Abstract:

Objective: This study aimed to understand the community structure of raptors in Changdao County of Shandong Province, China, and reveal the population dynamics, autumn migration timing, migration route and stopover sites of Oriental Honey Buzzard Pernis ptilorhynchus, so as to provide a scientific basis for the conservation and management of this species. Method: In the autumn of 1987-2019, the regular banding activities were conducted in the fixed site of Daheishan islands, Changdao County of Shandong Province, and the long-term monitoring data of the number of raptors were collected. Two Oriental Honey Buzzards were tagged with GPS transmitters in October 2019, to collect the autumn migration information. SPSS 22.0 was used to analysis the community composition of raptors and the population trend of Oriental Honey Buzzard. ArcView GIS 3.3 and Google Earth were used to analysis the GPS tracking data. Result: A total of 78 039 individuals of 29 raptor species were banded during 1987-2019. The number of Accipitriformes, Strigiformes and Falconiformes in the community accounted for 60.74%, 38.59%, and 0.66%, respectively. The Oriental Scops Owl (Otus sunia), Besra (Accipiter virgatus) and Eurasian Sparrowhawk (Accipiter nisus) were dominant in the raptor community, accounting for 32.54%, 29.48% and 23.19%, respectively. The dominance index of Oriental Honey Buzzard in the community showed an upward trend in the past 33 years, with an average annual increase by 4.1%. The stopover at Changdao mainly happened from mid September to Mid October in autumn migration process, and the population peaked from 19^th September to 2^nd October. According to the GPS tracking, both the adult female and juvenile male migrated across China in the southwest after leaving from Changdao, and arrived at their wintering grounds in Malaysia and Vietnam on November 18^th and December 7^th, respectively. The average travel speed of the adult female was at (44.6 ±17.5) km·h^-1 and the maximum speed was at 88.7 km·h^-1, which were faster than those of the juvenile male, averaged at (40.4 ±18.4) km·h^-1 and maximized at 81.7 km·h^-1. Conclusion: The dominance of the Oriental Honey Buzzard in the community shows an increasing trend. Compared to juvenile male, the adult female makes less stopover, travels longer distance, migrates faster and arrives at wintering ground of lower altitude earlier. Thus the Oriental Honey Buzzard may adopt a differential migration strategies that would reduce interspecific competition at stopover sites and wintering grounds. It can be inferred that different geographical populations may adopt the chain migration strategy, i.e., further northern wintering population breed in northernmost region, indicating that its breeding habitats quality gradually change with altitude.

Key words: raptors, Pernis ptilorhynchus, autumn migration, population dynamics, Changdao