Data on range-wide breeding habitat use of the critically endangered Yellow-breasted Bunting Emberiza aureola after population collapse

The population of the Yellow-breasted Bunting Emberiza aureola, a formerly widely distributed and abundant songbird of northern Eurasia, suffered a catastrophic decline and a strong range contraction between 1980 and 2013. There is evidence that the decline was driven by illegal trapping during migration, but potential contributions of other factors to the decline, such as land-use change, have not yet been evaluated. Before effects of land-use change can be evaluated, a basic understanding of the ecological requirements of the species is needed. We therefore compared habitat use in ten remaining breeding regions across the range, from European Russia to Japan and the Russian Far East. We also assessed large-scale variation in habitat parameters across the breeding range.
We found large variation in habitat use, within and between populations. Differences were related to the cover and height of trees and shrubs at Yellow-breasted Bunting territories. In many regions, Yellow-breasted Bun..., We compiled data from a network of collaborators that had monitored Yellow-breasted Buntings during the breeding season (May to July) in 2017, 2018 and 2019, following the report of strong declines in 2015 (Table 1). All contributors searched for singing males and used the individual song post as the centre of a 10 by 10 meters plot for habitat mapping (“presence plots”). We visually estimated the total vegetation cover [in %] and the cover [in %] of trees, shrubs, dwarf shrubs, grass, herbs and litter by standing at each of the four corners of the plot. We defined trees as a woody plant with a single trunk, and a shrub as a woody plant with more than one trunk. Low-growing shrubs (< 1 m height) were defined as dwarf shrubs (e.g. Salix myrtilloides). Reed was classified as grass. Woody parts of Artemisia were classified as herbs. If burned and dead parts were still attached to a plant, they were treated as part of it. We estimated the mean height [in cm] of trees, shrubs, dwarf shrub...,