SummarySince 2010, Jankowski’s Bunting Emberiza jankowskii has been listed as ‘Endangered’ on the IUCN Red List of Threatened Species. However, because no comprehensive surveys had been conducted, it was not known whether undiscovered populations existed elsewhere, so the population status of the species could not be assessed accurately. The aim of this study was to assess the breeding distribution and population size of Jankowski’s Bunting in China. Fifty sites in Inner Mongolia, and Jilin, Heilongjiang, Liaoning and Hebei Provinces were surveyed to locate suitable habitat and breeding populations of Jankowski’s Bunting. The surveyed sites included historical breeding distribution areas, wintering sites, and regions adjacent to historical breeding distribution areas. We confirmed that Jankowski’s Bunting has disappeared from most of its former breeding distributions, with the exceptions of Dagang, Xiergen and Tumiji. Additionally, 13 new breeding sites were discovered in Inner Mongolia. All currently known populations breed in Mongolian steppe-vegetation zones, with shrubs dominated by the natural Siberian apricot Prunus sibirica, indicating that this type of habitat is crucial for the survival of the species. Based on remote sensing, the suitable breeding habitat for Jankowski’s Bunting is estimated to be approximately 280 km2. The population size of Jankowski’s Bunting could range between 9,800 and 12,500 individuals, which is much higher than the numbers estimated in previous reports that were based on partial surveys. The suitable habitat remaining in Inner Mongolia would highly benefit from the implementation of the National Key Public Forest Protection Project. The population size of Jankowski’s Bunting is larger than previously estimated, but it is still threatened by habitat degradation and fragmentation, and our survey results reinforce the need for more research. The status of Jankowski’s Bunting in China still meets the IUCN criteria B2ab for an ‘Endangered’ species.

AimTo evaluate the patterns of bird assemblage and distribution in an endangered grassland system, taking into accounts both environmental and biotic effects. To further focus on an endangered songbird and associated steppe birds.LocationInner Mongolia, China.MethodsWe investigated the relative importance of abiotic and biotic factors driving the abundance and co‐occurrence of steppe birds in Inner Mongolia by using joint species distribution models. We examined the general patterns of species assemblage, with a focus on the endangered Jankowski's Bunting and other species potentially sharing the same niche or interacting with it, including potential competitors (especially the closely related Meadow Bunting), predators (corvids, raptors) and a parasite (cuckoo).ResultsThe studied steppe species exhibited varied responses to environmental variables, including climate, landscape and habitat predictors. We observed stronger species correlations due to residual covariates than to abiotic covariates. Jankowski's Bunting displayed strong positive co‐occurrences with other ground‐nesting songbirds and exhibited significant responses to all measured habitat and climate variables, indicating that this endangered bird has a high niche specialization and wide associations with other sympatric steppe bird species.Main conclusionOur results pointed out that climate, landscape and steppe habitat predictors are not the only factors structuring bird assemblages. Our results suggested that Jankowski's Bunting is an indicator of the occurrence of other species, especially open‐nesting specialized steppe songbirds, so it could act as a surrogate for overall steppe bird conservation. These findings are helpful for understanding how abiotic and biotic processes interactively alter bird communities and making effective management decisions to mitigate multiple threats to the entire community.

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Behavioral divergence among populations is common across taxonomic groups, still we know very little about anti-predator behaviors. Animal exposure to predation risk is variable in different ecological contexts. In addition, reproduction value of animals in different geographical regions usually varies. In this study, we tested whether cinereous tits Parus cinereus in different populations exhibited nest defense behaviors similar to those of nest or adult predators and whether their nest defense behaviors showed geographical variation. By using field dummy experiments, we observed tits’ nest defense behavior in nest predator common chipmunk Tamias sibiricus and red squirrel Sciurus vulgaris, adult predator Eurasian sparrowhawk Accipiter nisus and nonthreatening species Oriental turtle dove Streptopelia orientalis in the ZJ (44° N), DLS (18° N) and DZ (31° N) populations, respectively. The response scores varied significantly across the four dummies in ZJ-tits and DLS-tits but did not in DZ-tits. When facing the chipmunk, ZJ-tits showed the highest response score, and DZ-tits showed the lowest response score. When facing the squirrel, ZJ-tits showed a higher response score than tits in the other two populations. However, tits among the three populations responded similarly to a sparrowhawk or dove with slight response behaviors. In addition, response scores to nest predators were positively correlated with brood size across the three populations, but no trend was found for sparrowhawks or doves. Our results indicated that the nest defense behaviors of cinereous tits have evolved in response to large-scale geographical variation in ecological contexts and reproduction value.