Avian responses to an extreme weather event:The case of the‘Filomena’snowstorm in Madrid(central Spain)

Cold spells and severe weather may have detrimental effects in wild birds,but owing to the stochastic nature of these events,it is not always possible to measure their impacts.In January 2021,a strong snowstorm known as‘Filomena’affected Spain,mainly the region of Madrid(Central Spain),which was fully covered with snow and suffered freezing temperatures for a fortnight.Using bird surveys conducted in the winter-spring of 2020 and 2021(before and after Filomena)at same locations,we addressed the possible impact of the cold spell in three widespread gamebirds:Wood Pigeon(Columba palumbus),Eurasian Magpie(Pica pica)and Red-legged Partridge(Alectoris rufa).No significant abundance differences were found between years for none of the species and hunting pressure was only significantly reduced for Partridges,hence this species may have been negatively affected by Filomena.Results suggest that in response to Filomena,Pigeons conducted partial migration in search of better conditions,while Magpies aggregated in certain areas of Madrid and Partridges endured the harsh conditions within their home ranges.Our results highlight the importance to alleviate negative impacts of extreme weather events in wild birds through management actions,especially for sedentary species.

Asymmetrical introgression patterns between rusty-necklaced partridge (Alectoris magna) and chukar partridge (Alectoris chukar) in China

The rusty-necklaced partridge(Alectoris magna)and the chukar partridge(Alectoris chukar)are the most com­mon gamebirds in northern China.Previous comparisons of mitochondrial DNA(mtDNA)have revealed an in­trogression phenomenon between 2 species of partridge in the Liupan Mountain region of China.mtDNA is ma­ternally inherited,making it difficult to determine the origin of parental genes.We assessed the genetic variation and gene flow between these 2 species of partridges using 8 microsatellite loci as neutral diagnostic markers in 171 samples from the hybrid zone.Our data revealed an extensive divergence of genetic structure between populations of rusty-necklaced partridges and chukar partridges.In this study,we found that 19 samples had been previously morphologically identified as rusty-necklaced partridge were genetically identified as hybrids through Bayesian analysis using STRUCTURE analysis.These hybrids exhibited a mosaic of alleles that were derived from both parental lineages.However,chukar partridges did not present the genotype of the rusty-neck­laced partridge.Thus,our findings demonstrate that the hybridization between the 2 species was the result of asymmetrical introgression,with gene flow occurring only from the chukar partridge to the rusty-necklaced par­tridge.In addition,we also note the high linkage disequilibrium in populations of the rusty-necklaced partridge.These results indicate that although unidirectional introgression did not reduce genetic diversity of the Alectoris partridges,it affected the balance of gene flow between populations.The data from microsatellite DNA prompt­ed our concern about the genetic integrity of the rusty-necklaced partridge.