Eurasian Skylark Alauda Arvensis Research Articles

Connection between ecological niche changes and population trends in the Eurasian Skylark (Alauda arvensis) breeding in lowland and mountain areas of Southern Europe

Population responses to environmental changes can often vary geographically and between environments, potentially as a consequence of differing niche dynamics. The Eurasian Skylark Alauda arvensis is an open‐habitat passerine bird that is declining throughout Europe, mainly due to agricultural intensification. We compared population trends (1992–2021) of the species across three sub‐regions of northern Italy characterized by different environmental conditions and human pressures: the Alpine sub‐region (less anthropized mountains), the Plain (strongly anthropized and intensively cultivated) and the Oltrepò (extensively cultivated hills), with changes in the realized Grinnellian niches over three decades. In each sub‐region, niche comparisons did not show divergence over the study. However, we found an overall reduction in niche occupancy over time. In the Alpine sub‐region, a reduction in niche occupancy in hayfields and pastures was not associated with population decline; indeed, we found an increasing population (+164%), probably because high availability of natural grasslands counteracted niche contraction. Conversely, in the Plain and Oltrepò sub‐regions, the observed population declines (−99% and −36%, respectively) are associated with a general reduction of niche occupancy in arable lands that represented the core of the niche in these ranges. In the Plain, the lack of alternative suitable habitats might have limited any opportunity for the species to colonize new environments. Conversely, in the Oltrepò, the less severe population decline is combined with increased niche occupancy in hayfields and pastures at higher elevations. The joint application of population trend analysis and niche modelling as well as the decomposition of population changes across different environmental contexts can contribute to a better understanding of ecological processes affecting population dynamics, supporting policy‐makers to implement targeted conservation strategies.

AVIAN DIVERSITY AND ABUNDANCE IN RELATION TO SEASON, LIVESTOCK PRESENCE AND VEGETATION COVER IN A MEDITERRANEAN COASTAL WETLAND

Coastal wetlands are considered as systems of high avian diversity and are usually used for livestock production throughout the world. In this study, the diversity and seasonal abundance of avian species were monitored for two years on a monthly basis in a coastal grazing land in Evros Delta (Greece). The effects of livestock (cattle) presence and different classes of vegetation cover on the number of bird species were also investigated. A total of 96 bird species belonging to 29 families were recorded. The most commonly encountered species was the Eurasian skylark Alauda arvensis. The cattle presence was not significantly correlated (p>0.05) with the abundance of recorded bird species. On the contrary, patches with vegetation cover 25.1 - 50.0% and 50.1 - 75.0 % were used by more bird species in relation to patches with cover ≤25.0% or >75.0%. We concluded that the use of livestock grazing to preserve the desired vegetation cover (25 – 75%) is a promising management tool.

Characteristics of the Avifauna in a Rice Field Dominated Rural Area, and Habitat Use by Grassland Birds in Western Hokkaido, Japan

Rural areas provide various habitats for birds, and some studies have revealed habitat associations in rural bird communities in Japan. Previous studies have primarily focused on waterbirds or the habitat values of abandoned farmland, thus little is known about the importance of cultivated land for rural bird communities. Therefore, in this study, I clarified the characteristics of the avifauna in a rural area of the Ishikari Plain in Shinshinotsu Village, Western Hokkaido, and examined habitat utilization of cultivated land by eight major grassland species; Bull-headed Shrike Lanius bucephalus, Eurasian Skylark Alauda arvensis, Black-browed Reed Warbler Acrocephalus bistrigiceps, Siberian Rubythroat Calliope calliope, Stejneger's Stonechat Saxicola stejnegeri, Chestnut-eared Bunting Emberiza fucata, Black-faced Bunting E. spodocephala, and Common Reed Bunting E. schoeniclus. I conducted bird surveys along three 2-km line-transect routes among rice fields with some wheat, non-wheat crop fields, and weedy areas from April to October from 2016 to 2018. I recorded a total of 51 species of three general types: grassland birds, residential birds, and water birds. Rice fields in this study areas were flooded during early to mid-May to mid to late August, however species-specific habitat utilization analyses revealed that a small number of Eurasian Skylark, Stejneger's Stonechat, and Chestnut-eared Bunting inhabited the rice fields during study periods other than the flooding season. A relatively large number of Eurasian Skylark was observed in wheat fields and non-wheat crop fields throughout the study period, and Stejneger's Stonechat and Chestnut-eared Bunting were temporarily observed in those habitats. The other five species only rarely observed in rice, wheat, or non-wheat crop fields, but all eight species were observed in weedy areas. The characteristics of the avifauna in this rural area of Western Hokkaido proved to be quite different from previous studies conducted in the Kanto Region of Honshu. For the conservation of biodiversity and birds in rural areas, it is necessary to investigate the avifaunal characteristics of various regions of Japan.

Recent and Predicted Changes in Habitat of the Eurasian Skylark Alauda arvensis Based on the Link between the Land Cover and the Field Survey Based Abundance Data

The European avifauna on agricultural land has been permanently diminished over the past few decades. This phenomenon is clearly connected with agricultural intensification and the recent land cover changes. The main aims of this study were to identify the land cover preferences of a farmland bird species, the Eurasian Skylark Alauda arvensis in Hungary and investigate the link between the recent trend of the abundance of this species and the land-cover change. We employed GIS and statistical methods to assess the link between the abundance of this species based on the Hungarian common bird monitoring database (MMM) and the spatial proportion of the Corine Land Cover (CLC) categories in different buffer zones with 300, 600 and 1200 m from the observation points. Based on the significant statistical connections, we could identify and select land cover categories that serve as habitats and land cover categories that this bird species does not inhabit. The land cover preference of the Eurasian Skylark, in case of some land cover category, is depending on the grain scale (circle radius distance from the observation points). In analyses arable lands has been omitted because this land cover type is the well-known habitat of the species. According to our results, the Eurasian Skylark prefers permanent crops (vineyards, fruit trees and berry plantations) inside 600m and 1200m buffer zones, and pastures inside 1200m buffer zones, while it does not prefer urban fabric areas and heterogeneous agricultural, forests, and wetlands or water bodies inside 300m and 600m, scrub and/or herbaceous vegetation associations (transitional woodland-shrub and natural grassland areas) inside the 600m and 1200m radius buffer areas. The identification of these regional (European level) land-cover categories allowed us to analyse the recent (1990–2012) and the predicted (2006–2050) characteristics of habitat changes of this bird species, associated with land cover change. Based on our results, we could estimate that the Skylark habitat will decrease by 188 560 ha between 2006–2050 in Hungary.

Occurrence of Eurasian Skylark Alauda arvensis territories in relation to urban area and heterogeneous farmland

ABSTRACTWithin heterogeneous arable habitats close to urbanized Vienna, Austria, Eurasian Skylarks Alauda arvensis occurred at slightly lower densities than in other mixed farmland areas and at a much lower density than would be found in natural habitats. Territory density was negatively correlated with the occurrence of roads, tracks and high-intensity agricultural cultivation, possibly due to the resulting increased disturbance by humans.

Seed depletion and landscape structure affect aggregative response in two wintering passerine birds

ABSTRACTCapsule: Seed abundance but also seed depletion during winter modifies habitat use and aggregation behaviour of Eurasian Sky Lark Alauda arvensis and Meadow Pipit Anthus pratensis.Aims: To investigate the effect of seed abundance on the density of two passerine birds, the Eurasian Sky Larks and the Meadow Pipit, at an agricultural landscape scale during winter.Methods: Bird counts as well as seed density measurements were carried out in winter to quantify the aggregative response of farmland birds to seed abundance from November to March.Results: Seed resources varied by a factor of ten between crop types, but declined so sharply over the winter that seed abundance was low and similar among crop types by late winter. Sky Larks selected for higher seed density plots, but only at the end of winter when the resources were the lowest. Conversely, Meadow Pipits did not show any aggregative response to seed abundance.Conclusion: These results show that an uptake of seed-rich habitats in agricultural landscape would be very beneficial for wintering granivorous birds, by fulfilling the late winter ‘hungry gap’. The inclusion of seed mixtures in habitats that attract high densities of birds and retain seeds until late winter is of primary interest.

Changes in the breeding bird communities on mires and in surrounding forests in southeastern Norway during a 40-year period (1976–2015)

The breeding bird communities of 18 mires and surrounding forests in southeastern Norway were censused in 1976–77 and in 2015. We found that 53% of the mire species with sufficient data for analyses showed significant changes. Red-throated Diver Gavia stellata, Common Crane Grus grus, Wood Sandpiper Tringa glareola and Tree Pipit Anthus trivialis increased, whereas Northern Lapwing Vanellus vanellus, Black-headed Gull Chroicocephalus ridibundus, Meadow Pipit Anthus pratensis and Yellow Wagtail Motacilla flava decreased. There were also near significant decreases of Eurasian Curlew Numenius arquata and Eurasian Skylark Alauda arvensis. Population changes did not differ between short- and long-distance migrants. Species with marginal populations on mires declined more than mire specialist species, suggesting an indirect negative influence of problems in other habitats. Overall, there was a significant 19% decline in number of mire species, but a non-significant 7% increase in number of individuals. The bird community in the forests surrounding the mires showed significant population changes for 42% of the species with sufficient data for analyses, with increases in many resident forest species, but less so for migrants. Overall, there was a near significant 12% increase in number of forest species, and a significant 28% increase in number of individuals. Mire- and forest-associated species did not differ in population trends. Among short-distance migrants (mire and forest species combined), species wintering in agricultural habitats had more negative population changes than species wintering in other habitats. Thus, the breeding bird community on and around mires in this part of Norway has undergone large changes during the last 40 years. We discuss our results in relation to general trends of bird communities in northern Europe.

Evaluating the regional cumulative impact of wind farms on birds: how can spatially explicit dynamic modelling improve impact assessments and monitoring?

Summary The Eurasian skylark Alauda arvensis is very susceptible to the negative effects of wind farms. In northern Portugal, this evidence is particularly severe due to the skylark's preference for mountain breeding habitats where most wind farms are located. Facing the frequent failure of environmental impact assessments (EIA) to evaluate the cumulative impacts of wind farms on wildlife, this study aimed to develop and test a methodology to quantify local and regional consequences on birds, using skylarks as a test species, taking into account future predictable environmental changes. We propose a spatially explicit dynamic approach that combines the results from multiple modelling techniques under a common framework to assess the local and cumulative regional impacts of wind farms on skylark populations. This includes the following: (i) modelling the local impact of wind farms (in terms of collision mortality) on the skylark population dynamics by developing an index for quantitative assessments, (ii) determining the actual and future skylark breeding distribution across northern Portugal and (iii) integrating the above contributions in an emergent spatially explicit regional representation to capture the ecological cumulative consequences as a whole. The simulations show an increasing average local impact for the skylark breeding populations directly affected by wind farms, expressed in mean number of collision fatalities per UTM study unit (1 km2), representing 1·3% of the local breeders in 2006 and 4% in 2026. The distribution area of skylark breeding populations was predicted to decrease around 4·5% throughout a period of 15 years, as a result of the scenario of climate and land cover changes in the study area. When combined with a concomitant increase in skylark global mortality (c. 184%) induced by all wind farms in the study region, the above trend contributes to an intensification of the regional cumulative impact from 1·2% to 3·7% of the total estimated breeding individuals. Synthesis and applications. The proposed modelling framework represents a step forward in evaluating the multi‐scale cumulative consequences of wind farms on vulnerable birds, using skylarks as a test species. This could be used in the future to guide monitoring efforts and to improve the applicability of the data bases generated by long‐term ecological research and monitoring studies.

Vegetation structure and inter-individual distance affect intake rate and foraging efficiency in a granivorous forager, the Eurasian Skylark Alauda arvensis

Animals gain benefits from group living through increased probability of predator detection, dilution of individual risk and confusion of predators during attack. A further benefit involves larger groups in which individuals may further decrease the amount of time spent being vigilant, while maintaining the probability of predator detection by allocation of this extra time to foraging activities. Living in groups or flocks, however, also incurs costs, e.g., by increasing inter-group competition, with negative impacts on intake rates. Our aim was to investigate the trade-offs between the costs of competition and the benefits of group living in contrasted habitats. For prey species that rely on sight for detecting predators, vegetation structure may influence the perceived predation risk. Hence, we experimentally examined the combined effects of vegetation height and inter-individual distance on foraging time, intake rate and foraging efficiency in a granivorous species, the Eurasian Skylark (Alauda arvensis). Our experimental results based on temporally captive birds indicate that time devoted to foraging decreased with increasing inter-individual distance, but was unrelated to cover height. Conversely, increasing both vegetation height and distance with other group members did translate into a foraging disadvantage, i.e. reduced intake rate as well as foraging efficiency. Overall, our results show that both vegetation structure and inter-individual distances modify patch profitability, and therefore provide another example of how flock dynamics can influence the trade-off between vigilance and foraging.

Population Trends of Grassland Birds in Hokkaido, Focussing on the Drastic Decline of the Yellow-breasted Bunting

To examine the population trends of grassland and shrub birds in Hokkaido, we conducted line transect censuses in 2002 and 2003, in area where avifaunal studies had been performed in the 1970s and 1980s. To document the decline in the Yellow-breasted Bunting Emberiza aureola, birdwatching data were also analysed. The Yellow-breasted Bunting population has decreased drastically both in density and in distribution over the intervening thirty years. The decline in occupied breeding sites and in the population is continuing. Densities of Eurasian Skylark Alauda arvensis and Lanceolated Grasshopper Warbler Locustella lanceolata have also declined, although their range contractions are not yet severe. The ranges of Brown Shrike Lanius cristatus and Chestnut-eared Bunting E. fucata appear to have contracted. In contrast, data analysis revealed that the breeding range of Yellow Wagtail Motacilla flava has expanded in northern Hokkaido, but it is possible that the range had expanded in the past but had been overlooked. The present study suggests that the ranges of Bull-headed Shrike L. bucephalus and Gray's Grasshopper Warbler L. fasciolata had expanded, although some previous studies do not support this trend. In this study we were not able to clarify the reason why the population trends of these species have changed. Further research is necessary focussing on: breeding habitat analysis, breeding biology in relation to population trends, population trends in wintering and migration areas and clarification of migration routes. The population decline in the Yellow-breasted Bunting is both dramatic and very severe. This migratory species in particular requires immediate international conservation measures to avoid national and regional extinction.