Jaanus Elts

Consistent response of bird populations to climate change on two continents.

Birds populations allied in abundance Changes in climate can cause populations of species to decline, to increase, or to remain steady. Stephens et al. looked across species of common birds in Europe and the United States. Despite many differences between the two regions, expectations about how a species might respond to climate change did predict actual responses. Species predicted to benefit from increasing temperatures, or their associated effects, tended to increase, whereas those predicted to be negatively affected declined. Thus, even across widely varying ecological conditions and communities, climate change can be expected to alter population sizes. Science, this issue p. 84 The impact of climate change on population sizes of birds across continents can be predicted. Global climate change is a major threat to biodiversity. Large-scale analyses have generally focused on the impacts of climate change on the geographic ranges of species and on phenology, the timing of ecological phenomena. We used long-term monitoring of the abundance of breeding birds across Europe and the United States to produce, for both regions, composite population indices for two groups of species: those for which climate suitability has been either improving or declining since 1980. The ratio of these composite indices, the climate impact indicator (CII), reflects the divergent fates of species favored or disadvantaged by climate change. The trend in CII is positive and similar in the two regions. On both continents, interspecific and spatial variation in population abundance trends are well predicted by climate suitability trends.

Habitat Associations of Farmland Birds Across the East Baltic Region

The general structure of farmland bird communities in Estonia, Latvia and Lithuania was explored based on the large-scale survey in 2002. Input of major farmed habitats to the species richness and abundance of all bird species and groups of farmland specialist and declining species, as well as the abundance of individual farmland species across the region were assessed. The contribution of these to the communities. characteristics and the abundance of a number of farmland species varied across the region. Fewer species were associated with crop fields, especially where farmland was dominated by arable production. There abandoned fields featured as a positive predictor. More species were related to the presence of natural grasslands in the North and seeded grassland in the South of the region. The variation reflected the geographical position and differences in the fragmentation level of farmland, soil types and vegetation development pattern. The results are discussed in relation to agri-environment plann...

A global threats overview for Numeniini populations: Synthesising expert knowledge for a group of declining migratory birds

The Numeniini is a tribe of 13 wader species (Scolopacidae, Charadriiformes) of which seven are Near Threatened or globally threatened, including two Critically Endangered. To help inform conservation management and policy responses, we present the results of an expert assessment of the threats that members of this taxonomic group face across migratory flyways. Most threats are increasing in intensity, particularly in non-breeding areas, where habitat loss resulting from residential and commercial development, aquaculture, mining, transport, disturbance, problematic invasive species, pollution and climate change were regarded as having the greatest detrimental impact. Fewer threats (mining, disturbance, problematic native species and climate change) were identified as widely affecting breeding areas. Numeniini populations face the greatest number of non-breeding threats in the East Asian-Australasian Flyway, especially those associated with coastal reclamation; related threats were also identified across the Central and Atlantic Americas, and East Atlantic flyways. Threats on the breeding grounds were greatest in Central and Atlantic Americas, East Atlantic and West Asian flyways. Three priority actions were associated with monitoring and research: to monitor breeding population trends (which for species breeding in remote areas may best be achieved through surveys at key non-breeding sites), to deploy tracking technologies to identify migratory connectivity, and to monitor land-cover change across breeding and non-breeding areas. Two priority actions were focused on conservation and policy responses: to identify and effectively protect key non-breeding sites across all flyways (particularly in the East Asian- Australasian Flyway), and to implement successful conservation interventions at a sufficient scale across human-dominated landscapes for species’ recovery to be achieved. If implemented urgently, these measures in combination have the potential to alter the current population declines of many Numeniini species and provide a template for the conservation of other groups of threatened species.

A Reading Comprehension Formula of Reader and Text Characteristics

Readability formulae predict reading outcomes relying on text characteristics but they do not consider reader abilities. This paper describes ways of formulating a reading comprehension formula which includes reader and text characteristics. An experiment embracing 124 subjects and 48 texts serves to demonstrate the mechanisms through which the formula is developed. The applicability of the formula, its degree of precision, and power of predictability are discussed.

What are the important landscape componentsfor habitat selection of the ortolanbunting Emberiza hortulana in northernlimit of range

Abstract Ortolan buntings Emberiza hotulana have undergone one of the most severe population declines of any European farmland bird over the last thirty years. The aim of this study was to find out which habitat features, including crop characteristics, ortolan bunting prefers in Estonia in breeding areas. This study compared currently occupied and unoccupied ortolan bunting territories. Occupied areas contained significantly more tall broadleaf trees, crop types, structural elements (trees, bushes, roads, overhead power lines and buildings) and spring wheat, but also had lower crop drilling densities. Ortolan bunting territories were best described by a logistic regression model containing six variables: amount of structural point elements, length of power lines, amount of tall broadleaf trees and number of different crops had a positive effect, whereas crop density and area of autumn-sown crops had a negative effect. Based on the findings of this study, the following conservation measures can be recommended: lower crop densities; spring rather than autumn-sown crops; small-field systems containing a variety of crops; scattered scrub preserved or planted; habitat patches of permanent grasslands, hedges and tall broadleaf trees retained within the agricultural landscape.

Determination of optimal values of text characteristics

Abstract This paper introduces a new way of determining the optimal sentence and word lengths for defined groups of readers. The correlation coefficient between the percentage of long sentences and the text comprehension level depends on the positioning of the dividing line between the long sentences and the short sentences. If the line coincides with the line drawn by the readers, the correlation coefficient reaches its maximum. The idea was tested in an experiment on 93 students of Grades 8 and 10 in the secondary school. The optimal values for the 8th‐grade students were sentences of 72 letter spaces and words of 8.5 letters.

The genetic structure of the European breeding populations of a declining farmland bird, the ortolan bunting ( Emberiza hortulana ), reveals conservation priorities

Anthropogenic activities, such as agricultural intensification, caused large declines in biodiversity, including farmland birds. In addition to demographic consequences, anthropogenic activities can result in loss of genetic diversity, reduction of gene flow and altered genetic structure. We investigated the distribution of the genetic variation of a declining farmland and long-distance migratory bird, the ortolan bunting Emberiza hortulana, across its European breeding range to assess the impact of human-driven population declines on genetic diversity and structure in order to advise conservation priorities. The large population declines observed have not resulted in dramatic loss of genetic diversity, which is moderate to high and constant across all sampled breeding sites. Extensive gene flow occurs across the breeding range, even across a migratory divide, which contributes little to genetic structuring. However, gene flow is asymmetric, with the large eastern populations acting as source populations for the smaller western ones. Furthermore, breeding populations that underwent the largest declines, in Fennoscandia and Baltic countries, appear to be recently isolated, with no gene exchange occurring with the eastern or the western populations. These are signs for concern as declines in the eastern populations could affect the strength of gene flow and in turn affect the western populations. The genetic, and demographic, isolation of the northern populations make them particularly sensitive to loss of genetic diversity and to extinction as no immigration is occurring to counter-act the drastic declines. In such a situation, conservation efforts are needed across the whole breeding range: in particular, protecting the eastern populations due to their key role in maintaining gene flow across the range, and focussing on the northern populations due to their recent isolation and endangered status.

Are common bird monitoring schemes and opportunistic observations appropriate for estimating raptor trends

ABSTRACT Capsule: Transect-based common bird monitoring methods and opportunistic data from citizen scientists are not equal alternatives to mapping of raptors in study plots. Aims: To analyse the efficacy of common breeding and wintering bird monitoring schemes, as well as databases of casual bird observations, in providing population trends for raptors. Methods: We estimated trends for three raptor species using data from Estonian common bird monitoring schemes and a database of casual observations, and compared these with those resulting from special raptor monitoring programmes. Results: Significant trends for all three species were only detected using the specialized scheme Monitoring of Breeding Raptors in study plots, whereas Monitoring of Wintering Raptors showed some significant yearly fluctuations of the Common Buzzard Buteo buteo. However, Common Breeding and Wintering Bird Monitoring schemes provided uncertain trends, although results suggested a decline in the breeding Goshawk Accipiter gentilis population. Casual observations suggested recent declines in wintering populations of the Goshawk and Sparrowhawk Accipiter nisus, but data from more years are needed to validate this. Conclusion: Special monitoring schemes are most effective in monitoring raptor populations. Such schemes can be used to monitor trends of common and uncommon raptor species and provide additional information for their research and conservation.