天山地区三种自由放牧家畜食性和营养生态位的显微组织分析

为研究三种自由放牧家畜的食性及营养生态位,采集新疆地区新疆牦牛、焉耆马和巴音布鲁克羊的粪样各100份,同时将研究区域采集的主要常见植物标本进行鉴别,通过粪便显微组织分析三种家畜的食物组成及比例,并计算生态位宽度及重叠度.巴音布鲁克羊采食6科11属11种植物,主要为禾本科（58.89％）、豆科（15.84％）和莎草科（12.46％）.新疆牦牛采食7科13属13种植物,主要为禾本科（53.47％）、莎草科（17.25％）和豆科（11.51％）.焉耆马采食6科10属10种植物,主要为禾本科（54.23％）、莎草科（19.37％）和豆科（11.74％）.在食物多样性及生态住宽度方面,新疆牦牛的香农-维纳多样性指数（Shannonwiener index）与食物生态位宽度指数最高,焉耆马最低,而皮洛均匀度指数（Pielou evenness index）三者较相似.三种家畜间食性的主要差别在于采食种类和数量,与生境及采食行为关系密切.新疆天山同域分布的3种家畜之间食物重叠度较高,对食物资源表现出明显的竞争.     

Dietary patterns of two herbivorous rodents: Otomys unisulcatus and Parotomys brantsii in the Karoo

Differences and overlap in the diets of two sympatric, herbivorous rodents Otomys unisulcatus and Parotomys brantsii were investigated. Frequency of occurrence of plant species in the diets were compared with availability of the plants in the rodents' habitats. Both rodents are generalist herbivores, eating plants species in proportion to the availability in their habitats. Dietary patterns, diversity of diet and degree of overlap between rodent's diets are a function of food availability in the different habitats. It is suggested that these rodents separate niches on a spatial rather than trophic basis. Differences in dietary patterns are therefore not critical for niche separation but are the result of habitat segregation.     

Temporal niche overlap among insectivorous small mammals

Being active in the same environment at different times exposes animals to the effects of very different environmental factors, both biotic and abiotic. In the present study, we used live traps equipped with timing devices to evaluate the potential role of biotic factors (competition and food abundance) on overall overlap in the temporal niche axis of 4 insectivorous small mammals in high‐elevation grassland fields (‘campos de altitude’) of southern Brazil. Based on resources availability (invertebrates), data on animal captures were pooled in 2 seasons: ‘scarcity’ (June 2001–September 2001) and ‘abundance’ (November 2001–May 2002) seasons. We tested for non‐random structure in temporal niche overlap among the species in each season. These species were the rodents Oxymycterus nasutus (Waterhouse, 1837), Deltamys sp., Akodon azarae (Fischer, 1829), and the marsupial Monodelphis brevicaudis Olfers, 1818. The studied community was mainly diurnal with crepuscular peaks. Simulations using the Pianka index of niche overlap indicated that the empirical assemblage‐wide overlap was not significantly different from randomly generated patterns in the abundance season but significantly greater than expected by chance alone in the scarcity season. All the species showed an increase in temporal niche breadth during the abundance season, which appears to be related to longer daylength and high nocturnal temperatures. Patterns on both temporal niche overlap and temporal niche breadth were the opposite to those that we were expecting in the case of diel activity patterns determined by competition for dietary resources. Therefore, we conclude that competition did not seem to be preponderant for determining patterns of temporal niche overlap by the studied community.     

Effects of Wildlife on Cattle Diets in Laikipia Rangeland,Kenya

The impacts of wild herbivores on cattle diet selection were investigated in an East African rangeland during August 2001 and February 2002. The study compared cattle diets in plots exclusively accessible to cattle (C) and those accessible to megaherbivores (elephants and giraffes), non-megaherbivore wild herbivores > 15 kg (zebras, hartebeests, Grant's gazelles, oryx, elands, and buffaloes) and cattle (MWC); or non-megaherbivore wild herbivores and cattle (WC). There were no treatment differences in selection of most grass species in either sampling period (P > 0.05). However, selection of forbs differed among treatments during February when conditions were relatively dry and percent of bites taken by cattle on this forage class increased (P < 0.005) from 1.8% ± 0.3 to 7.7% ± 1.6 (mean ± SE). During this period, cattle took a lower percent of bites on forbs in MWC (4.3% ± 1.7; P = 0.01) and WC (5.9% ± 2.2; P = 0.03) than in C (12.9% ± 0.9). These patterns were generally driven by Commelina spp., which comprised 65% ± 9.4 of total bites on forbs. Notably, these differences were associated with differences in cover of forbs, which was positively correlated with percent of bites on forbs (r² = 0.86, P < 0.01). Because forbs may be critical components of cattle diets in such rangelands during relatively dry periods, these dietary changes may indicate potential seasonal costs of wildlife to cattle production. Looking for ways to offset such costs may be worthwhile for livestock properties that accommodate wildlife.     

Diet Composition,Forage Selection,and Potential for Forage Competition Among Elk,Deer, and Livestock on Aspen–Sagebrush Summer Range

We evaluated elk (Cervus elaphus), mule deer (Odocoileus hemionus), cattle (Bos taurus), and domestic sheep (Ovis aries) diet composition, diet overlap, and forage selection on aspen (Populus tremuloides Michaux)–sagebrush (Artemisia spp. L.) summer range in northeastern Nevada to understand potential for forage competition to provide better information for managing these communities. Diets were determined through microhistological fecal analysis from 1998 to 2000, and forage selection was evaluated at feeding sites in aspen and sagebrush communities in 1999 and 2000. Elk spring diets were the most diverse in composition; summer elk diets were dominated by forbs (59%–78%); deer consumed mostly woody browse (64%–72%); and cattle and sheep ate mostly graminoids. Lupines (Lupinus spp. L.) constituted ≥ 11% of elk, deer, and sheep diets in summer. Spurred lupine (Lupinus caudatus Kellogg) was the lupine typically selected in feeding sites and greatest consumption occurred in summer when total alkaloid levels were lowest. Highest diet overlap was between cattle and sheep in 1999 (68%) and lowest between deer and cattle in 2000 (3%). Summer elk and deer diets overlapped moderately (45%–59%). Diets did not differ between elk in spring with sheep, elk in summer with deer and sheep, or cattle with sheep. Cattle foraged selectively on forbs in aspen communities (68%) and on graminoids in sagebrush communities (88%), reflecting relative forage availabilities. We detected no differences among elk, cattle, and sheep for forage selection in aspen communities. Electivity indices indicated elk preferred forbs in aspen and sagebrush communities; cattle preferred graminoids in sagebrush; and foraging sheep preferred forbs in aspen. Our results suggest potential for forage competition among ungulates on aspen–sagebrush summer range is highest for forbs in aspen communities. Monitoring productivity and use of key forage species, particularly forbs in aspen communities, should complement management objectives on shared aspen–sagebrush summer range.     

Differences in natural antibody titres comparing free-ranging guanacos (Lama guanicoe) and capybaras (Hydrochoerus hydrochaeris)

Natural antibodies are an important component of innate humoral immunity but have not been investigated to any great extent in wild mammals. In the current study, serum natural antibody titres were measured by hemagglutination assay for two South American herbivores, the guanaco (Lama guanicoe) and the capybara (Hydrochoerus hydrochaeris). Results indicated that capybaras had antibody titres on average more than four times higher than guanacos (median titres 1:256 and 1:4, respectively), suggesting differences in investment in constitutive humoral immunity between the two species.     

Differences in diet between two rodent species,Mastomys natalensis and Gerbilliscus vicinus,in fallow land habitats in central Tanzania

Differences in the ecological niche requirements among rodent species competing in the same habitat may result from differences in the use of one to three resources: space, time and food or some combination of these. Alternatively, differences in resource use utilization among animal species may simply reflect availability of food, and when food is limited, different animal species compete. In this study, the diet of two rodent pest species, Mastomys natalensis and Gerbilliscus vicinus, coexisting in fallow land in central Tanzania were studied to assess the degree of diet differentiation among them. Dietary niche breadth of G. vicinus was greater than that of M. natalensis in all stages of the maize cropping seasons. The rodent species studied overlapped considerably in the food items consumed ranging from niche overlap (O_jk) of 0.77–0.89. Grains/seeds featured high in the diet of M. natalensis while plant material occurrence was high in G. vicinus. These two food categories may have contributed to differences in diet partitioning, which may, in turn, facilitate their coexistence in fallow land.     

Discovery and molecular characterization of a group A rotavirus strain detected in an Argentinean vicuña (Vicugna vicugna)

The wild vicuña (Vicugna vicugna) is one of the four species of native South American camelids (SACs) in addition to the wild guanaco, and their domesticated counterparts, alpaca and llama, respectively. Serological data have indicated the presence of group A rotaviruses (RVA) specific antibodies in all 4 members of the SAC, and so far, RVA has been detected from alpacas, llamas and guanacos. A total of 59 fecal samples from healthy wild newborn and juvenile vicuñas, raised in captivity in Jujuy, Argentina were collected and analyzed by ELISA to detect RVA antigen. Two samples (3%) were found to contain G8 RVA strains and one strain (RVA/Vicuña-wt/ARG/C75/2010/G8P[14]) was selected for further genome analyses, revealing the G8-P[14]-I2-R2-C2-M2-Ax-N2-T6-E3-Hx genotype constellation. Unfortunately, no sequence data could be obtained for NSP1 and NSP5. Except for the E3 NSP4 genotype, this partial genotype constellation is reminiscent to bovine RVA strains and bovine-like RVA strains isolated from sheep, guanaco, antelope and humans. This relationship was confirmed phylogenetically, providing further evidence of the widespread presence of this genotype constellation in animals belonging to the artiodactyls. In particular, a close phylogenetic relationship was found between C75 and guanaco RVA strain RVA/Guanaco-wt/ARG/Chubut/1999/G8P[14] for at least 5 gene segments, suggesting a partial conservation of the genotype constellation of RVA strains infecting different species of SACs, even though nowadays their natural habitats are not overlapping. The further monitoring of the sanitary health of wild newborn and juvenile vicuñas is essential to improve the management practices applied in their sustainable exploitation.     

中新天津生态城夏季啮齿类的空间生态位

2008年夏季对中新天津生态城的啮齿动物进行调查,采用Shannon-Wiener生态位宽度指数和Pianka生态位重叠指数对啮齿动物空间生态位进行了研究。结果表明,在捕获的5种啮齿动物中,小家鼠和黑线姬鼠的空间生态位宽度指数最高,分别为0.97和0.78;褐家鼠(Bi=0.58)和黑线仓鼠(Bi=0.51)次之;大仓鼠(Bi=0.36)最低。除了黑线姬鼠与其他4种啮齿动物两两之间空间生态位重叠指数均较小(C_P<0.50)外,其他4种啮齿动物两两之间均较高(C_P>0.50)。黑线仓鼠与褐家鼠空间生态位几乎完全重叠(C_P=0.99),在10对啮齿动物中,共有7对之间的空间生态位重叠指数大于0.70。由此可见,生态城啮齿动物之间存在资源竞争,主要原因是生态城是典型的盐碱湿地,可利用资源不丰富,使得动物分布相对集中,增加种间竞争。     

藏中矿区植物种群生态位特征研究

本文采用样方法以藏中矿区的3种群落为研究对象,对样地的植物种群进行系统调查,并计算其主要植物的重要值、生态位宽度和生态位重叠值。结果表明,不同群落类型优势种非常明显,并且具有较高的生态位宽度和生态位重叠。高寒矿区各植物优势种群与其它种群之间竞争激烈,群落结构极不稳定,群落可能正处于正向演替和逆向演替的拐点。     

Spatiotemporal interactions between wild boar and cattle: implications for cross-species disease transmission

Controlling infectious diseases at the wildlife/livestock interface is often difficult because the ecological processes driving transmission between wildlife reservoirs and sympatric livestock populations are poorly understood. Thus, assessing how animals use their environment and how this affects interspecific interactions is an important factor in determining the local risk for disease transmission and maintenance. We used data from concurrently monitored GPS-collared domestic cattle and wild boar (Sus scrofa) to assess spatiotemporal interactions and associated implications for bovine tuberculosis (TB) transmission in a complex ecological and epidemiological system, Doñana National Park (DNP, South Spain). We found that fine-scale spatial overlap of cattle and wild boar was seasonally high in some habitats. In general, spatial interactions between the two species were highest in the marsh-shrub ecotone and at permanent water sources, whereas shrub-woodlands and seasonal grass-marshlands were areas with lower predicted relative interactions. Wild boar and cattle generally used different resources during winter and spring in DNP. Conversely, limited differences in resource selection during summer and autumn, when food and water availability were limiting, resulted in negligible spatial segregation and thus probably high encounter rates. The spatial gradient in potential overlap between the two species across DNP corresponded well with the spatial variation in the observed incidence of TB in cattle and prevalence of TB in wild boar. We suggest that the marsh-shrub ecotone and permanent water sources act as important points of TB transmission in our system, particularly during summer and autumn. Targeted management actions are suggested to reduce potential interactions between cattle and wild boar in order to prevent disease transmission and design effective control strategies.

Electronic supplementary material

The online version of this article (doi:10.1186/s13567-014-0122-7) contains supplementary material, which is available to authorized users.     

Decaying toxic wood as sodium supplement for herbivorous mammals in Gabon

African rainforest harbors herbivores at high density. However, because plants and soils typically lack in some essential minerals, rainforest is not always a suitable habitat for herbivores. How they fulfill the mineral requirements is therefore an important question to animal ecology and conservation. Although large marshes, called ‘bais’, are often mentioned as efficient mineral-resource, little information on other sodium resources has still been available. Our laboratory works and field surveys found that a peculiar item, decaying wood stumps of Anthostema aubryanum, played as a major sodium resource for herbivores in Moukalaba-Doudou National Park, Gabon. When A. aubryanum is alive, the sodium content of its bark is low and its latex is toxic. Sodium is accumulated in decaying stumps (mean=1,343 mg/kg dry matter). Eight herbivores visited stumps to ingest the dead wood. Fecal sample analysis revealed that western lowland gorillas, a species most-frequently using the stumps, consumed large amount of the dead wood as regular food. Our findings suggest that decaying A. aubryanum is critical sodium-resources and is a key species for herbivores in our study area. Importance of the A. aubryanum may be particularly large there, because it is a limited sodium-rich material that is available year round. Our study site is known as the site where the densities of several herbivores are among the highest at Central Africa. The relatively high herbivores density in our study site may partly depend on decaying A. aubryanum as sodium resources.     

Preliminary study on the feeding habits of roe deer (Capreolus capreolus) in the western Alps

Roe deer feeding habits were studied in the western Alps during the summer season using the faecal analysis method. The diet of cattle grazing in the same area was also investigated and the trophical niche overlap between the two species was determined. The roe deer diet was found very variable and mostly composed of dicotyledons, with Leguminosae and Cistaceae as prevalent species. Monocotyledons, mainly represented by Graminaceae, were consumed to a lesser extent. A significant preference was observed for Cistaceae and other dicotyledons whereas a significant refuse was observed for Graminaceae and Asteraceae. These data confirmed the roe deer's behaviour to select food with a better nutritive value. Despite the differences between the cattle and roe deer's diets, the trophical niche overlap was quite high. This can be explained by the homogeneity of the plants covering the whole area which probably limited food selection by the roe deer.     

Learning Through Foraging Consequences: A Mechanism of Feeding Niche Separation in Sympatric Ruminants

Explanations for why sympatric ruminant species select diets composed of different plant species or plant parts have been controversial. Our explanation is based on learning from foraging consequences, which includes the influences that morphology, physiology, and experience have on diet selection. We conducted a trial with cattle (Bos taurus), sheep (Ovis aries), and goats (Capra hircus) and leafy spurge (LS; Euphorbia esula L.) to explore the interface between the learning and morphophysiological foraging models with these sympatric ruminants. After a pretrial adjustment period, the control group for each species received, via stomach tube on days 1 and 2, ground grass after eating a novel food (NF; rolled corn), and the treatment group for each species received ground air-dried LS after eating the NF. NF intake on days 2 and 3 was expressed as a percent of NF intake on day 1, and it declined considerably for cattle and sheep dosed with LS but did not decline for goats receiving it (P = 0.001). LS elicited learned aversive feeding responses from cattle and sheep but not from goats. The results are consistent with field observations that goats graze LS more readily than sheep or cattle do. Learning from foraging consequences offers an explanation for the unique diets of sympatric ruminant species.     

Competitor densities,habitat, and weather: effects on interspecific interactions between wild deer species

There is a growing interest on the potential interplay between weather, habitat, and interspecific competition on population dynamics of wild herbivores. Favorable environmental conditions may buffer the negative effects of competition; conversely, competition may be expected to be stronger under harsh environmental conditions. We investigated relationships between competitor abundance, weather, and habitat cover on density and local distribution of a medium-sized herbivore, the roe deer Capreolus capreolus, as well as its spatial overlap with fallow deer Dama dama in a Mediterranean protected area. Over 11 years (2007–2017), roe deer density was not affected by spring–summer rainfall in the previous year and decreased with increasing density of fallow deer in the previous year. Hence, over the considered temporal scale, results supported a major role of competition over weather in influencing population trends of roe deer. At a finer spatial scale, roe deer occupancy was negatively affected by local abundance of fallow deer, especially in “poorer” habitats. We found a slight support for a positive effect of fallow deer density on interspecific spatial overlap. Moreover, fine-scale spatial overlap between deer species increased with decreasing rainfall in spring–summer. Fallow deer were introduced to our study area in historical times and their role as superior competitors over roe deer has been found also in other study areas. We suggest a potential role of harsh weather conditions during the growing season of vegetation (i.e. scarce rainfall) in triggering the potential for ecological overlap, emphasizing the negative effects of interspecific competition.     

The effects of prey depletion on dietary niches of sympatric apex predators in Southeast Asia

Resource depletion exerts opposing pressures on co-occurring consumers to expand diets while limiting overlap with competitors. Using foraging theory as a framework, we tested the effects of prey availability on diet specialization and overlap among competing Asian predators: dhole, leopard, and tiger. We used scat analysis from a prey-poor site, combined with a quantitative synthesis of 40 other diet studies, to determine biomass of different prey types consumed by each predator. We then assessed diet composition in relation to prey density, and compared diet breadth and overlap between prey-poor and prey-rich sites. In prey rich areas, all three predators specialized on energetically profitable medium and large ungulates (>30 kg), resulting in narrow, overlapping niches. Each predator shifted toward less profitable small-bodied prey (≤30 kg) as preferred ungulates declined, whereas consumption of preferred ungulates was unrelated to small prey abundance, as predicted by foraging theory. Diet breadths doubled under prey depletion (except leopard), but overlap declined as diets diverged via species-specific traits that facilitated capture of different types of alternative prey. Asia's apex predators adapt similarly to depletion of mutually preferred ungulates by switching to more numerous but less profitable small prey. Yet they can also partition a depleted prey base through intrinsic niche differences, thereby avoiding competitive exclusion. Our findings illuminate the stabilizing properties of adaptive foraging and niche differences in ecological communities, and provide insights into the behavior and resilience of Asia's endangered apex predators in response to prey depletion in the heavily poached forests of this region.     

Prevalence of Bovine viral diarrhoea virus (BVDV) antibodies among sheep and goats in India

The aim of this study was to determine the prevalence of pestivirus antibodies in sheep and goats in India. A total of 2803 serum samples collected between 2004 and 2008 from 1777 sheep in 92 flocks and 1026 goats in 63 flocks belonging to 13 states were tested by competition ELISA for detection of pestivirus antibodies. In sheep, the true prevalence rate was 23.4% (95% confidence interval: 22.9%–27.0%) and in goats it was 16.9% (95% CI: 16.4%–21.3%). The flock level seroprevalence was 66.3% for sheep and 54.0% for goats. Geographical variation in individual and flock prevalence was highly significant. A significant association (p?<?0.05) was found between sheep and goat flocks having cattle contact and the flock level seroprevalence. The seroprevalence was lower in 6 months–1 year age group compared to the 1–2 year and >2 year age groups in both sheep and goats. Cross neutralization studies on 61 seropositive sheep and 34 seropositive goat samples representing all positive flocks, exhibited > four fold higher titre to bovine viral diarrhoea virus type 1 (BVDV-1) in 41 sheep and 23 goat samples and to BVDV-2 in one sheep and goat each. This study for the first time showed serological evidence of wide spread BVDV infections in Indian sheep and goats, with BVDV-1 predominating and BVDV-2 occasionally besides highlighting the potential risk of infection to other species, which needs to be considered whenever BVD control measures are initiated.     

Efficacy of the amino-acetonitrile derivative,monepantel, against experimental and natural adult stage gastro-intestinal nematode infections in sheep

Multiple drug resistance by nematodes, against anthelmintics has become an important economic problem in sheep farming worldwide. Here we describe the efficacy of monepantel, a developmental molecule from the recently discovered anthelmintic class, the amino-acetonitrile derivatives (AADs). Efficacy was tested against adult stage gastro-intestinal nematodes (GINs) in experimentally and naturally infected sheep at a dose of 2.5 mg/kg body weight when administered as an oral solution. Some of the isolates used in experimental infection studies were known to be resistant to the benzimidazoles or levamisole anthelmintics; strains resistant to the macrocyclic lactones were not available for these tests. Worm count-based efficacies of >98% were determined in these studies. As an exception, Oesophagostomum venulosum was only reduced by 88% in one study, albeit with a low worm burden in the untreated controls (geometric mean 15.4 worms). Similar efficacies for monepantel were also confirmed in naturally infected sheep. While the efficacy against most species was >99%, the least susceptible species was identified as Nematodirus spathiger, and although efficacy was 92.4% in one study it was generally >99%. Several animals were infected with Trichuris ovis, which was not eliminated after the treatment. Monepantel demonstrated high activity against a broad range of the important GINs of sheep, which makes this molecule an interesting candidate for use in this species, particularly in regions with problems of anthelmintic resistance. Monepantel was well tolerated by the treated sheep, with no treatment related adverse events documented.     

甘肃亚高山云杉人工林下植物种群生态位特征

根据野外110个样方的调查数据,应用Levins、Shannon-Wiener生态位宽度指数和Levins生态位重叠指数对甘肃亚高山云杉(Picea asperata)人工林下30个种(包括15种灌木和15种草本植物)的生态位特征进行定量分析。结果表明,灌木针刺悬钩子(Rubus pungens)、箭竹(Sinarundinaria nitida)、秀丽莓(Rubus amabilis)、草本东方草莓(Fragaria orientalis)、鸭茅(Dactylis glomerata)和紫花碎米荠(Cardamine tangutorum)的生态位宽度较大,表明这些物种适应能力强,分布范围广,倾向于泛化种。生态位宽的种群可能产生较小的生态位重叠,生态位较窄的种群间也会产生较大的生态位重叠,生态位宽度与生态位重叠程度无相关性。总体上看,亚高山云杉人工林下物种间生态位重叠程度均较小,种间竞争并不激烈。从生态响应来看,灌木层的红桦(Betula albo-sinensis)幼苗和草本层的老鹳草(Geranium wilfordii)发展性最强,今后可能会发展为云杉人工林下的优势种群。     

玛多县大型野生食草动物种群数量对草畜平衡的影响研究

以黄河源区玛多县为研究区域,利用无人机遥感技术调查了县域内藏野驴、藏原羚、岩羊等大型野生食草动物和家畜的种群数量,利用降尺度算法生成了2016年玛多县30 m空间分辨率的产草量数据,在此基础上估算了包括野生动物和家畜在内的草畜平衡状况,分析了大型野生食草动物对玛多县草畜平衡的影响。结果表明:1)通过飞行样带内种群密度,推算了玛多县内大型食草动物种群数量,分别与统计数据、暖季调查结果对比验证,估算出2017年冷季藏野驴、藏原羚和岩羊分别为1.71、1.60和0.93万匹(只),家牦牛、藏羊和马分别为7.08、10.22、0.12万头(匹、只),大型野生食草动物和家畜总计47.5万羊单位,大型野生食草动物羊单位数量与家畜羊单位数量之比为1∶4.5;2)仅考虑饲养家畜,载畜压力指数为1.13,表明草地略微超载;在综合考虑饲养家畜和野生动物的情况下,载畜压力指数为1.38,表明草地中度超载;3)若没有将大型野生食草动物纳入草畜平衡核算体系内,载畜压力将被低估22%。超载过牧是造成玛多县草地退化一个主要驱动因素,需人工补饲7.90万t干草或减畜30%才能维持草畜平衡。