Kerala Bird Atlas 2015-2020: features, outcomes and implications of a citizen-science project

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.