Seasonal resource use and niche breadth in an assemblage of coexisting grazers in a fenced Park

Many small Parks inKenyaare being fenced to control human-wildlife conflict. Some of these Parks have a diversity of large herbivores which might increase in density in the wake of fencing and subsequent compression of their home ranges due to closure of their migratory routes. It is important to understand the consequences of such an increase on the structuring of insularised herbivore assemblages in such Parks. We studied seasonal resource segregation and niche breadth variation as mechanisms of coexistence in a high density grazer assemblage inLakeNakuruNational Parkwhich is small and completely fenced. Diet composition and habitat use were considered as variables of resource use. We predicted that overlap in resource use and niche breadth would be the smallest among grazers with similar body weights in the dry season which is the most resource limiting for grazers in East Africa. Our results were contrary to the predictions because of lack of seasonal differentiation in the overlap of diet composition and habitat use, and in niche breadth. Overlaps in resource use were consistently high during both the wet and dry seasons, and niche breadth contraction during the dry season was not possible probably because of lack of species-specific niches during the dry season. Our results suggest that there might be competitive interactions in this grazer assemblage which is an important parameter to consider in the management of the Park.

A systematic scheme for monitoring waterbird populations at Shengjin Lake,China:methodology and preliminary results

Changes in the areas and quality of wetland habitat makes it imperative to monitor trends in the number of wintering waterbirds and their distribution in the Yangtze River floodplain, the most important waterbird region in eastern China, so that effective science-based action can be taken to ensure the survival and future recovery of the waterbirds of the region. However, obtaining accurate data on the number of waterbirds and distribution, which can be confidently compared across years and sites, is complicated by a number of factors which can affect count quality. It is essential to employ a survey methodology which maximizes count accuracy and precision and minimizes the bias inherent in counting waterbirds;failure to achieve these goals will lead to incorrect results and analytical problems. Recently we developed a systematic waterbird survey methodology which was tested, with promising results, in the winters of 2008/2009 and 2009/2010 at Shengjin Lake, an important wetland in the Yangtze River floodplain. The methodology involves dividing the lake into discrete survey areas, each containing a number of subareas, with clear boundaries, which were surveyed separately. Data, which included information on counts, distributions, the environment and disturbance, were collected in a standardized manner to maximize precision and minimize bias. We use the results from the surveys of the first two winters to provide examples of how the data can be employed to provide detailed information on the number of waterbirds, their distributions and habitat usage. Finally, we discuss the importance of wider application of the methodology throughout the Yangtze River floodplain to underpin a much needed floodplain-wide waterbird monitoring program.

Effect of methamidophos on soil fungi community in microcosms by plate count,DGGE and clone library analysis

Methamidophos was widely used a pesticide in northern China. The potential influences of methamidophos on soil fungal community in black soil were assessed by plate count, 28S rDNA-PCR-DGGE, and clone library analysis. Three methamidophos levels （50, 150, and 250 mg/kg） were tested in soil microcosms. Results from plate count during a 60-d microcosm experiment showed that high concentrations of methamidophos （250 mg/kg） could significantly stimulate fungal populations. DGGE （denaturing gradient gel electrophoresis） fingerprinting patterns showed a significant difference between the responses of culturable and total fungi communities under the stress of methamidophos. Shannon diversity indices calculated from DGGE profiles indicated that culturable fungi in all microcosms with methamidophos treatment increased after 1 week of incubation. However, the diversity indices of total fungi decreased in the first week, as compared to the stimulation of culturable fungi. At the 8th week, however, all the microcosms treated by methamidophos were similar to the control microcosms in community structure as suggested by the Shannon diversity indices for both culturable and total fungi. In contrast, after 1 week the fungal structure of culturable and unculturable both were disturbed to different extent under the stresses of methamidophos by clustering analysis. Clone sequencing analysis indicated the stimulation of pathogenic and unculturable fungal populations by methamidophos treatment, suggetsing potential risks of plant disease outbreak.

Impact of acetochlor on ammonia-oxidizing bacteria in microcosm soils

Acetochlor is an increasingly used herbicide on corn in North China. Currently, the effect of acetochlor on soil ammonia-oxidizing bacteria (AOB) communities is not well documented. Here, we studied the diversity and community composition of AOB in soil amended with three concentrations of acetochlor (50, 150, 250 mg/kg) and the control (0 mg acetochlor/kg soil) in a microcosm experiment by PCR-DGGE (polymerase chain reaction-denaturing gradient gel electrophoresis) and the phylogenetic analysis of excised ...

印度Ladakh地区斑头雁的数量、种群结构和栖息地利用(英文)

于 1998、 2 0 0 0和 2 0 0 2年在印度的Ladakh地区进行了野外考察以研究斑头雁的繁殖行为和种群大小。Ladakh地区的斑头雁集小群在淡水湖泊中的小岛上进行繁殖 ,不在树上和悬崖上繁殖。 5月份开始产卵。群内孵化的同步性较低。盐水湖岸上没有观察到进行繁殖或带有幼雏的斑头雁。作者所调查的Ladakh地区有 35 0 - 10 0 0只斑头雁 ,该物种的数量满足了Ramsar公约的有关规定 。

Wintering Swan Geese maximize energy intake through substrate foraging depth when feeding on buried Vallisneria natans tubers

Background: Foraging theory predicts that animals select patches that offer the highest net rate of energy gain. Hence, prey distribution patterns and spatiotemporal heterogeneity play important roles in determining animal feeding patch selection. For waterfowl foraging on buried aquatic plant tubers, the distribution and biomass of these plant organs vary with depth in the substrate. Since excavation costs also increase with depth, the energy intake of the animals foraging on these plants is highly sediment depth dependent. Methods: Here, using observations of Swan Geese (Anser cygnoides) foraging on Vallisneria natans tubers, we test our hypothesis that geese feeding on tubers buried at intermediate sediment depth maximize their daily energy intake because of the interaction between tuber size and abundance with depth. To do this, we measured the distribution patterns of buried Vallisneria tubers under both undisturbed conditions and post-exploitation by geese (i.e. giving-up conditions). We investigated the relationship between tuber size and burial depth, and total tuber biomass within each sediment layer in undisturbed and exploited plots. Finally, we compared modelled Swan Goose daily energy intake feeding on Vallisneria tubers buried at different sediment layers (1–10, 11–20 and 21–30 cm below the surface). Results: Dry weight of Vallisneria tubers linearly increased with burial depth, while average total dry weight density of tubers showed a unimodal relationship, peaking at intermediate levels. Not surprisingly, Swan Geese foraged most intensively on tubers buried at intermediate sediment depths, where they maximize their daily energy intake. Our results support our hypothesis that Swan Geese feeding on tubers at intermediate depths maximize their daily energy intake. Conclusions: Our study is the first to quantify foraging strategies of Swan Geese during the wintering period, emphasizing the importance of plant traits on foraging selection of belowground foragers.

Disturbance increases high tide travel distance of a roosting shorebird but only marginally affects daily energy expenditure

Background:Anthropogenic disturbance can negatively affect an animal's energy budget by evoking movement responses.Existing research focuses mainly on immediate displacement as a disturbance effect,since this can be easily observed in the field. However, effects on movement over longer timescales are poorly examined and it is largely unknown if and to what extent they reflect immediate responses.Longer-term responses could for example be larger than immediate responses if birds, after disturbance, return to the original location and thereby travel twice the immediate disturbed distance. Methods:We combined GPS tracking data with observational data to quantify the effects of anthropogenic (air force and walkers) and non-anthropogenic disturbances on distances travelled by roosting Eurasian Oystercatchers (Haematopus ostralegus) during the non-breeding season. We compared immediate displacement after a disturbance with distance travelled during the entire high tide period (longer-term response), while accounting for environmental factors.Additionally,we calculated energy expenditure due to disturbance based on observed disturbance frequencies.Results:Disturbance resulted in an immediate displacement response of ~200 m (median).Air force disturbances tended to yield larger immediate responses than walker and,especially,than non-anthropogenic disturbances.Longer-term responses and immediate responses were approximately similar,suggesting that,over longer timescales,spatial disturbance effects in the study area remain confined to immediate effects.However,disturbances were infrequent (0.17 disturbances per bird per hour) and most disturbances were of natural origin (62%).Consequently, anthropogenic disturbance of roosting oystercatchers in the study area on average costs 0.08% of the daily energy expenditure. Conclusions:Our results suggest that immediate spatial responses to disturbance can be a useful proxy for spatial responses over longer timescales.Over the non-exhaustive range of conditions investigated,energetic consequences of spatial disturbance responses for an oystercatcher in the study area are marginal due to low disturbance levels.

Multispecies hybridization in birds

Hybridization is not always limited to two species;often multiple species are interbreeding. In birds, there are numerous examples of species that hybridize with multiple other species. The advent of genomic data provides the oppotunity to investigate the ecological and evolutionary consequences of multispecies hybridization. The interactions between several hybridizing species can be depicted as a network in which the interacting species are connected by edges. Such hybrid networks can be used to identify ‘hub-species’ that interbreed with multiple other species. Avian examples of such ‘hub-species’ are Common Pheasant (Phasianus colchicus), Mallard (Anas platyrhynchos) and European Herring Gull (Larus argentatus). These networks might lead to the formulation of hypotheses, such as which connections are most likely conducive to interspecific gene flow (i.e. introgression). Hybridization does not necessarily result in introgression. Numerous statistical tests are available to infer interspecific gene flow from genetic data and the majority of these tests can be applied in a multispecies setting. Specifically, model-based approaches and phylogenetic networks are promising in the detection and characterization of multispecies introgression. It remains to be determined how common multispecies introgression in birds is and how often this process fuels adaptive changes. Moreover, the impact of multispecies hybridization on the build-up of reproductive isolation and the architecture of genomic landscapes remains elusive. For example, introgression between certain species might contribute to increased divergence and reproductive isolation between those species and other related species. In the end, a multispecies perspective on hybridization in combination with network approaches will lead to important insights into the history of life on this planet.

Population Dynamics of Large Herbivores and the Framing of Wildlife Conservation in Zimbabwe

This article reviews: 1) The role of natural and human-induced controls in influencing large herbivore populations;2) how human controls (i.e., policy instruments, incentives and provisions) influence human activities and wildlife conservation;and 3) media framing of wildlife conservation using Zimbabwe as a case study, in particular Gonarezhou National Park and adjacent areas. The review shows that droughts are important in influencing large herbivore populations in semi-arid ecosystems;political instability and economic collapse does not necessarily lead to increased illegal hunting in situations where policy instruments, such as laws, are enforced. A higher perceived effectiveness of Communal Areas Management Programme for Indigenous Resources was partly associated with a decline in human-wildlife conflicts and there was a spill-over effect of frames from the political domain into wildlife conservation following Zimbabwe’s land reforms in 2000. It is concluded that natural bottom-up processes (e.g., droughts) influence large herbivore population dynamics whereas policy instruments, incentives, provisions and societal frames mainly have a top-down effect on wild large herbivore populations in savanna ecosystems.

Avian introgression in the genomic era

Introgression,the incorporation of genetic material from one(sub)species into the gene pool of another by means of hybridization and backcrossing,is a common phenomenon in birds and can provide important insights into the speciation process.In the last decade,the toolkit for studying introgression has expanded together with the development of molecular markers.In this review,we explore how genomic data,the most recent step in this methodological progress,impacts different aspects in the study of avian introgression.First,the detection of hybrids and backcrosses has improved dramatically.The most widely used software package is STRUCTURE.Phylogenetic discordance(i.e.different loci resulting in discordant gene trees) is another means for the detection of introgression,although it should be regarded as a starting point for further analyses,not as a definitive proof of introgression.Specifically,disentangling introgression from other biological processes,such as incomplete lineage sorting,remains a challenging endeavour,although new techniques,such as the D-statistic,are being developed.In addition,phylogenetics might require a shift from trees to networks.Second,the study of hybrid zones by means of geographical or genomic cline analysis has led to important insights into the complex interplay between hybridization and speciation.However,because each hybrid zone study is just a single snapshot of a complex and continuously changing interaction,hybrid zones should be studied across different temporal and/or spatial scales.A third powerful tool is the genome scan.The debate on which evolutionary processes underlie the genomic landscape is still ongoing,as is the question whether loci involved in reproductive isolation cluster together in ‘islands of speciation' or whether they are scattered throughout the genome.Exploring genomic landscapes across the avian tree of life will be an exciting field for further research.Finally,the findings from these different methods should be incorporated into specific speciation scenarios,which can consequently be tested using a modelling approach.All in all,this genomic perspective on avian hybridization and speciation will further our understanding in evolution in general.

Improving the quantification of waterfowl migration with remote sensing and bird tracking

Accurately quantifying waterfowl migration patterns is pertinent to monitor ecosystem health and control bird-borne infectious diseases. In this review, we summarize the current understanding of the environmental mechanisms that drive waterfowl migration and then investigate the effect of intra- and inter-annual change in food supply and temperature(e.g., climate change) on their migration patterns. Recent advances in remote sensing and animal tracking techniques make it possible to monitor these environmental factors over a wide range of scales and record bird movements in detail. The synergy of these techniques will facilitate substantial progress in our understanding of the environmental drivers of bird migration. We identify prospects for future studies to test existing hypotheses and develop models integrating up-todate knowledge, high-resolution remote sensing data and high-accuracy bird tracking data. This will allow us to predict when waterfowl will be where, in response to shortand long-term global environmental change.

Effects of plant-soil feedback on tree seedling growth under arid conditions

Plants are able to influence their growing environment by changing biotic and abiotic soil conditions.These soil conditions in turn can influence plant growth conditions,which is called plant–soil feedback.Plant–soil feedback is known to be operative in a wide variety of ecosystems ranging from temperate grasslands to tropical rain forests.However,little is known about how it operates in arid environments.We examined the role of plant–soil feedbacks on tree seedling growth in relation to water availability as occurring in arid ecosystems along the west coast of South America.Methods In a two-phased greenhouse experiment,we compared plant–soil feedback effects under three water levels(no water,10%gravimetric moisture and 15%gravimetric moisture).We used sterilized soil inoculated with soil collected from northwest Peru(Prosopis pallida forests)and from two sites in north-central Chile(Prosopis chilensis forest and scrublands without P.chilensis).Important Findings Plant–soil feedbacks differed between plant species and soil origins,but water availability did not influence the feedback effects.Plant–soil feedbacks differed in direction and strength in the three soil origins studied.Plant–soil feedbacks of plants grown in Peruvian forest soil were negative for leaf biomass and positive for root length.In contrast,feedbacks were neutral for plants growing in Chilean scrubland soil and positive for leaf biomass for those growing in Chilean forest soil.Our results show that under arid conditions,effects of plant–soil feedback depend upon context.Moreover,the results suggest that plant–soil feedback can influence trade-offs between root growth and leaf biomass investment and as such that feedback interactions between plants and soil biota can make plants either more tolerant or vulnerable to droughts.Based on dissecting plant–soil feedbacks into aboveground and belowground tissue responses,we conclude that plant–soil feedback can enhance plant colonization in some arid ecosystems by promoting root growth.

Distributional congruence of mammalian herbivores in the Trans-Himalayan Mountains

Large-scale distribution and diversity patterns of mammalian herbivores, especially less charismatic species in alpine environments remain little understood. We studied distributional congruence of mammalian herbivores in the Trans-Himalayan region of Ladakh to see if the distributions of less prominent and smaller herbivores can be determined from those of larger and more prominent herbivores like ungulates. Using a similarity index, we assessed shared distributions of species in 20x20 km2 grid-cells in an area of about 80,000 km2. We used the Unweighted Pair-Group Method with Arithmetic Average （UPGMA） to classify mammalian herbivores into groups with similar distributions. We then used the G-test of independence to look for statistical significance of the groups obtained. We identified six groups of mammalian herbivores with distributions more similar than ex- pected at random. The largest group was composed of nine species whereas the other large group comprised six species. Canonical Correspondence Analysis （CCA）, used to relate the groups with environmental features, showed that the largest group occurred in higher and flatter areas, while the other large group occurred in lower and steeper areas. Large herbivores like ungulates can be used as surrogate for less prominent small herbivores while identifying areas for latter＇s protection in the inaccessible mountainous re- gions of the Trans-Himalaya [Current Zoology 59 （1）： 116-124, 2013].

Local temperature and El Niño Southern Oscillation influence migration phenology of East Asian migratory waterbirds wintering in Poyang,China

Temperature is a critical factor influencing avian phenology,due to its direct impact on food and water availability.Most previous studies have focused on the timing of spring migration and the arrival of birds at breeding grounds along the European and American flyways;little is known about migration ecology at the wintering sites along the Asian flyways.Using linear regression models,this study investigates how local temperature variation and EI Niño Southern Oscillation(ENSO)influences the arrival and departure timing of 9 waterbird species breeding in Mongolia or Siberia and overwintering in Poyang,China from 2002 to 2013.Birds mainly arrive at Poyang in October and depart for their breeding sites in March.Out of the 9 species,6 show a strong negative relationship between departure time and overwintering temperature in Poyang.Departure dates also show a negative association with overwintering ENSO and March ENSO for two species.Both local and large-scale climate indices show no influence on the arrival timing of waterbirds.We suggest that birds react to the annual variation of overwintering temperature:an earlier departure of waterbirds is facilitated by a warmer overwintering period and vice versa.The long-term accumulated temperature effect is more pronounced than ENSO and the short-term local temperature effect.Our findings could help quantify the potential impact of global warming on waterbirds.

Existing theories do not explain sex ratio variation at birth in monomorphic roe deer (Capreolus capreolus)

The phenomenon of skewed sex ratios at birth has been reported in many ungulate species.So far,no consistent trend has emerged for roe deer(Capreolus capreolus),because male-biased,female-biased and equal sex ratios at birth have all been found.Nevertheless,both the Trivers–Willard hypothesis and the theory of local resource competition have gained support.Despite the great number of studies carried out regarding the ecology of roe deer,too many aspects remain unclear,and contradictory results have been produced with respect to several crucial elements.Without further research,the discussion on which theory applies will therefore remain inconclusive.We put forward the argument that eventually the theories of Trivers–Willard and local resource competition can be considered as being not essentially different.After all,both theories explain the observed skewed sex ratios as being due to the effect of the progeny s sex on the mother s body condition and hence her reproductive success in subsequent years.Furthermore,neither theory is likely to prove to be suitable for roe deer,as several assumptions are unlikely to be met.In roe deer,skewed ratios probably only have a temporal character.As a matter of fact,several observations of skewed sex ratios in birds and mammals did not withstand the accumulation of further data,as sex ratios that were initially believed to be biased turned out to be equal in the long term.This is likely to be the case in roe deer as well.We hypothesize that roe deer,as r-strategists,will produce as many offspring as possible,regardless of sex.