DOI: 10.5061/dryad.g1jwstqzd
title: Data coverage, biases, and trends in a global citizen-science resource for monitoring avian diversity

description: Aim: Understanding and addressing the global biodiversity crisis requires
 ecological information compiled continuously from across the globe. Data
 from citizen science initiatives are useful for quantifying species’
 ecological niches and geographical distributions but can be difficult to
 apply towards biodiversity monitoring. The presence of fixed geographical
 locations reduces the opportunistic nature of citizen science data,
 allowing for more reliable and nuanced trend estimation. The eBird
 citizen-science programs contains predefined locations whose bird
 assemblages are sampled across years (‘hotspots’). For hotspots to
 function as a biodiversity monitoring resource, issues related to data
 coverage, biases, and trends need to be addressed. Location: Global.
 Methods: We estimated the survey completeness of species richness at
 300,500 eBird hotspots during the years 2002 to 2022. We documented
 sampling biases at eBird hotspot and non-hotspot locations during 2022
 based on protection status, temperature, precipitation, and landcover.
 Results: A total of 10,410 bird species (ca. 96.9% of total) were recorded
 at hotspots. The number hotspots and the quantity of data and unique
 participants and quality of species richness estimates has increased
 worldwide with the Nearctic containing the strongest and most consistent
 trends. Compared to non-hotspots, hotspots over sampled areas with higher
 protection status. Hotspots and non-hotspots over sampled warmer and
 wetter locations in the Antarctic, Nearctic, and Palearctic, and cooler
 locations in the Afrotropics, Australasia, and the Neotropics. Hotspots
 and especially non-hotspots over sampled urban areas. Hotspots and
 non-hotspots under sampled shrublands in Australasia. Hotspots and
 especially non-hotspots under sampled forests in the Afrotropics,
 Indomalaya, Neotropics, and Oceania. Main conclusions: Hotspots have
 captured a large component of the world’s avian diversity but have done so
 inconsistently across space and time. Data quantity and quality are
 increasing in many regions, but the presence of sampling biases and
 spatial uncertainty needs to be addressed when applying the data.
description: # Data coverage, biases, and trends in a global citizen-science resource
 for monitoring avian diversity One CSV file containing the results from
 the survey completeness analysis of 300,500 eBird hotspots conducted
 during four seasons from 2002 to 2022. ## Description of the data and file
 structure eBird-hotspot-table.csv The 300,500 eBird hotspots are
 considered in the analysis with their unique ID (loc_id) and their
 longitude and latitude. From these, the 76,200 eBird hotspots with
 sufficient data to estimate survey completeness for at least one season
 and year with observed species richness, estimated species richness, and
 estimated survey completeness (SC). ## Sharing/Access information The bird
 occurrence data are available from
 [https://science.ebird.org/en/use-ebird-data](https://science.ebird.org/en/use-ebird-data)