A Rare Observation: Forest Dormouse Occupying Nests of White-Crowned Penduline Tit.

We report a novel observation of forest dormouse () using and modifying nests of the white-crowned penduline tit () as den and breeding sites in the Xinjiang Uyghur Autonomous Region, China. In the Huocheng Ili River Valley National Wetland Park, 9 out of 56 nests were occupied by dormice, with predation on nestlings observed in only one nest during the late breeding period. In contrast, at the Buergen Beaver National Nature Reserve, where penduline tits exhibit later breeding, four out of six occupied nests, from a total of 53 collected, were subject to predation, with either eggs or nestlings being preyed upon. These findings highlight the potential influence of temporal overlap between the breeding cycles of forest dormice and white-crowned penduline tit, calling for more comprehensive research into the ecological consequences of this interaction under global change.