Explore the vast range of titles available.

Increasing populations of large herbivores have caused environmental damage around the world, and it is necessary to improve population management strategies. Culling is a traditional management method. Antlerless deer proportions, consisting of adult female deer and fawn in Cervidae in wildlife statistics, are directly related to population increases; thus, the culling-based removal of individuals from habitats and the removal of these antlerless individuals by game hunting and nuisance control might be effective approaches for reducing population sizes. We evaluated the effectiveness of antlerless culling on 17-year density trends in the sika deer (Cervus nippon) population across an area of 1175 km2 in Fukuoka Prefecture (Japan). In 11 out of 47 grids (area measuring 5 by 5 km), the densities of sika deer tended to decline; meanwhile, in the remaining 36 grids, the densities increased. These density trends were explained by changes in the proportion of antlerless culling, as the densities declined with increasing proportions of antlerless deer. The results affirm the theory that antlerless culling is effective in population management; it is posited that antlerless-biased culling could be a crucial measure in managing overabundant populations of herbivores, contributing to more effective conservation of forest environments.

Large mammalian herbivores (LMH) are known to suppress populations of small mammals in African savanna ecosystems; whether this suppression is driven by depletion of nutrients and food resources, or of cover, is poorly understood. Cattle management creates scattered, persistent, nutrient‐enriched areas (glades). Similarly, prescribed fire may enhance forage nutrition of burned patches. Both enriched microhabitats attract wild and domestic LMH and are fertilized by their wastes, but removal of vegetative cover by LMH or fire may negate the benefits of enhanced nutrition to risk‐averse small‐mammal species or individuals. We used replicated LMH exclusion experiments on red sandy loam and black‐cotton clay soils, and a multi‐scale burn experiment on black cotton to examine abundance, diversity, and biomass of small mammals across sites varying in vegetation cover and enrichment. Small‐mammal species composition varied dramatically among habitats. Species diversity and density on red sands were roughly double that of black cotton soils. Small‐mammal densities and diversity were dramatically greater inside LMH exclosures; maximal densities occurred inside fenced, nutrient‐rich, tall‐grass glades. Small‐mammal density was similar between black‐cotton burn sites and unburned matrix habitat but was significantly greater on unburned than burned patches within the burn sites. Burned patches contained less grassy cover up to 50 months post‐burn, although vegetation differences diminished following significant rains. Mice captured on burned patches traveled farther but were not heavier than mice captured on unburned patches. Small mammals were nearly 20‐fold more abundant on totally fenced glades than matrix habitat on both soils and ninefold more abundant on fenced bushland (non‐glades) on red sands. Unfenced glades supported intermediate densities in black cotton but lower densities in red sands because of close cropping by LMH. Total small‐mammal biomass tended to be greater on red sands (though mean body mass was greater on black cotton for two common species), within exclosures, and on glades. Both the grass rat and pouched mouse reached maximal densities within glade LMH exclosures on both soils. This and the positive association of small‐mammal densities with grass height and dead‐stem density suggest loss of cover is a primary driver of large‐herbivore suppression of certain savanna small mammals.

Wild large herbivores are declining worldwide. Despite extensive use of exclosure experiments to investigate herbivore impacts, there is little consensus on the effects of wild large herbivores on ecosystem function. Of the ecosystem functions likely impacted, we reviewed the five most‐studied in exclosure experiments: ecosystem resilience/resistance to disturbance, nutrient cycling, carbon cycling, plant regeneration, and primary productivity. Experimental data on large wild herbivores' effects on ecosystem functions were predominately derived from temperate grasslands (50% grasslands, 75% temperate zones). Additionally, data were from experiments that may not be of adequate size (median size 400 m2 despite excluding all experiments below 25 m2) or duration (median duration 6 years) to capture ecosystem‐scale responses to these low‐density and wide‐ranging taxa. Wild herbivore removal frequently impacted ecosystem functions; for example, net carbon uptake increased by three times in some instances. However, the magnitude and direction of effects, even within a single function, were highly variable. A focus on carbon cycling highlighted challenges in interpreting effects on a single function. While the effect of large herbivore exclusion on carbon cycling was slightly positive when its components (e.g. pools vs. fluxes of carbon) were aggregated, effects on individual components were variable and sometimes opposed. Given modern declines in large wild herbivores, it is critical to understand their effects on ecosystem function. However, this synthesis highlights strong variability in direction, magnitude, and modifiers of these effects. Some variation is likely due to disparity in what components are used to describe a given function. For example, for the carbon cycle we identified eight distinctly meaningful components, which are not easily combined yet are potentially misrepresentative of the larger cycle when considered alone. However, much of the observed difference in responses likely reflects real ecological variability across complex systems. To move towards a general predictive framework we must identify where variation in effect is due to methodological differences and where due to ecosystem context. Two critical steps forward are (a) additional quantitative synthetic analyses of large herbivores' effects on individual functions, and (b) improved, increased systematic exclosure research focusing on effects of large herbivores' exclusion on functions. A free Plain Language Summary can be found within the Supporting Information of this article. A free Plain Language Summary can be found within the Supporting Information of this article.

The green wave hypothesis (GWH) states that migrating animals should track or ‘surf’ high-quality forage at the leading edge of spring green-up. To index such high-quality forage, recent work proposed the instantaneous rate of green-up (IRG), i.e. rate of change in the normalized difference vegetation index over time. Despite this important advancement, no study has tested the assumption that herbivores select habitat patches at peak IRG. We evaluated this assumption using step selection functions parametrized with movement data during the green-up period from two populations each of bighorn sheep, mule deer, elk, moose and bison, totalling 463 individuals monitored 1–3 years from 2004 to 2014. Accounting for variables that typically influence habitat selection for each species, we found seven of 10 populations selected patches exhibiting high IRG—supporting the GWH. Nonetheless, large herbivores selected for the leading edge, trailing edge and crest of the IRG wave, indicating that other mechanisms (e.g. ruminant physiology) or measurement error inherent with satellite data affect selection for IRG. Our evaluation indicates that IRG is a useful tool for linking herbivore movement with plant phenology, paving the way for significant advancements in understanding how animals track resource quality that varies both spatially and temporally.

1. Globally, large carnivores are declining due to direct persecution, habitat loss, and prey depletion. The effects of prey depletion could be amplified by changes in the composition of the herbivore (prey) community that provoke changes in carnivore diets, but this possibility has received little attention. 2. We tested for changes over the past half-century in prey selection by the large carnivore guild in Zambia's Kafue National Park (KNP). 3. Across 52 predator-prey dyads, 71% of the observed changes showed that large prey have become less important and small prey have become more important. Consequently, dietary niche breadth has decreased for KNP carnivores and niche overlap has increased. 4. We tested whether changes in the importance of prey species are related to their current abundance and uniformly found that prey that have increased in importance are now relatively common, while those that have decreased in importance are now relatively rare. We identify four potential effects of these changes for conservation (through intraguild competition, group size, the energetics of hunting, and vulnerability to snaring) that warrant investigation. 5. Synthesis and applications. Patterns of prey selection by the large carnivores in Kafue National Park (KNP) have changed appreciably over the past half-century. Decreased predation on large prey, which are now relatively rare, has caused niche compression and increased overlap in carnivore diets. Predation by all KNP large carnivores now concentrates on four small prey species that remain relatively abundant (impala, puku, lechwe, and warthog). Methods to detect such changes in interactions between species are well-established, but are rarely applied to large carnivore-ungulate systems. To guide conservation of ecosystem function, monitoring programmes should consider whether prey depletion alters the patterns of predation or competition within the predator guild because these interactions strongly affect the distribution and abundance of both predators and prey. If the patterns seen in KNP are general, then where carnivores are limited by prey depletion, conservation efforts will be most effective if they focus on mitigating the loss of large prey. In KNP, targeted efforts to protect prey larger than 200 kg, particularly buffalo, should be a priority.

1. Because many large mammal species have wide geographical ranges, spatially distant populations may be confronted with different sets of environmental conditions. Investigating how home range (HR) size varies across environmental gradients should yield a better understanding of the factors affecting large mammal ecology. 2. We evaluated how HR size of a large herbivore, the roe deer (Capreolus capreolus), varies in relation to seasonality, latitude (climate), weather, plant productivity and landscape features across its geographical range in Western Europe. As roe deer are income breeders, expected to adjust HR size continuously to temporal variation in food resources and energetic requirements, our baseline prediction was for HR size to decrease with proxies of resource availability. 3. We used GPS locations of roe deer collected from seven study sites (EURODEER collaborative project) to estimate fixed-kernel HR size at weekly and monthly temporal scales. We performed an unusually comprehensive analysis of variation in HR size among and within populations over time across the geographical range of a single species using generalized additive mixed models and linear mixed models, respectively. 4. Among populations, HR size decreased with increasing values for proxies of forage abundance, but increased with increases in seasonality, stochastic variation of temperature, latitude and snow cover. Within populations, roe deer HR size varied over time in relation to seasonality and proxies of forage abundance in a consistent way across the seven populations. Thus, our findings were broadly consistent across the distributional range of this species, demonstrating a strong and ubiquitous link between the amplitude and timing of environmental seasonality and HR size at the continental scale. 5. Overall, the variability in average HR size of roe deer across Europe reflects the interaction among local weather, climate and seasonality, providing valuable insight into the limiting factors affecting this large herbivore under contrasting conditions. The complexity of the relationships suggests that predicting ranging behaviour of large herbivores in relation to current and future climate change will require detailed knowledge not only about predicted increases in temperature, but also how this interacts with factors such as day length and climate predictability.

Rangeland ecosystems worldwide are characterized by a high degree of uncertainty in precipitation, both within and across years. Such uncertainty creates challenges for livestock managers seeking to match herbivore numbers with forage availability to prevent vegetation degradation and optimize livestock production. Here, we assess variation in annual large herbivore production (LHP, kg/ha) across multiple herbivore densities over a 78-yr period (1940–2018) in a semiarid rangeland ecosystem (shortgrass steppe of eastern Colorado, USA) that has experienced several phase changes in global-level sea surface temperature (SST) anomalies, as measured by the Pacific Decadal Oscillation (PDO) and the El Ni~no–Southern Oscillation (ENSO). We examined the influence of prevailing PDO phase, magnitude of late winter (February–April) ENSO, prior growing-season precipitation (prior April to prior September) and precipitation during the six months (prior October to current April) preceding the growing season on LHP. All of these are known prior to the start of the growing season in the shortgrass steppe and could potentially be used by livestock managers to adjust herbivore densities. Annual LHP was greater during warm PDO irrespective of herbivore density, while variance in LHP increased by 69% (moderate density) and 91% (high density) under coldphase compared to warm-phase PDO. No differences in LHP attributed to PDO phase were observed with low herbivore density. ENSO effects on LHP, specifically La Ni~na, were more pronounced during cold-phase PDO years. High herbivore density increased LHP at a greater rate than at moderate and low densities with increasing fall and winter precipitation. Differential gain, a weighted measure of LHP under higher relative to lower herbivore densities, was sensitive to prevailing PDO phase, ENSO magnitude, and precipitation amounts from the prior growing season and current fall–winter season. Temporal hierarchical approaches using PDO, ENSO, and local-scale precipitation can enhance decision-making for flexible herbivore densities. Herbivore densities could be increased above recommended levels with lowered risk of negative returns for managers during warm-phase PDO to result in greater LHP and less variability. Conversely, during cold-phase PDO, managers should be cognizant of the additional influences of ENSO and prior fall–winter precipitation, which can help predict when to reduce herbivore densities and minimize risk of forage shortages.

The spatial heterogeneity of limiting soil resources is an essential factor determining ecosystem processes and function. It has been reported that large herbivores can strongly impact the variation and spatial distribution pattern of soil nitrogen (N). However, it remains unclear how large herbivores affect soil spatial heterogeneity and whether this influence is dependent on plant community diversity. Here we examined effects of different herbivore assemblages [no grazing; cattle grazing (CG); sheep grazing (SG); and mixed grazing (MG) of cattle and sheep] on soil N spatial heterogeneity in grasslands with high and low pre‐grazing plant diversity in an eastern Eurasian steppe. We found that herbivore grazing generated and maintained spatial patterns of soil nutrients, depending on herbivore assemblage and the level of pre‐grazing plant diversity. CG increased the spatial heterogeneity of soil available N in Leymus chinensis‐dominated steppe meadows, which were independent of pre‐grazing plant diversity. However, the effects of SG and MG strongly depended on grassland plant diversity, with an increased spatial heterogeneity of soil available N in the high‐diversity grassland, but not in the low‐diversity grassland. Synthesis and applications. We concluded that in a L. chinensis‐dominated eastern Eurasian steppe, cattle ranching could be considered as an optimal grazing management protocol to improve soil spatial heterogeneity because cattle grazing (CG) consistently increased soil spatial heterogeneity in the context of both low and high plant diversity. Nevertheless, soil spatial heterogeneity could be improved by any herbivore grazing regime [CG and/or sheep grazing (SG)] when high plant diversity is maintained. These findings highlight the importance of conserving plant diversity to maintain grassland structure and ecosystem function. In grassland systems with high plant diversity, herbivore grazing and plant diversity would jointly improve soil spatial heterogeneity, thus feeding back to maintain higher plant diversity. Therefore, high plant diversity could generate a positive feedback loop of herbivore–plant–soil interactions in grazed grassland systems. Our findings indicate the importance of herbivore assemblages in maintaining spatial heterogeneity in low‐ and high‐diversity grassland systems.

Culling large herbivores can reduce browsing damage. Our objective was to verify the effect of culling by considering spatial changes in browsing damage to test the hypothesis that the benefits of spatially biased culling extend to the spatial scale of culling. Culling sika deer (Cervus nippon) in Kumamoto Prefecture, Japan, increased from 2009–2017, but browsing damage remained stable across the prefecture; regional damage trends differed among grid meshes (i.e., 5 km × 5 km). Meshes with browsing damage reduction received higher culling pressure and a decline in the deer population. Browsing damage reduction from culling was not uniform across regions and was biased by spatial bias in culling. This study highlights the importance of spatial scale in large herbivore management and evaluation of its effect.

Various authors have suggested that extinctions and extirpations of large mammalian herbivores during the last ca. 50,000 years have altered ecological processes. Yet, the degree to which herbivore extinctions have influenced ecosystems has been difficult to assess because past changes in herbivore impact are difficult to measure directly. Here, we indirectly estimated changes in (theorised) herbivore impact by comparing the functional composition of current large (≥ 10 kg) mammalian herbivore assemblages to those of a no‐extinction scenario. As an assemblage's functional composition determines how it interacts with its environment, changes in functional compositions should correspond to changes in ecological impacts. We quantified functional composition using the body mass, diet and life habit of all wild herbivorous mammal species (n = 502) present during the last 130,000 years. Next, we assessed whether these changes in functional composition were large enough that the resulting assemblages could be considered functionally novel. Finally, we assessed where novel herbivore assemblages would most likely lead to changes in biome state. We found that 47% of assemblages are functionally novel, indicating fundamental changes in herbivore impacts occurred across much of the planet. On 20% of land, functionally novel herbivore assemblages have arisen in areas where alternative biome states are possible depending on the disturbance regime. Thus, in many regions, the late‐Quaternary extinctions and extirpations altered herbivore assemblages so profoundly that there were likely major consequences for ecosystem functioning. We find that 47% of assemblages are functionally novel, indicating that fundamental changes in herbivore impacts have occurred across the world. On 20% of land, functionally novel herbivore assemblages arose in areas where alternative biome states are possible depending on the disturbance regime. Thus, in many regions, the late‐Quaternary extinctions and extirpations altered herbivore assemblages so profoundly that there were likely major consequences for ecosystem functioning.