Ecology Of Herbivores Research Articles

Rethinking livestock encroachment at a protected area boundary

The presence of livestock inside protected areas, or "livestock encroachment," is a global conservation concern because livestock is broadly thought to negatively affect wildlife. The Maasai Mara National Reserve (MMNR), Kenya, exemplifies this tension as livestock is believed to have resulted in the declining wildlife populations, contributing to the strict and sometimes violent exclusion measures targeting Maasai pastoralists. However, research embedded in the real-world setting that draws insights from the social-ecological contexts is lacking. In this study, we conducted 19 mo of ecological monitoring covering 60 sites in MMNR and found that cattle presence inside the reserve did not significantly impact most co-occurring wild herbivores at the current intensity. Using the Hierarchical Modeling of Species Communities and Gaussian copula graphic models, we showed that cattle had no direct associations-neither negative nor positive-with nearly all wild herbivores despite frequently sharing the same space. Moreover, we did not detect resource degradation correlated with cattle presence near the MMNR boundary. Given the colonial legacy and land use history of Mara, entering MMNR becomes the only viable option for many herders. These results corroborate the emerging perspective that the ecological impacts of extensively herded livestock on wildlife might be more nuanced than previously thought. To effectively balance the needs of people, livestock, and wildlife, the current rigid livestock exclusion measures need to be reassessed to holistically consider herbivore ecology, local land use history, and modern politics of protected area management.

Body size modulates the extent of seasonal diet switching by large mammalian herbivores in Yellowstone National Park.

Prevailing theories about animal foraging behaviours and the food webs they occupy offer divergent predictions about whether seasonally limited food availability promotes dietary diversification or specialization. Emphasis on how animals compete for food predominates in work on the foraging ecology of large mammalian herbivores, whereas emphasis on how the diversity of available foods generally constrains dietary opportunity predominates work on entire food webs. Reconciling predictions about what promotes dietary diversification is challenging because species' different body sizes and mobilities modulate how they seek and compete for resources-the mechanistic bases of common predictions may not pertain to all species equally. We evaluated predictions about five large-herbivore species that differ in body size and mobility in Yellowstone National Park using GPS tracking and dietary DNA. The data illuminated remarkably strong and significant correlations between body size and five key indicators of diet seasonality (R 2 = 0.71-0.80). Compared to smaller species, bison and elk showed muted diet seasonality and maintained access to more unique foods when winter conditions constrained food availability. Evidence from GPS collars revealed size-based differences in species' seasonal movements and habitat-use patterns, suggesting that better accounting for the allometry of foraging behaviours may help reconcile disparate ideas about the ecological drivers of seasonal diet switching.

Increased intake of tree forage by moose is associated with intake of crops rich in nonstructural carbohydrates.

Animals representing a wide range of taxonomic groups are known to select specific food combinations to achieve a nutritionally balanced diet. The nutrient balancing hypothesis suggests that, when given the opportunity, animals select foods to achieve a particular target nutrient balance, and that balancing occurs between meals and between days. For wild ruminants who inhabit landscapes dominated by human land use, nutritionally imbalanced diets can result from ingesting agricultural crops rich in starch and sugar (nonstructural carbohydrates [NCs]), which can be provided to them by people as supplementary feeds. Here, we test the nutrient balancing hypothesis by assessing potential effects that the ingestion of such crops by Alces alces (moose) may have on forage intake. We predicted that moose compensate for an imbalanced intake of excess NC by selecting tree forage with macro-nutritional content better suited for their rumen microbiome during wintertime. We applied DNA metabarcoding to identify plants in fecal and rumen content from the same moose during winter in Sweden. We found that the concentration of NC-rich crops in feces predicted the presence of Picea abies (Norway spruce) in rumen samples. The finding is consistent with the prediction that moose use tree forage as a nutritionally complementary resource to balance their intake of NC-rich foods, and that they ingested P. abies in particular (normally a forage rarely eaten by moose) because it was the most readily available tree. Our finding sheds new light on the foraging behavior of a model species in herbivore ecology, and on how habitat alterations by humans may change the behavior of wildlife.

Vegetation biomass and topography are associated with seasonal habitat selection and fall translocation behavior in Arctic hares.

Habitat selection theory suggests that environmental features selected at coarse scales reveal fundamental factors affecting animal fitness. When these factors vary across seasons, they may lead to large-scale movements, including long-distance seasonal migrations. We analyzed the seasonal habitat selection of 25 satellite-tracked Arctic hares from a population on Ellesmere Island (Nunavut, Canada) that relocated over 100 km in the fall. Since no other lagomorph is known to perform such extensive movements, this population offered an ideal setting to test animal movement and habitat selection theory. On summer grounds hares selected low elevation areas, while on winter grounds they selected high vegetation biomass, high elevation, and steep slopes. During fall relocation, they alternated between stopover and traveling behavioral states (ratio 2:1). Stopover locations were characterized by higher vegetation heterogeneity and lower rugosity than traveling locations, while vegetation biomass and elevation interacted to explain stopover locations in a more complex way. The selected combination of environmental features thus varied across seasons and behavioral states, in a way broadly consistent with predictions based on the changing food and safety needs of hares. Although causality was not demonstrated, our results improve our understanding of long-distance movements and habitat selection in Arctic hares, as well as herbivore ecology in the polar desert. Results also provide strong support to animal movement and habitat selection theory, by showing how some important hypotheses hold when tested in a species phylogenetically distinct from most animal models used in this research field.

Grouping dynamics of the northernmost population of blackbuck (Antilope cervicapra) in Krishnasaar Conservation Area, Nepal

Blackbuck, Antilope cervicapra, are group-living grazers found in a wide range of habitats, from dry grasslands to open forests. Krishnasaar Conservation Area (KrCA) in Bardia, Nepal is home to the northernmost population of blackbuck. This population lives in close proximity to humans. As a population in an extreme of the species’ range and experiencing direct and indirect human influences, KrCA is suitable to study less explored facets of herbivore ecology and behavior. One such less explored behavior of herbivores is their grouping (herding) behavior. Grouping is commonly seen as an anti-predator response and could also be used in the context of anthropogenic threat. In this study we investigated herding behavior of blackbuck and ecological and anthropogenic factors that might influence the herding. To record the grouping behavior of blackbuck in the different habitat types, we used scan sampling methods for groups. A group was defined by including all individuals that are within 50 m of another individual. The influence of ecological and anthropogenic factors on herding pattern was assessed through simple regression modelling. We scanned animals for 89 hours and each hour had seven observations. The mean group size was 20.56 ±1.97 (mean ± SE). More than two-thirds of animals observed were female. We found larger herd sizes in the morning compared with herd sizes in the afternoon and evening. Our observations also showed that mixed herds were significantly larger in size than male-only, and female-only herds in both core and settlement zones. Our modelling of covariates predicted group type to be the single most influential factor influencing herd size. As herding behavior of animals reflect associated risk and resource factors, the finding of this work can be helpful in managing this isolated threatened population of blackbuck.

Horizontal viewsheds of large herbivores as a function of woodland structure.

There is great potential for the use of terrestrial laser scanning (TLS) to quantify aspects of habitat structure in the study of animal ecology and behaviour. Viewsheds-the area visible from a given position-influence an animal's perception of risk and ability to respond to potential danger. The management and conservation of large herbivores and their habitats can benefit greatly from understanding how vegetation structure shapes viewsheds and influences animal activity patterns and foraging behaviour. This study aimed to identify how woodland understory structure influenced horizontal viewsheds at deer eye height. Mobile TLS was used in August 2020 to quantify horizontal visibility-in the form of Viewshed Coefficients (VC)-and understory leaf area index (LAI) of 71 circular sample plots (15-m radius) across 10 woodland sites in North Wales (UK) where fallow deer (Dama dama) are present. The plots were also surveyed in summer for woody plant size structure, stem density and bramble (Rubus fruticosus agg.). Eight plots were re-scanned twice in winter to compare seasonal VC values and assess scan consistency. Sample plots with higher densities of small stems had significantly reduced VC 1 m from the ground. Other stem size classes, mean percentage bramble cover and understory LAI did not significantly affect VC. There was no difference in VC between summer and winter scans, or between repeated winter scans. The density of small stems influenced viewsheds at deer eye height and may alter behavioural responses to perceived risk. This study demonstrates how TLS technology can be applied to address questions in large herbivore ecology and conservation.

Variability in Plant–Herbivore Interactions

Plants and herbivores are remarkably variable in space and time, and variability has been considered a defining feature of their interactions. Empirical research, however, has traditionally focused on understanding differences in means and overlooked the theoretically significant ecological and evolutionary roles of variability itself. We review the literature with the goal of showing how variability-explicit research expands our perspective on plant–herbivore ecology and evolution. We first clarify terminology for describing variation and then review patterns, causes, and consequences of variation in herbivory across scales of space, time, and biological organization. We consider how incorporating variability improves existing hypotheses and leads to new ones. We conclude by suggesting future work that reports full distributions, integrates effects of variation across scales, describes nonlinearities, and considers how stochastic and deterministic variation combine to determine herbivory distributions.

Distinct gut bacterial composition in Anoplophora glabripennis reared on two host plants.

Anoplophora glabripennis (Coleoptera: Cerambycidae: Lamiinae) is an invasive wood borer pest that has caused considerable damage to forests. Gut bacteria are of great importance in the biology and ecology of herbivores, especially in growth and adaptation; however, change in the gut bacterial community of this pest feeding on different hosts is largely unknown. In this study, we investigated the gut bacterial communities of A. glabripennis larvae fed on different preferred hosts, Salix matsudana and Ulmus pumila, using 16S rDNA high-throughput sequencing technology. A total of 15 phyla, 25 classes, 65 orders, 114 families, 188 genera, and 170 species were annotated in the gut of A. glabripennis larvae fed on S. matsudana or U. pumila using a 97% similarity cutoff level. The dominant phyla were Firmicutes and Proteobacteria and the core dominant genera were Enterococcus, Gibbsiella, Citrobacter, Enterobacter, and Klebsiella. There was significantly higher alpha diversity in the U. pumila group than in the S. matsudana group, and principal co-ordinate analysis showed significant differences in gut bacterial communities between the two groups. The genera with significant abundance differences between the two groups were Gibbsiella, Enterobacter, Leuconostoc, Rhodobacter, TM7a, norank, Rhodobacter, and Aurantisolimonas, indicating that the abundance of larval gut bacteria was affected by feeding on different hosts. Further network diagrams showed that the complexity of the network structure and the modularity were higher in the U. pumila group than in the S. matsudana group, suggesting more diverse gut bacteria in the U. pumila group. The dominant role of most gut microbiota was related to fermentation and chemoheterotrophy, and specific OTUs positively correlated with different functions were reported. Our study provides an essential resource for the gut bacteria functional study of A. glabripennis associated with host diet.

Reconstructing herbivore diets: a multivariate statistical approach to interpreting amino acid nitrogen isotope values.

Recent studies have demonstrated that there exists significant variability in amino acid (AA) δ15N values of terrestrial plants, discriminating among plant types (i.e., legume seeds, grasses, tree leaves) as well as tissues of the same plant. For the first time, we investigate the potential of the spacing between the δ15N values of different AAs to differentiate between plant types and thus elucidate their relative importance in herbivore diet. Using principal component analysis, we show that it is possible to distinguish among five plant categories-cereal grains, rachis, legume seeds, herbaceous plants, and woody plants-whose consumption has different implications for understanding herbivore ecology and management practices. Furthermore, we were able to correctly classify the herbaceous plant diet of modern cattle using AA δ15N values of their tooth dentine adjusted for trophic enrichment. The AA δ15N patterns of wild and domestic herbivores from archaeological sites seem to be consistent with diets comprised predominantly of herbaceous plants, but there is variation in AA δ15N values among individuals that may reflect differing inputs of other plant types. The variation in AA δ15N values does not necessarily reflect the variation in herbivore bulk collagen δ13C and δ15N values, indicating that AA δ15N values have the potential to provide additional insights into plant dietary sources compared to bulk tissue isotope values alone. Future work should focus on defining trophic enrichment factors for a wider range of terrestrial herbivores and expanding libraries of primary producer AA δ15N values.

Calcified coralline algae have similar caloric value to uncalcified algae

A long-held paradigm in marine herbivore ecology is that calcified coralline algae are less nutritious than their uncalcified, fleshy counterparts, partially explaining why herbivores prefer to consume uncalcified algae. The basis for this assumption is that calcium carbonate (CaCO3) comprises a large portion of coralline thalli and is a dense, non-nutritious compound that lowers the relative caloric value. Caloric analyses generally make comparisons using dry weight, which is not a biologically relevant metric to assess algal caloric value: algae are not consumed dry and are consumed by volume rather than by weight. We determined the caloric value of 5 fleshy, uncalcified algal species and 5 calcified coralline algal species on a per-dry-weight and per-volume basis. Results clearly indicated that when compared on a per-dry-weight basis, uncalcified thalli were more calorie rich than coralline thalli. However, on a per-volume basis, coralline and uncalcified thalli were more similar, and the caloric value of some corallines exceeded that of some kelps. Our data show that calcified and uncalcified thalli have similar proportions of organic tissue, with a large portion of uncalcified thalli composed of water and a similar portion of calcified thalli composed of water and CaCO3. We argue that a volumetric assessment of the caloric values of macroalgae is more relevant and accurate than a dry-weight metric. The widespread observation that herbivores prefer uncalcified over coralline algae cannot be explained by differences in caloric content, indicating that another mechanism must account for many marine herbivores’ avoidance of calcified coralline algae.

Using functional groups to predict the spatial distribution of large herbivores on the Palaeo‐Agulhas Plain, South Africa, during the Last Glacial Maximum

ABSTRACTThroughout much of the Quaternary, lower sea levels in the southern Cape of South Africa exposed a different landscape to what we see today, the Palaeo‐Agulhas Plain (PAP). The PAP was dominated by large‐bodied and gregarious grazing species contrasting with the small‐bodied predominantly solitary species we find in the region today. The distribution of these herbivores would likely have been driven by similar drivers we see in contemporary herbivore ecology. Importantly, the occurrence of early humans and their associated technology would have also influenced the probability of herbivores occurring in an area. Here we create a predictive model for large herbivores using probability of occurrence of functional grouping in relation to environmental drivers and humans. We show how early humans influenced the distribution of large herbivores on the PAP alongside other environmental drivers. In the fynbos biome, probability of occurrence was highest for the medium‐sized social mixed feeders’ functional group in the thicket for small non‐social browsers, large browsers, and non‐ruminants and in grasslands for water‐dependent grazers. In our models, human influence affected functional groups to varying degrees but had the strongest effect on medium‐sized social mixed feeders.

Similar gut bacteria composition in Apriona germari on two preferred host plants.

Apriona germari is one of the most serious wood-boring pests that cause damage to economic and landscaping trees and has adapted to a wide range of plants as diet. Gut bacteria play an important role in biology and ecology of herbivores, especially in growth and adaptation. To investigate how plant hosts shape A. germari gut microbiota, A. germari larvae were collected from Populus tomentosa and Malus pumilal, and gut microbiomes were sequenced based on 16S rDNA high-throughput sequencing technology. A total of 853,424 high-quality reads were obtained and clustered into 196 operational taxonomic unitsunder a 97% similarity cutoff, which were annotated into 8 phyla, 10 classes, 21 orders, 34 families, 59 genera, and 39 species. Gibbsiella was the most dominant genus of intestinal bacteria, followed by Enterobacter and Acinetobacter. No significant difference was observed in larvae gut bacterial richness and diversity of A. germari collected from two hosts, though alpha diversity showed that the richness of gut bacteria in A. germari larvae collected on P. tomentosa was slightly higher than that in A. germari on M. pumilal, and beta diversity showed little difference between two host plants. The functional abundance analysis of the detected bacteria revealed fermentation, chemoheterotrophy, symbionts, and nitrate relative functions that highly possibly support wood-boring beetles to feed on woody tissues. Our study provided a theoretical basis for investigating the function of intestinal symbiosis bacteria of A. germari.

Aridification and orbital forcing of eastern African climate during the Plio-Pleistocene

We developed a composite outcrop proxy record of Plio-Pleistocene climate in eastern Africa using the radiometrically-dated sediments of the Omo Group that preserve evidence for early hominin evolution. New stable oxygen isotopic measurements from pedogenic carbonate nodules (δ18OPC, n = 270) are added to the existing database for a total of 759 observations spanning a ~ 3.6 Myr interval from 4.33–0.65 Ma. Linear interpolation of sample positions between tuffaceous marker horizons produced the chronostratigraphy of the δ18OPC record that was correlated to Indo-Pacific marine core sediment records and astronomical solutions of orbital climate forcing. Rainfall/evaporation changes inferred from the δ18OPC record carry orbital eccentricity signals, and the amplitude modulation of short eccentricity (~100 kyr) predicted by the astronomical solutions is evident during some intervals. δ18OPC variations recover many of the ~100 kyr cycles between ~4.3–0.7 Ma, with chronostratigraphic offsets between the Omo Group time series and astronomical solutions usually within the resolution of the radiometric uncertainties, i.e., ≤ 50 kyr; however, missing time at ~1.2 Ma contributes to nearly 150 kyr of offset. These δ18OPC data also indicate a long-term drying trend beginning at 2.11 Ma that correlates to a thicker eastern Indian Ocean mixed layer and upwelling in the eastern Pacific, implying a simultaneous response across the tropics to strengthening Walker Circulation. Published δ13CPC values from the same pedogenic carbonate nodules indicate that C4 vegetation abundances increased beginning at ~2.0 Ma, also suggesting climatic drying. Spectral analysis of the δ13CPC time series provides weaker evidence of orbital forcing as compared to the δ18OPC time series, particularly for long orbital eccentricity (405 kyr) and climatic precession (~20 kyr), suggesting other factors, such as feeding ecology of herbivores or global greenhouse gas, may have contributed to the vegetation patterns. The climatic precession component to the δ18OPC time series increases amplitude through strengthening Walker Circulation, which may signal a change in the intensity of interannual climate events. No indications were observed to suggest that the Plio-Pleistocene Northern Hemisphere glaciation resonated as either climatic cyclicity or an abrupt, stepwise shift in the regional hydroclimate. At major junctures of hominin evolution, including the origins of different genera and the earliest stone tools, environmental variability derived from the orbital forcing of the monsoon appears to have been low. However, we propose that at 2.11–1.66 Ma, directional aridity coupled with interannual climate events presented a new adaptive context where Homo erectus and Acheulian stone tools first appeared in eastern Africa.

The nutritional condition of moose co‐varies with climate, but not with density, predation risk or diet composition

A fundamental question about the ecology of herbivore populations pertains to the relative influence of biotic and abiotic processes on nutritional condition. Nutritional condition is influenced in important, yet poorly understood, ways by plant secondary metabolites (PSMs) which can adversely affect a herbivore's physiology and energetics. Here we assess the relative influence of various abiotic (weather) and biotic (intraspecific competition, predation risk and diet composition) factors on indicators of nutritional condition and the energetic costs of detoxifying PSMs for the moose population in Isle Royale National Park (USA). Specifically, we observed interannual variation in the ratio of urea nitrogen to creatinine (UN:C), an indicator of nutritional restriction, over 29 years and the ratio of glucuronic acid to creatinine (GA:C), an indicator of energetic investment in detoxifying PSMs, over 19‐years. Both UN:C and GA:C were measured in samples of urine‐soaked snow. Most importantly, climatic factors explained 66% of the interannual variation in UN:C, with moose being more nutritionally stressed during winters with deep snow and during winters that followed warm summers. None of the biotic factors (density, predation, diet composition) were useful predictors of UN:C or GA:C. The absence of a relationship between diet composition and either UN:C or GA:C suggests that the nutritional ecology of wild herbivores is probably complicated by fine‐scale variation in protein content and concentrations of PSMs amongst plants of the same species. UN:C increased with GA:C at both the individual and population‐level. That result is consistent with detoxification being energetically costly, such that it impairs nutritional condition and also highlights how spatio‐temporal variation in the intake and detoxification of PSMs may influence population dynamics. Lastly, because we observed interannual variation in nutritional condition over three decades and detoxification over two decades these findings are relevant to concerns about how herbivore populations respond to climate change.

Dietary trends in herbivores from the Shungura Formation, southwestern Ethiopia

Diet provides critical information about the ecology and environment of herbivores. Hence, understanding the dietary strategies of fossil herbivores and the associated temporal changes is one aspect of inferring paleoenvironmental conditions. Here, we present carbon isotope data from more than 1,050 fossil teeth that record the dietary patterns of nine herbivore families in the late Pliocene and early Pleistocene (3.6 to 1.05 Ma) from the Shungura Formation, a hominin-bearing site in southwestern Ethiopia. An increasing trend toward C4 herbivory has been observed with attendant reductions in the proportions of browsers and mixed feeders through time. A high proportion of mixed feeders has been observed prior to 2.9 Ma followed by a decrease in the proportion of mixed feeders and an increase in grazers between 2.7 and 1.9 Ma, and a further increase in the proportion of grazers after 1.9 Ma. The collective herbivore fauna shows two major change points in carbon isotope values at ∼2.7 and ∼2.0 Ma. While hominin fossils from the sequence older than 2.7 Ma are attributed to Australopithecus, the shift at ∼2.7 Ma indicating the expansion of C4 grasses on the landscape was concurrent with the first appearance of Paranthropus The link between the increased C4 herbivory and more open landscapes suggests that Australopithecus lived in more wooded landscapes compared to later hominins such as Paranthropus and Homo, and has implications for key morphological and behavioral adaptations in our lineage.

Movement ecology of large herbivores in African savannas: current knowledge and gaps

Abstract Nearly 90% of the world's large herbivore diversity occurs in Africa, yet there is a striking dearth of information on the movement ecology of these organisms compared to herbivores living in higher latitude ecosystems. The environmental context for movements of large herbivores in African savanna ecosystems has several distinguishing features. African large herbivores move in landscapes with high spatiotemporal variability, low predictability, seasonal restrictions in surface water as well as food resources, and exposure to a diverse assemblage of competitors, predators, and pathogens. These features influence mobility, diel activity routines, home‐range fidelity, and exposure to predation. We review the knowledge that has been gained about the movements of African herbivores from Global Positioning System (GPS) telemetry and identify important gaps in knowledge that exist. Topics addressed include seasonal movement patterns, daily activity schedules, space utilisation, water dependency, responses to risks of predation, pathogen transmission, social affiliations, and local population density determination. While the growing number of GPS telemetry studies has addressed a wide range of topics in Africa, they remain fragmentary in terms of places and species represented. Most research has been focussed on three species, and practices for data sharing and analysis should be improved. African landscapes are changing perhaps faster than any other region on Earth, with rapidly expanding human populations, massive infrastructure development projects, and changes in climatic regimes. There is a crucial need to establish relationships between herbivore movements and their changing environments, especially in Africa where most of the world's large herbivore diversity resides.

Long-term herbivore population dynamics in the northeastern Qinghai-Tibetan Plateau and its implications for early human impacts

Large herbivores are keystone species on the Qinghai-Tibet Plateau (QTP), but their past population ecology is the product of a complex combination of climatic changes and human activities that span the Holocene. In this study we use the record of dung-residing fungal spores (Sporormiella) in the stratified lake sediments of Genggahai Lake in the northeastern QTP to track changes in large herbivore populations. We hypothesize that the abundance of Sporormiella spores would decrease with the reduction of herbivore populations with the retreat of the summer monsoon after the mid-Holocene and the resulting vegetation degradation which is indicated by the pollen record. However, our results reveal an increase in Sporormiella spores after 5.7 ka (1 ka = 1000 cal yr BP), suggesting an increase in herbivore populations. Combined with regional archeological evidence, we infer that hunter–gatherers may have influenced the regional herbivore ecology and that the early Tibetan people may have domesticated or managed yaks and other herbivores in the northeastern QTP since 5.7 ka. The records of Sporormiella spores are interpreted within a robust chronostratigraphic framework provided by numerous radiocarbon dates from regional archeological sites, and the representation of Sporormiella spores during the Tang Dynasty is tested by a comparison with historical records of the livestock population of the region. Our findings potentially improve understanding of early human adaptation to environmental changes and past herbivore-steppe ecology in the QTP during the Holocene.

Linking land use and the nutritional ecology of herbivores: A case study with the Senegalese locust

Abstract Access to high‐quality food is a main driver of population dynamics. For herbivores, protein and carbohydrates are key nutrients that are notoriously variable in plants and are affected by land use. However, few studies have linked foraging decisions and performance in the laboratory to the nutritional landscape available in the field. Oedaleus senegalensis is a non‐model locust, a grass‐feeder, and the main pest of millet, a subsistence crop in the Sahel. In this study, we examined dietary preference and locust performance across a range of protein:carbohydrate ratios using the Geometric Framework methodology. We then applied a fitness landscape approach to visualize these results with the plant nutrient contents available across four land‐use types: millet, groundnut, fallow, and grazed fields. Finally, we contrasted our results with locust distribution in the field. Several locust species (O. senegalensis included) exhibit density‐dependent colour polymorphism; thus, we also reported individual coloration (brown or green). We found that O. senegalensis preferred moderately carbohydrate‐biased food 1:1.6 protein:carbohydrate ratio. All traits recorded (mass gain, development time, growth rate, moult success and performance index) were best near that ratio and declined on either side presenting a ‘hump‐shape’. Fallow fields contained more plants, particularly grasses, that were both abundant and closer to the optimal protein:carbohydrate ratio recorded from the laboratory experiments. When we surveyed O. senegalensis abundance and proportion, we found that they were more numerous in the fallow fields. Brown morph individuals, the ones associated with high density, were proportionally more abundant in fallow fields than green individuals. Our study provides evidence that variation in nutritional landscapes – relative to an herbivore's optimal nutrient balance – is a key driver of herbivore population distribution and abundance, and can be used to predict bottom‐up effects on herbivore species.

Cold temperature improves tannin tolerance in a granivorous rodent.

The foraging ecology of mammalian herbivores is regulated in part by their ability to detoxify plant secondary metabolites (PSM). Ambient temperature has been shown to alter liver function in rodents and the toxicity of some PSMs, but little is known about the physiological and nutritional consequences of consuming PSMs at different ambient temperatures. Furthermore, the effect of ambient temperature on the response of mammals to the most ubiquitous class of PSM, tannins, is unknown. We measured the effect of temperature and tannin intake on liver function, and the subsequent effect on the tannin tolerance of wild Japanese wood mice, Apodemus speciosus. The experiment involved acclimation to one of two ambient temperatures (10°C or 20°C) followed by acclimation to a diet of acorns (6.2% tannin DW). Liver function was measured both before and after acclimation to acorns by measuring the clearance time of a hypnotic agent. Finally, the mice were fed only acorns in a 5-day feeding experiment to assess their tolerance to tannin in the diet. Acclimation to acorns had a significant effect on liver function, but the direction of this effect was dependent on ambient temperature. Acorn consumption improved the liver function of wood mice at 10°C, but reduced liver function at 20°C, revealing a complex relationship between ambient temperature and tannin intake on liver function. Furthermore, mice with better liver function, indicated by faster clearance of the hypnotic agent, exhibited higher protein digestibility on an acorn-only diet, indicative of higher tannin tolerance. These results suggest that environmental temperature plays a significant role in the tolerance of A.speciosus to tannins, providing new insight into their seasonal feeding behaviour and winter ecology. We contend that cold-induced tannin tolerance may help to explain the population dynamics of mammalian herbivores with seasonal changes in the tannin content of their diet, and inform predictions about the response of these animals to a changing climate.

Adapt or die-Response of large herbivores to environmental changes in Europe during the Holocene.

Climate warming and human landscape transformation during the Holocene resulted in environmental changes for wild animals. The last remnants of the European Pleistocene megafauna that survived into the Holocene were particularly vulnerable to changes in habitat. To track the response of habitat use and foraging of large herbivores to natural and anthropogenic changes in environmental conditions during the Holocene, we investigated carbon (δ13 C) and nitrogen (δ15 N) stable isotope composition in bone collagen of moose (Alces alces), European bison (Bison bonasus) and aurochs (Bos primigenius) in Central and Eastern Europe. We found strong variations in isotope compositions in the studied species throughout the Holocene and diverse responses to changing environmental conditions. All three species showed significant changes in their δ13 C values reflecting a shift of foraging habitats from more open in the Early and pre-Neolithic Holocene to more forest during the Neolithic and Late Holocene. This shift was strongest in European bison, suggesting higher plasticity, more limited in moose, and the least in aurochs. Significant increases of δ15 N values in European bison and moose are evidence of a diet change towards more grazing, but may also reflect increased nitrogen in soils following deglaciation and global temperature increases. Among the factors explaining the observed isotope variations were time (age of samples), longitude and elevation in European bison, and time, longitude and forest cover in aurochs. None of the analysed factors explained isotope variations in moose. Our results demonstrate the strong influence of natural (forest expansion) and anthropogenic (deforestation and human pressure) changes on the foraging ecology of large herbivores, with forests playing a major role as a refugial habitat since the Neolithic, particularly for European bison and aurochs. We propose that high flexibility in foraging strategy was the key for survival of large herbivores in the changing environmental conditions of the Holocene.