Abundance Of Farmland Birds Research Articles

Woody semi‐natural habitats modulate the effects of field size and functional crop diversity on farmland birds

Abstract Agricultural intensification has simplified landscape composition and configuration, which has led to biodiversity declines. Increasing landscape‐wide crop heterogeneity can promote farmland biodiversity. However, knowledge is still lacking on how the effects of configurational and compositional crop heterogeneity (i.e. field size and crop diversity) are modulated by the amount of semi‐natural habitats in the landscape, especially across large scales. We tested how mean field size and functional crop diversity affect farmland bird diversity and abundance over three consecutive years, and how these effects are modulated by the amount of small woody features (SWF) in the landscape. We related data from a national bird monitoring scheme to field‐level information from a novel, high‐resolution remote sensing‐based crop type map. Smaller field sizes and higher functional crop diversity were not generally associated with a higher diversity or abundance of farmland birds. Associations varied with species' breeding habitat preferences and were modulated by the amount of SWF. In landscapes with a low SWF amount, species diversity and the abundance of species breeding in field edges or shrubs were negatively associated with increasing field size. However, where the amount of SWF was high, larger field size was associated with higher species diversity and abundance of field and shrub breeders. Diversity increased with higher functional crop diversity, as did the abundance of non‐field breeders in landscapes with a medium to high SWF amount. Field size tended to have a stronger effect on bird diversity and abundance than functional crop diversity. Policy implications: National and EU agricultural policies should adopt a landscape perspective by considering the amount of semi‐natural habitats when designing biodiversity‐enhancing measures that target field size and functional crop diversity. In landscapes with low SWF amount, decreasing field sizes may be particularly effective to promote farmland bird diversity and the abundance of non‐field breeders. In landscapes with a medium to high SWF amount, increasing functional crop diversity is likely more effective than reducing field sizes. Field and shrub breeders may be promoted by maintaining landscapes with large fields, only if these offer a high SWF amount, low agronomic yield potential and low productivity.

Grassland vegetation height affects bird responses to forest edges in Mediterranean open farmland

Afforestation affects Mediterranean farmland biodiversity due to loss and fragmentation of grassland habitats. While the influence of landscape context and plantation edges on farmland bird responses to afforestation is well-documented, less is known about the influence of grassland vegetation height and how it interacts with afforestation to influence bird communities. Here, we examined how changes in grassland vegetation height affect bird responses to afforestation in a farmland region in southern Portugal, and how these are affected by plantation type and edge. This region has experienced afforestation with eucalyptus, pine and oak stands, agricultural intensification, and frequent dry periods. To capture local and landscape-level changes, we collected data in two periods (2005 and 2014–15). Grassland vegetation height varied between sampling periods, emerging as a key factor affecting changes observed. Ground-nesting and cereal-associated species increased in abundance with taller vegetation in 2014–15, while in 2005, with drier weather and shorter vegetation, the species associated with ploughed fields were more abundant. Vegetation height effects on bird assemblages depended on plantation type and distance to plantation edges. Farmland bird abundance, including ground-nesting and cereal crops-associated species, increased with taller vegetation, particularly near oak and pine plantations. Conversely, species associated with ploughed fields declined with taller vegetation, especially near eucalyptus plantations. Results highlight complex interactions between vegetation height, plantation type, and edge proximity shaping avian assemblages. This study supports the importance of field and landscape-level management with special focus on grassland vegetation height and landscape heterogeneity for preserving open-farmland birds in fast-changing Mediterranean farmland landscapes.

Species Distribution Models at Fine Scale can Predict Local Abundance of Farmland Birds

Species Distribution Models at Fine Scale can Predict Local Abundance of Farmland Birds

Factors shaping insectivorous farmland bird abundance in intensively cultivated arable fields: Insights through the former Iron Curtain

The decline of farmland bird populations is a well-documented phenomenon that has primarily been attributed to agricultural intensification. However, the specific mechanisms that make intensively used farmland unsuitable for breeding birds have not yet been satisfactorily elucidated, particularly for insectivorous ground-nesting species. To bridge this knowledge gap, we studied the breeding abundance, invertebrate food supply and habitat characteristics of the Yellow Wagtail (Motacilla flava) in arable fields in the lowlands of south-western Slovakia. This region is characterized by the largest field sizes in the European Union, with conditions that are typical for high-intensity farmland areas in parts of Central and Eastern Europe where farmland underwent collectivization. Since Central and Eastern European farmland is considered one of the strongholds of the Yellow Wagtail in Europe, we tested the capacity of winter wheat, rapeseed and maize to support its local population. The Yellow Wagtail abundance was best predicted by habitat characteristics: birds chose fields without woody plants in their surroundings and with suitable crop height and coverage, while the effect of invertebrate food supply was insignificant. Focussing on individual crops, we found that the birds did not prefer the maize and rapeseed fields despite these having a richer food supply, likely because these crops had an unsuitable vegetation structure. The low overall abundance of the studied species indicates that farmland consisting of large fields creates unsuitable conditions for breeding. Therefore, agricultural policy instruments leading to a reduction of field size or the creation of herbaceous field edges should be supported.

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.

Long‐term fallows rate best among agri‐environment scheme effects on farmland birds—A meta‐analysis

AbstractAgri‐environment schemes (AES) serve to counteract the ongoing decline of farmland bird populations, but their success remains controversial. We conducted a meta‐analysis to compare standardized effect size estimates among European AES options—classified into 15 categories that capture relevant management practices—for farmland bird abundance and species richness. Effect strengths varied substantially between AES categories. Long‐term fallows, nonproductive crops such as wild bird seed mixtures, artificial food supply, and winter cover yielded the strongest positive associations with farmland bird abundance. Average effect sizes were larger but also more variable in cropland compared to grassland‐dominated farming systems. This observation highlights the need to develop more effective conservation schemes for grassland inhabitants, which face similarly severe population declines as cropland inhabitants. Schemes that provided large ecological contrasts between treatment and control sites yielded particularly strong relative benefits, but AES‐specific effect sizes further varied with foraging and nesting site guilds of the target species. Our study confirms that the AES that is currently implemented can benefit farmland birds. However, clear improvements require AES to focus on options with maximal improvements in habitat quality and to locally implement sufficiently diverse AES options to serve the often‐incongruent needs of several bird guilds and species.

Scale dependence of landscape-structure-based estimation of abundance of Eurasian skylark (Alauda arvensis)

The habitat and occurrence of farmland birds are strongly determined by the agricultural-landscape structure. Changes in land cover composition and configuration are one of the main causes of the significant decline in abundance of the Eurasian skylark (Alauda arvensis) in recent decades. This farmland-bird species is common in agricultural areas of Eurasia. In this study we investigate the land use factors involved in the decline in Central Europe, Hungary. We used two different land use/land cover (LULC) datasets, which were compiled at different scales: the Ecosystem Map of Hungary (EMH), a very precise LULC map based on a 0.04-ha minimum mapping unit, and the Corine Land cover (CLC) dataset, built using a 25-ha minimum mapping unit. We studied the impact of landscape composition and configuration on skylark abundance by using negative-binomial generalized linear models. After identifying skylark preferences among LULC categories at different scales, we calculated the EMH and CLC dataset-based landscape indices (such as mean patch size and mean fractal dimension index) of the skylark preferred (arable lands, pastures, grasslands and meadows) and the nonpreferred (artificial surfaces, forests, complex cultivation patterns and waters) LULC classes. Then we compared the results with field observations of skylark abundance in the database of Hungarian Common Bird Monitoring (MMM). On the basis of statistical analysis of connections between the landscape indices and the skylark-abundance data, we estimated skylark abundance for those areas where the skylark-abundance datasets from field observation were not available. We also tested the estimates by assessing model sensitivity when we input different-scale LULC data and used different observation windows (grain size). Our statistical model using EMH dataset explained 41.22% variance of the skylark abundance data, while the rest, 58.78% of variance is not accounted by the model presumably due to local environmental factors not considered in our model. The regional scale (CLC-based) estimation of skylark abundance yielded significantly lower accuracies (33.76% in 1200 m radius buffer zones and 34.11% in 600 m radius buffer zones). We conclude that the size of the landscape windows (grain size) land cover has a significant impact on the relationship between skylark and landscape structure. Our results can help to test the usefulness and limitations of the different-scale LULC databases and to find the optimal grain size for modelling and estimating farmland-bird abundance data and may support landscape scale conservation management plans.

Seasonal variation and crop diversity shape the composition of bird communities in agricultural landscapes in Nepal

Farmland birds are declining globally due to anthropogenic activities, with particularly few studies in Asian agricultural landscapes. Various studies have examined the impacts of landscape heterogeneity on farmland bird composition, but few have considered seasonal changes in bird diversity and examined functional feeding guild assemblages. Here, we disentangle the impact of seasonal variation (summer, monsoon, and winter), cropping practice (mixed crop, monocultural-crop, and fallow land), crop type (rice, wheat, maize, sugarcane, and other crops), landscape heterogeneity, and the number of houses and trees on the richness and abundance of farmland birds and their feeding guilds conducted within human-dominated agricultural landscapes of lowland Nepal. We established 116 transects (farmland = 100, forest = 8, and river = 8), and each transect was visited nine times from April 2018 to December 2019, with forests and river transect to test the dissimilarities in bird composition between those habitats and farmlands. We recorded 201 bird species in farmland, 133 in the forest, and 131 in river habitats. Bird composition on farmlands showed more dissimilarity with forest than river transects. We recorded nine globally, and 26 nationally threatened birds in farmlands. Seasonal variation and cropping practice significantly influenced the richness of all farmland birds and resident birds only, whereas species abundances vary by season only. We recorded higher species richness in the winter season and mixed crop fields but greater abundance in the monsoon and monoculture crop fields. Farmland bird richness increased with increasing tree numbers but decreased with increasing house numbers. Sugarcane fields had the highest bird richness within crop species, whereas rice fields had the greatest abundance. Seasons and cropping practice also shaped the assemblages of feeding guilds differently. In the context of increasing crop intensification globally, our study suggests that the governments in this region should encourage farmers to cultivate mixed crops and simultaneously restrict the urbanization of farmlands to protect bird diversity. Seasonality should be factored into analyses aimed at understanding bird diversity in agricultural landscapes.

Village modernization and reduced abundance of farmland birds: Why compensation for lost nesting sites may not be enough

Village modernization and reduced abundance of farmland birds: Why compensation for lost nesting sites may not be enough

Evaluating conservation tools in intensively-used farmland: Higher bird and mammal diversity in seed-rich strips during winter

Farmland biodiversity have experienced a steep decline over recent decades. Various conservation measures, including EU agri-environmental schemes (AES), have been designed to prevent further biodiversity loss. Despite the AES were criticized for limited benefits for biodiversity, the existing conservation evidence demonstrated some AES, such as seed-rich strips (SRS), can have a positive effect on overall biodiversity. However, evidence of the effectiveness of SRS during winter is largely missing in Eastern Europe or it is based on single-species evaluations. In our study, we investigate the effects of SRS on several taxa typical of the farmland (i.e., farmland birds, European hare, roe deer and small mammals) during winter, when these species may suffer from a lack of food sources. More specifically, we evaluated the effect of spatial location (hedges, forests, and open fields), time in the season (early and late winter), and area (Single Large or Several Small analysis, i.e., “SLOSS analysis”) of SRS on species richness and abundance of birds and mammals. SRS showed higher species richness and abundance than control transects, except for roe deer. The largest differences in abundance and species richness of farmland birds between the SRS and the controls were found in the fields. The highest abundance of European hare and small mammals were found in SRS located in the fields. Ordination analysis indicated that several bird species preferred SRS. Moreover, different birds occurred in strips adjacent to open fields, hedges, and forest, indicating that the landscape context of SRS can affect its use by different bird species. We found a significant decrease in the abundance of farmland birds and declining farmland species during late winter in the SRS, but not in the controls, suggesting the SRS may be depleted of seeds towards the end of winter. Finally, the SLOSS analysis indicated there was no clear difference in species richness between small-to-large and large-to-small strips accumulation, but the pooled abundance of all birds and mammals was generally higher at a few large rather than many small patches of the same cumulative size. Our findings suggest that SRS are a simple and cost-effective measure for farmland biodiversity conservation. Even relatively small SRS are used by many species and therefore should be promoted. SRS careful planning (e.g., location of SRS within the landscape and the choice of seed mixtures) can improve their effectiveness for biodiversity conservation.

Land consolidation negatively affects farmland bird diversity and conservation value

Land consolidation can negatively affect biodiversity, as it is usually followed by the expansion of arable land, a decrease in crop and land cover diversity, and an increase in the application of agrochemicals. The aim of our study was to compare the species’ composition and abundance of farmland birds, as well as habitat structure, on consolidated and non-consolidated sites in Goričko, NE Slovenia. Habitat diversity was much lower on consolidated sites compared to non-consolidated ones, with arable fields and associated habitats (e.g. grass field margins, field tracks) prevailing on the former. Non-consolidated sites held higher proportions of different types of meadows, hedgerows, solitary trees, succession and traditional orchards. Farmland bird diversity and the abundance of a majority of farmland bird species were higher on non-consolidated sites. The only two exceptions to this were the Eurasian Skylark and the Common Stonechat, which were more abundant on consolidated sites. Both of the species suffered population declines at Goričko in the period 1997–2016, bringing into question the suitability of intensively managed arable fields as their breeding and foraging habitat. Individual species’ regression analysis revealed that the most influential positive explanatory variable for the presence of Red-backed Shrike, Tree Sparrow and Common Whitethroat was non-consolidated, extensively managed mosaic landscape, whereas for the Yellowhammer this explanatory variable was superseded only by forest islands without traditional orchards. Land consolidation, as performed in Slovenia, negatively affects farmland bird diversity and its European conservation value, which is why it should not be performed on Natura 2000 sites, designated for nature conservation.

Dynamics of Farmland Birds in Traditional Agroecosystems: The Value of Countryside Elements in Avian Conservation

In India, urbanization and growth of cities have fragmented farmlands and the area under cultivation is dwindling. This study examined the ecological characteristics of rice fields, the inherent value of countryside elements and the relative occurrence of four species of farmland birds Dicrurus macrocercus, Turdoides affinis, Pavo cristatus, and Psittacula krameri along the Cauvery delta region, widely known as the granary of Tamil Nadu. The abundance and distribution of birds were analyzed at 30 sampling points for a year using the unlimited-radius point-counts. Among the four species recorded, D. macrocercus utilized more heterogeneous farmlands, while P. krameri was recorded in more intensively cultivated regions of the farmland. Pre-harvested rice fields predominantly supported species abundance and richness and exhibited a greater value for farmland birds than plowed, flooded or post-harvested fields. The abundance and richness of birds in agroecosystems increased with native vegetation cover and woody shelterbelts. D. macrocercus displayed greater tolerance towards monoculture plantations and elements within the mosaics like cable poles and power lines. Bird abundance in farmlands also correlated positively with decreasing distance from the mainland for D. macrocercus and T. affinis and showed a negative correlation for P. cristatus and P. krameri. D. macrocercus also displayed specialized resource utilization foraging techniques coinciding with cultivation activities resulting in bird-farmer mutualism. Cross-validation of the AIC models also showed that rice fields margined by greater amounts of vegetation cover and retention of species-specific modified elements supported the greatest abundance of farmland birds.

Organic animal farms increase farmland bird abundance in the Boreal region.

Agriculture is a primary driver of biodiversity loss worldwide, and several expensive schemes have been designed to make modern farming landscapes more hospitable for wildlife. One such market-based mechanisms is the agri-environment-climate schemes (AES) in the European Union (EU). AES compensate farmers for reducing land-use intensity and maintaining or introducing biodiversity-rich habitats. Despite their high costs, impacts of AES vary by measure, region and taxonomic group considered, and have rarely been studied over large areas covering an entire country. Here we assess the country-wide impact of several AES measures on bird abundance using citizen science data on birds and detailed information on AES take up from across Finland. We report a positive impact of organic animal farming on abundance of all farmland associated birds. This effect was particularly strong for insectivorous species, species that are associated to farmyards and long-distance species. None of the other AES measures considered for study did show any relationship with bird abundance. Overall, these findings highlight the potential positive impact that some compensatory measures, such as organic animal farming, may have on wildlife. Traditional animal husbandry is based on grazing of animals and restriction on external inputs, similarly to what is stipulated under organic production contract. As such, traditional animal husbandry may represent an effective landscape management tool for restoring or maintaining threatened species and ecosystems in rural areas of the EU. Ultimately, the apparent lack of a measurable effect of the other AES considered here supports the current move towards evidence-based regional targeting of compensatory measures, so as to concentrate scarce resources to where they can yield the highest ecological benefits.

Collapse of farmland bird populations in an Eastern European country following its EU accession

AbstractEastern European countries are considered a stronghold for the continent's farmland biodiversity. The abundance of farmland birds is one important element of this biodiversity. At the end of the 20th century, member states of the European Union (EU) experienced serious population declines of farmland birds due to agricultural intensification, which was not observed in the Eastern European nonmember states. In 2004, 10 mostly Eastern European countries acceded to the EU. It is thus important to ask whether this historical step resulted in changes of agricultural production and, in turn, in farmland bird populations. Here we used annual crop yields and monitoring data on farmland bird abundance in an Eastern European new EU‐member state and showed that agricultural production intensified and farmland bird populations declined steeply after country's EU accession. These results indicate that entering EU's Common Agricultural Policy caused significant deterioration of farmland biodiversity in a once biodiversity‐rich region.

Active farmsteads are year‐round strongholds for farmland birds

Abstract Farmland birds have experienced substantial declines over recent decades and various conservation measures have been designed to halt their massive decrease. The effectiveness of these measures is however limited, due to inappropriate identification of crucial breeding and wintering habitats. Identification of appropriate habitats, like farmsteads, and understanding seasonal changes in species richness and abundance of farmland birds within these habitats may therefore be key for farmland bird conservation. We investigated the effect of variation in farmstead management on alpha and gamma diversity of all farmland birds and red‐listed farmland birds in the Czech Republic. In particular, we evaluated the diversity of wintering and breeding birds at over 200 sites to explore: (1) differences in bird communities in three types of farmsteads and open farmland; (2) changes in species‐specific habitat preferences between winter and spring; and (3) effect of landscape composition, ruderal vegetation and altitude on bird assemblages. Farmsteads with animal production harboured the highest, whereas open farmland areas had the lowest, species richness and abundance of all farmland birds and red‐listed farmland birds. The decline of species richness in winter was more pronounced in farmland and abandoned farmsteads compared to farmsteads with plant and animal production. Single bird species showed different habitat preferences but the majority of species including red‐listed farmland birds changed preferences towards animal farmsteads during winter. Bird species richness was negatively correlated with altitude and positively with representation of ruderal vegetation. Rarefied gamma diversity confirmed local patterns for both all species and red‐listed species: the highest total species richness was observed in active animal farmsteads but differences among types were significant only during winter. Synthesis and applications. Active farmsteads are local bird diversity hotspots in agricultural landscapes, and host species of conservation concern. Our results highlight the importance of farmsteads during winter, which is a critical period for several wintering farmland species. Our research thus indicates that recent conservation measures for farmland birds should also focus on conservation within non‐farmed habitats, such as actively used farmsteads.

Grassland management in agricultural vs. forested landscapes drives butterfly and bird diversity

Calcareous grasslands and orchard meadows are among the most species-rich semi-natural habitats in Europe, but they are severely threatened by intensified land use and abandonment. Here, we focus on the effects of management vs. abandonment of these grasslands in agricultural vs. forest-dominated landscapes of Germany. We recorded butterflies and birds and classified them in farmland and woodland species according to their habitat preferences. Species richness and abundance of farmland butterflies were higher on calcareous grasslands than orchard meadows and benefited from forested landscapes in case of orchard meadows. Species richness of woodland butterflies was higher on abandoned than managed grasslands, independent of habitat type and landscape context. Richness and abundance of farmland birds benefited from managed orchard meadows, and were more abundant in agricultural landscapes. On calcareous grasslands, however, the abandonment led to higher richness and abundance of farmland birds. Woodland birds exhibited higher species richness in abandoned than managed grasslands, especially in orchard meadows. Woodland birds and butterflies appeared to be less affected by habitat type, management or landscape context than farmland species. Calcareous grasslands were much more important for butterfly diversity than orchard meadows, but suitability of orchards for butterflies was improved when embedded in forested landscapes. In contrast to butterflies, bird diversity benefited more from orchard meadows than calcareous grasslands, which had higher diversity when management was abandoned. In conclusion, landscape context can shape communities in these two grassland habitat types, so conservation management should consider reserves in both agricultural and forested landscapes and thereby, diversify regional biota.

Effects of agri-environmental habitat provision on winter and breeding season abundance of farmland birds

Farmland bird populations continue to show declines in spite of over 20 years of research and implementation of agri-environmental schemes (AES) intended to reverse this. Although it is well known that provision of winter food resources can attract farmland birds, there is continuing uncertainty over the ability of AES to provide tangible benefits for target species in terms of increased abundance. Answering these questions is hampered by interannual fluctuations in bird populations and the mobility and territoriality of farmland birds, which have complicated the interpretation of previous studies.We monitored birds for five years on a large arable estate in central England managed under varying levels of AES uptake (low level uptake of simple and widely applicable AES options, more extensive uptake of more complex AES options), and two control treatments (on-site and off-site). Bird abundance in winter and both total abundance and number of territories in the breeding season were calculated from monthly visits to 16 transects.Several species showed significantly higher winter abundance on AES treatments, particularly granivorous species (e.g. reed bunting, yellowhammer, linnet). Many other species (e.g. blackbird, chaffinch, robin) also showed significant differences in winter abundance between treatments on the estate and off-site controls. In the breeding season, linnet, reed bunting, goldfinch and combined granivorous birds showed higher abundance or number of territories on AES treatments compared to on-site controls. For most other species the differences were only significant between treatments on the estate and off-site controls. Independently of AES treatment, a lower coverage of cereals or greater Shannon diversity of crops in the local landscape also had a positive effect on the abundance of many species.Our results suggest that well-implemented AES can significantly enhance local populations of both farmland specialists of conservation concern and generalist species. Our results also show that, in many cases, these effects were only demonstrable at the farm scale, in comparison with off-site controls. This is probably due to high levels of movement and dispersal of birds resulting in a farm-scale spill-over of beneficial effects of agri-environment measures. Our results therefore highlight the importance of thinking beyond the single-farm scale when designing schemes or studies for monitoring the effectiveness of AES, and the importance of selecting appropriately located controls.

Large changes in the avifauna in an extant hotspot of farmland biodiversity in the Alps

SummaryLarge declines of farmland bird species have been observed in the lowlands of Western Europe, whereas important populations of some of these species have survived in parts of Eastern and Southern Europe and in small areas within Western Europe, e.g. in parts of the Alps. However, such extant hotspots of farmland biodiversity are at risk: The economic and technical developments threaten to erode biodiversity in existing hotspots, potentially repeating the collapse previously observed in Western Europe. We here present changes in the abundance of farmland birds in the Engadin in the Swiss Alps. Farmland birds such as WhinchatSaxicola rubetraand SkylarkAlauda arvensiswere still numerous in 1987/1988 when we first censused the area. During our second census period in 2009/2010, we noticed strong declines of such open country species, while several hedge and tree breeders as well as some species preferring warmer climate increased. We observed a good correlation between the change in the vegetation and in the birds. Both these changes were especially pronounced in areas with a recent agricultural improvement project. Thus, we believe that the change in farmland practices, which affected our mountainous study area much later than the lowlands, and possibly climate change, have led to a profound change in the regional avifauna. Using our data as a case study, we argue that similar, and similarly fast, changes may be on-going or imminent in many other areas with extant important populations of farmland species such as Whinchat and Skylark. Thus, our data add to the repeatedly declared urgency to adjust the advancement of agricultural subsidy systems to better accommodate biodiversity considerations, both in depauperated areas as well as in extant hotspots.

The effect of land type diversity and spatial heterogeneity on farmland birds in Norway

The decline in farmland birds observed throughout Europe during recent decades has attracted much attention. Agricultural intensification or land abandonment are commonly forwarded as key drivers. Several countries have established agri-environmental schemes (AES) to counter these negative trends among farmland birds. This paper reports a study of the relationship between land use and bird species in the agricultural landscape of Norway. The main objective was to investigate the effect of spatial heterogeneity and diversity of land use on total richness and abundance of farmland birds at a national level.Monitoring the distribution and abundance of birds is part of the Norwegian monitoring programme for agricultural landscapes. The monitoring programme is based on mapping of 1×1km squares distributed across the entire agricultural landscape. Within these squares permanent observation points are established for bird monitoring. Detailed interpretation of aerial photographs provides the land classification. We tested the relationship between landscape metrics at different levels of land type detail and species richness and abundance of farmland and non-farmland birds.There was a positive relationship between species richness and abundance of farmland birds and agricultural area. For non-farmland birds the relationship was negative. Spatial heterogeneity of land use was a significant positive factor for both farmland and non-farmland species. High land type diversity was positive for farmland bird richness, but negative for abundance. Non-farmland bird richness was not affected by land type diversity, but abundance had a negative response.The results presented in this paper highlight the importance of a spatial heterogeneous landscape. However, we also found that land type diversity could negatively affect the abundance of both farmland and non-farmland birds. Our findings suggest a need for different management approaches depending on whether the aim is increased species richness or abundance. Achieving both aims with the same means might be difficult. We thus suggest a need for land use analyses before proper management strategies can be implemented.

Moving Window Abundance – A method to characterise the abundance dynamics of farmland birds: The example of Skylark (Alauda arvensis)

Farmland birds are important indicators of the state of biodiversity in rural landscapes, and the occurrence and abundance of birds contribute to their importance as bioindicators. However, the measurement of farmland bird abundance can be difficult. The rapid growth of crop plants in the spring combined with disturbances related to farming practices, such as weed and pest control and other measures, can profoundly change the habitat suitability of arable fields for birds within a short period of time. Consequently, the existing dynamics must be incorporated into the applied methods, and a single value of bird abundance during the breeding season is insufficient to characterise the habitat functions of arable land. The abundance of farmland bird species is influenced by crop specific features, which profoundly change within the breeding season and which we have described using a novel concept called Moving Window Abundance. Based on field surveys in 29 observation areas within arable landscapes, each 1km2, Skylark with territorial behaviour were counted using a mapping method related to the habitats and growth of field crops, such as wheat and maize. To describe the dynamic characteristics of the abundance during the breeding season over the time period from 16 March to 18 July, three methods of Moving Window Abundance were tested: patchy, adjacent and overlapping. These methods differ in the time-space continuity of the considered time window throughout the breeding season. In the Patchy Moving Window Abundance method, we used the exact days in which field surveys were conducted throughout the entire time period of the field surveys. However, with the Adjacent Moving Window Abundance method, the time window included five-day, ten-day and semi-monthly adjacent windows; in the Overlapping Moving Window Abundance method, the time window shifted daily, with five-day, ten-day and semi-monthly overlapping windows used in the calculation procedure. The results indicated that the dynamic nature of Skylark abundance (i) reached a maximum level in the first breeding period in the agricultural landscape and (ii) exhibited large variations in level and time within the various field crops. Therefore, abundance was not described conventionally using a single numerical value but rather using mathematical functions based on the spatial scale of the landscape and habitat. We conclude with recommendations for further research to standardise farmland bird monitoring.