Birds have specific habitat needs as a function of their life cycle and reproductive stage. Migrant shorebirds that may fly from the Arctic to the southern tip of South America have foraging and habitat requirements a...Birds have specific habitat needs as a function of their life cycle and reproductive stage. Migrant shorebirds that may fly from the Arctic to the southern tip of South America have foraging and habitat requirements at sites where they stop to refuel before continuing their migration north or south. Throughout the world, shorebirds mainly forage on mudflats at low tide. Red knots (Calidris canutus rufa) are threatened in the United States and elsewhere, and it is critical to determine factors that might contribute to their decline. This paper uses Delaware Bay as a case study to examine shorebird (and red knot) use of the intertidal habitat, and competing claims to habitats they require during their northward migration, as well as some of the key stakeholders that play a role in protecting red knots. Shorebirds are drawn to Delaware Bay to feed on the eggs of Horseshoe Crabs (Limulus polyphemus) that are concentrated at the high tide. But they also feed on the intertidal mudflat. We examined intertidal habitat use on 17 beaches in an extensive study in 2015, and 5 key beaches in 2016. Most of the beaches were longitudinal, but four were more complex, and were used extensively for resting as well as foraging;numbers there were higher than on the longitudinal beaches. On foraging beaches, some shorebirds were present on over 85% of the intertidal censuses, and red knots were present on over 48% of the intertidal censuses. Average numbers of red knots on the longitudinal beaches varied from 0 to 354 ± 116 when any shorebirds were present, but averaged up to 1184 ± 634 when knots were present in 2015. Some beaches in 2015 had no knots (a beach with long-term aquaculture). Tide, intertidal location, and beach (name) determined the number of knots (and all shorebirds). Numbers decreased with distance from the mean high tide line. The average number of knots present in the intertidal mudflats two hours before or after low tide when knots were present (e.g. no censuses with zeros) was 2040 (=maximum flock size, in 2015). Major threats to red knots are from recreationists, overfishing of horseshoe crabs (reduction in egg prey base), and use of the intertidal by aquaculture. We discuss the role of stakeholders in conservation and protection of red knots.展开更多
Background:Anthropogenic disturbance can negatively affect an animal's energy budget by evoking movement responses.Existing research focuses mainly on immediate displacement as a disturbance effect,since this can ...Background:Anthropogenic disturbance can negatively affect an animal's energy budget by evoking movement responses.Existing research focuses mainly on immediate displacement as a disturbance effect,since this can be easily observed in the field. However, effects on movement over longer timescales are poorly examined and it is largely unknown if and to what extent they reflect immediate responses.Longer-term responses could for example be larger than immediate responses if birds, after disturbance, return to the original location and thereby travel twice the immediate disturbed distance. Methods:We combined GPS tracking data with observational data to quantify the effects of anthropogenic (air force and walkers) and non-anthropogenic disturbances on distances travelled by roosting Eurasian Oystercatchers (Haematopus ostralegus) during the non-breeding season. We compared immediate displacement after a disturbance with distance travelled during the entire high tide period (longer-term response), while accounting for environmental factors.Additionally,we calculated energy expenditure due to disturbance based on observed disturbance frequencies.Results:Disturbance resulted in an immediate displacement response of ~200 m (median).Air force disturbances tended to yield larger immediate responses than walker and,especially,than non-anthropogenic disturbances.Longer-term responses and immediate responses were approximately similar,suggesting that,over longer timescales,spatial disturbance effects in the study area remain confined to immediate effects.However,disturbances were infrequent (0.17 disturbances per bird per hour) and most disturbances were of natural origin (62%).Consequently, anthropogenic disturbance of roosting oystercatchers in the study area on average costs 0.08% of the daily energy expenditure. Conclusions:Our results suggest that immediate spatial responses to disturbance can be a useful proxy for spatial responses over longer timescales.Over the non-exhaustive range of conditions investigated,energetic consequences of spatial disturbance responses for an oystercatcher in the study area are marginal due to low disturbance levels.展开更多
Background:The allocation of resources between offspring size and number is a central question of life-history theory.Although several studies have tested the existence of this trade-off,few studies have investigated ...Background:The allocation of resources between offspring size and number is a central question of life-history theory.Although several studies have tested the existence of this trade-off,few studies have investigated how environmental variation influences the allocation of resources to offspring size and offspring number.Additionally,the relationship between population dynamics and the offspring size and number allocation is far less understood.Methods:We investigate whether resource allocation between egg size and clutch size is influenced by the ambient temperature and whether it may be related to apparent nest survival rate.We measured 1548 eggs from 541 nests of two closely related shorebird species,the Kentish Plover(Charadrius alexandrinus)and the White-faced Plover(C.dealbatus)in China,in four populations that exhibit contrasting ambient environments.We weighed females,monitored nest survival,and calculated the variance of ambient temperature.Results:Although we found that egg size and clutch size were all different between the four breeding populations,the reproductive investment(i.e.total clutch volume)was similar between populations.We also found that populations with a high survival rate had relatively larger eggs and a smaller clutch than populations with a low nest survival rate.The latter result is in line with a conservative/diversified bet-hedging strategy.Conclusions:Our findings suggest that plovers may increasing fitness by investing fewer,larger or many,small according local nest survival rate to make a similar investment in reproduction,and thereby may have an impact on population demography.展开更多
Background: Departure decisions and behaviors of migratory birds at stopover sites are expected to maximize fit?ness by trade?offs among avoiding predators, optimizing refueling(energy) capacity, and matching other li...Background: Departure decisions and behaviors of migratory birds at stopover sites are expected to maximize fit?ness by trade?offs among avoiding predators, optimizing refueling(energy) capacity, and matching other life?history events. We predict that species with different body sizes and migratory destinations will exhibit different behaviors when departing from the same stopover site. We also predict that with strong time constraint at the final pre?breed?ing stopover site, departure decisions may be less sensitive to exogenous factors, such as wind condition, compared to other stopover or nonbreeding sites.Methods: We recorded migratory departures of four shorebird species, i.e. Eurasian Curlew(Numenius arquata), Bar?tailed Godwit(Limosa lapponica), Great Knot(Calidris tenuirostris), and Grey Plover(Pluvialis squatarola), at Yaluji?ang Estuary Wetlands in China, a final pre?breeding stopover site in the northern Yellow Sea, from 2011 to 2014. We compared flock sizes, departure time and departure directions between species, and investigated the effects of tide and weather conditions(rain and ground wind speed and direction) on the departure decision of shorebirds.Results: We found that larger species departed in smaller flocks and were more variable in daily departure time. Departure trajectory of all four species appeared to be influenced by coastal topography. With the east–west coast?line and intertidal mudflat on the south, birds exhibited westward or eastward deflection from the shortest migra?tory routes. Bar?tailed Godwit was the only species that deviated to the southeast and did not climb over the land. Birds avoided departure during precipitation, while their departure was not related to ground wind benefit or tidal condition.Conclusions: Body size among species, which influences their vulnerability to predators, might be important in shaping shorebird departure strategies. Diverse departure directions could be the result of different wind use tac?tics in climbing stage. Narrow optimal time window of breeding might lead to reduced flexibility in departure date at a final pre?breeding site. Both endogenous and exogenous are important in shaping departure behaviors and decisions.展开更多
Many studies have demonstrated that some of the activities of people can disturb nesting and foraging birds, particularly along coasts and estuaries. Some managers respond to human disturbance of sensitive species by ...Many studies have demonstrated that some of the activities of people can disturb nesting and foraging birds, particularly along coasts and estuaries. Some managers respond to human disturbance of sensitive species by closing beaches, but most have stewards monitor and restrict access to beaches or portions of beaches. Yet little is known about the type of visitor or their perceptions of beach stewards. This paper explores the general acceptance of beach stewards and their role in conservation of red knots </span><span><span style="font-family:Verdana;">(</span><i><span style="font-family:Verdana;">Calidris</span></i> <i><span style="font-family:Verdana;">canutus</span></i> <i><span style="font-family:Verdana;">rufa</span></i><span style="font-family:Verdana;">),</span></span><span style="font-family:Verdana;"> other shorebirds, and horseshoe crabs </span><span><span style="font-family:Verdana;">(</span><i><span style="font-family:Verdana;">Limulus</span></i> <i><span style="font-family:Verdana;">polyphemus</span></i><span style="font-family:Verdana;">) </span></span><span style="font-family:Verdana;">along the Delaware Bay (New Jersey) beaches by interviewing 279 visitors during the stopover period. While most people came to see the shorebird and horseshoe crab spectacle (60%), many came for the scenery, tranquility, and recreation. Just over half of the people interviewed said that the stewards were helpful (58%), although most of those that answered this question later said that they provided conservation value (86%), but only 40% said they relied on the stewards for information. On a Likert rating scale of 1 to 5 (the highest value), the mean rating for whether it was important for stewards to be present was 3.87 ± 0.09, and the rating for the presence of stewards who can provide information was 3.71 ± 0.11. In contrast, protection of shorebirds was rated a mean of 4.79 ± 0.04. There were significant visitor type differences in how important stewards were, but not in the importance of stewards who can provide information. Fishermen, recreationists, and people coming for scenery and tranquility rated the presence of stewards higher than those visitors who were interested in either shorebirds or crabs (or both). Ratings also differed significantly as a function of age and gender;older adults and females rated characteristics higher than did people under 30 years and males. Information needs identified by stewards are also discussed. These data can be used by the managers developing a strategy for conservation of shorebirds and other species sensitive to disturbance, and for the implementation of an effective stewardship program.展开更多
Shorebirds migrate long-distances along the East Asian-Australasian Flyway(EAAF),exhibiting distinct spatiotemporal fluctuations in population dynamics.Because of habitat degradation and population declines at key sto...Shorebirds migrate long-distances along the East Asian-Australasian Flyway(EAAF),exhibiting distinct spatiotemporal fluctuations in population dynamics.Because of habitat degradation and population declines at key stopover sites along the EAAF,the South Korea's coastal wetlands have gained increasing attention for their ecological value.This study analyzed the shorebird population dynamics across 35 coastal wetlands in South Korea from 2016 to 2024 using data from the National Marine Ecosystem Monitoring Program.For the timeseries analysis,we employed three indicators:seasonal chan ges in abundance,short-term fluctuations(Fi),and long-term trends,assessed using the TRends and Indices for Monitoring data(TRIM)model.Abundance,species richness,and Shannon diversity indices were assessed across the regions during spring and autumn.The TRIM results revealed significant population increases in both seasons("Strong increase"in spring and"Moderate increase"in autumn).Species-level trends indicated notable increases in large-bodied shorebirds,including globally threatened species such as the Far Eastern Curlew(Numenius madagascariensis).Eurasian Curlew(N.arquata),and Eurasian Oystercatcher(Haematopus ostralegus),whereas other species showed variable responses.The Yellow Sea region(Gyeonggi,Chungcheong,and Western Jeolla)showed high biodiversity indices in spring,which may be associated with time-minimization strategies,whereas autumn patterns were characterized by more flexible and selective stopover use,possibly related to energy-minimization strategies.The East Coast and Jeju regions showed the lowest biodiversity indices.Furthermore,community-level analyses using Non-metric Multidimensional Scaling(NMDS)and PERMANOVA revealed distinct clustering of bird assemblages by macro-region and season,confirming significant spatial differentiation in community composition.These findings contrast with the broader declining trends reported across the EAAF and suggest that South Korea's coastal wetlands may serve as stable alternative stopover habitats,potentially supporting the redistribution or recovery of some species.This study highlights the importance of transboundary cooperation and region-specific habitat management that reflects local ecological contexts for effective conservation.展开更多
Conservation policies have been formulated for coastal wetlands in China,and exploration of conservation effectiveness based on waterbirds and their habitat is important for guiding conservation actions.We characteriz...Conservation policies have been formulated for coastal wetlands in China,and exploration of conservation effectiveness based on waterbirds and their habitat is important for guiding conservation actions.We characterized the effects of conservation efforts on shorebird diversity,habitat area and quality using long-term remote sensing data,and shorebird survey data in the Yellow River Delta.From 1997 to 2021,habitat area,quality and population number significantly declined by 49.8%(r=−0.72,p<0.05),13.6%(r=−0.72,p<0.05)and 60.67%(R2=0.77,p<0.05).Before 2012,habitat area(decreased by 38.2%,r=−0.62,p>0.05,slope=−0.25),quality(decreased by 10.53%,r=−0.68,p>0.05,slope=−0.008),and population size(significantly decreased by 94.5%,r=−0.95,p<0.05,slope=−7874.3)declined,and the decline in habitat area significantly contributed to population reductions(r=0.79,p<0.05).Since 2012,habitat area(increased by 14.3%,r=0.71,p>0.05,slope=0.12),quality(increased by 17.12%,r=0.83,p>0.05,slope=0.01),and population size(increased by 8.34%,R2=0.29,p>0.05)slightly increased.The coefficients of variation for habitat area and quality,and population size were smaller after 2012 than before 2012.These results suggest that conservation actions maintained the stability of waterbird populations and their habitat;additional actions are needed to mediate the conservation of other degraded habitats along coastal wetlands.展开更多
The carrying capacity of food resources for migrating shorebirds was estimated at a stopover site in the Yangtze River Estuary during the two migratory seasons(spring and autumn).From March to May and September to Nov...The carrying capacity of food resources for migrating shorebirds was estimated at a stopover site in the Yangtze River Estuary during the two migratory seasons(spring and autumn).From March to May and September to November 2005,the macrobenthos resources of the Jiuduansha Wetland were investigated,and most of the macrobenthos species in the newlyformed shoal were found to be appropriate food for shorebirds.Biomass measurements showed that the total food resource was about 4541.20 kg AFDW(Ash-Free Dry Weight)in spring and about 2279.64 kg AFDW in autumn.Calculations were also done in the available habitats(intertidal bare mudflat and Scirpus×mariqueter/Scirpus triqueter zones)for the shorebirds.The food resources in the available areas were about 3429.03 kg AFDWin spring and about 1700.92 kgAFDWin autumn.Based on the classification(by lean weight,basic metabolic rate and body length)of the shorebird community,and using the energy depletion model,it was theorized that all of the food resources in the Jiuduansha Wetland could support about 3.5 million shorebirds during spring season and 1.75 million shorebirds during autumn season.The shorebird carrying capacities in terms of the available food were about 2.6 million and 1.3 million birds during the two respective migration seasons.Considering the effect of intake rate,the potential carrying capacity was about 0.13–0.26 million shorebirds in the study area.The main factor restricting use of the area by shorebirds was the scarcity of available habitats for roosting at high tide rather than availability of food supply.We recommend restoring some wading pools in the dense Phragmites australis and Spartina alterniflora zones for shorebirds to roost in,to improve shorebirds’utilization efficiency of the resources in the Jiuduansha Wetland.展开更多
文摘Birds have specific habitat needs as a function of their life cycle and reproductive stage. Migrant shorebirds that may fly from the Arctic to the southern tip of South America have foraging and habitat requirements at sites where they stop to refuel before continuing their migration north or south. Throughout the world, shorebirds mainly forage on mudflats at low tide. Red knots (Calidris canutus rufa) are threatened in the United States and elsewhere, and it is critical to determine factors that might contribute to their decline. This paper uses Delaware Bay as a case study to examine shorebird (and red knot) use of the intertidal habitat, and competing claims to habitats they require during their northward migration, as well as some of the key stakeholders that play a role in protecting red knots. Shorebirds are drawn to Delaware Bay to feed on the eggs of Horseshoe Crabs (Limulus polyphemus) that are concentrated at the high tide. But they also feed on the intertidal mudflat. We examined intertidal habitat use on 17 beaches in an extensive study in 2015, and 5 key beaches in 2016. Most of the beaches were longitudinal, but four were more complex, and were used extensively for resting as well as foraging;numbers there were higher than on the longitudinal beaches. On foraging beaches, some shorebirds were present on over 85% of the intertidal censuses, and red knots were present on over 48% of the intertidal censuses. Average numbers of red knots on the longitudinal beaches varied from 0 to 354 ± 116 when any shorebirds were present, but averaged up to 1184 ± 634 when knots were present in 2015. Some beaches in 2015 had no knots (a beach with long-term aquaculture). Tide, intertidal location, and beach (name) determined the number of knots (and all shorebirds). Numbers decreased with distance from the mean high tide line. The average number of knots present in the intertidal mudflats two hours before or after low tide when knots were present (e.g. no censuses with zeros) was 2040 (=maximum flock size, in 2015). Major threats to red knots are from recreationists, overfishing of horseshoe crabs (reduction in egg prey base), and use of the intertidal by aquaculture. We discuss the role of stakeholders in conservation and protection of red knots.
基金provided by the Applied and Engineering Sciences domain of the Netherlands Organisation for Scientific Research(NWO-TTW 14638)by the Royal Netherlands Air Force,Birdlife Netherlands,NAM gas exploration,and Deltares
文摘Background:Anthropogenic disturbance can negatively affect an animal's energy budget by evoking movement responses.Existing research focuses mainly on immediate displacement as a disturbance effect,since this can be easily observed in the field. However, effects on movement over longer timescales are poorly examined and it is largely unknown if and to what extent they reflect immediate responses.Longer-term responses could for example be larger than immediate responses if birds, after disturbance, return to the original location and thereby travel twice the immediate disturbed distance. Methods:We combined GPS tracking data with observational data to quantify the effects of anthropogenic (air force and walkers) and non-anthropogenic disturbances on distances travelled by roosting Eurasian Oystercatchers (Haematopus ostralegus) during the non-breeding season. We compared immediate displacement after a disturbance with distance travelled during the entire high tide period (longer-term response), while accounting for environmental factors.Additionally,we calculated energy expenditure due to disturbance based on observed disturbance frequencies.Results:Disturbance resulted in an immediate displacement response of ~200 m (median).Air force disturbances tended to yield larger immediate responses than walker and,especially,than non-anthropogenic disturbances.Longer-term responses and immediate responses were approximately similar,suggesting that,over longer timescales,spatial disturbance effects in the study area remain confined to immediate effects.However,disturbances were infrequent (0.17 disturbances per bird per hour) and most disturbances were of natural origin (62%).Consequently, anthropogenic disturbance of roosting oystercatchers in the study area on average costs 0.08% of the daily energy expenditure. Conclusions:Our results suggest that immediate spatial responses to disturbance can be a useful proxy for spatial responses over longer timescales.Over the non-exhaustive range of conditions investigated,energetic consequences of spatial disturbance responses for an oystercatcher in the study area are marginal due to low disturbance levels.
基金This work was supported by Open Fund of Key Laboratory of Biodiversity Science and Ecological Engineering,Ministry of Education to Yang Liu,the China Postdoctoral Science Foundation(No.2019M663221)the British Ornithologists’Union’s Career Development Bursary in 2019 to Zitan Song,the National Natural Science Foundation of China(Nos.31600297)to Pinjia Queby the Hungarian Scientific Funding Agency,NKFIH(éLVONAL KKP-126949,K-116310)to Tamás Székely.
文摘Background:The allocation of resources between offspring size and number is a central question of life-history theory.Although several studies have tested the existence of this trade-off,few studies have investigated how environmental variation influences the allocation of resources to offspring size and offspring number.Additionally,the relationship between population dynamics and the offspring size and number allocation is far less understood.Methods:We investigate whether resource allocation between egg size and clutch size is influenced by the ambient temperature and whether it may be related to apparent nest survival rate.We measured 1548 eggs from 541 nests of two closely related shorebird species,the Kentish Plover(Charadrius alexandrinus)and the White-faced Plover(C.dealbatus)in China,in four populations that exhibit contrasting ambient environments.We weighed females,monitored nest survival,and calculated the variance of ambient temperature.Results:Although we found that egg size and clutch size were all different between the four breeding populations,the reproductive investment(i.e.total clutch volume)was similar between populations.We also found that populations with a high survival rate had relatively larger eggs and a smaller clutch than populations with a low nest survival rate.The latter result is in line with a conservative/diversified bet-hedging strategy.Conclusions:Our findings suggest that plovers may increasing fitness by investing fewer,larger or many,small according local nest survival rate to make a similar investment in reproduction,and thereby may have an impact on population demography.
基金financially supported by the National Natural Science Foundation of China(31071939,31572280,and 31772467)
文摘Background: Departure decisions and behaviors of migratory birds at stopover sites are expected to maximize fit?ness by trade?offs among avoiding predators, optimizing refueling(energy) capacity, and matching other life?history events. We predict that species with different body sizes and migratory destinations will exhibit different behaviors when departing from the same stopover site. We also predict that with strong time constraint at the final pre?breed?ing stopover site, departure decisions may be less sensitive to exogenous factors, such as wind condition, compared to other stopover or nonbreeding sites.Methods: We recorded migratory departures of four shorebird species, i.e. Eurasian Curlew(Numenius arquata), Bar?tailed Godwit(Limosa lapponica), Great Knot(Calidris tenuirostris), and Grey Plover(Pluvialis squatarola), at Yaluji?ang Estuary Wetlands in China, a final pre?breeding stopover site in the northern Yellow Sea, from 2011 to 2014. We compared flock sizes, departure time and departure directions between species, and investigated the effects of tide and weather conditions(rain and ground wind speed and direction) on the departure decision of shorebirds.Results: We found that larger species departed in smaller flocks and were more variable in daily departure time. Departure trajectory of all four species appeared to be influenced by coastal topography. With the east–west coast?line and intertidal mudflat on the south, birds exhibited westward or eastward deflection from the shortest migra?tory routes. Bar?tailed Godwit was the only species that deviated to the southeast and did not climb over the land. Birds avoided departure during precipitation, while their departure was not related to ground wind benefit or tidal condition.Conclusions: Body size among species, which influences their vulnerability to predators, might be important in shaping shorebird departure strategies. Diverse departure directions could be the result of different wind use tac?tics in climbing stage. Narrow optimal time window of breeding might lead to reduced flexibility in departure date at a final pre?breeding site. Both endogenous and exogenous are important in shaping departure behaviors and decisions.
文摘Many studies have demonstrated that some of the activities of people can disturb nesting and foraging birds, particularly along coasts and estuaries. Some managers respond to human disturbance of sensitive species by closing beaches, but most have stewards monitor and restrict access to beaches or portions of beaches. Yet little is known about the type of visitor or their perceptions of beach stewards. This paper explores the general acceptance of beach stewards and their role in conservation of red knots </span><span><span style="font-family:Verdana;">(</span><i><span style="font-family:Verdana;">Calidris</span></i> <i><span style="font-family:Verdana;">canutus</span></i> <i><span style="font-family:Verdana;">rufa</span></i><span style="font-family:Verdana;">),</span></span><span style="font-family:Verdana;"> other shorebirds, and horseshoe crabs </span><span><span style="font-family:Verdana;">(</span><i><span style="font-family:Verdana;">Limulus</span></i> <i><span style="font-family:Verdana;">polyphemus</span></i><span style="font-family:Verdana;">) </span></span><span style="font-family:Verdana;">along the Delaware Bay (New Jersey) beaches by interviewing 279 visitors during the stopover period. While most people came to see the shorebird and horseshoe crab spectacle (60%), many came for the scenery, tranquility, and recreation. Just over half of the people interviewed said that the stewards were helpful (58%), although most of those that answered this question later said that they provided conservation value (86%), but only 40% said they relied on the stewards for information. On a Likert rating scale of 1 to 5 (the highest value), the mean rating for whether it was important for stewards to be present was 3.87 ± 0.09, and the rating for the presence of stewards who can provide information was 3.71 ± 0.11. In contrast, protection of shorebirds was rated a mean of 4.79 ± 0.04. There were significant visitor type differences in how important stewards were, but not in the importance of stewards who can provide information. Fishermen, recreationists, and people coming for scenery and tranquility rated the presence of stewards higher than those visitors who were interested in either shorebirds or crabs (or both). Ratings also differed significantly as a function of age and gender;older adults and females rated characteristics higher than did people under 30 years and males. Information needs identified by stewards are also discussed. These data can be used by the managers developing a strategy for conservation of shorebirds and other species sensitive to disturbance, and for the implementation of an effective stewardship program.
文摘Shorebirds migrate long-distances along the East Asian-Australasian Flyway(EAAF),exhibiting distinct spatiotemporal fluctuations in population dynamics.Because of habitat degradation and population declines at key stopover sites along the EAAF,the South Korea's coastal wetlands have gained increasing attention for their ecological value.This study analyzed the shorebird population dynamics across 35 coastal wetlands in South Korea from 2016 to 2024 using data from the National Marine Ecosystem Monitoring Program.For the timeseries analysis,we employed three indicators:seasonal chan ges in abundance,short-term fluctuations(Fi),and long-term trends,assessed using the TRends and Indices for Monitoring data(TRIM)model.Abundance,species richness,and Shannon diversity indices were assessed across the regions during spring and autumn.The TRIM results revealed significant population increases in both seasons("Strong increase"in spring and"Moderate increase"in autumn).Species-level trends indicated notable increases in large-bodied shorebirds,including globally threatened species such as the Far Eastern Curlew(Numenius madagascariensis).Eurasian Curlew(N.arquata),and Eurasian Oystercatcher(Haematopus ostralegus),whereas other species showed variable responses.The Yellow Sea region(Gyeonggi,Chungcheong,and Western Jeolla)showed high biodiversity indices in spring,which may be associated with time-minimization strategies,whereas autumn patterns were characterized by more flexible and selective stopover use,possibly related to energy-minimization strategies.The East Coast and Jeju regions showed the lowest biodiversity indices.Furthermore,community-level analyses using Non-metric Multidimensional Scaling(NMDS)and PERMANOVA revealed distinct clustering of bird assemblages by macro-region and season,confirming significant spatial differentiation in community composition.These findings contrast with the broader declining trends reported across the EAAF and suggest that South Korea's coastal wetlands may serve as stable alternative stopover habitats,potentially supporting the redistribution or recovery of some species.This study highlights the importance of transboundary cooperation and region-specific habitat management that reflects local ecological contexts for effective conservation.
基金supported by the National Key Research and Development Program of China(2022YFF0802400)the Science and technology basic resources survey project(2021FY101002)the National Natural Science Foundation of China(42101105).
文摘Conservation policies have been formulated for coastal wetlands in China,and exploration of conservation effectiveness based on waterbirds and their habitat is important for guiding conservation actions.We characterized the effects of conservation efforts on shorebird diversity,habitat area and quality using long-term remote sensing data,and shorebird survey data in the Yellow River Delta.From 1997 to 2021,habitat area,quality and population number significantly declined by 49.8%(r=−0.72,p<0.05),13.6%(r=−0.72,p<0.05)and 60.67%(R2=0.77,p<0.05).Before 2012,habitat area(decreased by 38.2%,r=−0.62,p>0.05,slope=−0.25),quality(decreased by 10.53%,r=−0.68,p>0.05,slope=−0.008),and population size(significantly decreased by 94.5%,r=−0.95,p<0.05,slope=−7874.3)declined,and the decline in habitat area significantly contributed to population reductions(r=0.79,p<0.05).Since 2012,habitat area(increased by 14.3%,r=0.71,p>0.05,slope=0.12),quality(increased by 17.12%,r=0.83,p>0.05,slope=0.01),and population size(increased by 8.34%,R2=0.29,p>0.05)slightly increased.The coefficients of variation for habitat area and quality,and population size were smaller after 2012 than before 2012.These results suggest that conservation actions maintained the stability of waterbird populations and their habitat;additional actions are needed to mediate the conservation of other degraded habitats along coastal wetlands.
基金This study was sponsored by the National Technology Support Program(No.2006BAC01A14)Shanghai Technology&Science Administration Key Project(No.06DZ12303)Shanghai Educational Development Foundation.
文摘The carrying capacity of food resources for migrating shorebirds was estimated at a stopover site in the Yangtze River Estuary during the two migratory seasons(spring and autumn).From March to May and September to November 2005,the macrobenthos resources of the Jiuduansha Wetland were investigated,and most of the macrobenthos species in the newlyformed shoal were found to be appropriate food for shorebirds.Biomass measurements showed that the total food resource was about 4541.20 kg AFDW(Ash-Free Dry Weight)in spring and about 2279.64 kg AFDW in autumn.Calculations were also done in the available habitats(intertidal bare mudflat and Scirpus×mariqueter/Scirpus triqueter zones)for the shorebirds.The food resources in the available areas were about 3429.03 kg AFDWin spring and about 1700.92 kgAFDWin autumn.Based on the classification(by lean weight,basic metabolic rate and body length)of the shorebird community,and using the energy depletion model,it was theorized that all of the food resources in the Jiuduansha Wetland could support about 3.5 million shorebirds during spring season and 1.75 million shorebirds during autumn season.The shorebird carrying capacities in terms of the available food were about 2.6 million and 1.3 million birds during the two respective migration seasons.Considering the effect of intake rate,the potential carrying capacity was about 0.13–0.26 million shorebirds in the study area.The main factor restricting use of the area by shorebirds was the scarcity of available habitats for roosting at high tide rather than availability of food supply.We recommend restoring some wading pools in the dense Phragmites australis and Spartina alterniflora zones for shorebirds to roost in,to improve shorebirds’utilization efficiency of the resources in the Jiuduansha Wetland.
