Citizen-science driven exercises (e.g., bird surveys) and online platforms (e.g., eBird) provide voluminous data on bird occurrence but the data quality is often compromised. Bird atlases are based on standardized surveys and describe the distribution of bird species over a predefined region and have less biases, and thus are better suited for use in research. The recently concluded Kerala Bird Atlas (henceforth KBA) is Asia’s largest bird atlas in terms of geographical extent, sampling effort and species coverage. The entire state of Kerala was systematically surveyed twice a year during 2015–2020 and over 0.3 million records of 380 species from 25,000 checklists were aggregated. The dataset was filtered and various metrics were estimated. A few cells could not be surveyed due to logistical constraints or when they fell outside the state boundary. This variation in sampling effort had a minimal effect on survey completeness; the slope of the species accumulation curve suggests near-complete species sampling in over 70% of the cells. After eliminating nocturnal and pelagic species, in total 361 species were analyzed. Species count was higher in the dry season (Jan.–Mar.) than in the wet season (Jul.–Sep.). Species richness (count) and evenness were higher in the northern and central districts than in the southern districts. High elevation regions of the southern Western Ghats were the largest contiguous areas lacking sufficient sampling. Although most of the endemics were concentrated in the Western Ghats, threatened species were as likely to occur along the coasts as in the Ghats. The KBA dataset is a valuable resource for testing various ecological hypotheses and suggesting science-backed conservation measures. The Kerala Bird Atlas model could be replicated for similar atlases in other states or biogeographic regions of India.

The state of Kerala was divided into cells of size 3.75 minutes x 3.75 minutes (equivalent to 6.6 km x 6.6 km) aligned to Survey of India maps. A total of 1,096 cells were laid out covering the entire state. Each cell was further divided into four quadrants of size 3.3 km x 3.3 km. Each quadrant was then sub-divided into 9 sub-cells of size 1.1 km x 1.1 km. A single, randomly selected sub-cell in every quadrant was chosen for the survey. Field surveys were conducted from 2015 to 2020 twice a year, during dry (mid-Jan. to mid-Mar.) and wet (mid-July to mid-Sep.) seasons, exactly for 60 days in each season per year. Survey teams consisted of 2–5 volunteers, every bird species seen or heard during the 15-minute sampling session was noted. Volunteers uploaded checklists from the surveyed sub-cells to eBird, using the website or the app, and this data was later downloaded for analysis. 

This dataset consists of three input files (.RDS), one shape file (.shp) and one R script file (.R) for the analyses performed using the Kerala Bird Atlas: 2015-2020 dataset. 
These files are part of the publication "Kerala Bird Atlas 2015-2020: features, outcomes and implications of a citizen-science Project". There are no usage restrictions for this dataset except that all usages should provide an attribution as below

Kerala Bird Atlas Dataset (2021) Website Link. Accessed on DD Month Year

The outputs of this script are in the forms of shapefiles (.shp) and the attribute table contains the measured metrics.

This shapefile can be opened in QGIS/ArcGIS and the particular metric can be plotted.
In the script, only wet season data has been analyzed and the shapefiles have been generated. 
Dry season data can be analyzed by changing the word 'wet' to 'Dry' in the script and re-running the script.

The figures generated in the R platform were exported in svg format and annotated in Inkscape software.

The Cell IDs, Sub-cell IDs and List IDs of Great Hornbill (Buceros bicornis) records have not been provided since it is a sensitive species (https://ebird.org/india/news/ebird-sensitive-species). District names have been retained. Users interested in analyzing KBA records of Great Hornbill from any region (across Kerala or any district) may obtain the occurrence data from eBird by following due procedure for sensitive species (https://ebird.org/data/download/ebd), and get in touch with us for further assistance.

Contact:
Dr. P.O. Nameer, 
Professor (Wildlife), 
Kerala Agricultural University, Thrissur
nameer.po@kau.in