DOI: 10.5061/dryad.0rxwdbs0g
title: Data on range-wide breeding habitat use of the critically endangered Yellow-breasted Bunting Emberiza aureola after population collapse

description: 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 Buntings occupied early
 successional stages, including anthropogenic habitats characterized by
 mowing, grazing or fire regimes. We found that the probability of presence
 can be best predicted with the cover of shrubs, herbs and grasses. Highest
 probabilities were found at shrub cover values of 40 to 70 %. Differences
 in habitat use along a longitudinal gradient were small, but we found
 strong differences across latitudes, possibly related to habitat
 availability. We conclude that the remaining Yellow-breasted Bunting
 populations are not limited to specific habitat types. Our results provide
 important baseline information to model the range-wide distribution of
 this critically endangered species and to guide targeted conservation
 measures.
description: 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 (&lt; 1 m height) were defined as
 dwarf shrubs (e.g. <em>Salix myrtilloides</em>). Reed was
 classified as grass. Woody parts of <em>Artemisia</em> 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 shrubs, grass (, herbs and litter.
 Additionally, the cover of bare soil [in %] was estimated. Furthermore, we
 noted signs of fire, grazing or mowing from the current breeding season (0
 = no, 1 = yes). Moisture was estimated in four categories (0 = completely
 dry, 1 = moist or wet, 2 = waterlogged and 3 = standing open water or
 flooded soil). To analyse habitat
 use we additionally recorded all habitat parameters at pseudo-absence
 points, which were placed 100 m to the east of song posts (“absence
 plots”). We expected these absence plots to be outside of the territory,
 as distances between nests of 40-100 m were found (Rejmers 1966 in Glutz
 von Blotzheim & Bauer 1993). This allowed us to establish
 preferences for certain habitat features, as opposed to the descriptive
 notion of habitat use employed when only observational data at presence
 points is included. Additional pseudo-absence points were randomly
 selected in the Amur region, to get a representative sample (n &gt;
 30) for both burned and unburned wetlands.