Large-scale patterns of summer and winter bird distribution in relation to farmland type in England and Wales

Over the last 30 yr, the loss of traditional crop rotations and the polarisation of pastoral and arable farming have led to a marked reduction in mixed agriculture in Britain at both the individual farm and the landscape scale. We assess the potential impact of this change on lowland farmland birds by examining the extent to which distributions (as shown by national atlases of summer and winter birds) of different species are associated with arable, pastoral or mixed‐farming landscape types. Relatively few species appeared as either widespread generalists, equally associated across the three broad farmland types, or specialists associated only with one landscape type. Most were associated with two farmland types but distributions showed seasonal differences. During the breeding season there was an approximate ratio of 2:2:1 of species associated with arable, mixed and pastoral landscapes. However, in winter, most species were at highest abundance in mixed farming landscapes. This coincided with a reduction in the number of species associated with pastoral landscapes relative to the breeding season, whereas the number of species associated with arable landscapes remained relatively stable. These patterns are likely to be related to foraging requirements; granivorous birds tended to be associated with arable habitats, which tend to be more seed‐rich, and invertebrate‐feeding species tended to be associated with mixed or pastoral ones, which may be more invertebrate‐rich. The relative importance of mixed landscapes in winter was attributed to seasonal changes in the distribution of some invertebrate feeders, particularly small insectivores (pipits, chats and wagtails), and some of those species considered to be widespread in summer. The results have two important implications for future research. First, most research on farmland birds has, to date, focused on species associated with arable farming during the breeding season. More research is required on species associated with agricultural grasslands, reflecting its importance for farmland birds in Britain, and on the winter ecology of farmland birds in general. These results also emphasise the importance of mixed habitats for farmland birds, particularly in winter, and suggest that further changes in agricultural practices causing reduction in habitat diversity will be detrimental for the farmland bird community. However, widespread benefits may be derived from small scale measures that increase habitat diversity within farmland, for example field margin management options within agri‐environment schemes and support for traditional farming practices in some Environmentally Sensitive Areas.     

Agricultural habitat-type and the breeding performance of granivorous farmland birds in Britain

Conservation concern about granivorous birds has led to the implication of changing agricultural practices as causes of widespread population decline. We investigate relationships between breeding performance and the agricultural environment for ten granivorous farmland bird species (Stock Dove Columba oenas, Skylark Alauda arvensis, Tree Sparrow Passer montanus, Chaffinch Fringilla coelebs, Greenfinch Carduelis chloris, Linnet C. cannabina, Bullfinch Pyrrhula pyrrhula, Reed Bunting Emberiza schoeniclus, Yellowhammer E. citrinella and Corn Bunting Miliaria calandra). We analyse long-term, extensive data from the British Trust for Ornithology's Nest Record Scheme on breeding performance per breeding attempt with respect to farmland type (arable, grazing or mixed) and time (pre- and post-1975–76). The influence of habitat is investigated at two different scales: within the nesting territory and at the landscape level. Relationships between farmland type and (temporal changes in) breeding performance tended to be species-specific, but a few patterns were each common to some species. Improvements in breeding performance occurred across all three farmland types for four declining species. Grazing farmland seems to have deteriorated as breeding habitat for Linnet and arable/mixed farmland for Reed Bunting. Mixed farming at the territory scale supported better breeding performance for four species, three of which (Bullfinch, Yellowhammer and Corn Bunting) have declined concurrently with mixed farming. Pastoral landscapes supported better breeding performance for up to seven species, six of which have undergone large declines. Arable landscapes supported better breeding only for the stable or increasing Chaffinch and Greenfinch. Different relationships between farming regime and breeding performance were found at the two scales considered.     

Effects of landscape composition on farmland and red-listed birds in boreal agricultural-forest mosaics

Farmland birds have declined in large areas of western and northern Europe. This decline has been connected with changes in the agricultural landscape. We studied the effects of landscape composition on birds in a boreal agricultural-forest mosaic in SW Finland. This study was carried out with a grid-based approach: bird pairs were counted in 105 grid squares of 25 ha within an area of 26.25 km². The total density of farmland birds and density of red-listed species were related to the land cover variables using generalized linear modelling (GLM). Farmland birds consist of a variable group of species either breeding or feeding in agricultural land. The model explained a moderate proportion (49%) of the variation in the total density of farmland birds in the landscape. In a regression analysis cover of non-arable agricultural land (semi-natural grasslands, built-up areas) explained a much higher proportion (r²=0.49) of the variation in farmland bird density than that of arable land (cultivated fields and set-aside fields, r²=0.04). Semi-natural grasslands, which have drastically declined throughout NW Europe, and built-up areas (mainly farmyards) had the most significant positive effects on the density of red-listed species. The results emphasize the significance of semi-natural grasslands for the declining red-listed farmland bird species. Birds are usually not restricted to certain patches of habitat but use several patches in their home range. Thus, when studying bird-landscape relations for land use planning, we also recommend grid-based approaches covering the whole landscape variation.     

Low-Intensity Agricultural Landscapes in Transylvania Support High Butterfly Diversity: Implications for Conservation

European farmland biodiversity is declining due to land use changes towards agricultural intensification or abandonment. Some Eastern European farming systems have sustained traditional forms of use, resulting in high levels of biodiversity. However, global markets and international policies now imply rapid and major changes to these systems. To effectively protect farmland biodiversity, understanding landscape features which underpin species diversity is crucial. Focusing on butterflies, we addressed this question for a cultural-historic landscape in Southern Transylvania, Romania. Following a natural experiment, we randomly selected 120 survey sites in farmland, 60 each in grassland and arable land. We surveyed butterfly species richness and abundance by walking transects with four repeats in summer 2012. We analysed species composition using Detrended Correspondence Analysis. We modelled species richness, richness of functional groups, and abundance of selected species in response to topography, woody vegetation cover and heterogeneity at three spatial scales, using generalised linear mixed effects models. Species composition widely overlapped in grassland and arable land. Composition changed along gradients of heterogeneity at local and context scales, and of woody vegetation cover at context and landscape scales. The effect of local heterogeneity on species richness was positive in arable land, but negative in grassland. Plant species richness, and structural and topographic conditions at multiple scales explained species richness, richness of functional groups and species abundances. Our study revealed high conservation value of both grassland and arable land in low-intensity Eastern European farmland. Besides grassland, also heterogeneous arable land provides important habitat for butterflies. While butterfly diversity in arable land benefits from heterogeneity by small-scale structures, grasslands should be protected from fragmentation to provide sufficiently large areas for butterflies. These findings have important implications for EU agricultural and conservation policy. Most importantly, conservation management needs to consider entire landscapes, and implement appropriate measures at multiple spatial scales.     

Farmland as stopover habitat for migrating birds – effects of organic farming and landscape structure

Agricultural intensification in Europe has affected farmland bird populations negatively, both during summer and winter. Although the migratory period poses separate challenges on birds than breeding and wintering, the consequences of farming practices for birds during migration remain poorly investigated. We monitored abundance and species richness of migratory birds in autumn at matched pairs of organic and conventional farms situated either in intensively farmed open plains (homogeneous landscapes) or in small‐scale farming landscapes (heterogeneous landscapes) in southern Sweden. Total bird density did not differ between landscape types but was marginally higher on organic compared to conventional farms. When including taxonomic status in the model (passerines vs non‐passerines), we found significantly more birds on organic farms, and more non‐passerines in the homogeneous landscapes. The effect of farming practice and landscape type on density differed between functional groups. Omnivore density was higher in the homogeneous landscapes, and invertebrate feeders were marginally more abundant on organic farms. The effects of farming practice on the overall species richness and on the density of granivorous birds were landscape dependent. In the homogeneous landscapes, organic farms held a higher number of species and density of granivorous birds than conventional farms, but there was no such difference in the heterogeneous landscapes. Thus, organic farming can enhance abundance and species richness of farmland birds during migration, but the effect differs between landscape types and species. The effectiveness of organic farming was highest in the homogeneous landscape making it important to promote organic farming there. However, for some species during migration, increased heterogeneity in homogeneous landscapes may have negative effects. We propose that migratory bird diversity in homogeneous landscapes may be best preserved by keeping the landscape open, but that a reduced agricultural intensity, such as organic farming, should be encouraged.     

Testing agri‐environment delivery for farmland birds at the farm scale: the Hillesden experiment

The Hillesden experiment, established in 2005/2006 to test the delivery of biodiversity benefits under Environmental Stewardship, covers c. 1000 ha of arable farmland in central lowland England. It is a randomized block experiment with five replicates of three treatments: (1) CC: cross compliance, the control; (2) ELS: 1% of land removed from production for wildlife habitat provision; and (3) ELS‐X: 5% of land used for wildlife habitat, each treatment being applied to contiguous areas of 70–80 ha. Bird usage of winter food patches, comprising three different seed mixes, was monitored through the winter and was also related to seed yield. Winter and breeding season bird/territory abundance was recorded before and after the provision of the winter food patches. Bird use of the patches differed between seed mixes. There was large variation between individual patches in both seed yield and bird numbers and between individual bird species in their use of different seed mixes, suggesting that the availability of a range of patch types would be beneficial. Use of all patch types declined sharply in late January to February, indicating depletion and/or inability of birds to access shed seed. Winter bird abundance at a farm scale for all species combined, granivorous species and nine individual species increased for all monitored species when seed patches were available. At a treatment level, the increases tended to be greater in ELS‐X, where most of the patches were located. In the breeding season at a farm scale, the numbers of territories for all species combined and granivorous species increased significantly when seed patches had been available in the previous winter. There was little evidence of a treatment‐scale response. The provision of winter food appeared to increase winter bird abundance and to follow on into an overall increase in the breeding population, but if the latter effect is to be reflected elsewhere, this requires that sufficient breeding habitat is available to accommodate an increase.     

Rapid redistribution of agricultural land alters avian richness,abundance, and functional diversity

The conversion of natural, or seminatural, habitats to agricultural land and changes in agricultural land use are significant drivers of biodiversity loss. Within the context of land‐sharing versus land‐sparing debates, large‐scale commercial agriculture is known to be detrimental to biodiversity, but the effects of small‐scale subsistence farming on biodiversity are disputed. This poses a problem for sustainable land‐use management in the Global South, where approximately 30% of farmland is small‐scale. Following a rapid land redistribution program in Zimbabwe, we evaluated changes in avian biodiversity by examining richness, abundance, and functional diversity. Rapid land redistribution has, in the near term, resulted in increased avian abundance in newly farmed areas containing miombo woodland and open habitat. Conversion of seminatural ranched land to small‐scale farms had a negative impact on larger‐bodied birds, but species richness increased, and birds in some feeding guilds maintained or increased abundance. We found evidence that land‐use change caused a shift in the functional traits of the communities present. However, functional analyses may not have adequately reflected the trait filtering effect of land redistribution on large species. Whether newly farmed landscapes in Zimbabwe can deliver multiple benefits in terms of food production and habitat for biodiversity in the longer term is an open question. When managing agricultural land transitions, relying on taxonomic measures of diversity, or abundance‐weighted measures of function diversity, may obscure important information. If the value of smallholder‐farmed land for birds is to be maintained or improved, it will be essential to ensure that a wide array of habitat types is retained alongside efforts to reduce hunting and persecution of large bird species.     

Bioenergy production and Skylark (Alauda arvensis) population abundance – a modelling approach for the analysis of land‐use change impacts and conservation options

Bioenergy production is seen as one way of meeting future energy needs. The growing demand for biomass for energy production induces the cultivation of a few fast growing and high‐yielding energy crops on vast areas of arable land. This land‐use change has been found associated with the reduction of habitat suitability for farmland birds and a decline in farmland biodiversity in general. A large number of studies have assessed the ecological effects of energy crop cultivation at the local scale of a single field. This study focuses on regional landscape changes caused by increased energy crop cultivation, which includes reduction of crop‐type richness and spatial concentration of single crop‐types. We present a spatially explicit ecological model to assess the population‐level consequences of these effects on the abundance of the farmland bird species Skylark (Alauda arvensis). We also investigate the impacts of different land‐use scenarios and aim to identify adaptive conservation options. We show that (1) the impacts of increased energy crop cultivation on Skylark population abundance depend strongly on the landscape structure; (2) impacts could be tolerated as long as a certain minimum level of crop‐type heterogeneity is retained at the landscape level and (3) conservation actions are required and effective especially on landscapes where crop‐field size is large.     

Contrasting patterns of change in the distribution and abundance of farmland birds in relation to farming system in lowland Britain

Patterns of change in distribution (presence/absence) and abundance since the late 1960s were examined in 20 species of farmland bird in southern Britain in predominantly arable (eastern), predominantly mixed (central) and predominantly grassland (western) regions. Comparisons were made between changes in distribution and in abundance to determine whether these measures show similar relationships to environmental change. Local extinctions of selected species and reductions in species richness were significantly greater in the predominantly grassland region. Decreases in abundance were greatest in seven species in the predominantly arable region, two in the mixed region and nine in the grassland region. Changes in distribution and abundance showed consistent patterns in three species, turtle dove Streptopelia turtur L., yellow wagtail Motacilla flava L. and reed bunting Emberiza schoeniclus L. In another four species, grey partridge Perdix perdix L., lapwing Vanellus vanellus L., tree sparrow Passer montanus L. and corn bunting Miliaria calandra L., decreases in abundance were greatest in the arable region, yet declines in distribution were lowest. For other individual species, changes in distribution were too small to draw any conclusions in relation to farm type. We suggest that modern grassland systems are suboptimal habitats compared to arable or mixed agricultural land for many farmland species that occur at relatively low density in the more western, grass‐dominated region. Declines in abundance are therefore more likely to lead to local extinction in these areas than in eastern areas where abundance is higher. However, the role of changes in grassland management on bird populations requires further research. It is suggested that conclusions drawn from changes in distribution alone, in the absence of supporting data on changes in abundance, may be misleading where the aim is to assess how large‐scale spatial dynamics of populations relate to environmental change.     

Forecasting the Effects of Land Use Scenarios on Farmland Birds Reveal a Potential Mitigation of Climate Change Impacts

Climate and land use changes are key drivers of current biodiversity trends, but interactions between these drivers are poorly modeled, even though they could amplify or mitigate negative impacts of climate change. Here, we attempt to predict the impacts of different agricultural change scenarios on common breeding birds within farmland included in the potential future climatic suitable areas for these species. We used the Special Report on Emissions Scenarios (SRES) to integrate likely changes in species climatic suitability, based on species distribution models, and changes in area of farmland, based on the IMAGE model, inside future climatic suitable areas. We also developed six farmland cover scenarios, based on expert opinion, which cover a wide spectrum of potential changes in livestock farming and cropping patterns by 2050. We ran generalized linear mixed models to calibrate the effects of farmland cover and climate change on bird specific abundance within 386 small agricultural regions. We used model outputs to predict potential changes in bird populations on the basis of predicted changes in regional farmland cover, in area of farmland and in species climatic suitability. We then examined the species sensitivity according to their habitat requirements. A scenario based on extensification of agricultural systems (i.e., low-intensity agriculture) showed the greatest potential to reduce reverse current declines in breeding birds. To meet ecological requirements of a larger number of species, agricultural policies accounting for regional disparities and landscape structure appear more efficient than global policies uniformly implemented at national scale. Interestingly, we also found evidence that farmland cover changes can mitigate the negative effect of climate change. Here, we confirm that there is a potential for countering negative effects of climate change by adaptive management of landscape. We argue that such studies will help inform sustainable agricultural policies for the future.     

Agricultural intensification and farmland birds: new insights from a central European country

The relationship between agricultural intensification and a decline in farmland bird populations is well documented in Europe, but the results are mostly based on data from the western part of the continent. In the former socialist eastern and central European countries, political changes around 1990 resulted in a steep decline in the intensity of agriculture. Therefore, one would expect populations of farmland birds to have recovered under these conditions of lower agricultural intensity. We explored population trends of 19 farmland bird species in the Czech Republic between 1982 and 2003 using data from a large‐scale monitoring scheme, and, additionally, we looked for relationships between such population changes and a number of variables describing the temporal development of Czech agriculture. Most farmland species declined during the focal period, and this decline was steepest in farmland specialists (Northern Lapwing Vanellus vanellus, Skylark Alauda arvensis, Linnet Carduelis cannabina and Yellowhammer Emberiza citrinella). Although the intensity of agriculture was lower after than before 1990, the overall decline continued in most farmland bird species, albeit at a slower rate. The correlations between agricultural intensity and farmland bird decline showed opposite patterns to that found in other European studies, because bird populations were highest in years with the most intensive agriculture. We speculate that this pattern could have resulted from the impact of different driving forces causing farmland bird decline in different periods. The high intensity of agriculture could have caused the decline of the originally abundant populations before 1990. After 1990, the decreasing area of arable land could be the most important factor resulting in the continued decline of farmland bird populations. Our results demonstrate that the drivers of farmland bird population changes could differ across Europe, and thus investigations into the effect of farmland management in different parts of the continent are urgently required.     

Organic farming at local and landscape scales benefits plant diversity

Agri‐environment schemes (AES) have been suggested to counter negative effects of agricultural intensification and enhance farmland biodiversity, but evaluations have produced inconsistent results. We suggest that this is partly a consequence of scale‐dependence, i.e. that the consequence of organic farming will differ depending on the scale of uptake in a particular landscape. To test our hypothesis on diversity of forbs, we designed a landscape scale study using spatially explicit information about the Swedish AES for organic farming. The study system consisted of uncultivated field borders along paired fields (organic and conventional) in matched landscapes with either a high or a low proportion of organic faming, allowing separate tests of the effects of farming practice at the local and the landscape scale. The local effect of organic farming was consistently strong, with higher diversity in borders adjoining organic fields, most likely due to the lack of herbicide use on organically managed farmland. Thus, we show that not only the proportion of semi‐natural habitat is important for farmland biodiversity, but that also the management of cropland can influence the diversity in semi‐natural habitats. Furthermore, forb richness was also higher in borders situated in landscapes with a high proportion of organic land, irrespectively of local management, possibly as a result of dispersal of mainly annual plant species from the organically managed fields into the borders (mass effect). Our results demonstrate that farming practice at a local and a landscape scale independently can influence plant species richness, indicating that organic farming can influence diversity also at larger spatial scales and outside the organically managed land. Our study highlight the importance of studying multiple scales, including both local and landscape factors to provide a better understanding of biodiversity patterns.     

The relationship between multi‐scale habitat heterogeneity and farmland bird abundance

It has recently been proposed that losses in farmland habitat heterogeneity may have been a primary driver of the profound declines exhibited by many farmland bird species in recent decades. However, it has yet to be demonstrated which facets of heterogeneity and what spatial scales are most important for birds. Here we analyse the relationship between abundance and features of landscape heterogeneity at three spatial scales (1, 9 and 25 km²) for 32 bird species commonly associated with farmland. Heterogeneity was quantified using three contrasting indices reflecting 1) the spatial mixing of land uses, 2) variation in field sizes and 3) the density of field boundaries. The spatial mixing of land‐uses explained, on average, the most variation in, and was most likely to be positively associated with, abundance at all spatial scales. The majority of species (66–75%, depending on the spatial scale) were more common in heterogeneous landscapes overall; however, migrants, those under a high level of conservation concern and farmland specialist species tended to be less abundant in more heterogeneous landscapes at all scales. Ground‐nesting species were also more likely to be found in more homogeneous habitats than non‐ground‐nesters, but only at the finest spatial scale. Relationships between abundance and heterogeneity were generally consistent across spatial scales; however, species of high conservation concern had more variable associations compared with other species. These results highlight a potential role for farmland habitat heterogeneity in determining the abundance of many farmland species but suggest that population responses to an increase in heterogeneity would not be unanimously positive and would probably have negative impacts on some species, notably those that are already threatened.     

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 1 km², 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.     

Multi-species spatially-explicit indicators reveal spatially structured trends in bird communities

Multi-species indicators are often used to assess biodiversity trends. By combining population trends across several species they summarise trends across a community. Composite indicators such as these are useful for examining general temporal patterns and may suggest important drivers of biodiversity change. However, they may also mask substantial spatial variation in population trends, particularly when they are calculated over large spatial regions. We produced spatially-explicit indicators for farmland and woodland bird communities in the UK and further separate these into trends for generalist and specialist species within each group. We found considerable spatial variation in the indicators, which is masked by indicators calculated at the national level. The farmland community indicator showed mostly positive trends in western areas and extensive declines in south-east England. The woodland community indicator showed a north–south divide, with increases in Scotland and northern England and stability in the southern regions. For both communities, indicator trends for specialist species were more negative than those for generalists. We found no significant difference in farmland community indicators between arable land and improved grassland. Woodland specialists had significantly more negative trends in broadleaf compared to coniferous woodlands, suggesting habitat-type is one of the drivers of changes in the woodland community. These spatial patterns in bird population trends may be used to highlight regional conservation priorities and identify where those may differ from the national scale. In combination with information about other environmental changes, they may also be used to develop hypotheses about potential drivers of change. We advocate that this approach is adopted for other taxa and geographical areas.     

Should conservation strategies consider spatial generality? Farmland birds show regional not national patterns of habitat association

A key assumption underlying any management practice implemented to aid wildlife conservation is that it will have similar effects on target species across the range it is applied. However, this basic assumption is rarely tested. We show that predictors [nearly all associated with agri-environment scheme (AES) options known to affect European birds] had similar effects for 11 bird species on sites with differing farming practice (pastoral vs. mixed farming) or which differed in the density at which the species was found. However, predictors from sites in one geographical region tended to have different effects in other areas suggesting that AES options targeted at a regional scale are more likely to yield beneficial results for farmland birds than options applied uniformly in national schemes. Our study has broad implications for designing conservation strategies at an appropriate scale, which we discuss.     

From savannah to farmland: effects of land‐use on mammal communities in the Tarangire–Manyara ecosystem,Tanzania

Land‐use change is considered a major driver of biodiversity loss. In the western part of the Tarangire–Manyara ecosystem, we assessed large mammal species richness along a land‐use gradient (national park, uninhabited pastoral area and settled pastoral‐ and farmland). We found the highest species richness in the national park and in the pastoral area and lowest species richness in the settled and farmed area. There was little evidence of seasonal changes in species diversity. Except for top‐order carnivores, all functional feeding guilds were still represented in pastoral and settled areas. Although we did not find significant differences in body mass distributions and species’ representation of feeding guilds between the study sites, there was a trend that omnivores, mesopredators and top‐order carnivores tended to occur at lower species richness in agricultural areas than in the pastoral and fully protected areas. These results indicate that areas used for livestock keeping can maintain high wildlife species richness and that direct and indirect effects of agricultural and settlement expansions are the main drivers of species richness loss in the Tarangire–Manyara ecosystem and possibly other African savannah ecosystems. These results are useful for informed land‐use planning that aims to maintain species diversity and ecological connectivity between protected areas.     

Land use changes affect distributional patterns of desert birds in the Baja California peninsula, Mexico

Reliable plans for desert bird conservation will depend on accurate prediction of habitat change effects on their distribution and abundance patterns. Predictive models can help highlight relationships between human‐related and other environmental variables and the presence of desert bird species. Presence/absence of 30 desert bird species of Baja California peninsula was modelled on the basis of explanatory variables taken from the field, maps, and digital imagery. Generalized linear models were fit to each bird species using both variables representing human activity and other environmental factors as predictors that might influence distribution. Probability of species presence was used as a habitat suitability index to evaluate the effect of human activity when the model contained a significant human activity variable. No differences were found in bird species richness between natural sites and those transformed by agriculture or urbanization. Of 59 bird species recorded in surveys, 34% were positively or negatively associated with human‐transformed habitats. Fourteen species seem to benefit from transformation of natural vegetation by agriculture or urbanization, while six were negatively affected. Sensitivity analyses of final models indicated all were robust. Results suggest that the occurrence of a large percentage of bird species inhabiting scrub habitats is sensitive to human habitat transformation. This finding has important conservation implications at regional scale as fragmentation and conversion of desert ecosystems into agricultural and urban areas affect the distribution of species that are highly selective for scrub habitat. Land use and anthropogenic activities seem to change ecological patterns at large spatial scales, but other factors could drive species richness distribution too (i.e. individual species response, species–energy relationships). The spatial modelling approach at regional scale used in this study can be useful for designing natural resource management plans in the Sonoran desert scrub.     

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 × 1 km 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.