Resource use and the nutritional status of sable antelope in the Okavango Delta region of northern Botswana

The resource‐use patterns and nutritional status of sable antelope herds were investigated in the Okavango Delta region of northern Botswana for comparison with those documented for declining sable antelope populations elsewhere in southern Africa. GPS collars recorded the relative use of floodplain, upland and wooded grassland habitats by the sable herds while VHF beacons facilitated locating the herds for direct observations on feeding. Surprisingly, the sable herds made greatest use of upland grasslands, rather than the floodplain grasslands exposed after floodwater had receded, during the dry season months. In the upland grasslands, they exploited tall, fibrous grass species that retained quite high levels of greenness through the dry season. This ability, together with partial use of the floodplain and some browsing on new leaves and flowers, helped maintain dietary nitrogen and phosphorus levels, as indicated by faecal nutrient levels, above maintenance thresholds through the dry season. Hence, the sable herds in the study region did not seem to be limited nutritionally under the rainfall and flooding conditions prevailing during the study.     

The importance of post‐fire regrowth for sable antelope in a Southern African savanna

Burning is commonly used in savannas to stimulate grass regrowth for grazing ungulates. We recorded the relative use of burns occurring at different stages in the seasonal cycle, as well as in different regions of the landscape by two herds of sable. We also recorded behavioural measures of foraging efficiency and faecal nutrient contents as an indication of nutrient gains. Sable consistently concentrated their grazing on burned areas provided there was sufficient green regrowth during the dry season. In these circumstances they grazed for longer per feeding station, showed a slower step rate while foraging, and shorter between‐patch moves, and a higher probability of encountering acceptable food per step taken while foraging than on unburnt areas. In the year when only a burn with insufficient regrowth was available, sable continued to forage in the area that had been burned during the previous year. Faecal crude protein was substantially higher at the end of the dry season in the year when burned areas were utilized. Accordingly early dry season fires can be important in helping sable bridge the nutritional limitations posed by the dry season, provided sufficient soil moisture remains to promote adequate grass regrowth.     

Dynamic spatial partitioning and coexistence among tall grass grazers in an African savanna

Competitive relationships among mobile animals may be expressed through dynamically changing spatial relationships over different time frames. Less common species that are apparently inferior competitors may be able to coexist with more abundant species by concentrating in regions of the landscape little utilized by the former at spatio‐temporal scales from annual or seasonal ranges to the specific foraging localities exploited at different stages of the annual cycle. Spatial relationships may be influenced further by dependencies on other resources, predation risks and facilitatory interactions under certain conditions. Our study aimed to determine whether competition with more abundant zebra and buffalo restricted the abundance of sable antelope in a region where these three tall‐grass grazers overlapped in their herd distributions. We tracked the simultaneous movements of animals representing herds of these species over two dry seasons and one wet season using GPS‐GSM collars, and estimated seasonal or monthly range extents and their overlap. We also compared daily separation distances between these animals against the null pattern expected if their movements had been independent, and assessed how prior grazing by buffalo influenced the subsequent use of these localities by sable. The range of the sable herd was mostly separated from the seasonal range of the buffalo herd during the late dry season of 2006 and throughout the dry season of 2007. Seasonal home ranges of zebra herds overlapped partially with the range of the sable herd during most of the year. Even during times when their ranges overlapped, sable were rarely recorded within <1 km of the buffalo herd. Prior grazing by buffalo beyond a threshold level inhibited later use of these localities by sable, but the sable were nevertheless able to exploit places that were little utilized by buffalo at that time. Sable were less able to evade overlap with the small, mobile zebra herds, and hence more vulnerable to competitive exclusion by zebra than by buffalo. Our findings demonstrate how less abundant species can restrict competition from more abundant competitors through dynamic spatial partitioning in regions where their home ranges overlap.     

Modelling ungulate dependence on higher quality forage under large trees in African savannahs

In African savannahs, large trees improve grass quality, particularly in dry and nutrient poor areas. Enhanced below-canopy grass nutrients, such as nitrogen and phosphorus contents should therefore attract and benefit grazers. To predict whether ungulates really need these forage quality islands we focused on four grazer species, i.e., zebra, buffalo, wildebeest, and warthog, differing in body size and digestive system. We confronted literature estimations of their feeding requirements with forage availability and quality, observed in three South African savannah systems, through linear modelling. The model predicted the proportion of below-canopy grass that grazers should include in their diet to meet their nutritional requirements.During the wet season, the model predicted that all animals could satisfy their daily nutrient requirements when feeding on a combination of below- and outside-canopy grasses. However, wildebeest, having relatively high nutrient demands, could meet their nutrient requirements only by feeding almost exclusively below canopies.During the dry season, all animals could gain almost twice as much digestible protein when feeding on below – compared to outside-canopy forage. Nonetheless, only warthogs could satisfy their nutrient requirements – when feeding almost exclusively on below-canopy grasses. The other ungulate species could not meet their phosphorus demands by feeding at either site without exceeding their maximum fibre intake, indicating the unfavourable conditions during the dry season.We conclude that grazing ungulates, particularly warthog, zebra, and buffalo, actually depend on the available below-canopy grass resources. Our model therefore helps to quantify the importance of higher quality forage patches beneath savannah trees. The composition of grazer communities depending on below-canopy grasses can be anticipated if grazer food requirements and the abundance of large trees in savannahs are known. The model suggests that the conservation of large single-standing trees in savannahs is crucial for maintenance of locally grazing herbivores.     

Seasonal changes of impala (Aepyceros melampus, Lichtenstein, 1812) faecal helminth egg counts through a one-year period

The study was done in Lake Mburo area, Uganda, consisting of Lake Mburo National Park and surrounding ranches. The study involved monitoring changes of output of helminth eggs per gram (e.p.g.) by impala for 12 months. Fresh faecal samples, 178 in total, were collected from the rangeland and subjected to floatation and culture tests. There was a peak faecal e.p.g. output from March to April and from October to November. This period coincided with time of high rainfall and calving peak of impala. There was no faecal e.p.g. observed during the dry spell from June to July.     

Potential effects of prescribed savannah burning on the diet selection of forest buffalo (Syncerus caffer nanus) in Lopé National Park,Gabon

Seasonality and management are factors that may affect the diet selection of the forest buffalo (Syncerus caffer nanus). Fire is considered a major driving force in savannah systems and prescribed burning is a commonly applied conservation tool in protected areas such as Lopé National Park, Gabon. Prescribed annual fires contribute to the maintenance of open areas and provide high‐quality forage for forest buffalo, a major herbivore in the park. We used microhistological faecal analysis to determine the diet selection of forest buffalo and measured the extent of variation between a dry season, preburn and a wet season, postburn sampling period. The buffalo diet comprised mainly of monocotyledons, primarily grasses (Poaceae) and sedges (Cyperaceae). Intake of open‐area‐associated plant species was higher in the wet season, postburn treatment sampling period (97%) than the dry season, preburn sampling period (87%), which corresponded conversely to a reduction in forest‐associated Marantaceae plants (10% versus 1%). High proportions of grasses and sedges in the diet signify the importance of open areas for forest buffalo. Controlled burning as tool for maintenance of open areas may play a key role in the meta‐population management of the forest buffalo.     

Food consumption and faecal deposition of plant nutrients by black swans (Cygnus atratus Latham) in a shallow New Zealand lake

Deposition of faeces by black swans (Cygnus atratus Latham) feeding on benthic algae in a shallow New Zealand lake was determined by collection of faeces from the lake bottom and from the shore. The two methods showed good agreement after adjustment for the weight loss on immersion. The mean daily faecal output per swan was 52 g dry weight. The nitrogen content of the faeces averaged 2.3% of dry weight, and was dominated by soluble organic nitrogen (59% of total N). Phosphorus averaged 0.44% of dry weight, with 66% of it being particulate, and 30% soluble reactive phosphorus. Although faecal inputs of total phosphorus were sufficient to generate concentrations of 15–30 mg m^–3, the faecal contributions of both N and P were only a minor component of the fluctuations observed in the lake, and were also small in relation to the total nutrient pool in the water and benthic algae. Waterfowl faeces appear to have low ratios of N to P, which will favour dominance of the phytoplankton by cyanobacteria in lakes where the faecal component of nutrient loads is large. The few data available suggest that the nitrogen content of waterfowl faeces is largely independent of that in their food. Food consumption, calculated by using cellulose as an indigestible faecal marker, was 104 g dry weight swan^–1 d^–1, a figure that appears low in relation to those for other swan species. Even the highest published figure for food intake by a swan is only about one half of the corresponding average metabolically-adjusted figures for geese, and we caution against the uncritical use of bioenergetic models for determining rates of food consumption and defaecation.     

III. Quantitative aspects of phosphorus excretion in ruminants

Ruminant phosphorus excretion and metabolism were studied through a database. Faecal endogenous phosphorus is the main pathway of phosphorus excretion and averages 0.85 of total faecal phosphorus. The remaining 0.15 is unabsorbed dietary phosphorus. Faecal endogenous phosphorus is mainly unabsorbed phosphorus, with saliva being the major source, and is correlated to factors influencing saliva secretion (DM intake, physical dietary characteristics and dietary phosphorus content). Another source of faecal endogenous phosphorus is rumen microbial phosphorus that escaped solubilisation during post-rumen digestion. All factors stimulating microbial growth would increase phosphorus uptake by the rumen microbes and consequently the faecal endogenous phosphorus. Understanding the determinants of faecal endogenous phosphorus flow will help to precise the determination of net phosphorus requirements for maintenance. The role of plasma phosphorus in urinary phosphorus loss is discussed.     

The nutrient status of the Kromme River estuary,South Africa

The Kromme is a small estuary in rural eastern Cape, South Africa with a relatively unpopulated and undisturbed catchment. Physical and chemical variables including the major nutrients and E. coli were examined. It was found to be a well oxygenated, well mixed estuary with some stratification in its upper reaches. Nutrient levels were generally low with nitrate values higher in winter than during summer. While no overt seasonality was detected for phosphorus, levels were comparatively high. Faecal E. coli levels were low with a mean count of 26 per 100 ml for the estuary. Along the Kromme, nutrients were highest at the confluence of the Geelhoutboom tributary suggesting it was a major nutrient contributor. At the head of the Kromme, silicate and E. coli were significantly linked to riverflow, while nitrate was correlated with rainfall. In the Geelhoutboom, only nitrate was correlated with riverflow and rainfall. When nutrient gradients (total inorganic nitrogen, total phosphorus and silicate) were correlated against salinity, significant relationships were observed for nitrogen and silicate (Kromme and Geelhoutboom) and for phosphorus along the Geelhoutboom, but not the Kromme, reflecting differences in sub-catchments. An overall N:P atomic ratio of 0.89:1 was found for the system, with more nitrogen relative to phosphorus at the head of the Kromme and vice versa for the Geelhoutboom and mouth. The Kromme is low in nitrogen, conservative in silicate and low in phosphorus while the Geelhoutboom supplies nitrogen, phosphorus and silicate to the system. Although there may be nutrient absorption by sediments in the upper estuary, and by macrophytes in the lower estuary, the Kromme may be classified as a non-conservative mesotrophic marine-dominated estuary which probably exhibits some nutrient recycling.     

Nutrient leaching and settling rate characteristics of the faeces of Atlantic salmon (Salmo salar L.) and the implications for modelling of solid waste dispersion

The present study determined the settling velocity and leaching rates of carbon and nitrogen from the faecal matter of Atlantic salmon (Salmo salar L.) fed two commercial diets, high energy (HE) and standard, in three separate experiments (December, March and May) which coincided with winter, spring and summer. Faecal settling velocities for individual samples were in the range of 3.7–9.2 cm s^?1. There were significant differences (P < 0.05) in settling velocities among the three experiments, with lowest velocities measured in faecal samples collected in winter and highest velocities measured in samples collected in summer. There were no significant differences (P > 0.05) in faecal settling velocity among fish fed the different diet types. Faecal nutrient content in the different treatment groups prior to leaching was 269–318 mg g^?1 for carbon and 28–37 mg g^?1 for nitrogen. Both carbon and nitrogen contents were higher in faeces from fish fed the standard diet than in fish fed the HE diet (P < 0.05). Thus the use of HE diets resulted in a 12% reduction in faecal carbon content and an 8% reduction in faecal nitrogen when compared with standard diets. There were no consistent differences in faecal carbon among samples collected during the three experiments; however, significant differences in faecal nitrogen content were detected in samples collected on the three different occasions. Leaching of faecal carbon and faecal nitrogen ranged between 4–14% and 9–16% of the original amount, respectively, after 2.5‐min immersion in sea water, although there was no further significant (P > 0.05) leaching after this time. No significant difference in nutrient leaching rate was found in faeces of fish fed HE and standard diets, and no significant differences in leaching rates were apparent among samples collected at different times of the year. These values suggest there may be an overestimation by dispersion models of the amount of nutrients entering seabed sediments. The amount of nutrients leaching from faeces may also have an important role in nutrient flux in the water column.     

Dynamics of ungulates in relation to climatic and land use changes in an insularized African savanna ecosystem

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.     

Seasonal variation in forages utilized by the African buffalo (Syncerus caffer) in the succulent thicket of South Africa

The succulent thicket of the Eastern Cape, South Africa, is characterized by densely wooded vegetation that is dominated by succulents with little understory of ephemeral and weakly perennial grasses and forbs. Studies have developed around the question: how do bulk grazers such as the African buffalo (Syncerus caffer) survive in the succulent thicket? In this study, the diet of the African buffalo at the Great Fish River Reserve (GFRR) was studied in two seasons (wet and dry). The diet profile was assessed from faecal matter, using the micro‐histological analysis method. During the wet season, grass species contributed 72% to the diet while 28% was contributed by browse species. In the dry season there was a significant increase in the intake of browse by 5% (χ² = 19.94, df = 11, P < 0.05). There were species that were neglected in the wet season but became principal dietary items in the dry season, these included Setaria neglecta, Cymbopogon plurinodis, Capparis sepiaria and Portulacaria afra. Diet quality, as estimated from faecal samples, suggested that the buffalo were nutritionally stable; however, the presence of sarcoptic mange in the buffalo suggests nutritional stress.     

Feeding preferences and nutritional niche of wild water buffalo (Bubalus arnee) in Koshi Tappu Wildlife Reserve,Nepal

The nutritional characteristics of food resources play an important role in the foraging behavior of animals and can provide information valuable to their conservation and management. We examined the nutritional ecology of wild water buffalo (Bubalus arnee; hereafter “buffalo”) in the Koshi Tappu Wildlife Reserve of Nepal during autumn using a multidimensional nutritional niche framework. We identified 54 plant species as being foraged by buffalo. We found that buffalo consumed graminoids and forbs 2–3 times more frequently than browse items. Proximate analyses of the 16 most frequently foraged plants indicated that buffalo diets were highest in carbohydrate (40.41% ± 1.82%) followed by crude protein (10.52% ± 0.93%) and crude fat (1.68% ± 0.23%). The estimated macronutrient balance (i.e., realized nutrient niche) of the buffalo diet (20.5% protein: 72.8% carbohydrate: 6.7% lipid) was not significantly different than the average balance of all analyzed food items based on 95% confidence regions. Our study suggests that buffalo are likely macronutrient specialists, yet may be generalists in the sense that they feed on a wide range of food items to achieve a nutrient balance similar to that available in forage items. However, the four most frequently consumed items tended to be higher in protein energy than less frequently consumed foods, suggesting some preference for higher protein forage relative to relatively abundant carbohydrates. Although limited in scope, our study provides important information on the nutritional ecology of buffalo, which may be useful for the conservation and management of this endangered species.     

How landscape scale changes affect ecological processes in conservation areas: external factors influence land use by zebra (Equus burchelli) in the Okavango Delta

Most large‐bodied wildlife populations in sub‐Saharan Africa only survive in conservation areas, but are continuing to decline because external changes influence ecological processes within reserves, leading to a lack of functionality. However, failure to understand how landscape scale changes influence ecological processes limits our ability to manage protected areas. We used GPS movement data to calculate dry season home ranges for 14 zebra mares in the Okavango Delta and investigated the effects of a range of landscape characteristics (number of habitat patches, mean patch shape, mean index of juxtaposition, and interspersion) on home range size. Resource utilization functions (RUF) were calculated to investigate how specific landscape characteristics affected space use. Space use by all zebra was clustered. In the wetter (Central) parts of the Delta home range size was negatively correlated with the density of habitat patches, more complex patch shapes, low juxtaposition of habitats and an increased availability of floodplain and grassland habitats. In the drier (Peripheral) parts of the Delta, higher use by zebra was also associated with a greater availability of floodplain and grassland habitats, but a lower density of patches and simpler patch shapes. The most important landscape characteristic was not consistent between zebra within the same area of the Delta, suggesting that no single foraging strategy is substantially superior to others, and so animals using different foraging strategies may all thrive. The distribution and complexity of habitat patches are crucial in determining space use by zebra. The extent and duration of seasonal flooding is the principal process affecting habitat patch characteristics in the Okavango Delta, particularly the availability of floodplains, which are the habitat at greatest risk from climate change and anthropogenic disturbance to the Okavango's catchment basin. Understanding how the factors that determine habitat complexity may change in the future is critical to the conservation of large mammal populations. Our study shows the importance of maintaining flood levels in the Okavango Delta and how the loss of seasonal floodplains will be compounded by changes in habitat configuration, forcing zebra to change their relative space use and enlarge home ranges, leading to increased competition for key resources and population declines.     

Soluble nitrogen and phosphorus excretion of exotic freshwater mussels (Dreissena spp.): potential impacts for nutrient remineralisation in western Lake Erie

1. Recent increases in phytoplankton biomass and the recurrence of cyanobacterial blooms in western Lake Erie, concomitant with a shift from a community dominated by zebra mussels (Dreissena polymorpha) to one dominated by quagga mussels (D. bugensis), led us to test for differences in ammonia‐nitrogen and phosphate‐phosphorus excretion rates of these two species of invasive molluscs. 2. We found significant differences in excretion rate both between size classes within a taxon and between taxa, with zebra mussels generally having greater nutrient excretion rates than quagga mussels. Combining measured excretion rates with measurements of mussel soft‐tissue dry weight and shell length, we developed nutrient excretion equations allowing estimation of nutrient excretion by dreissenids. 3. Comparing dreissenid ammonia and phosphate excretion with that of the crustacean zooplankton, we demonstrated that the mussels add to nitrogen and phosphorus remineralisation, shortening nitrogen and phosphorus turnover times, and, importantly, modify the nitrogen and phosphorus cycles in Lake Erie. The increased nutrient flux from dreissenids may facilitate phytoplankton growth and cyanobacterial blooms in well‐mixed and/or shallow areas of western Lake Erie.     

ELEPHANT ECOLOGY IN THE QUEEN ELIZABETH NATIONAL PARK, UGANDA

1. 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.     

Steeply Increasing Growth Differential Between Mixture and Monocultures of Tropical Trees

Studies of biodiversity and terrestrial ecosystem functioning have concentrated almost exclusively on temperate grasslands. To broaden the reach of biodiversity‐functioning research, five fast growing species, comprising three eudicot trees and two congeneric palms (none symbiotic with nitrogen‐fixing microorganisms), were grown for 13 yr in a replacement‐series mixture and monocultures on a fertile soil in a high‐rainfall area of lowland Costa Rica. The mixture accrued more biomass and had greater net productivity than the average, but not the most productive, monoculture. Relative Land Output (a measure of comparative yield) increased steeply. The combined evidence points to an increase in resource partitioning or facilitation among species over time. Spatial partitioning of aboveground space (for light capture) and soil (possibly for retrieval of deep nitrogen), and facilitation of phosphorus availability by one species, are mechanisms that may account for the inferred complementarity. Extending the generalized findings on biodiversity–productivity relationships from well‐studied grasslands to tropical forests is warranted. Mixtures of fast growing trees can out‐perform the average of their component monocultures, whether the metric is biomass accrual or productivity. The modular growth of long‐lived structure enables arborescent species to retain crown space previously captured and may lead to increased spatial partitioning and facilitation of resources over time.     

Distributional niche of relatively rare sable antelope in a South African savanna: habitat versus biotic relationships

The geographic distribution of a species is governed by climatic conditions, topography, resources and habitat structure determining the fundamental niche, while the local distribution expressed via home range occupation may be compressed by biotic interactions with competitors and predators, restricting the realised niche. Biotic influences could be especially important for relatively rare species. We investigated how rainfall, geology, land type and abundance of other ungulate species serving as competitors or prey for predators contributed to the patchy distribution of sable antelope herds within Kruger National Park. Data were provided by annual aerial surveys of ungulate populations conducted between 1978 and 1988. Sable herds were more commonly present on granitic and sandstone substrates than on more fertile basalt. They occurred both in the moist south‐west and dry north of the park. They were most abundant in sour bushveld and mopane savanna woodland, and mostly absent from knob thorn‐marula parkland. The presence of sable was negatively associated with high concentrations of impala and wildebeest, less consistently related to the abundance of zebra, and positively associated with the occurrence of buffalo herds. Best supported models included the separate effects of the most abundant grazers along with land type. Interspecific relationships seemed more consistent with vulnerability to predation as the underlying mechanism restricting the distribution of sable herds than with competitive displacement. Sable favoured land types distinct from those where wildebeest, the most preferred prey of lions, and impala, numerically the most important resident prey species, were most abundant. Hence the risk of predation, associated with habitat conditions where abundant prey species are most concentrated, can exert an overriding influence on the distribution of rarer species in terms of their home range occupation.     

Faecal corticosteroid levels as an indicator of well-being in the tammar wallaby, Macropus eugenii

Faecal corticosteroid levels were measured in five female tammar wallabies, Macropus eugenii, at Macquarie University, NSW, Australia, to assess their reliability as indicators of well-being in this species. Animals were challenged with a change in conditions over the course of approximately 1 week, comprising movement from group yards to isolation in individual yards, in order to impose a disturbance to homeostasis ("stress"). Faecal samples were collected in 24-h intervals during the study period and analysed for corticosteroid concentration. The use of enzyme immunoassay for the measurement of corticosteroids in marsupial faecal pellets was validated. We observed a significant increase in faecal corticosteroids upon isolation and movement. Faecal corticosteroids remained above initial levels in all five animals throughout the study period, suggesting that faecal corticosteroid concentrations may be a useful indicator of a change in animal well-being. Faecal corticosteroid levels did not correlate with serum cortisol levels, implying that the use of noninvasive methods in a representative marsupial, the tammar wallaby, has the potential to provide information that is not readily apparent using blood-based protocols. Faecal corticosteroid analysis therefore has the potential for application in monitoring the well-being of captive and managed marsupial populations, as part of an integrated system of measures of animal health and well-being.     

Screening for Tannin Degradation by Rumen and Faecal Samples of Wild and Domestic Animals in Ethiopia

Summary Tannins limit the use of fodder trees as feed for ruminants. Removal of the effects of tannins would thus improve the nutritional quality of these trees. This prompted the study to evaluate the effect of rumen or faecal mixed cultures from different animals on tannin degradation. Tannin extracts, tannic acid and gallic acid were used to enrich media to assess if rumen or faecal mixed cultures could degrade the phenolic compounds. Rumen fluid of Acacia-adapted sheep, sheep fed on wheat bran, bush duikers (Sylvicapra grimmia) and goats fed on Leucaena pallida and Sesbania goetzei were separately inoculated into Growth Study Medium (GSM) and incubated for 5-15 days. Faecal samples from dikdik (Madoqua guentheri), camel (Camelus dromedarius), zebra (Equus quagga), Grant’s gazelle (Gazella granti) and hartebeest (Alcelaphus buselaphus) were also separately inoculated into GSM media and incubated from 3-5 days. TLC results showed that mixed cultures from rumen fluids of Acacia-adapted sheep, sheep on wheat bran, goats on Leucaena pallida and Sesbania goetzei partially hydrolysed tannic acid to pyrogallol. Complete degradation of the heterocyclic ring in tannic acid and gallic acid was achieved by the mixed cultures from the faecal samples of dikdik and this was confirmed by HPLC. Mixed cultures from faecal samples of camel hydrolysed gallic acid to phloroglucinol. This study has demonstrated that faecal microorganisms of Ethiopian dikdik could completely degrade hydrolysable tannin.