Linking plant composition and arthropod abundance to establish little bustard breeding requirements in pastureland dominated landscapes

Most research on steppe bird habitat selection has been focused on the effects of management regimes or vegetation structure. However, much less is known on how plant composition is related with steppe bird occurrence. We investigated microhabitat of little bustard territorial males and females during the nesting and chick-rearing season in areas with dominance of pastureland focusing on plant composition. We searched for relationships between preferred vegetation and arthropod abundance in order to identify the contribution of different vegetation typologies in providing essential trophic resources for the species. Surveys of little bustards were made using car and foot transects. Plant composition was obtained within a 50 × 50 cm square at four sampling replicates and arthropod availability was sampled using a sweep net. Statistical procedures were conducted in three steps: (1) analysis of variance was used to identify at univariate level the plant composition and arthropod variables that were significantly related with both male and female occurrence sites; (2) principal components analysis was performed using the variables with significant results at univariate level; (3) model averaging on generalized linear and mixed models was applied to evaluate the selection probability of each principal component. The species occurs in sites with high floristic richness and high abundance of Fabaceae species, although plant composition differs from male to female sites. These variables were found to be crucial to provide higher abundances of arthropods, notably of Acrididea, Formicidae and some groups of Coleoptera which are decisive for the selection of displaying or female breeding sites

The importance of grazing regime in the provision of breeding habitat for grassland birds: The case of the endangered little bustard (Tetrax tetrax)

In Mediterranean dry grasslands, grazing by domestic animals is an important agricultural activity on dry grasslands. Several bird species occur in these grazed habitats and are now experiencing a near continuous decline. We investigated the impact of livestock grazing on the threatened little bustard (Tetrax tetrax L.). The study was conducted at the NATURA 2000 Site/Important Bird Area of Cabrela, Portugal. Our main goals were to investigate responses of little bustard territorial males and breeding females to different livestock management practices, namely pasture types, stocking rates and sward structure. Bird distribution was surveyed using car and foot surveys. Data on grazing was supplied by land managers every 10 days from February to June through field interviews. Generalised additive models and model averaging were used to compute predictive models. Results indicate that higher probabilities of occurrence were found in long-term pastures and under light-moderate grazing conditions (stocking rates around 0.4 LU/ha). Conversely, lower probabilities of occurrence were found in ungrazed or heavy grazed fields. Males occurred mostly in large fields, but this variable seemed to be less important for females. On the other hand, green plant cover and the vegetation height were good predictors for the occurrence of females but not for males. Females used mostly pastures with vegetation height around 20–25 cm. Our results suggest that grazing management plans that aim to conserve little bustard populations should consider (1) the maintenance of the larger long-term pastures and (2) the use of light-moderate stocking rates (0.2–0.6 LU/ha)

Structured Linearization of Discrete Mechanical Systems for Analysis and Optimal Control

Variational integrators are well-suited for simulation of mechanical systems because they preserve mechanical quantities about a system such as momentum, or its change if external forcing is involved, and holonomic constraints. While they are not energy-preserving they do exhibit long-time stable energy behavior. However, variational integrators often simulate mechanical system dynamics by solving an implicit difference equation at each time step, one that is moreover expressed purely in terms of configurations at different time steps. This paper formulates the first- and second-order linearizations of a variational integrator in a manner that is amenable to control analysis and synthesis, creating a bridge between existing analysis and optimal control tools for discrete dynamic systems and variational integrators for mechanical systems in generalized coordinates with forcing and holonomic constraints. The forced pendulum is used to illustrate the technique. A second example solves the discrete LQR problem to find a locally stabilizing controller for a 40 DOF system with 6 constraints.Comment: 13 page

Priorizando la investigación para la conservación de las aves esteparias: Una prospección bibliográfica

With the aim to identify priorities in conservation-oriented research, this paper reviews the level of scientific attention given to steppe birds in Spain during the last 50 years. We surveyed scientific literature using Thomson Reuters Web of Science and the journal Ardeola, using the English names of 28 species of steppe birds and the word "Spain" as search terms. Every species was assigned a Scientific Attention Index (SAI), based on the number of articles published on each of them. In addition, a vulnerability measure (Vulnerability Score; VS) was calculated for each species on the basis of the trend estimate provided by the Sacre or Noctua monitoring programmes, or according to expert criteria. The sample gathered (432 articles) was a significant and thus representative proportion of WOS and Ardeola contents on the species considered. The most studied species was the red-legged partridge Alectoris rufa, with 83 papers (20.15%); while the least studied was the short-eared owl Asio flammeus (1 paper; 0.24%). The most studied knowledge area was Habitat Selection (92 papers; 22.17%), while the least was Niche/Climate, with nine papers (2.17%). Preferred habitat (grass steppe, shrub steppe or mixed) was not a significant factor in the level of scientific attention given to the different species. However, large-sized species (non-Passerines) were significantly more studied than small-sized ones (Passerines), indicating a research bias for the former group. Finally, no significant relationship was found between SAI and VS, which suggests that research effort has been allocated irrespective of the species' conservation status. These results highlight the scarce scientific attention given to most steppe birds in Spain in spite of their overall high vulnerability, and for most of the knowledge areas considered. On the other hand, they also show the high relative importance of research carried out in Spain, in both the Mediterranean and world contexts. This work underscores the need to focus scientific effort on certain species, especially those that currently show more regressive trends or higher levels of vulnerability, and in most areas of knowledgeThis work was carried out with the only support of the REMEDINAL 3 project of the Comunidad de Madri

Nest site habitat selection and nesting performance of the Great Bustard Otis tarda in southern Portugal: implications for conservation

We present results on breeding parameters, nesting performance and nest habitat selection of the globally threatened Great Bustard Otis tarda, gathered during a 3-year study in Castro Verde (southern Portugal). A total of 107 nests were located. The estimated average onset of laying was 22 April (SD 5 12 days, n 5 8). The incubation period ranged from 25 March to 15 June. Nearly 95% of females incubated between 1 April and 31 May. Mean clutch size was 2.12 (SD 5 0.69, n 5 86), showing no significant inter-annual differences. There was no significant relationship between clutch size and average nest finding date, although, on average, nests were found later each year. Hatching occurred between 21 April and 26 June. The estimated proportion of eggs hatched per nest (hatching percentage) was 87.5% in 2002 (n 5 8), 64.0% in 2003 (n 5 33) and 75.8% in 2004 (n 5 33). Overall nesting success for the three years was 71% (n 5 107). The main causes of nesting failure were agricultural activities, mainly ploughing and harvesting, followed by corvid predation. Nests were spatially aggregated up to 800–1,500 m. At larger scales, the spatial distribution of nests can be considered random or uniform. Females showed a clear preference for nesting in cereal fields, followed by young fallows, old fallows, ploughed fields and then other habitats, although the intensity of selection of particular habitats varied between years. Nests were associated with both cereals and fallows, thus aggregating where those habitat types occurred within the study area. These results provide the first complete description of the nesting process in a Great Bustard population, as well as important cues to the assessment of conservation measures implemented in Castro Verde, an area holding around 80% of the Portuguese population of this species (application of EU agri-environmental schemes, power line signalling, water-point provision in dry years)info:eu-repo/semantics/publishedVersio

Between and within-year effects of haying on grassland bird

In recent years, haying has extended to Iberian Mediterranean dry grasslands potentially threatening grassland birds. We evaluate the between and within-year effects of haying on grassland birds in Alentejo region, Portugal. Our main goals were: (1) to investigate variations on bird abundance and species richness in the fields hayed, with respect to past haying events occurred in a field and its surroundings and (2) to investigate the shifts in bird abundance, species richness and spatial dynamics resulting from haying a field and its surrounding area in a given year. We conducted grassland bird censuses during the breeding season through point counts from 2012 to 2015. The relationship between bird abundance/richness and past haying events was investigated using Generalized Linear Models whereas within-year effects of haying were analysed using Generalized Additive Models. Bird abundance in a field was positively related with the surface hayed in the vicinity of that field in the previous year. However, contrasting yearly effects were found for non passerines. Also, some species prefer fields with less haying events or surface hayed, whereas others occur mostly in fields frequently managed for haying. Haying a field leads, in the short term, to its abandonment by birds, and thus to a decrease in bird abundance and, for some species, to spatial concentration in surrounding fields offering suitable habitat. We conclude that within-year effects of haying have higher impact on grassland birds than between-year effects. Maintaining haying at low levels by rotating haying yearly through the different fields in each farm and using partial haying may be an adequate way to ensure an effective management of grassland bird populations.Fundação para a Ciência e Tecnologi

The adequacy of alfalfa crops as an agri-environmental scheme: A review of agronomic benefits and effects on biodiversitye

The agriculture intensification required to provide enough food commodities for humans has negative impacts on the environment. To reduce these drawbacks Agri-Environmental Schemes (AES) have been implemented in Europe since the last decade of the twentieth century. One of the measures included in these schemes was the introduction of alfalfas in crop rotation systems. In order to evaluate their suitability as an AES, we synthesize knowledge on the agronomical benefits of alfalfa cultivations, as well as on the relationships of alfalfa crops with biodiversity at three taxonomic levels: vascular plants, arthropods, and vertebrates. Based on the articles reviewed, alfalfas can help restoring native grassland communities due to the nutrient enrichment they provide. Moreover, this legume crop usually ensures food resources not only for invertebrates, but also for vertebrates. Alfalfas tend to harbour a stable arthropod community that benefits surrounding crops by improving ecological processes (pollination, pest predation) and reducing the need to use agrochemicals. At the same time, arthropod abundance attracts vertebrates, especially birds, which supports the role of alfalfa as a conservation tool to favour endangered farmland birds. Additionally, alfalfa crops may function as a reservoir habitat for voles, which are a preferred food resource for farmland-foraging raptors, many of them endangered. On the other hand, birds nesting in alfalfa crops may suffer higher nest destruction rates due to frequent cuts, and voles using alfalfa crops may also create agricultural damage in surrounding crops in certain cases. The review also highlights that negative ecological relationships of alfalfa crops with biodiversity can be minimized, and positive effects may also be maximized under the appropriate management of this crop. Examples of such management actions include cut delays or higher cuts to avoid nest destruction, the use of grazing cattle to reduce the impacts of rodent pests, reduced frequency of cutting or maintaining unharvested strips in the field to maximize positive effects on predatory arthropods and vole availability to raptors. We conclude that alfalfa crops can be considered globally beneficial for farmland biodiversity and a useful management tool for conservation in agricultural landscapes, for example as an AES, but that management should be adapted to particular taxonomical or functional groupsThis paper contributes to project S2018/EMT-4338 REMEDINAL TECM from Comunidad de Madrid and Chair UAM-CTFC-TotalEnergies Steppe-Forwar

Reducing Power Losses in Smart Grids with Cooperative Game Theory

In a theoretical framework of game theory, one can distinguish between the noncooperative and the cooperative game theory. While the theory of noncooperative games is about modeling competitive behavior, cooperative game theory is dedicated to the study of cooperation among a number of players. The cooperative game theory includes mostly two branches: the Nash negotiation and the coalitional game theory. In this chapter, we restrict our attention to the latter. In recent years, the concept of efficient management of electric power has become more complex as a result of the high integration of distributed energy resources in the scenarios to be considered, mainly distributed generation, energy storage distributed, and demand management. This situation has been accentuated with the appearance of new consumption elements, such as electric vehicles, which could cause a high impact on distribution gridworks if they are not managed properly. This chapter presents an innovative approach toward an efficient energy model through the application of the theory of cooperative games with transferable utility in which the management, capacity, and control of distributed energy resources are integrated to provide optimal energy solutions that allow achieving significant savings in associated costs. This chapter presents a general description of the potential of the application of the theory to address Smart Grid, providing a systematic treatment