Long-term and large-scale multispecies dataset tracking population changes of common European breeding birds

Around fifteen thousand fieldworkers annually count breeding birds using standardized protocols in 28 European countries. The observations are collected by using country-specific and standardized protocols, validated, summarized and finally used for the production of continent-wide annual and long-term indices of population size changes of 170 species. Here, we present the database and provide a detailed summary of the methodology used for fieldwork and calculation of the relative population size change estimates. We also provide a brief overview of how the data are used in research, conservation and policy. We believe this unique database, based on decades of bird monitoring alongside the comprehensive summary of its methodology, will facilitate and encourage further use of the Pan-European Common Bird Monitoring Scheme results.

POPULATION SIZE CHANGE IN RURAL AREAS OF WEST POMERANIAN VOIVODESHIP IN 2011–2014

The aim of this study is to discuss changes in thepopulation and indicate the main reasons of these changes inrural areas of West Pomeranian voivodeship. The study wasconducted on the local level and based on Central StatisticalOffice data from the years 2010 to 2014. In the first part ofthe research, main demographic information is discussed. Itincludes population density, natural increase per 1000 populationand net migration per 1000 population in rural areasof West Pomeranian voivodeship. In the next part of the research,the average population growth rate was counted in theyears 2011–2014. Based on these changes, researched unitswere divided into four groups – two groups with positivechanges and two groups with negative changes. Subsequently,the main reasons of the changes in population size were analyzedin particular groups including natural increase, migration,population structure by age, level of unemployment andentrepreneurship. All indicators were designated as averagesfrom 2011 to 2014. According to the results in most of the researchunits, the net migration determined the population size.The net migration was characterized by higher absolute valuesthan natural increase. The population size changes are relatedto density. The lowest density areas are more depopulated.Moreover, the population size changes are positive related tothe level of entrepreneurship and negative related to the levelof unemployment.

Demographic inference using genetic data from a single individual: separating population size variation from population structure

The rapid development of sequencing technologies represents new opportunities for population genetics research. It is expected that genomic data will increase our ability to reconstruct the history of populations. While this increase in genetic information will likely help biologists and anthropologists to reconstruct the demographic history of populations, it also represents new challenges. Recent work has shown that structured populations generate signals of population size change. As a consequence it is often difficult to determine whether demographic events such as expansions or contractions (bottlenecks) inferred from genetic data are real or due to the fact that populations are structured in nature. Given that few inferential methods allow us to account for that structure, and that genomic data will necessarily increase the precision of parameter estimates, it is important to develop new approaches. In the present study we analyse two demographic models. The first is a model of instantaneous population size change whereas the second is the classical symmetric island model. We (i) re-derive the distribution of coalescence times under the two models for a sample of size two, (ii) use a maximum likelihood approach to estimate the parameters of these models (iii) validate this estimation procedure under a wide array of parameter combinations, (iv) implement and validate a model choice procedure by using a Kolmogorov-Smirnov test. Altogether we show that it is possible to estimate parameters under several models and perform efficient model choice using genetic data from a single diploid individual.