Until recently,Limosa limosa melanuroides was thought to be the only subspecies of Black-tailed Godwit in the East Asian-Australasian Flyway.For this reason,all previous occurrences and counts of Black-tailed Godwits ...Until recently,Limosa limosa melanuroides was thought to be the only subspecies of Black-tailed Godwit in the East Asian-Australasian Flyway.For this reason,all previous occurrences and counts of Black-tailed Godwits in the flyway have been assigned to melanuroides.However,a larger-bodied subspecies,bohaii,has recently been discovered in the flyway.As a result,the occurrence of Black-tailed Godwits in the flyway needs to be reconsidered such that the specific distribution of each subspecies becomes known.To this end,we developed a simple discriminant function to assign individuals to subspecies based on their bill and wing length.Cross-validation with individuals known to be bohaii or melanuroides,based on molecular analysis,showed the developed function to be 97.7%accurate.When applied to measurements of godwits captured at 22 sites across 9 countries in East-Southeast Asia and Australia,we found that bohaii and melanuroides occurred at most sites and overlapped in their distribution from Kamchatka to Australia.We examined photos from all along the flyway to verify this surprising result,confirming that both subspecies co-occur in most locations.Based on these results,we hypothesise that bohaii and melanuroides from the west of their breeding ranges mostly migrate over Chinese mainland.Birds of both subspecies from the east of their ranges are expected to migrate along the Pacific Ocean.We encourage ringing groups in East-Southeast Asia and Australia to use this simple method to keep adding knowledge about Black-tailed Godwits in the East Asian-Australasian Flyway.展开更多
As an apex predator in arid steppe,saker falcon plays a crucial role in maintaining ecosystem balance.Understanding their movement patterns concerning conspecific competition and prey availability is important for the...As an apex predator in arid steppe,saker falcon plays a crucial role in maintaining ecosystem balance.Understanding their movement patterns concerning conspecific competition and prey availability is important for their conservation.We aim to understand how movement pattern of breeding saker falcons relates to prey availability.Twelve adult sakers were tracked during the breeding seasons,using satellite transmitters.Throughout the breeding season,sakers exhibited territorial behavior,with minimal overlap in range use among neighboring conspecifics.Males occupied larger areas(mean=2,397 ha,median=1,221 ha),compared to females(mean=1,241 ha,median=554 ha),and it remained consistent throughout breeding season.Female home range size increased notably during a late nestling stage and post-fledging dependence periods,indicating release from brooding constraints.Notably,we found a negative relationship between male home range size and prey availability.In high rodent density areas,males occupied smaller areas(mean=1,135 ha,median=1,034 ha),contrasting with low rodent density areas(mean=6,815 ha,median=6,516 ha).However,no significant relationship was observed between female home range size and prey availability.We also noted instances of nest abandonment and early dispersal behavior in some females,potentially influenced by a handicapping effect of tagging.Our findings offer valuable insight into how prey availability shapes saker falcon space use and defines their spatial requirements for successful breeding.This knowledge is crucial for the conservation and management of globally endangered saker falcons,informing targeted habitat protection and resource management strategies.展开更多
基金funded by the National Natural Science Foundation of China[31830089,31801985,32270518]。
文摘Until recently,Limosa limosa melanuroides was thought to be the only subspecies of Black-tailed Godwit in the East Asian-Australasian Flyway.For this reason,all previous occurrences and counts of Black-tailed Godwits in the flyway have been assigned to melanuroides.However,a larger-bodied subspecies,bohaii,has recently been discovered in the flyway.As a result,the occurrence of Black-tailed Godwits in the flyway needs to be reconsidered such that the specific distribution of each subspecies becomes known.To this end,we developed a simple discriminant function to assign individuals to subspecies based on their bill and wing length.Cross-validation with individuals known to be bohaii or melanuroides,based on molecular analysis,showed the developed function to be 97.7%accurate.When applied to measurements of godwits captured at 22 sites across 9 countries in East-Southeast Asia and Australia,we found that bohaii and melanuroides occurred at most sites and overlapped in their distribution from Kamchatka to Australia.We examined photos from all along the flyway to verify this surprising result,confirming that both subspecies co-occur in most locations.Based on these results,we hypothesise that bohaii and melanuroides from the west of their breeding ranges mostly migrate over Chinese mainland.Birds of both subspecies from the east of their ranges are expected to migrate along the Pacific Ocean.We encourage ringing groups in East-Southeast Asia and Australia to use this simple method to keep adding knowledge about Black-tailed Godwits in the East Asian-Australasian Flyway.
基金funded by and undertaken on behalf of the Environment Agency Abu Dhabi(EAD)under a memorandum of understanding with Mongolia’s Ministry of Environment and Green Development(MEGD)supported by the National Natural Science Foundation of China(31930013,32361133559)+1 种基金the Third Xinjiang Scientifc Expedition Program(grant no.2022xjkk0801)the CASTWAS President’s Fellowship Programme(BB).
文摘As an apex predator in arid steppe,saker falcon plays a crucial role in maintaining ecosystem balance.Understanding their movement patterns concerning conspecific competition and prey availability is important for their conservation.We aim to understand how movement pattern of breeding saker falcons relates to prey availability.Twelve adult sakers were tracked during the breeding seasons,using satellite transmitters.Throughout the breeding season,sakers exhibited territorial behavior,with minimal overlap in range use among neighboring conspecifics.Males occupied larger areas(mean=2,397 ha,median=1,221 ha),compared to females(mean=1,241 ha,median=554 ha),and it remained consistent throughout breeding season.Female home range size increased notably during a late nestling stage and post-fledging dependence periods,indicating release from brooding constraints.Notably,we found a negative relationship between male home range size and prey availability.In high rodent density areas,males occupied smaller areas(mean=1,135 ha,median=1,034 ha),contrasting with low rodent density areas(mean=6,815 ha,median=6,516 ha).However,no significant relationship was observed between female home range size and prey availability.We also noted instances of nest abandonment and early dispersal behavior in some females,potentially influenced by a handicapping effect of tagging.Our findings offer valuable insight into how prey availability shapes saker falcon space use and defines their spatial requirements for successful breeding.This knowledge is crucial for the conservation and management of globally endangered saker falcons,informing targeted habitat protection and resource management strategies.
