Farmland Species Research Articles

Diversity in Irish and British avifauna assemblages: What can variation in diversity profiles reveal about the forces that drive assemblage composition and structure?

Ireland and Britain are two islands located at Europe's westernmost edge, both of which act as the final breeding outposts for many bird species within their European ranges. Despite their similar geographic locations and geological histories, Ireland and Britain host different breeding avifauna assemblages. Diversity profiles, which can serve as more robust alternatives to classic diversity indices, were employed in this study to explore disparities in the two islands' breeding avifauna assemblages. Variations in assemblages were explored, along with their potential drivers, through analyses at three levels: island-scale breeding bird assemblage compositions, island-scale diversity profiles considering 49 common breeding species, and habitat-specific diversity profiles considering assemblages in east/central Irish farmland and East Anglian farmland. Analysis of the two islands' breeding avifauna assemblages revealed that the Irish assemblage is a complete subset of the British assemblage. Analyses of Irish and British assemblages at both an island scale and a habitat scale revealed patterns linking land use to trends within the two islands' avifauna assemblages. Irish assemblages contained greater proportions of insectivorous farmland species by abundance, while British assemblages contained greater proportions of seed-eating farmland species; both trends appeared to be related to structural differences in agricultural land use on the two islands. The British and East Anglian assemblages exhibited higher diversity across all analyses, which appeared to be driven by the assemblages' higher relative abundances of species that were most genetically distinct. This study highlights the ability of diversity profiles to impart more information than classic diversity indices by incorporating species similarity data.

The role of a non-native forest in the stopover ecology of migratory passerines

During their journey, migratory birds need stopover sites where they can replenish their energy stores. Mosaic forests of agricultural areas, often planted with non-native trees, can provide opportunities for birds to do this. In the present work, I sought to answer the question of the importance of these habitats for migratory birds. For this reason I studied the stopover ecology of 15 species of long- and short-distance migratory passerines. I calculated the minimum stopover duration and the extent of fat accumulation per species and by dividing species into different groups by habitat use and migration distance. For three species, I also estimated their possible flight ranges based on the accumulated fat, body mass and wing length. My results show that the planted oleaster forest has a different role in the stopover habits of the species studied. The body mass of the birds typically did not changed significantly during the time they spent in the area. Forest and farmland species spent the longest time in the area. Despite the possibly high rate of intra- and inter-specific competition, the area can provide sufficient food for birds throughout the whole period. Short-distance migrants stored less fat than long-distance migrants, probably due to the different migration strategies. Flight distances varied according to the migratory habits of the species. From a conservation biology point of view, the study highlighted the role of these habitats in bird migration.

Space–Time Patterns of Nest Site and Nesting Area Selection by the Italian Population of European Rollers: A 3-Year Study of a Farmland Bird Species

The European Roller Coracias garrulus has suffered greatly from breeding habitat loss due to the renovation of old farmhouses and rural buildings and changing agricultural practices that took place extensively across Europe in the last decades. As a consequence, this species experienced a significant decline, and local extinctions of breeding populations were recorded in several European countries. We investigated nest sites and nesting area selection by the Italian Roller population during the breeding period (May–August) between 2016 and 2018. We collected 711 points from field surveys and used four types of point pattern analysis to detect space-time patterns of nest site and nesting area selection. We found that: (a) the spatial distribution of selected (i.e., occupied) nest sites was significantly nonrandom (p < 0.01) for all years and months; (b) only 2.6% of the selected nest sites was located within parks or reserves; (c) there were significant (p < 0.01) latitudinal, longitudinal, and altitudinal shifts of selected nest sites between May and August; (d) the geographical barycentres of selected nest sites shifted northward by about 80 km per month from May (southernmost barycentre) to August (northernmost barycentre); (e) four main nesting areas (7886 km2 in total) occurred in central and southern Italy, whose utilization by the European Rollers differed between months but not between years; (f) the detected nesting areas corresponded mainly to non-irrigated arable lands (41.22% of their extent) and natural grasslands (12.80%). Our results are useful to support conservation strategies for the breeding sites of this farmland species, which is not a regular visitor to protected areas in Italy.

Habitat characteristics and the rate of decline in a threatened farmland bird, the ortolan bunting Emberiza hortulana

Farmland habitats witness steep declines in biodiversity. One rapidly declining farmland species is the ortolan bunting Emberiza hortulana. In Finland, a staggering 99% of the population has been lost during the past 30 years. Changes in the breeding habitats have been proposed as a reason for the decline, although hazards during migration and wintering may also play a role.We gathered a 19‐year data set of Finnish ortolan buntings and studied which spatial characteristics, habitat features, and climate factors might explain the population growth rate at the singing‐group level. As explanatory variables we used region, density of small‐scale structures, proportion of agricultural area in the landscape, diversity of crop types, proportion of bare ground, and temperature and precipitation of previous breeding season.Higher population growth rates were associated with higher crop type diversity and higher proportion of bare ground. The mosaic of various crop plants and bare ground may provide a wider array of feeding, hiding and nesting places, and an easier access to food. Higher growth rates were also associated with landscapes dominated by interconnected agricultural land, which may reflect the species' sociability and avoidance of forested areas. The North Ostrobothnia region had higher growth rates compared to other regions.We suggest that northern populations of ortolan bunting should be targeted for further studies on feeding and breeding ecology as well as for urgent conservation actions, such as increasing crop type diversity and bare ground.

Habitat preferences of European turtle dove Streptopelia turtur in the Czech Republic: implications for conservation of a rapidly declining farmland species

Habitat preferences of European turtle dove Streptopelia turtur in the Czech Republic: implications for conservation of a rapidly declining farmland species

Changes in thermal niche position and breadth of bird assemblages in Spain in relation to increasing temperatures

AbstractAimAnimal communities around the world are responding to climate change by altering their taxonomic composition, mainly through an increase in the colonisation rate of warm‐dwelling species and the local extinction of cold‐dwelling ones. We assessed whether the taxonomic composition of bird assemblages in peninsular Spain has changed in accordance with the recent increase in temperature. We also evaluated the role of species thermal affinities and population dynamics on these changes.LocationPeninsular Spain.TaxonBirds.MethodsWe compared assemblages reported in the last Spanish breeding bird atlases (1998–2002 vs. 2014–2018) in 10 × 10 km squares. We described species' thermal niches by overlaying global species breeding distributions and world temperature metrics (based on mean, minimum, maximum and range), and then aggregated them to obtain a set of community thermal indices for each assemblage (CTIs and CTR for ranges). Long‐term average temperatures and local current temperatures were related to changes in CTIs using spatial GLMMs, which considered habitat change. We identified the species most responsible for variation in assemblages and regressed species' influence on thermal affinities and population dynamics.ResultsCTIs increased with temperature and warm‐dwelling species became more prevalent to the detriment of cold‐dwelling ones. However, we found a counteracting effect of temperature and habitat. Cold‐dwelling forest species were among the most influential species, mainly through colonisation, while warm‐dwelling farmland species contributed through local extinctions (both attenuated local increases in CTI). The mean thermal breadth of assemblages (CTR) decreased with temperatures.Main conclusionsThe taxonomic composition of bird assemblages shifted in line with the main expectations due to global change (thermophilisation), mainly due to local colonisation of warm‐dwelling species, although it did not show the pattern of thermal homogenisation suggested elsewhere. Our results add further evidence of the interplay between climate warming and land‐use change in the ongoing adjustment of animal communities.

Breeding in an agricultural landscape: conservation actions increase nest survival in a ground-nesting bird

AbstractAgricultural intensification has affected wildlife across Europe, triggering steep declines and regional extinctions of farmland birds. Effective conservation activities are essential for the preservation of biodiversity in an agricultural landscape, but current efforts have not succeeded in halting these declines. Here we investigate a ground-nesting shorebird, the collared pratincole Glareola pratincola, which has shifted its habitat use in Central Europe over the last 20 years from alkaline grasslands to intensively managed agricultural fields. We show that nesting success was different between three agricultural habitat types, with the highest nesting success in fallow lands and the lowest in row crops. Nesting success was also associated with the timing of breeding and breeding density, as nests produced early in the breeding season and those in high-breeding-density areas hatched more successfully than those produced later in the season and at low density. We implemented direct conservation measures including marking nests and negotiating with farmers to avoid cultivating the field between nest markers, controlling nest predators and, most recently, creating suitable nesting sites and foraging areas for pratincoles. As a result of these conservation actions, nest survival increased from 11.2% to 83.5% and the size of the breeding population increased from 13 to 56 pairs during 2012–2021. Thus, we show that agricultural landscapes can continue to provide suitable habitats, and targeted conservation actions have the potential to reverse the declines of farmland species.

Modelling the effectivity of a land sparing strategy to preserve an endangered steppe-land bird population in cereal farmland: Scopes and limits

Agricultural intensification and the disappearance of fallow land have been identified as a major driver of biodiversity loss in European farmland. In particular, the dramatic population decline of the little bustard (Tetrax tetrax), a flagship bird species in western European cereal farmland, has been largely attributed to the loss of this crucial habitat. Demographic modelling showed that low breeding success and reduced female survival were co-responsible for the little bustard population decline in a NE Iberian cereal pseudo-steppe. An equilibrium finite rate of change can be achieved by raising either female adult survival or fecundity. In both cases, the required increases fall within a biological meaningful range, but a combination of both would be more feasible in practice. Setting farmland aside as managed fallow can boost fecundity to the required equilibrium value, but the potential of this management action is seriously reduced as mortality increases. Socio-economically acceptable amounts of spared-land can only be achieved if actions to reduce mortality are undertaken in combination with providing fallow land. Actions to reduce both natural and anthropogenic mortality have so far been neglected by little bustard conservation programs. Both are needed if we seek to guarantee the long-term viability of the species and an acceptable share of conservation effort from stakeholders. Our results show that the holistic adaptive management approach adopted here can be used to evaluate the effectiveness and limitations of conservation decisions and to provide insights for conservation projects.

The occurrence of a flagship raptor species in intensive agroecosystems is associated with more diverse farmland bird communities: Opportunities for market-based conservation

Traditional livestock systems have supported farmland biodiversity for millennia. However, modern intensive husbandry is challenging wildlife persistence in agroecosystems. We assessed the multiscale determinants of the species richness of breeding bird communities, as well as the occurrence of a flagship raptor species, the lesser kestrel Falco naumanni, in an intensive agroecosystem mostly dedicated to the production of the world-renowned Parmigiano Reggiano cheese. We relied on three avian community richness metrics reflecting a gradient of increasing association with farmed landscapes, i.e. the overall breeding bird species richness, the richness of farmland species, and the richness of ground-nesters (i.e. species that mostly breed within crops) and tested their association with the landscape, agricultural, and pedological variables as well as with lesser kestrel occurrence. We showed that environmental variables determining overall richer avian assemblages did not coincide with those shaping farmland and ground-nesting species richness, thus challenging the potential effectiveness of conservation actions. However, such actions could be optimized by taking into account different spatial scales affecting different species groups. Indeed, landscape heterogeneity, semi-natural/marginal habitats, and a moderate cover of build-up areas enhanced overall species richness at a small spatial scale. At a broader scale, landscape heterogeneity enhanced farmland species richness, whereas fragmentation determined by urbanization negatively affected ground-nesters. Avian community richness metrics were maximized at an intermediate cover of three prevailing crops (winter, summer, and hay crops), increasing when they co-occurred, i.e., in the presence of crop rotation. Lesser kestrel occurrence was associated with richer assemblages of ground-nesting species because this raptor and ground-nesters showed analogous ecological requirements. These findings suggest that the lesser kestrel can be regarded as an ideal flagship for market-based conservation initiatives (e.g., tailored to the production of biodiversity-friendly agri-food products) in intensive agroecosystems since actions aimed at improving the foraging habitats of the species are likely to benefit co-occurring farmland birds of conservation interest.

Long-term game species dynamic as indicator for changing landscape quality

Urban sprawl, increased traffic and modern forestry, as well as the globalisation of agriculture, have increasingly been affecting the landscape and its quality as habitat for species especially since the middle of the last century. Still, there are hardly any methods nor indicators which can measure the quality of the landscape for species over a long period. In this study, we investigated the influence of landscape structure and landscape quality on harvest data of 28 game species in South Tyrol, Italy, over the last 150 years. The harvest data were used to assess the population dynamics of individual species and habitat guilds since 1870.As a first result, we could show, on the examples of six species, that count population data were highly correlated with harvest data and are therefore well suited to estimate their population size. Second, the populations of ungulates consistently increased during the study period. The numbers of mesocarnivores as well as smaller forest and alpine game species increased strongly until the 1970s/80s of the last century, followed by a decline. The populations of farmland species and some synanthropic species have decreased substantially, and some species have even disappeared completely. Based on these results, we were able to show, in a third step, that the landscape quality for game species in South Tyrol has developed differently: In particular, the agriculturally used habitats have lost quality, whereas forests and alpine regions have initially gained quality due to the extensification of use; during the last five decades, the quality decreases again, at least for small game species. Our results thus provide concrete implications for the active improvement of the landscape quality for farmland and forest species, as well as indications for future priorities in funding support of alpine pasture management.

Agricultural spider decline: long-term trends under constant management conditions

There is widespread evidence for a worldwide trend of insect decline, but we have much fewer data about recent temporal trends in other arthropod groups, including spiders. Spiders can be hypothesised to similarly decline because of trophic dependence on insects and being equally sensitive to local and global environmental changes. Background trends in arthropod populations can be verified if we decouple large-scale environmental transitions, such as climate change, from local factors. To provide a case study on baseline spider community trends, we observed changes in the spider community of an unsprayed alfalfa field and its margin 23 years apart under largely unchanged local conditions. We aimed to determine whether there are changes in spider abundance, species richness and mean species characteristics. Spider abundance per unit effort decreased dramatically, by 45% in alfalfa and by 59% in the margin, but species richness and most characteristics remained unchanged. Community composition in both habitats shifted and became more similar by the current study period. The population decline was especially marked in certain farmland species. We propose that in the absence of local causative factors, spider abundance decline in our study indicates a reduction of spider populations at landscape and regional scales.

Assessing the role of invasive weeds in the impact of successional habitats on the bird assemblage in overgrowing agriculture

Agricultural habitats are assumed to be biodiversity refuges. However, some studies treat agricultural land management as a cause of the biodiversity decline, to which habitat loss and heterogeneity may contribute. Between the crops, the successional habitats appear – ruderal plant communities and bush areas. Their influence on farmland biodiversity is unknown. This research assessed the impact of spatial relationships between agricultural areas, semi-natural meadows and successional habitats on the bird species richness, Shannon diversity index, and Faith’s phylogenetic diversity index. An additional habitat variable was the presence of weeds, i.e., invasive Caucasian hogweeds Heracleum sp., treated as crops in the past. The birds and habitats research was on 74 sites set in pairs (invaded vs control) in south-eastern Poland. Results showed that birds assembling in agricultural and semi-natural areas were more diverse and contained protected farmland species, while birds appearing in overgrown habitats (i.e., successional and invaded) were clumped with their habitat requirements. In the presence of plant invaders, ruderal habitats negatively affected the bird phylogenetic diversity index. In invaded sites, bush areas had no positive effects on the Shannon diversity index and species richness of birds, in contrast with control sites. The presented research suggests the need to re-evaluate the importance of successional non-crop habitats considered positive in agricultural landscapes if those habitats develop in areas with plant invasion.

Alarming decline of the Little Bustard Tetrax tetrax in one of its two population strongholds in Sardinia, Italy

Summary Farmland biodiversity is declining worldwide, and especially in Western countries largely owing to the large-scale intensification of agricultural practices. The Little Bustard Tetrax tetrax is a steppe bird adapted to agro-pastoral ecosystems in Western Europe, and is one of those many farmland species declining due to changes in agricultural production systems. In the EU, the majority of the extant population of this species is concentrated in the Iberian Peninsula. In Italy, the species has now disappeared from the mainland and is currently present only in Sardinia, where two populations, in the central-western areas, hold about two-thirds of the whole island’s numbers, with the rest scattered across numerous smaller nuclei. While there are indications and anecdotal information suggesting a possible population decline during recent decades, robust monitoring across different time periods that would allow a comparison of numbers is lacking in Sardinia. Here we repeated a Little Bustard survey performed in 2008 in two areas of western Sardinia: Abbasanta, which is one of the two strongholds for the species in Sardinia, and Campeda, which holds a small population (about 10 territorial males). Using the same methodology as in the past survey, we assessed current population size and density, and quantified changes over time. We found alarming declines, at a rate of around 30% in 14 years in both areas, with an estimated current population of 87 males in Abbasanta and 8 males in Campeda. We highlight current and emerging threats, such as the downsizing of the Special Protection Area of Abbasanta, and the encroachment of solar power plants within the same area.

Taiwan's Breeding Bird Survey reveals very few declining species

Multi-species indicators (MSIs) have been useful tools for reflecting the state of taxa and ecosystems at global, regional, and national levels. However, most indicators are from Europe and North America, and there are few from the world’s major tropical and subtropical biodiversity hotspots, often in large part because of insufficient data availability. We modelled the population trajectories of 107 regularly-occurring breeding bird species in Taiwan (100 native and seven introduced species) and developed MSIs for (i) forest, (ii) farmland, and (iii) introduced bird species based on the Taiwan Breeding Bird Survey dataset between 2011 and 2019. Individual population trajectories for 87 species did not show a significant change, those for 11 species grew significantly, and those for two species declined significantly. All MSIs show significant growth. Based on the phylogenetic generalised least squares (PGLS) results, the forest bird indicator increased somewhat more rapidly than the farmland bird indicator, perhaps reflecting very low rates of deforestation contrasting with more rapid land use change on farmlands in Taiwan. Some of the forest and farmland species, however, showed rapid declines, and most of these atypical decliners were common species or carnivores. Further, the PLGS results show that the introduced species indicator had more rapid growth than native species indicators, posing a potential risk for the integrity of native bird communities in the near future as well as compromising broader ecosystem intactness. Our study provides important information on bird population changes in subtropical Asia. The MSIs will be updated regularly and will be used to provide information to support conservation policies in Taiwan.

Farmland birds on forest clear-cuts: Liked by some, avoided by others

Many bird species typical to farmland have declined in numbers in recent decades. Some farmland bird species occur outside farmland in other open man-made habitats, such as forest clear-cuts. Given that in Sweden the total area of clear-cuts (5–6 %) almost equals that of farmland (8 %), clear-cuts have the potential to be an important habitat for some farmland birds. We investigated how bird community composition and species abundance on Swedish clear-cuts varied with geographical region, clear-cut characteristics and the surrounding landscape, with special focus on farmland species. Based on short visits in 2017–2019, we surveyed the occurrence of birds on 300 representative clear-cuts in Sweden, including six regions and 1300 km of latitude. We counted 1170 birds of 66 different species, including 10 out of 15 bird species in existing farmland bird indicators. Both bird community composition and species abundance varied with clear-cut size, age, vegetation height, region and proportion of nearby farmland, depending on species’ ecology. All six farmland species being proportionally common on clear-cuts are, when in farmland, dependent on residual habitats such as pastures and field borders with bushes and trees. In contrast, a third of the dedicated farmland species were scarce in clear-cuts, probably avoiding them because of predator-related avoidance of forest edges and/or a lack of suitable nest sites or food resources. To determine the full importance of forest clear-cuts for farmland species, and potentially make them more favourable for farmland birds, more studies are needed on the reproductive success on clear-cuts and which site features make them suitable habitat. This study did not determine the consequences of clear-cuts for forest birds across the forest cycle, consequences which needs to be balanced against any gains for farmland birds.

Grassland restoration benefits declining farmland birds: A landscape-scale before-after-control-impact experiment

The decline of farmland bird populations starting in the 1980s has induced intense research on farmland biodiversity conservation in Europe. Although many studies assessing the effectiveness of agri-environmental schemes have concentrated on birds, farmland birds, surprisingly, have not yet been targeted directly by permanent, landscape-scale restoration of grassland ecosystems on former croplands in Europe. We compared farmland bird responses to grassland restoration by grass sowing, alfalfa sowing followed by spontaneous grassland recovery, and hay transfer (impact sites) with responses to extensive, low-intensity cropland cultivation (controls) in a Before-After-Control-Impact design, and also compared extensive croplands against a baseline reference of intensive croplands. Point counts in 69 sites on 910 ha in at least two years before and three years after the interventions showed that farmland bird species richness increased in both restored grasslands and in extensive croplands, whereas abundance and Shannon diversity increased only in restored grasslands but not in extensive croplands. Abundance increased in restored grasslands for five farmland species and two species of conservation importance, and in extensive croplands for one farmland and one species of conservation importance. Active restoration by grass sowing increased both species richness and diversity and active restoration by hay transfer increased abundance, while passive restoration targeting spontaneous grassland recovery after alfalfa sowing increased richness and abundance. Extensive croplands had four-five times more species and individuals than intensive croplands. Our results suggest that landscape-scale grassland restoration can locally reverse regional farmland bird declines and can thus be a promising tool in farmland biodiversity conservation.

Habitat factors influencing the breeding birds on animal farms: can modern agricultural infrastructure be good for birds?

In large parts of Europe biodiversity in agricultural landscapes has experienced strong declines over the past decades because of land-use change and intensification of cultivation methods, but more recently also due to modernization of villages. One of the aspects of modernization is the arising of large specialized poultry and pig farms. Our study carried out in central and east-central Poland focused on the role of habitats within 101 animal farms in relation to bird species richness and number of pairs. We also compared the density of some bird species on farms and in neighbouring villages to determine the importance of the farm environment for the birds. Species richness increased with the number of buildings, the number of trees and the presence of piles of rubble. The number of pairs increased with the number of trees, and the presence of ponds and piles of rubble. Many-times higher densities on farms than in surrounding villages of several species were noteworthy: Black Redstart, Northern Wheatear, White Wagtail and Crested Lark. Animal farms are an important refuge for several species, including those belonging to drastically declining farmland species. Despite the opinion that the modernization of the villages is having a disastrous effect on the avifauna, the modernization may also have positive aspects for some bird species.

Farmstead modernization adversely affects farmland birds

Abstract Farmland biodiversity is declining at an alarming rate and various conservation measures have been implemented to reverse this negative trend. Farmsteads within agricultural landscapes were recently identified as farmland bird hotspots, so we ask whether the modernization of farmsteads has substantially reduced their conservation potential for farmland birds. We assessed the effect of farmstead modernization on 29 farmland bird species in rural landscapes on 97 dairy farms across the Czech Republic, investigating differences in farmland bird abundance and species richness, as well as nest abundance of declining farmland species breeding in buildings, by comparing new/modernized with old and mixed farmsteads. Additionally, we investigated how farmstead size and environmental variables influenced avian assemblages on farmsteads. Farmland bird abundance was almost 3‐fold lower in new/modernized farmsteads compared to mixed and old farmsteads (this difference was mostly driven by building‐nesters and noncrop‐nesters). Similarly, species richness was higher in old and mixed farmsteads compared to new farmsteads. Old cow sheds hosted more nests (both old and new nests; by a factor of 1.6–21) of house sparrows Passer domesticus, barn swallows Hirundo rustica and house martins Delichon urbicum compared to new cow sheds. Importantly, effects of environmental variables were negligible or smaller compared to the farmstead type, suggesting that bird abundance and species richness on farmsteads was primarily driven by farmstead modernization rather than the structure of surrounding farmland. Synthesis and applications. Farmstead modernization may have strong adverse effects on farmland bird populations due to reducing the availability of critical high‐quality nesting and foraging opportunities. Modernization is largely financed from existing EU funds, which directly conflicts with EU biodiversity strategies aiming at halting biodiversity loss. We therefore recommend (i) including compensatory measures to increase nesting and foraging opportunities for birds during farmstead construction/modernization, (ii) increasing awareness of these problems among critical stakeholders and (iii) increasing support to small‐sized traditional farms to retain and improve habitat conditions for declining farmland species.

Responses of birds to vineyard abandonment in Slovakia

Vineyards are semi-natural, human-modified ecosystems where the extent of natural elements is determined primarily by the type of management and by the abandonment rate. In this study, we analyzed bird assemblages in 40 vineyard plots in six wine-growing regions of Slovakia. We examined bird communities on managed and abandoned vineyards to identify possible patterns. Environmental and spatial predictors of species richness and abundance were analyzed using partial redundancy analysis (pRDA) and a generalized additive model (GAM). Bird communities were influenced by both environmental and spatial factors. As expected, elevation explained most of the variation in bird assemblages. Tree coverage was found to be more important than the vineyard abandonment rate in explaining the observed variability. Only a portion of the variance in the species data reported by pRDA was accounted for by the difference in vineyard abandonment degree. Our results show that the species richness of all birds was positively correlated to vegetation density (captured by NDVI). Herb and shrub cover had less effect on bird species richness than tree cover and the presence of traditional agricultural vineyard landscapes. However, shrub density emerged as a key explanatory factor for the abundance of habitat specialists. Our study shows that, depending on whether the goal is to promote the diversity and abundance of farmland or non-farmland bird species, different conservation biology approaches should be used. Increasing the landscape diversity and avoiding large vineyard abandonment are necessary if we are to stem the decline of valuable farmland species. • The area of managed vineyards in Slovakia continues to decrease. • The species richness of all birds positively correlated to NDVI. • Tree coverage was found to be one of the most important factors in explaining bird species variation. • The shrub density turned out to be a key explanatory factor of habitat specialist abundance. • Bird abundance and species richness increased continuously with the presence of the traditional agricultural landscape.

Site-based vs. species-based analyses of long-term farmland bird datasets: Implications for conservation policy evaluations

Conservation of Europe’s biodiversity increasingly depends on funds invested within Natura 2000 farmland. Performance of these investments is estimated by the official Farmland Bird Index indicator, that merges species-specific trends for farmland species estimated with the standard TRIM method. We here reanalyze the long-term datasets used to calculate the Spanish Farmland Bird Index by computing abundance and richness of selected bird groups at the point census scale rather than by merging species’ trends. We test whether community trends at site scales differed according to agricultural habitat types (annual, perennial, and mosaic croplands) and locations inside or outside Natura 2000 sites, using both the TRIM method and generalized mixed models. Site-based analyses showed a general increase in bird abundance and richness outside the Natura 2000 network, and a general decrease in perennial and mosaic croplands inside it. Increasing trends were due to non-farmland birds occupying farmland, as farmland species showed significant decreasing trends overall, especially inside Natura 2000 sites and for steppic birds. Trends for threatened birds in annual cropland located inside Nature 2000 were positive, but trends for threatened farmland birds were negative overall, especially in mosaic croplands. Results were qualitatively consistent among statistical methods, although quantitative estimates varied widely among methods, habitats, Natura 2000 location, and relevant bird groups. Site-based analyses of long-term databases confirmed overall trends detected by species-based official reports, and complement them by suggesting additional reasons for failures at reverting negative trends in farmland biodiversity. Regionally-targeted conservation measures should be developed and/or extended to improve these results, and their results monitored at the farm scale to complement the low spatial resolution of volunteer-based bird monitoring schemes. Combination of broad–scale citizen science programs with cause-effect, finer-scale studies will help disentangle the causes of the observed patterns to develop better and more efficient recommendations for conservation measures in farmland areas.