README file for data Data include: -Mainland_GB.csv: this csv file containing hectads of mainland Great Britain that were used to perform all the analyses. Each row represents a hectad. The columns contain: the name of the hectad according to the Ordnance Survey National Grid, the longitude, and the latitude. -Climatic A and ClimaticC: these two csv files contain the climatic variables for the time periods 1968-1972 and 2007-2011, respectively. Montly climate data were downloaded from https://catalogue.ceda.ac.uk/uuid/4dc8450d889a491ebb20e724debe2dfb for the periods 1963-1972 and 2003-2011 and we estimated temperature and precipitation related variables per hectad for each time period using QGIS. Each row represents a hectad in both files. The columns contain: the name of the hectad accroding to the Ordnance Survey National Grid, the mean temperature (degrees Celsius), the mean precipitation (millimeters ), the mean range of temperature (Celsius degrees), the mean temperature of the warmest month (degrees Celsius), and the mean temperature of the coldest month (degrees Celsius). - HILDAA and HILDAC: these two csv files contain the percentage of land cover for the period 1970 and 2010. Gross land cover data were retrieved from HIstoric Land Dynamics Assessment (HILDA) maps (http://www.geo-informatie.nl/fuchs003/#) and we estimated percentage of different land cover per hectad and time period using QGIS. Each row represents a hectad in both files. The columns contain: the name of the hectad accroding to the Ordnance Survey National Grid, percentage cover by cropland, percentage cover by forest, percentage cover by grassland, percentage cover by other land-cover, percentage cover by settlement, and percentage cover by water. -human.popA and human.popC: these two csv files contain total human population per hectad of 1975 and 2015, i.e. for the year closest available to each atlas’ period. Data were downloaded from Global Human Settlement Layer and total human population per hectad and year were estimated using QGIS. Each row represents a hectad in both files. The columns contain: the name of the hectad accroding to the Ordnance Survey National Grid, and human population. - elevation: this csv file contains elevation-related variables of mainland Great Britain. Data were downloaded from https://land.copernicus.eu/imagery-in-situ/eu-dem/eu-dem-v1.1 and elevation-related variables were estimated using QGIS. Each row represents a hectad in both files. The columns contain: the name of the hectad accroding to the Ordnance Survey National Grid, mean elevation (meters), and standard deviation of elevation. - Species list: this csv file contains the list of alien and native species that were included in our analyses after excluding marine species, and species present as scarce, winter and passage visitors and species that traits were not available. Each row represents a species. The columns contain: the scientific name of the species, the category of the species according to British Trust of Ornithology, the status of the species according to the British Trust of Ornithology, and alien/native status. - name_changes: this csv file contains the changes of scientific names of the species from the first to third period. Each row represents a species that its scientific name has changed. The columns contain: the previously used scientific name of the species, the current scientific name of the species. - Traits: this csv file contain the traits of the native species used in the analyses. Traits were compiled from datasets (Storchová et al., 2018, https://doi.org/10.1111/geb.12709) and electronic databases (Handbook of the Birds of the World Alive, https://www.hbw.com). Each row represents a native species. The columns contain: body mass (grams), clutch size (number of eggs), foraging location: water, foraging location: vegetation, foraging location:aerial, foraging location:animals, habitat: ground water, habitat: grass of low vegetation, habitat: shrub layer understorey, habitat: midstorey, habitat: canopy, activity time: diurnal, activity time: nocturnal, activity time: crepuscular, diet:herbivore, diet:invertebrates, diet:carnivore, diet: omnivore, and diet:prey. - Diversity data can be downloaded from https://www.bto.org/our-science/data/what-data-are-available. Download the dataset "Breeding and wintering bird distributions in Britain and Ireland (ZIP, 11.72 MB)" which is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.and copied into the folder of the working directory (Gillings et al. (2019). Breeding and wintering bird distributions in Britain and Ireland from citizen science bird atlases. Global Ecology and Biogeography, 28(7), pp.866-874). Files that are used: distributions.csv and species_lookup - Grid of Great Britain (United Kingdom) can be downloaded from https://gadm.org/ and copied into the folder of the working directory. Data distributed by GADM are under the GADM licence according to which data are freely available for academic use and other non-commercial use. Redistribution or commercial use is not allowed without prior permission. Using the data to create maps for publishing of academic research articles is allowed. SCRIPTS DESCRIPTION The script is divided into three parts - 1_Prepare environmnetal and diversity data: this .txt file contains functions required to prepare environmental and diversity data to estimate range shifts of alien and native breeding birds between the the time periods 1968-1972 and 2007-2011, to estimate beta diversity and its components of alien and native communities per time period, and to implement Generalized Dissimilarity Models to explore the effect of abiotic factors (climate, land cover, human population, and elevation) on alien and native β-diversity and their components and of native diversity (species richness and functional diversity) on alien β-diversity by Generalized Dissimilarity Modelling. - 2_Estimate range shifts metrics: this .txt file contains functions to estimate range shifts of alien and native breeding birds between the the time periods 1968-1972 and 2007-2011, - 3_Run GDMs: this .txt file contains functions to estimate beta diversity and its components of alien and native communities per time period, and to implement Generalized Dissimilarity Models to explore the effect of abiotic factors (climate, land cover, human population, and elevation) on alien and native β-diversity and their components and of native diversity (species richness and functional diversity) on alien β-diversity by Generalized Dissimilarity Modelling. -Nstar function: this .txt file contains an updated version of the function to estimate Nstar beta diversity metric (Lazarina et al., 2013, doi: 10.1111/2041-210x.12013). -Windrose function: this .txt file contains the function to reproduce the windrose plot contained in the article. All the available packages are included in 1_Prepare environmnetal and diversity data Due to the size of the data loaded and analyses performed, we advise to separately: 1. run the 1_Prepare envirnmnetal and diversity data and then 2_Estimate range shifts metrics and 2. run the 1_Prepare envirnmnetal and diversity data and then 3_Run GDMs. In this case, a separate workfile is adviced for each beta diversity matrix and component of alien and native communities to avoid memory issues. We provide functions to reproduce the figure 1 and figure 2 of our study. Figure 3 and Figure 4 were produced in Inkscape, a Free and open source vector graphics editor, by combining plots produced by code provided into 3_Run GDMs.