Herding Strategies of the Datoga Pastoralists of Tanzania: Is Household Labor a Limiting Factor

Datoga herding follows a cyclical pattern depending on the availability of grazing and water. This analysis focuses on two questions: (a) Is the herding strategy followed by individual households limited by the amount of labor available to that household? and (b) does the herding strategy followed by individual households influence the dynamics of cattle herds? The results show that the availability of labor on a household level does not influence either the herding strategies used by individual households, or the dynamics of cattle herds. This suggests that once minimum labor requirements are met, livestock productivity is insensitive to additional labor inputs.     

The Landscape Ecology of Pastoral Herding: Spatial Analysis of Land Use and Livestock Production in East Africa

Understanding landscape-scale patterns of herding is critical in identifying and assessing the impacts of pastoral grazing. Here, a general model of herding is developed based on the Sukuma agropastoral system in the Rukwa Valley, Tanzania. Using this conceptual framework, the factors affecting the maximum distances herds travel from home and the distribution of grazing around pastoral settlements are examined. The distribution of dry season water structured the landscape-scale distribution of grazing throughout the year, not just during the dry season. Water availability strongly affected the distances herds ranged from home in the dry season and the distribution of grazing around pastoral settlements throughout the year. Associations between cattle productivity and herding practices were also examined. The effects of traveling further from home, keeping cattle in large herds, and using/living in areas of high settlement densities were examined on the following measures of productivity: intake rates, foraging behavior, milk yields, and body conditions. Cattle from larger herds were observed to walk more while actively foraging and engage in more walking bouts (taking ten steps without taking a bite). The increased walking of large herds may explain why they range farther from home and highlight the importance and ubiquity of herd splitting among pastoralists. However, herd size effects were not apparent in intake rates or milk yields. Milk yields were negatively affected by traveling farther from home. These data demonstrate substantial variability within herding populations and show interesting similarities with herding systems in substantially more arid areas.     

The Distribution of Grazing Pressure in Relation to Vegetation Resources in Semi-arid West Africa: The Role of Herding

In semi-arid West Africa, livestock are increasingly managed by sedentary producers in close proximity to expanding cropped lands. To evaluate the agricultural and environmental implications of this trend, a study was conducted to investigate the effect of grazing management on the spatial distribution of grazing pressure, the forage provided animals during the grazing period, and local herd-forage ratios across three agropastoral landscapes characterized by varying cultivation pressure. During the 19-month study period, data on herbaceous vegetation, livestock populations, and grazing itineraries were collected. These data were referenced to land units averaging 70 ha in area. Using this approach, each of 3,819 grazing itineraries was characterized as to: 1. the sum of the products of the palatable forage mass of a particular land unit and the time spent grazing by the herd within that unit (FAT, expressed in kg-hours ha⁻¹); and 2. the average palatable herbaceous forage mass encountered by livestock across the itinerary weighted by the time spent in the land units crossed (FA, expressed in kg ha⁻¹). The spatial dispersion of livestock grazing around human settlements was found to decline with a reduction in herding labor investment (herded>herd-release>free pasture). Multiple regression analyses of itinerary data demonstrate that both FAT and FA also decline with a reduction in herding labor investment. Herded and herd-release managed livestock were offered more palatable forage and grazed areas of higher forage availability than free-pastured animals. This supports arguments that as the investment of time and effort into herding declines, feed supply to livestock will decline and the potential for grazing-induced environmental change will increase.     

Changing Access to Labor,Pastures, and Knowledge: The Extensification of Grazing Management in Sudano-Sahelian West Africa

The broader ecological and social contexts within which livestock husbandry of Sudano-Sahelian West Africa operates have changed significantly over the past thirty years. This study concerns how: (1) these broader trends have affected the quantity and quality of labor investments into livestock herding; and (2) the ecological and animal nutritional implications of observed variation in labor investments into herding. The study was conducted in a 500 km² area of western Niger using a combination of qualitative interviews of herders and herd managers, household composition surveys, herd composition monitoring, grazing management monitoring and georeferenced vegetation and livestock grazing itinerary data. Statistical analyses were performed using a two-staged approach: (1) analysis of the factors affecting the allocation of labor to herding at the level of the managing household; and (2) analysis of the effect of herd characteristics, season, microgeography and herders’ social position on herders’ effort and the nutritional and ecological impacts of these efforts. The results of these analyses support the conclusion that the changing regional context of livestock husbandry leads to a reduction in labor (quantity and quality) investment or an “extensification” of herding with significant implications for livestock productivity and the environment.

Coping with Uncertainty and Variability: The Influence of Protected Areas on Pastoral Herding Strategies in East Africa

A large number of East African pastoralists reside around protected areas (PAs). Over the last few decades pastoralists have been affected by the loss of grazing lands and increasing climatic variability. Many pastoralists who reside around PAs have resorted to grazing inside PAs to counter environmental variability. However, there is little information on how PAs influence the herding strategies of pastoralists. This case study from southern Kenya employs a spatially and temporally explicit mixed-methods approach to understand and evaluate the herding strategies of pastoralists around a PA. The results find that pastoralists access PAs on a regular basis, regardless of seasonality or herd size. Movement into PAs was partly driven by the loss of grazing land to conservancies. PAs affected pastoral herding by presenting differential opportunity costs to disparate groups. However, households with large herd sizes utilized the most flexible strategies to counter environmental variability and uncertainty.     

The role of cross-border transhumance in influencing resident herders’ cattle husbandry practices and use of genetic resources

For centuries, the humid West African coastal country of Benin attracts cattle herders from neighboring Sahelian countries such as Niger, Burkina Faso and Nigeria. Each year, several thousands of cattle are trekked over hundreds of kilometers to Benin following established and non-established transhumance corridors. This cross-border mobility has been shown to play an important role in ensuring the productivity of the transhumant herds through adequate late dry season access to pastoral resources. Yet, its effects on the traditional agro-pastoral production systems that are encountered along the routes in Benin have never been explicitly investigated. Therefore, we collected socio-economic household data, herd characteristics and management data from 104 resident herders and 38 transhumant herders in 2 vegetation zones of Benin. To determine whether or not the proximity to transhumance corridors affects sedentary production systems, characteristics of cattle herds and farmers’ management practices were compared between villages close to (within a 25 km buffer) and far from (outside a 25 km buffer) transhumance corridors within and between vegetation zones using non-parametric statistical tests. Existing relationships between resident and transhumant herders were also identified and characterized. Subsequently, herd characteristics and management practices were compared between resident herders having relationships with transhumant herders and those without. Herd sizes of resident herders living close to transhumance corridors were larger (P < 0.01) than those of their counterparts living far away. Also, proximity to transhumance corridors had positive effects on herd management practices. The relationships between resident and transhumant herders were governed by a variety of interests including encampment/manuring contracts, exploitation of grazing lands and watering points, trading and bartering of cattle. This exchange of cattle is an important driver of change in the breed composition of local herds and represents an opportunity for resident herders to enhance their herds’ productivity through crossbreeding. However, the mere replacement or indiscriminate crossbreeding of local cattle breeds with those kept by transhumant herders threatens the sustainability of the traditional resident herding systems by increasing the risk of genetic erosion and loss of valuable adaptive traits in indigenous animal genetic resources.     

Individualized Pastureland Use: Responses of Herders to Institutional Arrangements in Pastoral China

This paper analyzes increasingly individualized herding behavior after the implementation of a grazing ban policy in northern China based on empirical research in 12 pastoralist villages. The findings reveal that de-collectivization of pastureland has not necessarily led to direct changes in individual land use strategies. Instead, a wider institutional context influenced by the implementation of a grazing ban has led to more individualized herding and increased short-term considerations of profit maximization in the study area, both of which are seen to undermine the sustainable use of pastureland. Based on our observations of herder responses to privatization, the grazing ban and a short experiment with lifting the grazing ban, we propose that the special characteristics of grassland and pastoralism call for institutions that facilitate locally originated pasture land use practice (e.g., co-operative herding, self-organized management) instead of exclusive reliance on a rigidly defined private property regime focused on fixed property boundaries.     

Herders' Perceptions, Practice, and Problems of Night Grazing in the Sahel: Case Studies from Niger

A survey was conducted from February to June of 1997 among livestock herders in two villages of Niger, Kodey and Toukounous, on their perceptions, practice, and problems of night grazing. Cattle and sheep were the species that were taken out for night grazing by the herders. Small herd size and labor constraints were mentioned as the principal reasons for not practicing night grazing. Major benefits of night grazing included good body condition, herd growth, increased milk production, prevention of diseases, and reduction in herd mortality. Insecurity, difficulty in staying awake at night, labor constraints, and damage to crops by animals were given as problems of night grazing. According to the herders, grazing time (duration) during the day and night was shorter in the wet season than in the dry season. In the wet season animals were herded (followed and closely supervised by herders), whereas in the dry season, animals were mostly left to range freely in both villages. In general, children herded the animals during the day, while adults were responsible for night-time herding. Herders' perceptions on night grazing as regards animal production parameters such as weight development, water consumption, fecal output and feeding behavior are consistent with available experimental results. Therefore, future technical research needs to recognize the constraints faced by herders and determine how to overcome them to improve technical and economic efficiency.     

Conflicting management objectives on the Colorado Plateau: Understanding the effects of bison and cattle grazing on plant community composition

The American Bison (Bison bison Linnaeus) in the Henry Mountains are one of the last free-roaming, genetically pure herds of bison remaining in North America. Anecdotal evidence indicates that this herd is utilising a cattle winter range during the summer and fall, creating a conflict between the state agency that manages the bison, and the Bureau of Land Management (BLM) and local ranchers. In theory, the addition of bison grazing pressure could reduce forage availability in the short term and lead to undesired changes in the plant community in the long term. Our objective was to determine whether bison have altered the plant species composition of the cattle winter range. We characterised plant species composition, percent cover, and grazing intensity on three adjacent, geomorphologically similar mesas. Grazing regimes were different on the three mesas, one with bison and cattle present, one with cattle only present, and the third with neither cattle nor bison present. Vegetation surveys were accompanied by a 28-year remote sensing time series to test for temporal shifts in an index of primary productivity. We found a higher grazing intensity on two dominant forage species on the bison plus cattle grazed mesa in fall, before the cattle were turned out to winter pasture. Despite this difference in grazing intensity, we found few differences in species composition, percent cover, or NDVI across the three grazing regimes. Our results suggest that high intensity summer bison grazing, while likely creating short-term reductions in forage availability, has not caused differences in plant community composition or productive potential. Shifts in community composition can take years to unfold and just as long to correct; therefore, continued monitoring of the combined effects of cattle and bison is needed.     

Grazing impacts on the diversity and composition of alpine rangelands in Northwest Yunnan

Aims The eastern Himalayan region of Southwest China represents the world's most biodiverse temperate region as well as a cultural hotspot undergoing rapid cultural and ecological change. This area represents the center of origin for many plant groups including horticulturally valuable species of Pedicularis, Rhododendron and Primula. Alpine meadows here also provide summer pastures for Tibetan yak herders and the source for important medicinal plants. Stocking levels for livestock here have quadrupled over the last five decades and shrubs are encroaching into many historical rangelands. Yak herders voice concerns over both shrub encroachment and shrinking grasslands. In this study, we sought to determine: (i) Are alpine rangelands in Deqin County overgrazed and degraded? (ii) What are the local impacts of grazing on plant diversity and community composition? And (iii) which environmental variables covary with these differences in species composition across the grazing gradient?Methods To examine the ecological impacts of grazing in Deqin County, northwest Yunnan and assess its long-term sustainability, we used county records to determine historical population and livestock numbers, confirmed the results of interviews by Haynes (2011) and surveyed plant species richness and cover along a grazing gradient extending away from herder huts. Along these transects, we sampled 1?m 2 quadrats at 5 m intervals, noting species present and percent cover for vascular plants, grasses, sedges, rushes, moss, lichen, exposed rock, bare ground and feces. We also measured the average and maximum plant height within each quadrat. We then computed species richness for each of the 38 transects, calculating alpha and beta diversities. We used one-way ANOVAs to compare mean species richness values and average and maximum plant height across grazing intensities. To chart changes in composition along the 100m gradient, we also plotted the percent cover of graminoid, forb, shrub and bare ground versus distance from the hut. We applied NMS ordination to relate community patterns to environmental variables and grazing intensity using distances to determine species groupings.Important findings Livestock impacts are clearly evident with proportions of grass and bare ground decreasing, shrubs increasing and forbs maintaining even cover with increasing distance from the huts. In comparison with earlier surveys of sites farther from huts, we found reduced plant cover and diversity. Plant species richness almost doubles with increasing distance from herder huts from 9.9 to 19.3 species per 1 m 2 quadrat. An ordination of species and environmental variables demonstrates that grazing strongly affects plant community com position across these plots with strong impacts on palatable plants. If herd sizes remain large and suitable areas for grazing continue to decline, the cumulative impacts of grazing appear likely to degrade the rich diversity of the region and reduce rangeland quality, threatening its ability to sustain current grazing levels.     

Novel epidemiological model of gastrointestinal nematode infection to assess grazing cattle resilience by integrating host growth,parasite, grass and environmental dynamics

Gastrointestinal nematode (GIN) infections are ubiquitous and often cause morbidity and reduced performance in livestock. Emerging anthelmintic resistance and increasing change in climate patterns require evaluation of alternatives to traditional treatment and management practices. Mathematical models of parasite transmission between hosts and the environment have contributed towards the design of appropriate control strategies in ruminants, but have yet to account for relationships between climate, infection pressure, immunity, resources, and growth. Here, we develop a new epidemiological model of GIN transmission in a herd of grazing cattle, including host tolerance (body weight and feed intake), parasite burden and acquisition of immunity, together with weather-dependent development of parasite free-living stages, and the influence of grass availability on parasite transmission. Dynamic host, parasite and environmental factors drive a variable rate of transmission. Using literature sources, the model was parametrised for Ostertagia ostertagi, the prevailing pathogenic GIN in grazing cattle populations in temperate climates. Model outputs were validated on published empirical studies from first season grazing cattle in northern Europe. These results show satisfactory qualitative and quantitative performance of the model; they also indicate the model may approximate the dynamics of grazing systems under co-infection by O. ostertagi and Cooperia oncophora, a second GIN species common in cattle. In addition, model behaviour was explored under illustrative anthelmintic treatment strategies, considering impacts on parasitological and performance variables. The model has potential for extension to explore altered infection dynamics as a result of management and climate change, and to optimise treatment strategies accordingly. As the first known mechanistic model to combine parasitic and free-living stages of GIN with host feed-intake and growth, it is well suited to predict complex system responses under non-stationary conditions. We discuss the implications, limitations and extensions of the model, and its potential to assist in the development of sustainable parasite control strategies.     

Plant functional traits under cattle grazing and fallow age scenarios in a tropical dry forest of Northwestern Mexico

Evaluating plant functional traits helps to understand how plants respond to changing environmental conditions and resource availability associated with disturbance events. Livestock production is one of the primary drivers of tropical forest loss and degradation. Livestock alter environmental conditions within the forest by grazing, trampling and nutrient inputs, which in turn can influence species composition and functional traits of species. Understanding how livestock influence functional traits along a successional gradient is poorly understood. Here, we studied the effect of cattle grazing and fallow age on plant functional traits and soil nutrients in secondary and old-growth tropical dry forests. We analyzed plant functional traits of the most important species in successional and old-growth forest communities in both cattle present and cattle excluded plots. Our results showed the effects of cattle grazing and fallow age on plant functional traits, with fallow age explaining more variation than cattle grazing. In early succession, functional traits were associated with water conservation (thicker leaves, lower specific leaf area), and in later successional they were linked with sunlight conservation (larger height, higher specific leaf area). The presence of large fruits and seeds in advanced successional sites suggests high resource availability, which may help plants to successfully reproduce. Moreover, under cattle grazing some functional traits are associated with herbivory defense (high foliar dry weight and thick leaves). Even though N and C increased as succession advanced, the sites with cattle grazing had higher NH4 and NO3 concentrations as a result of fecal deposition. Plant functional traits responded to fallow age than to cattle grazing. Our study showed that cattle exclusion, as a management and biodiversity conservation strategy, contributes positively to soil nutrition. Thus, fallow age and cattle exclusion facilitate soil recovery and allows establishing species with suitable functional attributes for overcoming environmental filters in abandoned cattle fields.     

An Integrated Approach to Modeling Grazing Pressure in Pastoral Systems: The Case of the Logone Floodplain (Cameroon)

The discussion about the impact of pastoral systems on ecosystems has been profoundly shaped by Hardin’s “tragedy of the commons” argument that held pastoralists responsible for overgrazing the range. Recent studies have shown that grazing ecosystems are much more complex and dynamic than was previously assumed and that pastoralists adaptively manage these systems. However, we still have little understanding how everyday herding affects ecosystems at the landscape level. We conducted a study of daily herd movements and grazing strategies in a mobile pastoral system in the Logone floodplain, Cameroon. We integrated GPS/GIS technology, video recordings of animal behavior, and ethnographic methods to develop a more accurate measurement of grazing pressure that takes into account both livestock densities and grazing behavior. We used the resulting grazing pressure data to evaluate existing conceptual models of grazing pressure at a landscape level. We found that models that predict that grazing pressure is skewed towards the direction of water most accurately reflect the situation in the Logone floodplain in the dry season. However, we found that the higher grazing pressure is not only the result of a higher density of cattle but also a change in the grazing behavior of animals after watering. Finally, we caution that the models of grazing pressure in the dry season cannot simply be extrapolated to the landscape level because mobile pastoralists do not remain in one central place.     

Is there safety in numbers? The effect of cattle herding on biting risk from tsetse flies

In sub-Saharan Africa, tsetse (Glossina spp.) transmit species of Trypanosoma which threaten 45-50 million cattle with trypanosomiasis. These livestock are subject to various herding practices which may affect biting rates on individual cattle and hence the probability of infection. In Zimbabwe, studies were made of the effect of herd size and composition on individual biting rates by capturing tsetse as they approached and departed from groups of one to 12 cattle. Flies were captured using a ring of electrocuting nets and bloodmeals were analysed using DNA markers to identify which individual cattle were bitten. Increasing the size of a herd from one to 12 adults increased the mean number of tsetse visiting the herd four-fold and the mean feeding probability from 54% to 71%; the increased probability with larger herds was probably a result of fewer flies per host, which, in turn, reduced the hosts' defensive behaviour. For adults and juveniles in groups of four to eight cattle, > 89% of bloodmeals were from the adults, even when these comprised just 13% of the herd. For groups comprising two oxen, four cows/heifers and two calves, a grouping that reflects the typical composition of communal herds in Zimbabwe, approximately 80% of bloodmeals were from the oxen. Simple models of entomological inoculation rates suggest that cattle herding practices may reduce individual trypanosomiasis risk by up to 90%. These results have several epidemiological and practical implications. First, the gregarious nature of hosts needs to be considered in estimating entomological inoculation rates. Secondly, heterogeneities in biting rates on different cattle may help to explain why disease prevalence is frequently lower in younger/smaller cattle. Thirdly, the cost and effectiveness of tsetse control using insecticide-treated cattle may be improved by treating older/larger hosts within a herd. In general, the patterns observed with tsetse appear to apply to other genera of cattle-feeding Diptera (Stomoxys, Anopheles, Tabanidae) and thus may be important for the development of strategies for controlling other diseases affecting livestock.     

High Female Mortality Resulting in Herd Collapse in Free-Ranging Domesticated Reindeer (Rangifer tarandus tarandus) in Sweden

Reindeer herding in Sweden is a form of pastoralism practised by the indigenous Sámi population. The economy is mainly based on meat production. Herd size is generally regulated by harvest in order not to overuse grazing ranges and keep a productive herd. Nonetheless, herd growth and room for harvest is currently small in many areas. Negative herd growth and low harvest rate were observed in one of two herds in a reindeer herding community in Central Sweden. The herds (A and B) used the same ranges from April until the autumn gathering in October–December, but were separated on different ranges over winter. Analyses of capture-recapture for 723 adult female reindeer over five years (2007–2012) revealed high annual losses (7.1% and 18.4%, for herd A and B respectively). A continuing decline in the total reindeer number in herd B demonstrated an inability to maintain the herd size in spite of a very small harvest. An estimated breakpoint for when herd size cannot be kept stable confirmed that the observed female mortality rate in herd B represented a state of herd collapse. Lower calving success in herd B compared to A indicated differences in winter foraging conditions. However, we found only minor differences in animal body condition between the herds in autumn. We found no evidence that a lower autumn body mass generally increased the risk for a female of dying from one autumn to the next. We conclude that the prime driver of the on-going collapse of herd B is not high animal density or poor body condition. Accidents or disease seem unlikely as major causes of mortality. Predation, primarily by lynx and wolverine, appears to be the most plausible reason for the high female mortality and state of collapse in the studied reindeer herding community.     

Genotype × region and genotype × production level interactions in Holstein cows

The identification of the presence of genotype by environment interaction effects on important traits in Holstein cattle allows for the use of international genetic evaluations and a more efficient design of regional genetic evaluation programmes. The aim of this study was to determine the genotype × environment interaction effects in Chilean Holstein dairy cattle through the analysis of records corresponding to calvings between 1998 and 2015. Herds were classified in the central and southern regions of Chile based on herd location as well as by high and low levels of production environments based on the fat plus protein yield averages per herd within each region. The central region has a Mediterranean climate and a confined production system while the southern region has a humid temperate climate and a production system based on grazing with supplementation. Traits studied were milk yield (MY), fat yield (FY), protein yield (PY), fat content (FC) and protein content (PC) by lactation, age at first calving (AFC) and calving interval (CI). Several four-trait mixed animal models were applied to environmental category data as different traits, which included herd-year-calving season (herd-year-birth season for AFC) and lactation number as fixed effects, and animal additive genetic, sire-herd, permanent environment and residual effects as random effects. Genetic correlations (r_g) for MY, FY, FC, PC and CI were found to decrease as differences between environmental categories increased. The r_g between the most extreme environmental categories considered in this study for AFC (0.26) was the only one found statistically lower than 0.60. Genetic correlation values statistically lower than 0.80 (P < 0.05) were observed for AFC, CI, MY, FY and PY between some environmental categories. If separate genetic evaluations are adopted as practical criteria when the value of r_g is lower than 0.60, the consequence of improving a multi-trait economic breeding objective in this population is likely to be small unless extreme environmental categories are considered. However, a moderate decrease in selection response and re-ranking of selection candidates is expected for AFC, CI and yield traits when selection is performed in different environmental conditions. Genotype × environment interaction effects involving production systems in a Mediterranean climate and confinement vs. Temperate Oceanic climate and grazing with supplementation, and between two fat plus protein yield level categories within each environment, were at most moderate for the studied traits.     

Grazing as a factor structuring grasslands in the Pyrenees

Questions: What are the relative roles of abiotic and grazing management factors on plant community distribution in landscapes? How are livestock type and stocking rate related to changes in vegetation structure and composition? Location: Sub‐alpine grasslands in the central and eastern Pyrenees. Methods: Multivariate analysis and variance partitioning methods were used to evaluate the relative roles of environmental factors in structuring vegetation composition and diversity patterns in three surveys on differently managed grasslands. Results: Vegetation composition within a region was affected by environmental factors hierarchically, changing first according to abiotic factors and then to grazing management. At landscape scales, abiotic factors explained two‐fold more variation in vegetation composition than grazing factors. Within landscape units, cattle grazing increased vegetation heterogeneity at landscape and patch scales, while sheep grazing favoured the presence of a specific set of species with high conservation value. Species composition was highly responsive to management variables compared to diversity components. Conclusions: The combination of sheep and cattle grazing at various stocking rates is an effective tool to preserve the diversity of plant species and communities within a region with a long tradition of livestock management, through the scaling up of effects by local processes occurring in patches at smaller scales.     

Cattle-tsetse contact in relation to the daily activity patterns of Glossina morsitans submorsitans in The Gambia

Abstract. The daily flight activity patterns of one of the main vectors of animal trypanosomiasis in West Africa, Glossina morsitans submorsitans , were assessed using four different methods. Results from all the methods showed that there was some flight activity nearly every hour in all seasons but they differed in the level of contact between grazing cattle herds and G.m.submorsitans. In the late dry season, trap data indicated that there was negligible activity from midday to late afternoon, whereas observations of tsetse contact with cattle herds or hand-net collections on herd followings showed no fall in attack rates on the cattle by G.m.submorsitans.
Differences between trap and animal-baited collection data may be attributable to the type of G.m.submorsitans sampled by each method. Male G.m.submorsitans captured by traps were more fat depleted than those caught on ox-baited flyrounds or by hand-net collections on herd followings. All methods showed that male G.m.submorsitans were most fat depleted in the late dry season and least in the early dry season. It was concluded that the traps were mainly sampling the spontaneous flights of G.m.submorsitans. Hunger and endogenous rhythms increase the likelihood of spontaneous flights towards dusk, particularly in conditions such as those at midday in the very hot, late dry season. However, the presence of cattle herds in infested habitats probably activated nearby G.m.submorsitans and the continual movement through the grazing areas ensured contact with tsetse throughout grazing.
The data indicated that strategic management of herd grazing times cannot eliminate the risk of trypanosomiasis transmission occurring, irrespective of the harshness of the dry season climate. An assessment of the level of this risk could only be measured suitably by collecting tsetse using animal-baited methods, not from trap data.     

Efficacy of Integrating Herder Knowledge and Ecological Methods for Monitoring Rangeland Degradation in Northern Kenya

The world-wide debate on land degradation in arid lands, usually linked to local land use practices, does not reflect methodological advancements in terms of assessments and monitoring that integrate local communities’ knowledge with ecological methods. In this paper, we evaluated the efficacy of three different methods related to herder assessments and monitoring of land degradation; herder knowledge and ecological methods of assessing impacts of livestock grazing along gradients of land use from settlement and joint monitoring of selected marked transects to understand long-term vegetation changes in southwestern Marsabit northern Kenya. The performance of each method was carefully evaluated and interpreted in terms of the indicators used by herders and ecologists. Herder interpretations were then related to ecologists’ empirical analysis of land degradation. The Rendille nomads have a complex understanding of land degradation which combines environmental and livestock productivity indicators, compared to conventional scientific approaches that use plant-based indicators alone. According to the herders, the grazing preference of various livestock species (e.g., grazers versus browsers) influences perceptions of land degradation, suggesting degradation is a relative term. The herders distinguished short-term changes in vegetation cover from long-term changes associated with over-exploitation. They attributed current environmental degradation around pastoral camps, which shift land use between the alternating wet and dry seasons, to year-round grazing. We deduced from long-term observation that herders interpret vegetation changes in terms of rainfall variability, utilitarian values and intensification of land use. Long-term empirical data (23 years) from repeated sampling corroborated herder interpretations. Land degradation was mostly expressed in terms of declines in woody plant species, while spatial and temporal dynamics of herbaceous species reflected the effects of seasonality. The efficacy of the three methods were inferred using explanatory strengths of ecological theory; insightfulness of the methods for describing land degradation and the likelihood of using the methods for promoting local community participation in the implementation of the UN Convention on Combating Desertification (CCD) and the Convention on Biological Diversity (CBD).     

Environmental factors accounting for benthic macroinvertebrate assemblage structure at the sample scale in streams subjected to a gradient of cattle grazing

Macroinvertebrate assemblages were related to environmental factors that were quantified at the sample scale in streams subjected to a gradient of cattle grazing. Environmental factors and macroinvertebrates were concurrently collected so assemblage structure could be directly related to environmental factors and the relative importance of stressors associated with cattle grazing in structuring assemblages could be assessed. Based on multivariate and inferential statistics, measures of physical habitat (% fines and substrate homogeneity) had the strongest relationships with macroinvertebrate assemblage structure. Detrital food variables (coarse benthic and fine benthic organic matter) were also associated with assemblage structure, but the relationships were never as strong as those with physical habitat measures, while autochthonous food variables (chlorophyll a and epilithic biomass) appeared to have no association with assemblage structure. The amount of variation explained in taxa composition and macroinvertebrate metrics is within values reported from studies that have examined macroinvertebrate metric–sediment relationships. The % Coleoptera and % crawlers had consistent relationships with % fines during this study, which suggests they may be useful metrics when sediment is a suspected stressor to macroinvertebrate assemblages in Blue Ridge streams. Findings from this study also demonstrate the importance of quantitative sampling through time when research goals are to identify relationships between macroinvertebrates and environmental factors.