Suchergebnisse

Interspecific competition is a dominant force in animal communities that induces niche shifts in ecological and evolutionary time. If competition occurs, niche expansion can be expected when the competitor disappears because resources previously inaccessible due to competitive constraints can then be exploited (i.e., ecological release). Here, we aimed to determine the potential effects of interspecific competition between the little bustard (Tetrax tetrax ) and the great bustard (Otis tarda ) using a multidimensional niche approach with habitat distribution data. We explored whether the degree of niche overlap between the species was a density‐dependent function of interspecific competition. We then looked for evidences of ecological release by comparing measures of niche breadth and position of the little bustard between allopatric and sympatric situations. Furthermore, we evaluated whether niche shifts could depend not only on the presence of great bustard but also on the density of little and great bustards. The habitat niches of these bustard species partially overlapped when co‐occurring, but we found no relationship between degree of overlap and great bustard density. In the presence of the competitor, little bustard's niche was displaced toward increased use of the species' primary habitat. Little bustard's niche breadth decreased proportionally with great bustard density in sympatric sites, in consistence with theory. Overall, our results suggest that density‐dependent variation in little bustard's niche is the outcome of interspecific competition with the great bustard. The use of computational tools like kernel density estimators to obtain multidimensional niches should bring novel insights on how species' ecological niches behave under the effects of interspecific competition in ecological communities. ; Belianes and Bellmunt fieldwork was financed by REGSEGA (Regs Sistema Segarra‐Garrigues), Departament de Medi Ambient i Habitatge (Generalitat de Catalunya). Funding was also provided by the Spanish Ministry of Science (CGL2009‐13029/BOS); the REMEDINAL2 and REMEDINAL3 networks of the CAM (S‐2009/AMB/1783 and S2013/MAE‐2719). R.T. was supported by a PhD grant from the Spanish Minister of Education (FPU grant no. AP2009‐0762) and a postdoctoral fellowship funded by REMEDINAL3 (S2013/MAE‐2719). FC was supported by the Andalucía Talent Hub Program launched by the Andalusian Knowledge Agency, cofounded by the European Union's Seventh Framework Program, Marie Skłodowska‐Curie actions (COFUND–Grant Agreement n° 291780) and the Ministry of Economy, Innovation, Science and Employment of the Junta de Andalucía.

Interspecific competition is a dominant force in animal communities that induces niche shifts in ecological and evolutionary time. If competition occurs, niche expansion can be expected when the competitor disappears because resources previously inaccessible due to competitive constraints can then be exploited (i.e., ecological release). Here, we aimed to determine the potential effects of interspecific competition between the little bustard (Tetrax tetrax) and the great bustard (Otis tarda) using a multidimensional niche approach with habitat distribution data. We explored whether the degree of niche overlap between the species was a density-dependent function of interspecific competition. We then looked for evidences of ecological release by comparing measures of niche breadth and position of the little bustard between allopatric and sympatric situations. Furthermore, we evaluated whether niche shifts could depend not only on the presence of great bustard but also on the density of little and great bustards. The habitat niches of these bustard species partially overlapped when co-occurring, but we found no relationship between degree of overlap and great bustard density. In the presence of the competitor, little bustard's niche was displaced toward increased use of the species' primary habitat. Little bustard's niche breadth decreased proportionally with great bustard density in sympatric sites, in consistence with theory. Overall, our results suggest that density-dependent variation in little bustard's niche is the outcome of interspecific competition with the great bustard. The use of computational tools like kernel density estimators to obtain multidimensional niches should bring novel insights on how species' ecological niches behave under the effects of interspecific competition in ecological communities. ; Seventh Framework Programme, Grant/Award Number: 291780; Ministerio de Ciencia e Innovación, Grant/Award Number: CGL2009-13029/BOS; Ministerio de Educación, Cultura y Deporte, Grant/Award Number: AP2009-0762; REGSEGA; Departament de Medi Ambient i Habitatge; REMEDINAL2, Grant/Award Number: S-2009/AMB/1783; REMEDINAL3, Grant/Award Number: S2013/MAE-2719; Andalusian Knowledge Agency; European Union's Seventh Framework Program Marie Skłodowska-Curie actions (COFUND–Grant Agreement n° 291780); Ministry of Economy, Innovation, Science and Employment of the Junta de Andalucía. ; Peer Reviewed

Background: Steppe-birds face drastic population declines throughout Europe. The Dupont's lark Chersophilus duponti is an endangered steppe-bird species whose European distribution is restricted to Spain. This scarce passerine bird could be considered an 'umbrella species', since its population trends may reveal the conservation status of shrub-steppes. However, trends for the Spanish, and thus European, population of Dupont's lark are unknown. In this work, we evaluated Dupont's lark population trends in Europe employing the most recent and largest compiled database to date (92 populations over 12 years). In addition, we assessed the species threat category according to current applicable criteria (approved in March 2017) in the Spanish catalogue of threatened species (SCTS), which have never been applied to the Dupont's lark nor to any other Spanish species. Finally, we compared the resulting threat categories with the current conservation status at European, national and regional levels. Methods: We fitted switching linear trend models (software TRIM—Trends and Indices for Monitoring data) to evaluate population trends at national and regional scale (i.e. per Autonomous Community) during the period 2004–2015. In addition, the average finite annual rate of change (λ¯) obtained from the TRIM analysis was employed to estimate the percentage of population size change in a 10-year period. A threat category was assigned following A1 and A2 criteria applicable in the SCTS. Results: Trends showed an overall 3.9% annual decline rate for the Spanish population (moderate decline, following TRIM). Regional analyses showed high inter-regional variability. We forecasted a 32.8% average decline over the next 10 years. According to these results, the species should be listed as 'Vulnerable' at a national scale (SCTS). At the regional level, the conservation status of the species is of particular concern in Andalusia and Castile-Leon, where the species qualifies for listing as 'Endangered'. Discussion: Our results highlight the concerning conservation status of the European Dupont's lark population, undergoing a 3.9% annual decline rate. Under this scenario, the implementation of a wide-ranging conservation plan is urgently needed and is vital to ensuring the conservation of this steppe-bird species. The role of administrations in matters of nature protection and the cataloguing of endangered species is crucial to reverse declining population trends of this and other endangered taxa. ; This work was supported by the Education, Youth and Sport Bureau (Madrid Regional Government) and the European Social Fund for the Youth Employment Initiative (reference number PEJ15/AMB/AI-0059). This research is a contribution to the Excellence Network Remedinal 3CM (S2013/MAE2719), supported by Madrid Regional Government; the project 'Scientific basis for the National Conservation for Dupont's Lark in Spain', funded by the Biodiversity Foundation of the Ministry of Agriculture and Fisheries, Food and Environment; the Life Ricotí project (LIFE15-NAT-ES-000802), supported by the European Commission; and the BBVA-Ricotí project, funded by the BBVA Foundation.

Background: Steppe-birds face drastic population declines throughout Europe. The Dupont's lark Chersophilus duponti is an endangered steppe-bird species whose European distribution is restricted to Spain. This scarce passerine bird could be considered an 'umbrella species', since its population trends may reveal the conservation status of shrub-steppes. However, trends for the Spanish, and thus European, population of Dupont's lark are unknown. In this work, we evaluated Dupont's lark population trends in Europe employing the most recent and largest compiled database to date (92 populations over 12 years). In addition, we assessed the species threat category according to current applicable criteria (approved in March 2017) in the Spanish catalogue of threatened species (SCTS), which have never been applied to the Dupont's lark nor to any other Spanish species. Finally, we compared the resulting threat categories with the current conservation status at European, national and regional levels. Methods: We fitted switching linear trend models (software TRIM—Trends and Indices for Monitoring data) to evaluate population trends at national and regional scale (i.e. per Autonomous Community) during the period 2004–2015. In addition, the average finite annual rate of change (λ) obtained from the TRIM analysis was employed to estimate the percentage of population size change in a 10-year period. A threat category was assigned following A1 and A2 criteria applicable in the SCTS. Results: Trends showed an overall 3.9% annual decline rate for the Spanish population (moderate decline, following TRIM). Regional analyses showed high inter-regional variability. We forecasted a 32.8% average decline over the next 10 years. According to these results, the species should be listed as 'Vulnerable' at a national scale (SCTS). At the regional level, the conservation status of the species is of particular concern in Andalusia and Castile-Leon, where the species qualifies for listing as 'Endangered'. Discussion: Our results highlight the concerning conservation status of the European Dupont's lark population, undergoing a 3.9% annual decline rate. Under this scenario, the implementation of a wide-ranging conservation plan is urgently needed and is vital to ensuring the conservation of this steppe-bird species. The role of administrations in matters of nature protection and the cataloguing of endangered species is crucial to reverse declining population trends of this and other endangered taxa ; This work was supported by the Education, Youth and Sport Bureau (Madrid Regional Government) and the European Social Fund for the Youth Employment Initiative (reference number PEJ15/AMB/AI-0059). This research is a contribution to the Excellence Network Remedinal 3CM (S2013/MAE2719), supported by Madrid Regional Government; the project 'Scientific basis for the National Conservation for Dupont's Lark in Spain', funded by the Biodiversity Foundation of the Ministry of Agriculture and Fisheries, Food and Environment; the Life Ricotí project (LIFE15-NAT-ES-000802), supported by the European Commission; and the BBVA-Ricotí project, funded by the BBVA Foundation.

Edge effect is a strong driver of change in fragmented landscapes. In the last few decades, agricultural land-use intensity at field scale has increased and, consequently, the edges between crops and natural vegetation matrix have sharpened. Interspersed crops produce now negative effects not only by direct habitat destruction, but also by inputs of agrochemicals that may spread their effects on the surroundings. These processes are taking place worryingly in steppe habitats in Iberian Peninsula where the high diversity of bird communities and other taxa they hold is at risk. The aims of this study were to evaluate the edge effect of crops on i) the microhabitat quality of a natural landscape matrix and ii) the space use of a threatened habitat-specialist steppe bird, the Dupont's lark (Chersophilus duponti). We carried out microhabitat sampling and bird surveys within and around crops interspersed in a typical Iberian shrub-steppe matrix during spring and autumn 2016 and spring 2017. Microhabitat quality was measured by sampling vegetation structure and arthropod biomass (as proxy of food availability) within and at increasing distances (1, 10 and 50 m) to seven crops. The intensity of space use by the Dupont's lark was estimated applying a Kernel density function on the spatial point pattern of the males' territories. Vegetation structure variables were summarized by Principal Components Analysis. Linear Mixed Models and model averaging were used to test for effects of distance to crop on microhabitat quality and space use by the Dupont's lark. Distance to crop significantly affected microhabitat quality. A patchy structure of herbaceous and shrub was found outside crops in all sampling dates, with more shrub cover and less herbaceous cover as the distance to crops increased. Biomass of hypogeous arthropods significantly decreased when the distance to crops was lower than 50 m. The intensity of space use by Dupont's lark varied according to the sampling date, being higher in spring, and as the distance to crops and the biomass of hypogeous arthropods increased. Negative effects of crops on the space use of this bird species might be shaped both by the effect of the crop itself and by its edge effect on hypogeous arthropods. Our results point to an edge effect of crops of 10–50 m on natural vegetation structure, arthropod availability and use of space by the Dupont`s lark, which suggests that the effective area of optimal habitat available for true steppe species could be overestimated ; This study was supported by the Education, Youth and Sport Bureau (Madrid Regional Government, Spain) and the European Social Fund for the Youth Employment Initiative (Spain) [PEJ15/AMB/AI-0059], the European Commission (Spain) [Life-Ricotí project LIFE15-NAT-ES-000802] and the BBVA Foundation (Spain) [BBVA-Dron Ricotí project 026107]. This is a contribution to the Excellence Network Remedinal 3CM (Spain) (S2013/MAE2719), supported by Comunidad de Madrid

Steppe ecosystems worldwide are affected by agricultural development and generally unprotected. Spanish shrub-steppes contain endangered avifauna, and this paper analyses their state of habitat conservation, the changes that have occurred in the last decade, primary productivity and its relationship with land exploitation and the richness of threatened birds, and avifauna responses to habitat loss. Fifty steppe remnants distributed throughout Spain and inhabited by Dupont's lark Chersophilus duponti, an endangered passerine representative of shrub steppe-like habitat, were studied. The study fragments were generally affected by agriculture exploitation, and steppe cover had significantly decreased in several isolated patches during the period 1991-1999. Steppe habitat recovered slightly in areas with low plant productivity indices, and decreased in extent in the most productive areas, in line with EU (European Union) agricultural policy recommendations to abandon marginal land of low productivity. The low overall primary productivity of Iberian steppes opened the way to industrial activities (mining, waste collection and wind-farming), which in the study areas occurred more frequently in steppe than in other habitat types that are more attractive to the public (woodland) or more productive (farmland). The emerging wind industry little affected the study plots, but the presence of anemometers suggests that the impact is likely to increase in the near future, especially in the largest steppelands. Dupont's lark was sensitive to the fragmentation of its habitat; crowding occurred in isolated and small fragments, possibly as a consequence of habitat constraints and species dispersal dynamics. Fragments inhabited by Dupont's lark also hosted other steppe birds with a high conservation value; the community of endangered birds, mostly adapted to arid conditions, was richest in the less productive sites. Only four shrub-steppe fragments are given some kind of protection throughout Spain, testifying to the limited public awareness about the value of this habitat. Urgent action is required to restore this habitat through abandonment of less productive farmland, and to create a network of protected and connected steppelands, in order to assure the long-term viability of steppe specialists and the preservation of a habitat that is unique in Western Europe. This should be coupled to an effort to increase social consciousness of the ecological value of steppes and arid landscapes in general. © 2006 Foundation for Environmental Conservation. ; Peer Reviewed

Context
The negative effects of agricultural intensification and policies, use of pesticides, fertilisers and mechanised harvesting on several populations of pseudo-steppe birds have increasingly required more detailed and effective habitat suitability models. Distribution models of farmland species are prone to incur recordings of false absence data. Ecological Niche Factor Analysis (ENFA) allows identification of environmental predictors of species distribution by using presence data only.

Aims
We quantified the diurnal habitat preferences and niche width of one steppe species, the stone curlew (Burhinus oedicnemus), with unfavourable conservations status in a Mediterranean area and reclassified a map with respect to habitat suitability classes according to the resulting distribution model.

Methods
Ecological Niche Factor Analysis was used with GIS cartography customised with habitat and anthropogenic variables recorded during field surveys carried out in four study plots (~500 ha) and at different spatial scales.

Key results
The stone curlew selected areas with low vegetation cover, such as fields following artichoke harvesting and tillage, close to rural buildings and unpaved roads. In contrast, the stone curlew avoided areas with high vegetation cover and areas highly disturbed by human-induced fires. The occurrence of natural vegetation was neither preferred nor avoided. The most robust model was based on a large-scale analysis (200 m from the bird location points), according to which the optimal area for stone curlew distribution during its breeding season was restricted to 1% of the entire study area.

Conclusions
Two uncorrelated factors, 'marginality' and 'tolerance', described the stone curlew's niche in the area. The first index indicated selection for habitats that were marginal with respect to those available in the area, whereas the second indicated a species with a medium–wide environmental niche. In particular, the stone curlew occupied a much more restricted niche (low tolerance) in relation to individual variables. The use of customised databases at a large scale of analysis was found to more effectively reveal ecological requirements of this marginal and specialised species.

Implications
Our results allowed us to indicate practical land management actions for the stone curlew, such as prevention of human-induced fires and increase of pastoral activities. Our results indicated a potentially positive role of little-disturbed service roads along rural buildings in stone curlew distribution, which warrants further research. In addition, studies are needed to verify the presence of an ecological trap in artichoke fields, their preferred habitat. As we showed for the stone curlew, niche analyses conducted at a large scale using customised databases could greatly improve habitat suitability models of farmland species.

Introduction. The popularity of images of birds of prey in Scythian art makes us pay more attention to the place of birds of prey in the life of the Scythian world. Birds of prey were actively used in the hunting practice, and hunting with hunting birds was an elite form of hunting common in open spaces.

Materials. The first information about nurseries of hunting birds belongs to ancient China of the 7th century BC. Images of hunting birds appear on Hittite basreliefs of the 13th century BC. They are also known in the Assyria of the time of Sargon II.

Analysis. The active participation of the Scythians in political events in the Middle East allows us to assume that the Scythians are familiar with this method of hunting. In Scythian culture, there are a series of images of attacking birds, which should be seen as naturalistic sketches.

Results. The abundance of bone remains of hunting birds in the cultural layers of Scythian settlements and the presence of a burial of a man with a Falcon in the materials of the Elizavetovskoe hillfort directly indicates the use of hunting birds in the South Easten European continent steppe as early as the 4th century BC.

Knowledge of feeding ecology of declining species, such as farmland birds, is essential to address their conservation requirements, especially when their habitats are suffering important reductions of trophic resources. In this study, we apply a metabarcoding approach to describe the diet composition of six of the most significant farmland birds inhabiting European cereal pseudo-steppes: little bustard, great bustard, pin-tailed sandgrouse, black-bellied sandgrouse, red-legged partridge, and common quail. We further studied seasonal diet variations (autumn to spring) in all species but the common quail, whose diet was studied during spring and summer. We show that study species´ diets mostly consisted of plants, although in the case of little bustard and great bustard arthropods are also highly relevant. Among arthropods, we found high proportions of thrips, arachnids, and springtails, which were previously unreported in their diet, and some taxa that could be used as antiparasitic food. Moreover, we report that little bustard's diet is the least rich of that of all studied species, and that diet of all these species is less diverse in winter than in autumn and spring. Diet composition of these declining species supports the importance of natural and semi-natural vegetation and landscape mosaics that can provide a wide variety of arthropods, plants, and seeds all year-round. ; This paper contributes to the REGRESSEDS project (CGL2016-75278-R funded by MINECO, Spain). This study is also a contribution to project Sistemática, Biogeografía, Ecología del comportamiento y Evolución (IT1163-19) funded by Basque Country Government. Additional funds for this study were provided by the projects 201630E096 funded by CSIC (recipient BA) and AGROPERDIZ (SBPLY/17/180501/ 000245) funded by the "Junta de Comunidades de Castilla-La Mancha" and "Fondo Europeo de Desarrollo Regional" (recipient FM & BA). Xabier Cabodevilla was supported by a Ph.D. grant, financed by the Basque Country Government (grant no. PRE_2018_2_0273). ; Peer reviewed

This study was funded by project POCI-01-0145-FEDER-016664 (PTDC/AAG-REC/5007/2014), supported by Norte Portugal Regional Operational Programme (NORTE 2020), under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (ERDF). The study was also sponsored by the Portuguese Foundation for Science and Technology (FCT) through projects PTDC/ AGR-AAM/102300/2008 (FCOMP-01-0124-FEDER-008701) and PTDC/BIA-BIC/2203/2012 (FCOMP-01-0124-FEDER-028289), under FEDER funds through the Operational Programme for Competitiveness Factors – COMPETE and by National Funds through FCT – Foundation for Science and Technology, and grants to PFR (SFRH/BD/87530/ 2012) and JS (SFRH/BD/63566/2009). LR received support from the Portuguese Ministry of Education and Science and the European Social Fund, through FCT, under POPH – QREN – Typology 4.1 (post-doc grants SFRH/BPD/62865/2009 and SFRH/BPD/93079/2013). PB was supported by EDP Biodiversity Chair. FM was supported by the REN Biodiversity Chair and FCT (IF/01053/2015) ; High Nature Value (HNV) farmland is declining in the EU, with negative consequences for biodiversity conservation. Agri-environment schemes implemented under the Common Agricultural Policy have addressed this problem, with recent proposals advocating direct support to HNV farming systems. However, research is lacking on the economics of HNV farming, which makes it difficult to set the level and type of support that ensure its sustainability. In this paper, we focused on a Special Protection Area for steppe bird conservation, analysing how economic incentives, biophysical and structural features govern the choice of farming system. We found that persistence of the traditional farming system important for steppe birds was associated with economic incentives, resistance to change, and good quality soils, whereas a shift to specialised livestock production systems was favoured by higher rainfall and less fragmented farms. A supply curve built using the choice model predicted that the proportion of traditional farming increased from 20% to 80% of the landscape, when economic incentives increased from about 100€/ha to 160€/ha. Overall, our study highlights the dependence of HNV farming systems on economic incentives, and provides a framework to assess the effects of alternative policy and market scenarios to sustain farmland landscapes promoting biodiversity conservation. ; authorsversion ; published

Conserving biodiversity on farmland is an essential element of worldwide efforts for reversing the global biodiversity decline. Common approaches involve improving the natural component of the landscape by increasing the amount of natural and seminatural habitats (e.g., hedgerows, woodlots, and ponds) or improving the production component of the landscape by increasing the amount of biodiversity-friendly crops. Because these approaches may negatively impact on economic output, it was suggested that an alternative might be to enhance the diversity (compositional heterogeneity) or the spatial complexity (configurational heterogeneity) of land cover types, without necessarily changing composition. Here, we develop a case study to evaluate these ideas, examining whether managing landscape composition or heterogeneity, or both, would be required to achieve conservation benefits on avian diversity in open Mediterranean farmland. We surveyed birds in farmland landscapes of southern Portugal, before (1995–1997) and after (2010–2012) the European Union's Common Agricultural Policy (CAP) reform of 2003, and related spatial and temporal variation in bird species richness to variables describing the composition, and the compositional and configurational heterogeneity, of the natural and production components of the landscape. We found that the composition of the production component had the strongest effects on avian diversity, with a particularly marked effect on the richness of farmland and steppe bird species. Composition of the natural component was also influential, mainly affecting the richness of woodland/shrubland species. Although there were some effects of compositional and configurational heterogeneity, these were much weaker and inconsistent than those of landscape composition. Overall, we suggest that conservation efforts in our area should focus primarily on the composition of the production component, by striving to maximize the prevalence of biodiversity-friendly crops. This recommendation probably applies to other areas such as ours, where a range of species of conservation concern is strongly associated with crop habitats ; info:eu-repo/semantics/publishedVersion