Specialist Bird Research Articles

Hunting efficiency of Red-footed Falcons in different habitats

Abstract We studied hunting success of 13 male Red-footed Falcons by radio-telemetry in the second phase of chick rearing. We coded 484 hunting events, and the success measured in captured prey biomass/minute was exceedingly high in corn fields. This is mainly caused by the fact that the effectiveness of hunting for vertebrate prey was high on the harvested stubble fields. Moreover the observed falcons hunted for insects in these stubble field and alfalfa fields most successfully. In the studied habitat the chick feeding period of Red-footed Falcons coincide with the harvest of cereal fields, and the suddenly created lower vegetation cover increases temporarily the accessibility of prey items. Till they were available and could be efficiently harvested, the falcons hunted on the fields within a 1 km radius from the nesting colony for the more profitable vertebrate prey. Thereafter they searched for vertebrate prey on the fields located at average 1–2.5 km distance from the colony. In the later zone falcons started to hunt insects, too, but approximately third of the captured insects (36.4%) was consumed immediately and was not delivered to the colony. Conversely larger prey was almost always (98.1%) carried directly to the nest site. Only one part of the Field Voles was observed to be eaten regularly: the brain. Finally later in the breeding season falcons were observed more and more often to hunt in the nearest fields again, this time for insects. Probably due to the depletion of the distant plots, the closer fields with lower investment became a competitive alternative for the birds. Our results highlight the fact that even for such characteristic short-grass specialist birds as Red-footed Falcons the prey sources offered by arable lands might be temporarily exploited with success. Hence it is very important to integrate the measures offered by agri-environment schemes into the management of this threatened species.

Environmental gradients explain species richness and community composition of coastal breeding birds in the Baltic Sea.

Scientifically-based systematic conservation planning for reserve design requires knowledge of species richness patterns and how these are related to environmental gradients. In this study, we explore a large inventory of coastal breeding birds, in total 48 species, sampled in 4646 1 km2 squares which covered a large archipelago in the Baltic Sea on the east coast of Sweden. We analysed how species richness (α diversity) and community composition (β diversity) of two groups of coastal breeding birds (specialists, i.e. obligate coastal breeders; generalists, i.e. facultative coastal breeders) were affected by distance to open sea, land area, shoreline length and archipelago width. The total number of species per square increased with increasing shoreline length, but increasing land area counteracted this effect in specialists. The number of specialist bird species per square increased with decreasing distance to open sea, while the opposite was true for the generalists. Differences in community composition between squares were associated with differences in land area and distance to open sea, both when considering all species pooled and each group separately. Fourteen species were nationally red-listed, and showed similar relationships to the environmental gradients as did all species, specialists and generalists. We suggest that availability of suitable breeding habitats, and probably also proximity to feeding areas, explain much of the observed spatial distributions of coastal birds in this study. Our findings have important implications for systematic conservation planning of coastal breeding birds. In particular, we provide information on where coastal breeding birds occur and which environments they seem to prefer. Small land areas with long shorelines are highly valuable both in general and for red-listed species. Thus, such areas should be prioritized for protection against human disturbance and used by management in reserve selection.

Impact of landscape composition and configuration on forest specialist and generalist bird species in the fragmented Lacandona rainforest, Mexico

With accelerated land-use change throughout the tropics, an increasing proportion of global biodiversity is located in human-modified landscapes. Understanding the relative effects of landscape composition and configuration on biodiversity is needed to design effective conservation strategies. Yet this topic is poorly understood because most studies have been performed at the patch scale, and do not assess the impact of landscape structure on species. Using a multi-model inference approach, we assessed the relative effect of landscape composition (i.e. percentage of forest cover and matrix composition) and landscape configuration (i.e. number of forest patches and forest edge density) on α- and β-diversity of birds in 17 forest fragments and three areas of continuous forest within the Lacandona rainforest, Mexico. We tested these impacts at two spatial scales (100 and 500ha) for forest specialist and generalist birds. In general, forest specialist birds showed stronger responses to landscape characteristics than generalist species, particularly to variations in landscape composition at the 100-ha scale. The loss of forest cover represented the main threat to forest specialist birds, with a negative impact on α-diversity that was consistent across the two spatial scales. In contrast, at the two spatial scales generalist birds seemed to be favored by forest loss, as α-diversity of these birds increased in landscapes with lower forest cover and higher number of forest patches. If current deforestation rates continue, several forest specialists are likely to disappear. Future conservation and management initiatives should therefore prevent deforestation in this biodiversity-rich but vanishing tropical forest ecosystem.

Habitat management effects on Prealpine grassland bird communities

Currently, land abandonment constitutes a serious threat for many species tied to semi-natural grasslands. In southern Europe, the conservation of many grassland bird communities largely depends on low-intensity mountain farming. In this study, we analysed the effects of the main farming practices promoting grassland maintenance, i.e. grazing and mowing, on species richness of a Prealpine grassland bird community and on the breeding densities of the two commonest grassland species, the skylark (Alauda arvensis Linnaeus, 1758) and the tree pipit (Anthus trivialis Linnaeus, 1758). The two study sites were located between 1100 and 2000 m above sea level in the Italian central Prealps. Grassland species richness was positively affected by grazing, and increased with increasing distance from the nearest woodland. Skylark density was positively influenced by mowing, grassland cover extent and distance from woodland, with the latter effect occurring only at a single study site. Finally, tree pipit density was positively affected by grazing. Our findings suggest that, in order to maintain open grasslands below the natural treeline and enhance the biodiversity of grassland bird communities, grazing should be preferred over mowing. Moreover, woodland edge effects may have a negative impact on mountain grassland bird communities. Advancing woodlands and abandonment of low-intensity farming and grazing practices may therefore constitute a serious threat for open-habitat specialist bird species of the Alpine region.

How High Nature Value (HNV) farmland is related to bird diversity in agro-ecosystems – Towards a versatile tool for biodiversity monitoring and conservation planning

Within the European Union, national approaches of a ‘High Nature Value (HNV) farmland’ indicator have been developed to inform about the potential of agricultural landscapes to maintain biodiversity. We assessed how bird species abundance, richness and community composition, particularly of specialist species, were associated with the German HNV farmland indicator as an area-based aggregate and with its particular components which were semi-natural landscape elements and agricultural patches with characteristic plant species mapped in representative sample plots.The aggregated HNV indicator score showed a weak but positive relationship with generalist bird species only, while specialist species were associated with individual HNV farmland features characterizing wet grasslands and open farmland. Bird community analysis revealed three groups of HNV farmland features representative of particular landscape types: (1) complex landscapes with vertical woody structures such as hedgerows or small woodlands, (2) wet grasslands and (3) open agricultural land of low land-use intensity. Large portions of unexplained variance, however, indicated that the small-scaled HNV farmland features recorded without considering the landscape context may not have fully captured all important drivers of bird diversity in agricultural landscapes.To achieve a better representation of habitat requirements particularly of specialist bird species we propose surveying HNV farmland in a landscape context and calculating landscape-specific scores for highly structured, wetland-dominated and open landscapes of low land-use intensity. As compared to the aggregated indicator, the small-scale HNV farmland survey data would more efficiently enfold its potential for tailoring conservation schemes specifically to a given landscape type and its associated bird species.

Individual specialization in a shorebird population with narrow foraging niche

Individual specialization in resource use is a widespread driver for intra-population trait variation, playing a crucial evolutionary role in free-living animals. We investigated the individual foraging specialization of Black-tailed Godwits (Limosa limosa islandica) during the wintering period. Godwits displayed distinct degrees of individual specialization in diet and microhabitat use, indicating the presence of both generalist and specialist birds. Females were overall more specialist than males, primarily consuming polychaetes. Specialist males consumed mainly bivalves, but some individuals also specialized on gastropods or polychaetes. Sexual dimorphism in bill length is probably important in determining the differences in specialization, as longer-billed individuals have access to deep-buried polychaetes inaccessible to most males. Different levels of specialization within the same sex, unrelated to bill length, were also found, suggesting that mechanisms other traits are involved in explaining individual specialization. Godwits specialized on bivalves achieved higher intake rates than non-specialist birds, supporting the idea that individual foraging choices or skills result in different short-term payoffs within the same population. Understanding whether short-term payoffs are good indicators of long-term fitness and how selection operates to favour the prevalence of specialist or generalist godwits is a major future challenge.

Restoration Practices Have Positive Effects on Breeding Bird Species of Concern in the Chihuahuan Desert.

Woody plant encroachment into grasslands is a global concern. Efforts to restore grasslands often assume that removal of woody plants benefits biodiversity but assumptions are rarely tested. In the Chihuahuan Desert of the Southwestern United States, we tested whether abundances of grassland specialist bird species would be greater in plant communities resulting from treatment with herbicides to remove encroaching shrubs compared with untreated shrub‐dominated areas that represented pre‐treatment conditions. In 2010, we surveyed breeding birds and vegetation at 16 treated–untreated pairs. In 2011, we expanded the survey effort to 21 treated–untreated pairs, seven unpaired treatment areas, and five reference grassland areas. Vegetation in treatment areas had higher perennial grass foliar and basal cover and lower shrub foliar cover compared with untreated areas. Several regionally declining grassland specialists exhibited higher occurrence and relative abundance in treated areas. A shrubland specialist, however, was associated with untreated areas and may be negatively impacted by shrub removal. Bird community composition differed between treated and untreated areas in both years. Our results indicate that shrub removal can have positive effects on grassland specialist bird species, but that a mosaic of treated and untreated areas might be most beneficial for regional biodiversity.

斑块生境中食果鸟类对南方红豆杉“(Taxus chinensis var. mairei)”种子的取食和传播

生境斑块化对食果鸟类的移动行为产生影响，进而影响其对植物种子的传播格局和效率。南方红豆杉（<em>Taxus chinensis </em>var. <em>mairei</em>）是我国一级保护植物，在南方山区多因人为干扰而呈斑块状分布。2011年，2012年10月底到12月中，以分布于福建梅花山国家级自然保护区红豆杉生态园中南方红豆杉种群为对象，研究斑块生境中鸟类对南方红豆杉种子的取食和传播行为，并评估专性鸟类和泛性鸟类的传播效率。结果发现：南方红豆杉源斑块共吸引22种食果鸟类取食红豆杉种子，并与13种鸟类形成了种子传播关系。不同年间，黑短脚鹎（<em>Hypsipetes leucocephalus</em>）都是植物的主要传播鸟类，而其他鸟类传播者种类具有一定的年间变化。生境斑块化导致专性鸟类黑短脚鹎和泛性鸟类红嘴蓝鹊（<em>Urocissa</em> <em>erythrorhyncha</em>）种子传播效率差异。与红嘴蓝鹊相比，黑短脚鹎飞行的平均距离较短（（16.3±11.0）m，Mean±SD，<em>n </em>= 125），传播距离相对较近；且它们取食后偏好在源斑块中活动，喜栖息在同种成树、甜楮（<em>Castanopsis eyrei</em>）及其他阔叶树等栖树上。红嘴蓝鹊取食后常在斑块间移动，常停歇在同种成树和毛竹（<em>Phyllostachys heterocycla</em>）上，传播距离相对较远（（24.9±20.0）m，Mean±SD，<em>n </em>= 95）。空间一致性结果表明，黑短脚鹎移动距离对幼苗更新距离的空间一致性程度高；而红嘴蓝鹊偏好生境与幼苗更新生境一致性程度高。结果表明，斑块生境中植物能与专性鸟类、泛性鸟类之间形成种子传播互惠关系，且种子传播效率受到专性鸟类和泛性鸟类传播距离和传播生境的影响。;Human disturbance causes the continual loss of natural habitats, and can result in fragmented habitats consisting only of patchy remnants. This habitat modification can lead to changes in plant-animal interactions. Understanding how the movement behavior of animal dispersers affects the regeneration patterns of plant species in patchy environments has been one of the main objectives of ecologists in recent years. Many previous studies have investigated seed dispersal only in terms of the dispersal distance. However, from the perspective of successful plant growth, it is not only important how far seeds are dispersed, but also where they are finally deposited. The quality of seed dispersal crucially depends on the movement patterns of the dispersing animal vectors; however, few ecological studies have focused on how the patchiness of habitats affects the movement patterns of specialist and generalist bird species, and thus, how habitat patchiness affects plant recruitment. Chinese yew (<em>Taxus chinensis</em> var. <em>mairei</em>) is listed as a Category 1 protected species in China, and it has also been listed as a globally endangered species in the IUCN Red List. A large proportion of the wild population of Chinese yew is distributed in patchy environments, and relies on bird vectors for seed dispersal. Previous studies have shown that Chinese yew seedlings can successfully establish away from mature trees as a result of seed dispersal by birds in the Corvidae and Pycnonotidae. However, it is still unknown how habitat patchiness affects the movement patterns of specialist and generalist bird species, and thus, how it affects the regeneration of Chinese yew and the persistence of its populations. In this study, we studied bird dispersal of Chinese yew seeds in the yew ecological garden of Meihuashan National Reserve. We studied the foraging and dispersing behavior of frugivorous birds in this typical patchy environment, and compared the contributions of a specialist (<em>Hypsipetes leucocephalus</em>) and generalist (<em>Urocissa erythrorhyncha</em>) species to seed dispersal by analyzing their post-foraging movement behaviors. The results showed that the Chinese yew source patch attracted 22 species of frugivorous birds to feed on seeds. A mutualistic seed dispersal relationship was formed between 13 bird species and Chinese yew. The main disperser of Chinese yew seeds was <em>H. leucocephalus. </em>There were annual differences in the other disperser species. The effectiveness of seed dispersal differed between the specialist and generalist bird species. After foraging for Chinese yew seeds, the movement and habitat selection differed between the habitat generalist (<em>U. erythrorhyncha</em>) and habitat specialist (<em>H. leucocephalus</em>) bird species. This may explain the differences in the seed dispersal distance and seed deposition sites between these two species. The habitat specialist bird species dispersed seeds over a short distance (16.3±11.0 m, mean±SD; <em>n </em>= 125) and the seeds were randomly distributed in a bamboo recruitment patch. The generalist species always moved between habitat patches and removed the seeds to the recruitment patch, dispersing seeds over a longer distance (24.9±20.0 m, mean±SD; <em>n</em>= 95). There was a high concordance between the movement distance of the specialist species and the seedling recruitment distance (<em>χ</em>²= 5.844, <em>P </em>= 0.211), and also a high spatial concordance between the habitat of the generalist species and the seedling recruitment habitat (<em>χ</em>²= 4.582, <em>P </em>= 0.205). Our results highlight that seed dispersal mutualistic relationships can form between Chinese yew and both specialist and generalist bird species. The effectiveness of Chinese yew dispersal was affected not only by the dispersal distances of specialist and generalist bird species, but also by the habitat in which the seeds were deposited.

Local improvement of skylark and corn bunting population trends on intensive arable landscape: a case study of the conservation toolNatura 2000

AbstractFor the past 20 years, different policy and regulatory tools such as the agri‐environment schemes (AES) and theNatura 2000 network have been used inEurope to halt the ongoing decline of farmland birds resulting from agricultural intensification. Despite their wide implementation, bird populations are still declining at national andEuropean scales, thus questioning the effectiveness of these schemes. Here, we examined the impact of the designation in 2004 of aSpecialProtectionArea (SPA) for the little bustard on the local trends of two non‐targeted, common but declining farmland birds, the skylark and the corn bunting, in an intensive arable landscape of westernFrance. From 1996 to 2012, trends in skylark presence or abundance decreased whereas trends in corn bunting abundance first decreased and then showed a recovery; the trends differed between outside and inside theSPA. Outside theSPAand consistently with trends at the national andEuropean scales, skylark abundance sharply decreased whereas corn bunting abundance first decreased and then stabilized or even slightly increased. Within theSPA, the skylark declined less, and the corn bunting abundance increased at a faster rate than outside. Our results suggest that the implementation of aSPAin this arable landscape had a positive impact on these two farmland passerines, at least for corn buntings, for which the implementation ofAESclearly improved habitat. Our results also suggest that the extensive implementation ofSPAsmay have had a positive impact on bird population trends in farmlands at a regional level, wherec. 150 000 ha (15–20% of total arable landscape) have been designated since 2004. However, theSPAnetwork (withinNatura 2000) currently covers a mere 3.7% ofFrench arable landscape, and it is therefore no surprise that specialist birds in farmland are still declining nationally.

Does fragmentation increase extinction thresholds? A European‐wide test with seven forest birds

AbstractAimTheory predicts that fragmentation aggravates habitat loss, increasing the extinction threshold of habitat specialists. However, contradictory empirical results have fuelled claims that fragmentation has been overemphasized, and more attention should be given to habitat loss for preserving species. We assess variation in species sensitivity to forest amount and fragmentation and evaluate if fragmentation is related to extinction thresholds in seven forest bird species.LocationEurope.MethodsWe use the percentage of forest cover and the proportion of cover occurring in the largest patch to partition effects of forest amount versus fragmentation, and apply logistic regression to model the presence–absence of 17 forest bird species. For seven species showing robust models, we define two fragmentation scenarios, low and maximum, across the forest cover gradient and quantify species' sensitivity to forest contraction with no fragmentation, and to fragmentation under constant forest cover. Finally, we develop two tests of the extinction threshold hypothesis by comparing the occurrence probability of each species under the two fragmentation scenarios at different forest covers.ResultsAs expected, forest contraction had negative impacts on the occurrence probability of all seven species modelled, but – in line with theory – fragmentation also led to a higher extinction threshold for three (Western capercaillie, Hazel grouse and Eurasian pygmy‐owl). One species (Black woodpecker) exhibited the opposite pattern indicating that it probably benefits from fragmentation. Differences among species responses may reflect dispersal abilities, specializations in resources/habitat characteristics and/or sensitivity to potential modifications of interspecific interactions.Main conclusionsAlthough forest amount is of primary importance for the persistence of forest specialist birds, fragmentation is also relevant for some, and neglecting forest fragmentation would be a mistake for these species. Species‐specific traits can be helpful for interpreting species' reactions to fragmentation, and it should not be assumed that it always, or never, matters.

Deforestation in central Chile causes a rapid decline in landscape connectivity for a forest specialist bird species

AbstractThe abundance of woodland birds in fragmented forest landscapes may depend on the properties of patch networks. Understanding the consequences of deforestation on woodland birds, therefore, necessarily requires determining which changes in landscape structure make a major contribution to the degradation and subdivision of patch networks. In this study, we addressed how accelerated deforestation in central Chile has modified the landscape structure and function for thorn‐tailed rayaditos—a woodland specialist bird. Using a graphical approach based on the habitat use and movement patterns of rayaditos, we quantified the reduction of the internal connectivity of components (i.e., connected patch networks) in the last two decades and determined the main mechanisms responsible for this connectivity loss. Forest cover decreased 61.7 % between 1989 and 2009. The component size, the fraction of components with ≥1 occupied patches and the number of patches per component experienced a large decline during the study period. Over time, most forest cover (ca. 80 %) was contained in only two components. The connectivity of components decreased steeply by 90 %. Only the loss of large patches made a highly significant contribution to explaining changes in connectivity, while the removal of stepping stones was marginally significant. The conversion of forest both to shrubland and to peri‐urban areas were the only land‐use variables explaining connectivity change with effects that changed over time. Conservation measures to ensure persistence of rayaditos populations in central Chile should be focused on the retention of key elements for connectivity.

Multi-scalar analysis of bird communities in Monferrato Astigiano woodlands

In this study we focused on deciduous managed forests in north-western Italy and investigated relationships between bird diversity and forest descriptors both at the habitat and landscape level through a seasonal, guild-based approach. Birds were censused by point counts in randomly selected plots of 50 m radius. Each census plot was described in habitat structure terms by using the Bitterlich variable plot-radius method. Landscape metrics were measured within 250, 500 and 1000 m radius circles of each plot using an existing GIS database. We first identified specialist and generalist species according to the presence/absence of each species in relation to habitat structure measurements, then we tested for the effects of habitat and landscape variables on community and guild parameters (bird species richness, abundance and Shannon diversity) using generalized linear models (GLMs). Our analyses showed that in general, guild parameters relative to specialists were especially influenced by oak biomass and oak core area irrespective of the season, while parameters of generalists were influenced by oak core area in winter and by landscape fragmentation parameters in spring. Results clearly showed that the retention of native oaks both at the habitat and landscape level is the key-factor for the conservation of diversity of specialist bird species in deciduous, originally oak-dominated woods.

Perennial Agroenergy Feedstocks as En Route Habitat for Spring Migratory Birds

Increased production of bioenergy crops in North America is projected to exacerbate already heavy demands upon existing agricultural landscapes with potential to impact biodiversity negatively. Grassland specialist birds are an imperilled avifauna for which perennial-based, next-generation agroenergy feedstocks may provide suitable habitat. We take a multi-scaled spatial approach to evaluate the ability of two candidate second-generation agroenergy feedstocks (switchgrass, Panicum virgatum, and mixed grass–forb plantings) to act as spring migratory stopover habitat for birds. In total, we detected 35 bird species in mixed grass–forb plantings and switchgrass plantings, including grassland specialists and species of state and national conservation concern (e.g., Henslow’s Sparrow, Ammodramus henslowii). Some evidence indicated that patches with higher arthropod food availability attracted a greater diversity of migrant bird species, but species richness, total bird abundance, and the abundance of grassland specialist species were similar in fields planted with either feedstock. Species richness per unit area (species density) was relatively higher in switchgrass fields. The percent land cover of forest in landscapes surrounding study fields was negatively associated with bird species richness and species density. Habitat patch size and within-patch vegetation structure were unimportant in predicting the diversity or abundance of spring en route bird assemblages. Our results demonstrate that both switchgrass and mixed grass–forb plantings can attract diverse assemblages of migrant birds. As such, industrialized production of these feedstocks as agroenergy crops has the potential to provide a source of en route habitat for birds, particularly where fields are located in relatively unforested landscapes. Because industrialization of cellulosic biomass production will favor as yet unknown harvest and management regimes, predicting the ultimate value of perennial-based biomass plantings for spring migrants remains difficult.

Comparison of avifaunal diversity in and around Neora Valley National Park, West Bengal, India

Anthropogenic intervention has led to conversion of much of the global diversity by means of habitat alterations. The present study was carried out to investigate the importance of habitat quality and habitat heterogeneity for the diversity, distribution and abundance of avifauna in and around Neora Valley National Park (NVNP) during April-May 2010. A total of 73 bird species belonging to 25 families were recorded during the present study applying a modified point count method. Forest edges were found to be most diverse with a total count of 54 bird species having an abundance of 172.53 number of birds ha-1. Study areas with human settlements was represented by a total species count of 24 with an abundance of 130.39 number of birds ha-1 while a total species count of 22 with an abundance of 69.32 number of birds ha-1 was recorded from thick vegetation assemblage with close canopy cover. This site specific occurrence pattern for avifauna was reflected in the study of diversity indices. The highest Shannon-Wiener general diversity score of 3.77 was recorded for bird species from forest edges. Study areas with dense canopy closure were found to support more habitat specialist bird species while areas having human settlements harboured more opportunistic bird species. An overall negative influence of human settlements on bird diversity, distribution and abundance was evidenced from the present study and needs further investigation. Moreover, intensive studies will certainly enrich our knowledge of avian diversity and distribution pattern from the present study location.

Influence of grain size on species–habitat models

High resolution remote sensing data facilitate the use of small-scale habitat features such as trees or hedges in the analysis of species–habitat relationships. Such data potentially enable more accurate species–habitat mapping than lower resolution data. Here, for the first time, we systematically investigated this hypothesis by altering the spatial resolution from 1 m up to 1000 m grain size in species–habitat models of 13 bird species. The study area covered the Nidda river catchment in central Germany, a large heterogeneous landscape of 1620 km 2. A high resolution habitat map of the area was converted to coarser spatial and thematic resolutions in seven steps. We investigated how model performance responded to grain size, and we compared the differential effects of spatial resolution and thematic resolution on model performance. Explained deviance ( D 2) of the bird models generally decreased with coarser spatial resolution of the data, although it did not decrease monotonically in all species. On average across all species, model D 2 decreased from 41.5 at 1 m grain size to 15.9 at 1000 m grain size. Ten species were best modelled at 1 m, two species at 3 m and one species at 32 m grain size. Model performance degraded continuously with increasing grain size, both in habitat generalist and habitat specialist bird species, and was systematically lower in habitat generalists. The higher model performance observed at finer grain sizes was most likely caused by the combination of three factors: (1) high spatial accuracy of bird records and (2) a more precise location and delineation of habitat features and, (3) to a lesser degree, by more habitat types differentiated in maps of finer resolution. We conclude that higher spatial and thematic resolution data can be essential for deriving accurate predictions on bird distribution patterns from species–habitat models. Especially for bird species that are sensitive to specific land-use types or to small-scaled habitat features, a grain size of 1–3 m seems most promising.

Modelling Species' Climatic Distributions Under Habitat Constraints: A Case Study withCoturnix coturnix

Coturnix coturnix is a climatically widespread farmland specialist bird with a well-known distribution in the Iberian Peninsula. Therefore, its current real distribution can be finely mapped. We used recent atlas data and high-resolution climate layers to model the climatic distribution of this species. Next, we compared the obtained predictive maps with the real distribution of the species. Precise information about underestimation and overestimation of model predictions at different sample sizes was obtained. An increase in sample size allowed the predicted distribution to approach the current real distribution, but unbalanced the climatic prediction. This is because the distribution of occurrences is mostly determined by habitat, which depends more on agricultural factors and less on climate. Modelling the climatic distribution of widespread species while ignoring habitat constraints could lead to a non-equilibrium scenario where obtained predictions may not be reliable.

Low‐intensity agriculture increases farmland bird abundances in France

Summary 1. Farmland biodiversity continues to decline mainly because of agricultural intensification and land abandonment. Agri‐environment schemes can be designed to halt this loss by favouring extensification of agricultural practices and through sympathetic management of field boundaries and fallow land. In Europe, High Nature Value (HNV) farmland is defined as low‐intensity farmland supporting or associated with a high rate of biodiversity, in terms of species richness or habitat diversity and therefore plays a crucial role in the maintenance of European biodiversity. However, no large‐scale analysis has explored the role of these areas in achieving conservation goals. 2. We analysed information from widely used indicators in order to describe the impact of low‐intensity agriculture on farmland biodiversity in France. We used the HNV farmland indicator, based on agricultural statistics such as the Farm Structure Survey and the grassland survey, and common bird indicators, i.e. the Farmland Bird Indicator (FBI), the Community Specialization Index (CSI) and species richness indexes, based on the French Breeding Bird Survey. 3. Temporal trends in the farmland bird indicator showed that populations of farmland birds were more likely to increase inside HNV areas compared to non‐HNV areas. Although species richness is not higher within HNV farmland, bird communities are composed by more specialist species than in non‐HNV areas. In addition, these specialist bird species are significantly more abundant in HNV areas. 4. Synthesis and applications. Further farmland biodiversity decline is potentially reversible through an appropriate management of HNV areas. Existing and future agri‐environment schemes should focus on preserving and extending HNV farmland, by favouring the maintenance of low‐intensity agriculture and landscape complexity. Priority should be given to preserving diversity at the community level, with the help of adequate indicators, such as the ones presented here. The role of HNV farmland or similar concepts in combining agriculture and biodiversity goals should be further analysed and further used as large‐scale conservation tools.

Specialist response to proportion of arable land and pesticide input in agricultural landscapes

Increases in farming practice intensity and landscape simplification are two well-known threats for many farmland bird species. Nevertheless, the effects of these two factors may differ strongly among species. Here, we propose to use the specialist–generalist concept to assess which bird species are most affected by these two factors. Bird density and intensity of farming practices were assessed within a sample of 58 farms across the Seine-et-Marne region in France, using point counts and a standardised farmer survey. The local abundance of 41 farmland and non-farmland species was related to farming intensity (pesticide applications) and landscape simplification (proportion of arable land), which was quantified using generalised least square models to account for spatial autocorrelation. The more specialised the farmland and non-farmland birds were, the more negatively affected they were by the intensity of farming practices, relative to the generalist bird species. Local habitat simplification had a more positive effect on abundance of the most specialist farmland bird species. This latter relationship was not significant when tested at a landscape scale, which strongly suggests that the sensitivity of farmland specialists to landscape simplification is scale-dependent. Some non-farmland species’ abundance was also reduced by farming intensity and local landscape simplification suggesting that low-input agri-environmental measures could benefit both farmland and non-farmland specialists, regardless of local and landscape habitat context. However, if diversity-enhancing measures should benefit non-farmland populations, it is likely that they do not favour farmland specialist species which are more at risk. We suggest designing of priority areas for farmland specialist birds, and landscape managing accordingly.

Independent colonization of multiple urban centres by a formerly forest specialist bird species

Urban areas are expanding rapidly, but a few native species have successfully colonized them. The processes underlying such colonization events are poorly understood. Using the blackbird Turdus merula, a former forest specialist that is now one of the most common urban birds in its range, we provide the first assessment of two contrasting urban colonization models. First, that urbanization occurred independently. Second, that following initial urbanization, urban-adapted individuals colonized other urban areas in a leapfrog manner. Previous analyses of spatial patterns in the timing of blackbird urbanization, and experimental introductions of urban and rural blackbirds to uncolonized cities, suggest that the leapfrog model is likely to apply. We found that, across the western Palaearctic, urban blackbird populations contain less genetic diversity than rural ones, urban populations are more strongly differentiated from each other than from rural populations and assignment tests support a rural source population for most urban individuals. In combination, these results provide much stronger support for the independent urbanization model than the leapfrog one. If the former model predominates, colonization of multiple urban centres will be particularly difficult when urbanization requires genetic adaptations, having implications for urban species diversity.

Historic landscape change and habitat loss: the case of black grouse in Lower Saxony, Germany

The declines of many specialist bird species in the agricultural landscapes of Central Europe have resulted in small and isolated populations. In the case of the black grouse, a ground-nesting bird species with large spatial requirements, empiric evidence about underlying landscape changes is scarce. In this study, we examined land cover and land cover changes in a farmland-forest mosaic in eastern Lower Saxony, Germany and how they affect occurrence and persistence of black grouse. Spatial information came from historic topographic maps from 1958 to 1975. The results show profound conversions of habitat to forest and farmland but also an increase in settlement area. Habitat conversions and suburbanization were negative correlates of black grouse persistence. Habitat models from before and after a decline period differed in some of the predictors and suggest black grouse habitat to be more diverse before the land cover changes. Our study confirms that land use factors at a landscape scale extent contribute to explain black grouse occurrence and thus can complement important small scale factors like the quality and size of individual habitat patches. Results also show that landscape factors affect black grouse distribution predominantly from an area much greater than an individual black grouse home range. Our models may be further evaluated on present-day landscapes and might be used to evaluate large-scale habitat availability for black grouse.