showed a clear preference for mature and harvested crops, as they are able to feed on fibrous and coarse plant materials, such as husks and stems (Owaga 1975). Highly nutritious, mature and harvested maize seems to be an attractive crop for zebra to feed on during the late rainy season. ...
Wildlife species damaging crops can cause substantial losses to farmers and at the same time create negative attitudes against wildlife and conservation efforts that may result in negative interactions against wildlife and lead to human-wildlife conflicts (HWCs). For the analysis of negative interactions between humans and terrestrial wildlife species, a globally applicable scheme for monitoring was developed and applied over 6 years in study areas of two Asian (Nepal and India) and two African (Zambia and Tanzania) countries. Factors influencing crop consumption by eight different groups of herbivores were monitored and analyzed using generalized linear models. Seasonality, crop availability, type and the phenological stage of the crop seem to play an important role in the crop damaging behavior of herbivores. Crop consumers such as elephants (Loxodonta africana and Elephas maximus), zebra (Equus quagga spp.) and boars/hogs (Sus scrofa, Potamocherus larvatus and Phacochoerus africanus) show preferences for harvested and/or maturing crops. Rhinos (Rhinoceros unicornis) and antelopes/deer (Taurotragus oryx, Aepyceros melampus, Boselaphus tragocamelus and Axis axis) damage the highest numbers of fields with crops at an intermediate growth stage. The findings of this study can inform management of HWCs in areas where people and wildlife coexist. Furthermore, this study demonstrates the benefits of standardized HWC assessments in order to compare data from different continents and between different species to be able to draw generalized conclusions for the management of HWC.
... This approach allows extracting material properties of the tested particles in a specific indentation depth and can therefore also reliably describe inhomogenous ultrastructures. We use Themeda triandra as a focal phytolith species because it is a common forage plant by a wide range of herbivorous mammals such as wildebeest, zebra [38][39][40], Grant's gazelle, Thomson's gazelle [40], zebu [38,40] and hartebeest [38]. ...
Grasses are an important part of the forage of many herbivorous mammals and their phytoliths have long been regarded as the most important agent of tooth wear. Recent work has challenged this “paradigm” in finding evidence 1. of native phytoliths to be much softer then tooth enamel and 2. indicating, that phytolith hardness is highly variable, 3. prone to methodology and 4. not easy to be related to habitat conditions. We conduct controlled silica-cultivations measuring SiO2 content in the common forage grass Themeda triandra. Phytoliths are extracted natively, and nano-indentation values are measured. Phytolith hardness in Themeda triandra is found to be independent of silicate availability in the substrate. We further investigate the phytolith ultrastructure of Hordeum vulgare phytoliths. Phytoliths are shown to be an anisotropic composite of at least 3 components, silica bodies, inter-body matrix (both mineralised) and globular inclusions (likely non-mineralised). It can be argued, that indentation will be largely influenced by the heterogeneity of the structure and thus nano-indentation measurements will largely reflect the matrix and its mechanical properties but not necessarily the silicate bodies, which make up the vast majority of a phytolith.
... Migratory wildlife species are especially vulnerable to land use changes because they require multiple habitats and widely spatially separated resources throughout their annual migratory cycle (Berger, 2004;Bolger, Newmark, Morrison, & Doak, 2008;Harris, Thirgood, Hopcraft, Cromsigt, & Berger, 2009;Morrison & Bolger, 2012;Morrison & Bolger, 2014). However, zebra appeared less sensitive to land use changes in AKP than wildebeest probably owing to their non-ruminant, bulk feeding style, enabling them to subsist on poor-quality diets (Owaga 1975). Their population increase during 1988-1998 was associated with elevated rainfall during this period (average 734 mm ± 26) compared to 1977-1987 (577 mm ± 11) and 1999-2014 (627 mm ± 20). ...
Fragmentation, degradation and loss of natural habitats are now recognised as major threats to wildlife conservation and mobile pastoralism in East African savannas. These processes are driven primarily by land tenure and policy, increasing human population, expansion of settlements and agricultural farms, road networks, urban development and fencing. To understand and characterise the forces driving habitat fragmentation, we analyse how biophysical (soils, slope, rainfall, rivers) and human-created (roads, towns, parks, quarries) features influence where people choose to fence the land in the Athi-Kaputiei ecosystem of Kenya. We also explore the consequences of land fragmentation through fencing on the abundance and distribution of wildlife and livestock populations. We show that fences are most highly concentrated along the major roads and around the major urban centres. Movements of migratory wildebeest and zebra between the Nairobi National Park and the pastoral Kitengela Plains adjoining the park on the south are getting increasingly impeded by increasing concentration of fences. Populations of wildebeest and other herbivores have collapsed to a small fraction of their former abundance largely owing to destruction of their habitats and obstruction of their movements between the park and the pastoral lands by fences and other land use developments. Conserving the key seasonal wildlife dispersal areas in the Athi-Kaputiei Plains is critical to ensuring the future viability of several key wildlife species in Nairobi National Park. Several initiatives, including a conservation land lease program has been launched, but their spatial coverage and funding levels would need to be greatly expanded to secure sufficient open spaces for both wildlife and livestock.
... The Grevy's zebra (Equus grevyi, n=7) inhabits semi-arid grass/shrub land mainly in Kenya [68][69][70][71], where up to 70% of its diet results from grazing long and dry grasses, the remaining 30% are acquired by browsing notably either during droughts or in areas of overgrazing [68]. The blue wildebeest (Connochaetes taurinus, n=7) occupies similar environments as the zebras but it feeds on fresh short grasses (88%), and up to 12% browse depending on season [72][73][74][75]. Both are classified as grazers [20,76]. ...
Once erupted, mammal cheek teeth molars are continuously worn. Contact of molar surfaces with ingesta and with other teeth contribute to this wear. Microscopic wear features (dental surface texture) change continuously as new wear overprints old texture features. These features have been debated to indicate diet. The general assumption in relating occlusal textures to diet is that theyare independent of masticatory movements and forces. If this assumption is not accepted, one needs to propose that occlusal textures comprise signals not only from the 'last supper' but also from masticatory events that represent ecological, species- or taxon-specific adaptations, and that occlusal textures therefore give a rather unspecific, somehow diet-related signal that is functionally inadequately understood. In order to test for mechanical mechanisms of wear, we created a hypothesis matrix that related sampled individuals with six tribological variables. Three variables represent mechanically relevant ingesta properties, and three represent animal-specific characteristics of the masticatory system. Three groups of mammal species (free ranging Cetartiodactyla and Perissodactyla, free ranging primates, and artificially fed rabbits) were investigated in terms of their 3D dental surface textures, which were quantified employing ten ISO 25178 surface texture parameters. We first formulated a set of specific predictions based on theoretical reflections on the effects of diet properties and animal characteristics, and subsequently performed discriminant analysis to test which parameters actually followed these predictions. We found that parameters Vvc, Vmc, Sp, Sq allowed the prediction of both, ingesta properties and properties of the masticatory system, if combined with other parameters. Sha, Sda and S5v had little predictive power in our dataset. Spd seemed rather unrelated to ingesta properties and made this parameter a suitable indicator of masticatory system properties.
... These comparative nutritional data, obtained from animals at pasture for the first time, therefore do not support the second hypothesis, and suggest that equids achieve higher nutrient extraction rates than bovids on all forages, at pasture as in stalls (Duncan et al. 1990;Illius & Gordon 1992). Gwynne & Bell (1968), Stewart & Stewart (1970), Owaga (1975), Hansen - The nutritional model proposed to explain the coexistence of equids and grazing bovids ( Janis 1976) assumed that bovids extract more nutrients per day than equids on medium-quality forage, so the results reported here do not support it. However, further data are clearly needed from temperate ecosystems in winter, when low food availability may limit the rate of intake by horses, and from tropical ecosystems, where the grasslands often have low basal cover and may be less favourable for equids. ...
... Among grazers, it was observed that faecal CP of blue wildebeest was higher than that of cattle in communal and commercial management types. Although blue wildebeest eat grasses only, they are highly selective for leaf blades year-round and prefer short grass with high nutrient quality (Owaga 1975, Sinclair 1974, Skinner and Smithers 1990). Therefore, harvesting behaviour and preference of short grass by blue wildebeest contributed to higher faecal CP than in cattle. ...
We used faecal profiling to assess diet quality of animals under three different management types in a semi-arid savanna, northwest of Kimberley, Northern Cape, South Africa. The levels of faecal crude protein (FCP) and faecal phosphorus (FP) of free-ranging springbok (Antidorcas marsupialis) and blue wildebeest (Connochaetes taurinus) on a game ranch, goats and cattle grazing in a communally-managed area, as well as cattle grazing under commercial management were determined in the wet and dry seasons over a period of two years. Plant and soil analyses were also conducted. Goats had the highest FCP and FP of all species in all seasons during the study. It appeared that selective feeders (goats and springbok) and short-grass feeders (wildebeest) do not suffer from low forage quality because their FCP and FP levels were above critical values during all seasons. Contrastingly, cattle need nutrient supplementation because their FCP and FP were below critical nutritional values during the dry seasons. Plant and soil chemical characteristics, especially soil P, had an influence on faecal quality during the study. Clay pans provide an important habitat because of the high soil quality and, consequently, high diet quality. Our surprising finding that faecal CP levels were higher under communal management than under commercial management may be ascribed to higher nutrient deposition (due to higher stocking rates) and greater diet selectivity available to free-ranging animals under communal management. Higher faecal CP and P levels in game animals may also be ascribed to unrestricted movement and, consequently, greater access to palatable plants. The results of this study demonstrate the value of faecal profiling for management of semi-arid savanna livestock and game.
... It follows that waterbuck diet is more demanding than that of buffalo (Spinage 1982) with which it otherwise shares a very similar diet (Sinclair 1977). Buffalo diet is also dominated by grasses (Halley and Minagawa 2005) whereas zebra are non-ruminant grazers able to rapidly process large quantities of low quality forage (Owaga 1975). Since habitats utilized by buffalo, waterbuck and zebra in LNNP overlap extensively throughout the year (Mwangi and Western 1998), this increases chances of exploitative competition for forage in times of scarcity, as well as for space and water. ...
Land use change and human population growth are accelerating the fragmentation and insularization of wildlife habitats worldwide. The conservation and management of wildlife in the resultant ‘island’ ecosystems in the context of global warming is challenging due to the isolation and reduced size of the ecosystems and hence the scale over which ecosystem processes can operate. We analyzed trends in numbers of nine large herbivores in Kenya’s Lake Nakuru National Park to understand how rainfall and temperature variability, surrounding land use changes, and boundary fencing affected wildlife population dynamics inside the park during 1970–2011. Buffalo, zebra and Thomson’s gazelle numbers increased persistently. Grant’s gazelle and impala increased initially then gradually declined. Waterbuck and warthog numbers progressively declined to levels that potentially threatened their local population persistence. The total biomass of ungulates tripled from 1970 to 2011, with buffalo replacing waterbuck as the predominant species in biomass. Increased competition from buffalo and zebra, heightened predation and illicit human harvests probably all contributed to the declines by waterbuck and warthog. Density-dependent limitation of population growth within the park confines was evident for buffalo, impala, eland, giraffe, Grant’s and Thomson’s gazelles. Fluctuations in the lake level related to varying rainfall affected changes in animal abundance through expansion of the lake area and flooding of grasslands bordering the lake. Unusually, the most stressful conditions were associated with high water levels following high rainfall. There was also evidence of carry-over effects from prior habitat conditions affecting all species. The relatively stable populations of all species except warthog and waterbuck demonstrate the remarkable capacity of this small, insularized park to retain viable populations of most of the large herbivores, without much management intervention.
... Second, this ability to subsist on low quality forage, when combined with relatively large body size and its concomitant lowering of transport costs, enables plains zebra to undergo large migrations to track changing resources. Thirdly, plains zebra typically move into a grassland ahead of other grazers and, by removing the older growth layer of lignified stems, sheaths, and seed heads, open it up to grazing by the more selective ruminants, such as wildebeest and Thompson's gazelle, which concentrate on the tender and nutritious new growth (Owaga 1975). Thus, on the Serengeti Plains and elsewhere, plains zebra play a key role in initiating the pattern of succession within the grazer community, thereby enriching the variety and numbers of herbivores that these grasslands sustain (Bell 1971). ...
... E. grevyi occurs in the semi-arid grass/shrubland464748, where it grazes on up to 70% long and dry grasses and at least 30% browse during times of drought or in areas of overgrazing [46,49,50]. C. taurinus shares similar habitats further to the south compared to E. grevyi and feeds on fresh short grasses (88%) and up to 12% browse, depending on the season51525354. Traditionally, both are considered grazers5556575859. D. bicornis inhabits savannah and succulent bushveld areas [60] and consumes more than 90% browse, including mainly Acacia leaves, twigs, herbs and succulents606162. ...
Large herbivorous mammals have evolved chewing systems capable of processing a large variety of structurally diverse foods. Three-dimensional (3D) surface texture parameters are applied to investigate wear mechanisms related to tooth morphology, food source, and chewing dynamics. We tested 46 industrial 3D surface texture parameters for their capability to robustly indicate specific biomechanics in two grazing (Blue Wildebeest and Grevy's Zebra) and two browsing (Giraffe and Black Rhinoceros) ungulate mammals. These species inhabit sub-Saharan Africa and represent foregut and hindgut fermenters. The results did not indicate a wavelength threshold that can consistently separate the structural (morphology) from the functional (diet) signals in the microtextures of the species studied. This implies that no structural signal is present at this scale. The most effective surface texture parameters for discriminating species with different diets are the parameters of height (Sa), functional (Smc, Sxp), volume (Vmc, Vv, Vvc, Vvv), density of furrows (medf), isotropy (IsT), and flatness (FLTt, FLTp, FLTq) of tooth surface textures. The surface textures of grazers are characterised by more anisotropy, higher height and volume values, more peaks and deeper furrows than browsers. In addition to discriminate between dietary preferences, surface texture parameters reflect the dynamic processes in the occlusal space that can scarcely be observed in situ. We found that during mastication, the occlusal gap is larger when the food consumed consists of more grasses and is smaller when browse is comminuted. With the narrowing of the occlusal gap, high peaks of surface texture are more likely to be ground down, either by attrition (tooth-tooth contact) or by fast fluid movements due to hydrodynamic pressures. A larger food bolus, in turn, is more likely to prevent peaks from being flattened. Thus, the surface texture parameters provide a tool set for understanding masticatory function directly at the enamel surface at a micrometre scale.
... taurinus) inhabits the shortgrass plains and requires water at least every day or two in the dry season (IUCN SSC Antelope Specialist Group 2008). Besides the grazing component, which consists mainly of fresh short grasses, up to 12% of materials from browsing can be included in the diet, depending on the season ( Ego et al. 2003;Gagnon and Chew 2000;Owaga 1975;Skinner and Smithers 1990). ...
Mammals inhabit all types of environments and have evolved chewing systems capable of processing a huge variety of structurally diverse food components. Surface textures of cheek teeth should thus reflect the mechanisms of wear as well as the functional traits involved. We employed surface textures parameters from ISO/DIS 25178 and scale-sensitive fractal analysis (SSFA) to quantify dental wear in herbivorous mammals at the level of an individual wear enamel facet. We evaluated cheek dentitions of two grazing ungulates: the Blue Wildebeest (Connochaetes taurinus) and the Grevy's Zebra (Equus grevyi). Both inhabit the east African grassland savanna habitat, but they belong to fundamentally different taxonomic units. We tested the hypothesis that the foregut fermenting wildebeest and the hindgut fermenting zebra show functional traits in their dentitions that relate to their specific mode of food-composition processing and digestion. In general, surface texture parameters from SSFA as well as ISO/DIS 25178 indicated that individual enamel ridges acting as crushing blades and individual wear facets of upper cheek teeth are significantly different in surface textures in the zebra when compared with the wildebeest. We interpreted the complexity and anisotropy signals to be clearly related to the brittle, dry grass component in the diet of the zebra, unlike the wildebeest, which ingests a more heterogeneous diet including fresh grass and herbs. Thus, SSFA and ISO parameters allow distinctions within the subtle dietary strategies that evolved in herbivorous ungulates with fundamentally different systematic affinities but which exploit a similar dietary niche.
... This was conducted to test whether giraffe are able to detect the type of ant present on the tree before they decide browse on it. Given the fluid social structure of the giraffe (Estes, 1991) and seasonal movements of ungulates in this ecosystem (Owaga, 1975) as well as by efforts to identify individuals from their distinctive markings, data were not recorded from the same individual more than once. Giraffe data were collected between June and July of each year to coincide with peak activity and full leaf growth. ...
In obligate ant-plant mutualisms, the asymmetric engagement of a single plant species with multiple ant species provides the opportunity for partners to vary in their behaviour. Variation in behaviour has implications for the interactions with third-party species such as herbivores. This study assessed the effect of obligate ant-mutualists (Crematogaster mimosae, Crematogaster nigriceps and Tetraponera penzigi) inhabiting the African ant-acacia (Acacia drepanolobium) on three mega-herbivore browsers: the Maasai giraffe (Giraffa camelopardalis tippelskirchi), the reticulated giraffe (Giraffa c. reticulata) and the black rhino (Diceros bicornis). Giraffes are abundant and wide-ranging herbivores of the acacias, whereas black rhinos are localized and perennial herbivores of the acacias. Multiyear field studies comparing the ants' aggressive behaviour and browsing by mega-herbivores suggested differences between the tending abilities of the primary ant species inhabiting A. drepanolobium. Trees occupied by the aggressive ant species C. mimosae had significantly less browsing by giraffes and black rhino than trees occupied by other ant species. The results of this study provide evidence that ant-mutualists on African acacias can serve as deterrents to mega-herbivores and that different ant species vary in their tending abilities.
... These large herbivores have maintained an annual migratory circuit between the park and the Athi-Kapiti plains, which is inhabited by the pastoral Maasai community. The migratory large herbivores utilize short grass on the Athi-Kapiti plains, which forms the wet season concentration area, where they may also breed and calve (Owaga, 1975). Movements of cattle also occur because of the pastoral lifestyle of the ethnic Maasai. ...
The goal of the study was to establish whether the changes in land use affect resource utilization by large migratory herbivores in the Athi-Kapiti ecosystem. Athi-Kapiti ecosystem comprises Nairobi National Park and the Athi-Kapiti plains (community livestock grazing grounds). Land use information was obtained from existing literature. Pin frame technique and harvest method were used for plant biomass sampling, while road and foot counts were conducted for migratory large herbivores and livestock within the ecosystem, from November 2003 to May 2004. Emphasis was given to the wildebeest (Connechaetes taurinus), zebra (Equus burchelli) and cattle. Results show that green plant biomass available in the park was significantly different from that on Athi-Kapiti plains [Wilcoxon (two-tailed), P < 0.05]. Further analysis showed significant seasonal differences in the park [T test (two-tailed), P < 0.05]. In the community grazing area, significant monthly and seasonal variations in plant biomass were evident (one way ANOVA, P < 0.05). In summary, more wildebeest were observed on Athi-Kapiti plains than in the park. The zebra showed monthly variations within the whole ecosystem, resulting in a distinct movement pattern. Plant biomass varied depending on the rainfall, which in turn influenced the movement of migratory herbivores within the ecosystem.
... These comparative nutritional data, obtained from animals at pasture for the first time, therefore do not support the second hypothesis, and suggest that equids achieve higher nutrient extraction rates than bovids on all forages, at pasture as in stalls (Duncan et al. 1990;Illius & Gordon 1992). Gwynne & Bell (1968), Stewart & Stewart (1970), Owaga (1975), Hansen & Clark (1977), Olsen & Hansen (1977), Sinclair (1977), Krysl et al. (1984) and Putman (1996 ...
Equids are generalist herbivores that co‐exist with bovids of similar body size in many ecosystems. There are two major hypotheses to explain their co‐existence, but few comparative data are available to test them. The first postulates that the very different functioning of their digestive tracts leads to fundamentally different patterns of use of grasses of different fibre contents. The second postulates resource partitioning through the use of different plant species. As domestic horses and cattle are used widely in Europe for the management of conservation areas, particularly in wetlands, a good knowledge of their foraging behaviour and comparative nutrition is necessary.
In this paper we describe resource‐use by horses and cattle in complementary studies in two French wetlands. Horses used marshes intensively during the warmer seasons; both species used grasslands intensively throughout the year; cattle used forbs and shrubs much more than horses. Niche breadth was similar and overlap was high (Kulczinski’s index 0·58–0·77). Horses spent much more time feeding on short grass than cattle. These results from the two sites indicate strong potential for competition.
Comparative daily food intake, measured in the field during this study for the first time, was 63% higher in horses (144 g DM kg W −0·75 day ⁻¹ ) than in cattle (88 g DM kg W −0·75 day ⁻¹ ). Digestibility of the cattle diets was a little higher, but daily intake of digestible dry matter (i.e. nutrient extraction) in all seasons was considerably higher in horses (78 g DM kg W −0·75 day ⁻¹ ) than in cattle (51 g DM kg W −0·75 day ⁻¹ ). When food is limiting, horses should outcompete cattle in habitats dominated by grasses because their functional response is steeper; under these circumstances cattle will require an ecological refuge for survival during winter, woodland or shrubland with abundant dicotyledons.
Horses are a good tool for plant management because they remove more vegetation per unit body weight than cattle, and use the most productive plant communities and plant species (especially graminoids) to a greater extent. They feed closer to the ground, and maintain a mosaic of patches of short and tall grass that contributes to structural diversity at this scale. Cattle use broadleaved plants to a greater extent than horses, and can reduce the rate of encroachment by certain woody species.
... We suggest that in the absence of regrowth, wildebeest trate on tall grass patches to maximize dry-matter intake because digestibility is less a function of grass height. Indeed , previous studies of wildebeest forage selection have shown that their diets broaden during the dry season (Casebeer and Koss 1970; Owaga 1975; Ben-Shahar 1991), indicating little variation in profitability among food types (Stephens and Krebs 1986). An alternative hypothesis is that habitats with grass of intermediate greenness and height provide the best combination of minerals needed for gestation, growth, or lactation (McNaughton 1988McNaughton , 1990 Murray 1995). ...
We investigated the spatial distribution of radio-marked wildebeest (Connochaetes taurinus) in the Serengeti ecosystem in relation to the distribution of their food resources, comparing patterns in the wet and dry seasons and at local and landscape spatial scales. A mechanistic model of ruminant energy optimization predicted that wildebeest should maximize energy intake on swards 3 cm high and maintain energy balance on swards between 3 and 10 cm high. At the ecosystem scale, wildebeest preferred short and intermediate-height grass of moderate greenness during both the wet and dry seasons. This was consistent with the model prediction which suggests that large-scale movements by wildebeest are motivated, at least partially, by an energy-maximizing strategy. At the local scale, however, wildebeest showed spatial selectivity only on the basis of grass greenness, not on grass height. This differed from model expectations and may have resulted from wildebeest exploiting ephemeral green flushes of grass caused by localized rainfall in their movement radius. According to these results, the influence of other nutritional or behavioural factors on wildebeest distributions is not rejected, yet they suggest the potentially important role of an energy intake maximizing strategy on movement patterns. Our findings show that wildebeest movements are broadly similar to those of other large herbivores that migrate in response to resource gradients.
... Modern equids prefer graz- Ž . ing over browsing Owaga, 1975;Duncan, 1992 , but North American feral horses consume significant Ž amounts of browse Committee on Wild and Free- . Roaming Horses and Burros, 1982 . ...
Mammoths and mastodons are common in Pleistocene deposits, yet these proboscideans and many other animals disappeared suddenly ≈10,000 years ago. In this study, we reconstruct the diets of proboscideans and associated mammals through isotopic analysis of carbonate in tooth enamel apatite in order to test nutritional hypotheses for late Pleistocene extinction. We analyzed specimens from six sites in Florida, ranging from full glacial (>21,000 BP) to late glacial (14,750 to 10,000 BP) age. The oxygen isotope composition of mammalian apatite covaries with meteoric water composition, which in turn varies with climate. Consequently, oxygen isotope analysis can be used to assess the potential for time-averaging or mixing of specimens from different geographic regions within fossil assemblages. The carbon isotope composition of an herbivore is controlled by the isotopic composition of the plants that it ingests. Carbon isotope analysis reveals that mastodons ate chiefly C3 plants, presumably trees, shrubs and herbs, whereas mammoths consumed chiefly C4 grass. Several nutritional hypotheses for late Pleistocene extinction entail the assumption that extinct taxa had specialized diets. The resource partitioning and focused feeding preferences of Florida's proboscideans corroborate this assumption, but they do not, in themselves, prove that nutritional stress was the cause of the late Pleistocene extinction.
... taurinus) inhabits the shortgrass plains and requires water at least every day or two in the dry season (IUCN SSC Antelope Spe- cialist Group 2008). Besides the grazing component, which consists mainly of fresh short grasses, up to 12% of materials from browsing can be included in the diet, depending on the season (Ego et al. 2003; Gagnon and Chew 2000; Owaga 1975; Skinner and Smithers 1990). ...
Mammals inhabit all types of environments and have evolved chewing systems capable of processing a huge variety of structurally diverse food components. Surface textures of cheek teeth should thus reflect the mechanisms of wear as well as the functional traits involved. We employed surface textures parameters from ISO/DIS 25178 and scale-sensitive fractal analysis (SSFA) to quantify dental wear in herbivorous mammals at the level of an individual wear enamel facet. We evaluated cheek dentitions of two grazing ungulates: the Blue Wildebeest (Connochaetes taurinus) and the Grevy's Zebra (Equus grevyi). Both inhabit the east African grassland savanna habitat, but they belong to fundamentally different taxonomic units. We tested the hypothesis that the foregut fermenting wildebeest and the hindgut fermenting zebra show functional traits in their dentitions that relate to their specific mode of food-composition processing and digestion. In general, surface texture parameters from SSFA as well as ISO/DIS 25178 indicated that individual enamel ridges acting as crushing blades and individual wear facets of upper cheek teeth are significantly different in surface textures in the zebra when compared with the wildebeest. We interpreted the complexity and anisotropy signals to be clearly related to the brittle, dry grass component in the diet of the zebra, unlike the wildebeest, which ingests a more heterogeneous diet including fresh grass and herbs. Thus, SSFA and ISO parameters allow distinctions within the subtle dietary strategies that evolved in herbivorous ungulates with fundamentally different systematic affinities but which exploit a similar dietary niche.
... Another possibility not addressed in this study however, is that ungulates can forage on the same plant species but eat different parts. This is for example seen in African Wildebeest and Zebra (Owaga 1975). However, in the case of Mongolia, where the rainfall is low, and the herbaceous biomass is also relatively small, we assume that both species select for plant leaves. ...
Re-introduced Przewalski horses in Hustai National Park, Mongolia could suffer from food competition with other herbivore species through food resource depletion. Diet composition of the Przewalski horse (Equus ferus przewalskii), red deer (Cervus elaphus) and four livestock species (sheep, goat, cattle and horse) were studied, using micro histological analysis of faecal samples in the summer of 2005 and winter of 2006 ¿ 2007. We expected that herbivores become less selective in food choice in winter regarding to summer, resulting in a larger diet breadth, a larger similarity in diet and a larger dietary overlap in winter, potentially triggering exploitative competition by depletion of shared resources. Vegetation biomass decreased during winter, and the different herbivores species in HNP changed their diet from summer to winter. As expected diet breadth, diet similarity and dietary overlap were significantly larger in winter in comparison to summer. The existence of competition by resource depletion between the different species cannot be ruled out. Vegetation biomass was probably not a limiting factor according to the correlation between annual rainfall and herbivore species biomass, however the forage quality may be limiting, triggering competition.
Many diverse hypotheses have been suggested for the stripes of the plains zebra Equus quagga. We propose a new hypothesis that this adaptation represents visual interspecies signalling to facilitate mixed-species herding. Mixed-species herds likely offer enhanced protection from predation. They can also facilitate feeding for both zebra and other grazers, as zebra are hindgut fermenters and prefer different foliage to associating ruminants. This mechanism, uniquely, can explain why stripes might evolve in zebra and not in other large African grazers (because of their different digestive strategy). This signalling mechanism is not exclusive, however, and could operate alongside one or more of the previously postulated mechanisms selecting for zebra stripes.
Resource competition and niche partitioning among the exceptionally high number of sympatric ungulates of the Early Pleistocene site of Coste San Giacomo (Central Italy) is here examined through the study of their dietary proclivities and body size. The main aim of this study is to investigate the niche differentiation mechanisms that let the fossil ungulates coexist in the same region. We also provide information about the complementarity of two different methodologies that observe diet variation at a different time scales (inner and outer mesowear) in the study of dental wear patterns of fossil ungulates. Results from analyses of dental wear degree and body masses predictions show that a wide range of feeding behaviours were adopted by the taxonomical groups (i.e., cervids, bovids and equids) in order to avoid competition. Among larger ungulates diet ranges from strict browsing (Eucladoceros sp., Gazellospira torticornis), to mixed feeding (Gallogoral meneghinii, Leptobos sp.) to pure grazing (Equus stenonis), whereas smaller taxa are more selective feeders (Axis cf. lyra, Croizetoceros cf. ramosus) with only one exception (Gazella borbonica). When taxa with the same feeding behaviour occurred in the same habitat, competition was minimised by differences in body size.
The historic ranges of three equid species native to north-east Africa are analysed with respect to annual rainfall, several temperature parameters and a satellite-derived multispectral index of primary productivity. Equus africanus Fitzinger, Equus grevyi Oustalet and Equus burchelli Gray used to largely replace each other, geographically, with narrow zones of range overlap occurring between E. africanus and E. grevyi in the Awash valley, and between E. grevyi and E. burchelli in southern Ethiopia and northern Kenya. The three species are shown to succeed each other along an environmental gradient. The position of each species on this gradient and the resulting location and extent of its range are discussed. Competitive exclusion, specific adaptations and historic events are likely determinants of equid distribution. In the area of sympatry between E. grevyi and E. burchelli, mixed habitat characters as well as environmental fluctuations seem to prevent either species from excluding the other. Different social organizations of E. grevyi and E. burchelli and the resulting migratory patterns may be adaptations to the environment in their allopatric ranges; in their sympatric range they could alleviate competition.
This paper examines changes in the use of sites and lithic raw materials during the later Middle Stone Age (MSA) and early Later Stone Age (LSA) in East Africa. It proposes two models of hunter-gatherer land use and technological organization in East African savannas and examines changes in the procurement and use of raw materials in MSA and LSA lithic assemblage sequences from Lukenya Hill, Kenya, and Nasera Rockshelter, Tanzania. Changes in procurement strategies across the transition are related to technological change, mechanical properties of raw materials, and changes in site use and in mobility.
This paper gives the results of a study conducted at Game Ranching Ltd, situated at the Athi Kapiti Plains, Kenya, to determine the dietary composition of cattle ( Bos indicus L), kongoni ( Alcephalus buselaphus Pallas) and wildebeest ( Connochaetes taurinus Burchell), through two forage growing seasons (wet and dry). The dietary preferences and overlaps between the species were also determined.
The diet preference of the three herbivores was determined using a microhistological analysis technique. The three dominant grasses in the ranch: Themeda triandra Fork, Digitaria macroblephara (Hack.) Stapf and Penisetum mezianum Leeke, formed the major diets of the animals. The browse component of the diets increased during the dry season by about 100% for all the animal species, with cattle always having twice as much browse as the wild herbivores. However, the animals selected similar diets in terms of plant species during both seasons but were more selective during the wet season. Dietary overlaps were always above 75%, but more than this during the dry season. The dietary overlaps were lower between cattle and wild herbivores than between the wild herbivores. The diet preference index for the animals differed from season to season, and from plant to plant.
Small herbivores such as lagomorphs, rodents and orthopterans are important consumers in grasslands. Techniques of data collection by microscope analysis of stomach contents and quantitative analysis of results are presented for assessing dietary overlap and potential competition for food resources among different classes of herbivores. Example analysis of data for small herbivores and ungulates from an area south of Nairobi National Park, Kenya, are presented. In the average growing season, diet overlap between angulates and small herbivores is low, and therefore, potential for competition slight. Considering sesonal variation in food resources availability and extreme shortages documented for occasional seasons, it is probable that periodic competition occurs. Hares are potentially the greatest competitors with ungulates in such conditions, because of their wide niche breadth and spatial overlap with ungulates. Assessment of the degree and implications of periodic competitive interactions requires careful analysis of niche breadth and overlap on the food resource gradient based upon a spatial and temporal evaluation of habitat utilization.
Body condition of male gazelles inhabiting the Athi-Kapiti Plains, Kenya, fluctuated seasonally. Preferences for upper topographic levels by Thomson's gazelle and for depressions by Grant's gazelle exposed these species to dissimilar biophysical resources and accounted for asynchronous trends in body condition. Thomson's gazelle benefited from early grass growth which occurred along hilltops immediately following the rainy season. Although responding more slowly, body condition of Grant's gazelle was maintained longer into the dry season because of greater use of dicotyledons and the persistence of soil moisture in lower areas.
La condition physiologique des mâles de gazelles dans les plaines de Athi-Kapiti (Kenya) fluctue avec les saisons. La préférence pour des niveaux topographiques élevés chez la gazelle de Thomson et pour les dépressions chez la gazelle de Grant expose ces espéces à des ressources biophysiques différentes et explique les tendances asynchrones de leur condition physiologique. La gazelle de Thomson profite de la croissance de l'herbe précoce sur les crêtes juste après la saison des pluies. Bien qu'elle réagisse plus lentement, la condition physiologique de la gazelle de Grant se maintient plus longuement en saison sèche à cause de l'utilisation plus complète de dicotylédones et de la persistance d'un sol humide dans les zones basses.
Ruminants are unevenly distributed across the range of body sizes observed in herbivorous mammals; among extant East African species they predominate, in numbers and species richness, in the medium body sizes (10–600 kg). The small and the large species are all hind-gut fermenters. Some medium-sized hind-gut fermenters, equid perissodactyls, coexist with the grazing ruminants, principally bovid artiodactyls, in grassland ecosystems. These patterns have been explained by two complementary models based on differences between the digestive physiology of ruminants and hind-gut fermenters. The Demment and Van Soest (1985) model accounts for the absence of ruminants among the small and large species, while the Bell/Janis/Foose model accounts both for the predominance of ruminants, and their co-existence with equids among the medium-sized species (Bell 1971; Janis 1976; Foose 1982). The latter model assumes that the rumen is competitively superior to the hind-gut system on medium quality forages, and that hind-gut fermenters persist because of their ability to eat more, and thus to extract more nutrients per day from high fibre, low quality forages. Data presented here demonstrate that compared to similarly sized grazing ruminants (bovids), hind-gut fermenters (equids) have higher rates of food intake which more than compensate for their lesser ability to digest plant material. As a consequence equids extract more nutrients per day than bovids not only from low quality foods, but from the whole range of forages eaten by animals of this size. Neither of the current nutritional models, nor refinements of them satisfactorily explain the preponderance of the bovids among medium-sized ungulates; alternative hypotheses are presented.
Late Quaternary paleoenvironmental data for East Africa are derived primarily from montane sources and thus we know little about the changing composition of East African savannas. Four archaeological sites at Lukenya Hill in the savanna of the Athi-Kapiti Plains of Kenya that date to the last 40,000 yr preserve a large mammalian fauna. The prehistoric hunters concentrated on migratory ungulates and virtually ignored the resident inselberg ungulates throughout the occupation. Faunas of the last glacial maximum are dominated by an extinct small alcelaphine antelope. Arid-adapted ungulates are present that are regionally absent historically, and Pelorovis is present as well. The small alcelaphine and arid-adapted ungulates are absent in the Holocene deposits. This suggests that there was an expansion of dry savannas during the last glacial maximum. The last glacial maximum aridity, combined with a lack of pastoral-set fires, would have resulted in a vegetative mosaic distinct from the present. Dry woody growth and dry and/or tall grass, all of which are poor forage for ungulates, would have been common where seasonally moist short grasslands are presently extant. These conditions favored the large-bodied, highly hypsodont species in Africa that became extinct with the onset of wet conditions during the early Holocene.
The concentration of over 25,000 ungulates inside Ngorongoro Crater on a 250 km2 patch of the African plains was a major reason for designating the Ngorongoro Conservation Area as a World Heritage Site in 1979. As one of East Africa’s premier tourist attractions, it is also a major source of foreign exchange for Tanzania. This paper reports the decline of populations of wildebeest, Thomson’s and Grant’s gazelles since the mid-1980s and the rise to dominance of the buffalo, the results of research carried out from 1996 to 2000 on the Crater ungulates, and discusses natural and anthropogenic factors that may be linked to the population changes.Samples comparing young:adult female ratios in Ngorongoro and Serengeti populations indicated higher survival rates of Crater wildebeest and zebra young, and lower survival rates of Thomson’s gazelle. The possibility that predation by lions and spotted hyenas was responsible for reductions in the ungulate populations is belied by corresponding declines in the number of predators.Further research in the Ngorongoro Conservation Area is urgently needed to increase understanding of this complex ecosystem and promote effective stewardship, not only of Ngorongoro Crater but of the Serengeti ecosystem, of which the NCA is an integral part, comprising an International Biosphere Reserve. Our recommendations include establishment of a scientific advisory board and a research center that would attract and accommodate Tanzanian and foreign scientists.
1. Most methods of studying the food preferences of grazing herbivores are difficult or impossible to apply under conditions such as those encountered on the East African plains, which have an outstanding large-mammal fauna and a rich herbaceous flora. There are therefore few data regarding the preferences of these mammals. 2. A method involving the identification of plant epidermis in faeces avoids some of the limitations of other techniques. It has been used elsewhere both with large mammals and with other groups, but usually where the numbers of animal and plant species are fewer; the data obtained have usually been qualitative only. 3. The present study examines the qualitative and quantitative potential of the method under East African conditions. It has been limited to grasses, and to their leaf epidermis. It has involved feeding experiments with seven animal species (six ruminants and one non-ruminant) and, for quantitative purposes, eight species of grasses, the number of the latter being limited by practical considerations. 4. The results indicate that perennial grasses forming more than 5~%, by fresh weight, of a constant diet can be identified in the faeces. No information was obtained regarding species which form a smaller, regular part of the diet, or on ephemerals regularly forming more than 5%. 5. With a changing diet perennials temporarily forming a major part will be identified within a period governed by the times of throughput and elimination (see 6 below). Grasses eaten in occasional small quantities may not be identified; the evidence was insufficient to indicate whether ephemeral species are less likely to be recorded. 6. In both the ruminants and the non-ruminant the period between the first ingestion of a grass and its first appearance in the faeces (time of throughput) was 20-30 h; the period between the last ingestion and last appearance in the faeces (time of elimination) was about 3 days in the non-ruminant and 5-6 days in the ruminants. 7. Since the major constituents of the diet can be identified in the faeces, quantitative data on a frequency basis, indicating the relative importance of different grasses in the diet, can be obtained. 8. The proportions of epidermis from different grasses can be estimated in the faeces by measuring the area of fragments or by using point quadrats; counts of fragments are invalid for this purpose since different grasses break into fragments differing significantly in size. The proportions so measured do not necessarily represent those ingested, however, since different grasses may be digested to different extents. The fact that epidermis from both leaf surfaces survives digestion in some species and from only one in others does not account for all these differences. There are also significant differences between animals in the extent to which particular grasses are digested. 9. Although for intensive studies involving a few plant and animal species it might be possible to establish correction factors to allow for variations in digestibility, this and the subsequent analyses would be extremely time-consuming; it must therefore be accepted that most studies must be limited to obtaining quantitative data on a frequency basis.
Fragments of plant cuticile found in the faeces are compared with a set of references prepared from the leaves of known plants. The cuticle patterns, as far as studied, are characteristic for each species and the fragments can be used to identify the plants grazed and an estimate made of the botanical composition of the diet. The results presented in this preliminary study are purely qualitative.The advantage of this method is that it in no way interferes with the normal habits of the ,mimal, and it may be used for any animals grazing on any type of pasture.
The point-centered quarter method of sampling grassland vegetation is critically examined. Statistical techniques of processing data collected by the method are presented. These techniques are discussed in the light of findings from a sampling experiment at Matopos Experiment Station, Rhodesia.
S ummary
The ecological separation of 14 common ungulate species living in close contact with each other in a Tanganyika game reserve is shown to be achieved by six different factors:
1. the occupation of different vegetation types and broad habitats;
2. the selection of different types of food;
3. the occupation of different areas at the same season;
4. the occupation of the same area at different seasons;
5. the use of different feeding levels in the vegetation;
6. the occupation of different dry season refuges in the Masai area when the competition for food is greatest (zebra and wildebeest).
Habitat preferences are indicated by the frequency distribution of each species along the central of three 8,000 yard parallel transect paths which were traversed nearly daily for four years. Characteristic patterns of frequency are apparent for each of the species in the vegetation zones represented in the transect area. Certain species show a tendency, sometimes strong, to concentrate along the boundaries between adjoining vegetation zones and in the ecotones between the zones. This is ascribed to a greater diversity of food, availability of shelter from the sun and/or greater protection from predators.
Records of the animal species eating particular plant species are shown and (qualified in the light of other observations) used to deduce food preferences. The species are classified broadly into grass‐eaters, browsers and mixed feeders (grass and browse). In the case of the three common grass‐eaters, buffalo, wildebeest and zebra, a percentage analysis of the grass species eaten indicates that little differential preference is shown but that they take the palatable grasses largely in proportion to the frequency in which they occur in the habitats most used by the ungulate concerned. Buffalo are separated by their preference for denser vegetation. Wildebeest and zebra largely overlap ecologically in all respects except that the bulk of the populations of each species move to different dry season areas. Those species which are able to live without drinking free water, notably impala and Grant's gazelle, are able to make use of wild areas of waterless country when the animals requiring water are forced to move into dry season concentration areas near water.
The influence of the animals on the habitats and on other species is discussed and instances are given of species helping to shape the habitat to the advantage of both themselves and other species. Elephants are the main habitat modifiers and their capacity to improve water supplies and change the vegetation, and their facilitation of the feeding of other species is described. The formation of mixed herds is interpreted as being protective to one or both species concerned and is a further important facilitation. Little or no hindrance of one ungulate species by another was seen although herbivores show antagonistic behaviour towards carnivores smaller than themselves.
A study was conducted of grass selectivity shown by four herbivores on open range lands of Kenya Masailand. At four seasons over one year, wildebeest, zebra and kongoni (Coke's hartebeest) were taken. Stomach materials and faeces were sampled from each animal. Faecal samples were collected from cattle that had been grazing in the same area. Simultaneously, vegetation availability assessments were made.
A comparison of techniques for determining the food selectivity indicates that faecal and stomach-content analyses provide similar results when the diets are almost entirely grass.
The selectivity exhibited by the four herbivores was determined by faecal analyses. Three grass species were preponderant in all diets as well as in the available menu. In comparing the selectivity shown for the three dominant grasses there is a high degree of similarity even though statistical differences are demonstrated. All animals favoured Themeda triandra over Pennisetum mezianum and Digitaria macroblephara. Kongoni displayed the highest degree of selectivity and cattle and zebra had the greatest similarity in diets. Each animal species had a wide spectrum of grasses in their diets: these contained a greater number of species during the drier seasons than during the rainy seasons.
Wild animals had a greater diet variation between seasons than did cattle, the diet of the latter remaining much more consistent than the combination of available grasses.
1. Techniques are described for cannulating the cæcum, ventral and dorsal colon of the horse.
2. Cæcal and colonic movements consisted of irregular contractions of which three types were recognized. Withholding food caused reduction in frequency or cessation of all contractions of cæcum and ventral colon; the dorsal colon remained unaffected. No evidence was obtained of antiperistaltic movements, as judged by the movement of carbon granules.
3. Adrenaline inhibited and carbamylcholine increased the frequency of the contractions. Histamine and posterior pituitary extract inhibited movements.
4. The concentration of volatile fatty acid in the liquor of the cæcum and ventral colon was decreased by withholding food and increased by feeding. This effect was not marked in the dorsal colon. The proportion of propionic acid in the ventral colon was greater than in the dorsal colon.
5. The rate at which cotton‐threads disintegrated when suspended in the cæcum, ventral and dorsal colon decreased in an oral‐caudal direction. Withholding food greatly reduced the rate of disintegration.
Some functions of the large intestine of the horse. Quurt. J f . exp. Physiof Rate of passage of digesta through the ruminant digestive tract. In: Phjsiologj-of' Digestion in the Rurninant
- F
- C C Balch
- R C Campling
References ALEXANDER, F. (1952) Some functions of the large intestine of the horse. Quurt. J f. exp. Physiof. 37, BALCH, C.C. & CAMPLING, R.C. (1965) Rate of passage of digesta through the ruminant digestive tract. In: Phjsiologj-of' Digestion in the Rurninant (Ed. by R. W. Dougherty,), pp. 104-108.
969) The use of herb layer by grazing ungulates in the Serengeti
- Butterworths
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Butterworths, Washington. BELL, R.H.V. (1 969) The use of herb layer by grazing ungulates in the Serengeti. Synip. Br. E d. SIC. (Ed. by Adam Watson). Blackwell Scientific Publications, Oxford and Edinburgh. BOGDAN, A.V. (1958) A Revised List of K r n g Grasses with Keys for Identification. Government Printers, Kenya.
The population ecology of the wildebeest in the Serengeti
- R M Watson
WATSON, R.M. (1967) The population ecology of the wildebeest in the Serengeti. Ph.D. thesis, Univer-Grassl, Congr. Session, IB, 443-447. grassland vegetation. J. Range Mgmt, 21, 370-380.
Afr. wildl. J. I, 63-92. plains. Bot. Jb. 84, 63-74. ferences of grazing herbivores
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Reserve, Tanganyika. E. Afr. wildl. J. I, 63-92. plains. Bot. Jb. 84, 63-74. ferences of grazing herbivores. J. uppl. Ecol. 4, 83-1 11. 131-138. sity of Cambridge.
Wildlife versus cattle
- Qvortrup S.A.
Plant cuticle as an aid to determine the diet of grazing animals
- Hercus B.H.