Pied Avocets(Recurvirostra avosetta)are common migratory shorebirds in the East Asian–Australasian Flyway.From 2019 to 2021,GPS/GSM transmitters were used to track 40 Pied Avocets nesting in northern Bohai Bay to identify annual routines and key stopover sites.On average,southward migration of Pied Avocets started on 23 October and arrived at wintering sites(mainly in the middle and lower reaches of the Yangtze River and coastal wetlands)in southern China on 22 November;northward migration started on 22 March with arrival at breeding sites on 7 April.Most avocets used the same breeding sites and wintering sites between years,with an average migration distance of 1124 km.There was no significant difference between sexes on the migration timing or distance in both northward and southward migration,except for the departure time from the wintering sites and winter distribution.The coastal wetland of Lianyungang in Jiangsu Province is a critical stopover site.Most individuals rely on Lianyungang during both northward and southward migration,indicating that species with short migration distances also heavily rely on a few stopover sites.However,Lianyungang lacks adequate protection and is facing many threats,including tidal flat loss.We strongly recommend that the coastal wetland of Lianyungang be designated as a protected area to effectively conserve the critical stopover site.
Yang WuWeipan LeiBingrun ZhuJiaqi XueYuanxiang MiaoZhengwang Zhang
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 (Calidriscanutusrufa), other shorebirds, and horseshoe crabs (Limuluspolyphemus) 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 provi
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.
Zitan SongXin LinPinjia QueNaerhulan HalimubiekeQin HuangZhengwang ZhangTamás SzékelyYang Liu
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,energeti
Hans LinssenMartijn van de PolAndrew M.AllenMitzi JansBruno J.EnsKaren L.KrijgsveldMagali FrauendorfHenk-Jan van der Kolk
Introduction:The Florida coast is one of the most species-rich ecosystems in the world.This paper focuses on the sensitivity of the habitat of threatened and endangered shorebirds to sea level rise induced by climate change,and on the relationship of the habitat with the coastline evolution.We consider the resident Snowy Plover(Charadrius alexandrinus nivosus),and the migrant Piping Plover(Charadriusmelodus)and Red Knot(Calidris canutus)along the Gulf Coast of Mexico in Florida.Methods:We analyze and model the coupled dynamics of habitat patches of these imperiled shorebirds and of the shoreline geomorphology dictated by land cover change with consideration of the coastal wetlands.The land cover is modeled from 2006 to 2100 as a function of the A1B sea level rise scenario rescaled to 2 m.Using a maximum-entropy habitat suitability model and a set of macroecological criteria we delineate breeding and wintering patches for each year simulated.Results:Evidence of coupled ecogeomorphological dynamics was found by considering the fractal dimension of shorebird occurrence patterns and of the coastline.A scaling relationship between the fractal dimensions of the species patches and of the coastline was detected.The predicted power law of the patch size emerged from scale-free habitat patterns and was validated against 9 years of observations.We predict an overall 16%loss of the coastal landforms from inundation.Despite the changes in the coastline that cause habitat loss,fragmentation,and variations of patch connectivity,shorebirds self-organize by preserving a power-law distribution of the patch size in time.Yet,the probability of finding large patches is predicted to be smaller in 2100 than in 2006.The Piping Plover showed the highest fluctuation in the patch fractal dimension;thus,it is the species at greatest risk of decline.Conclusions:We propose a parsimonious modeling framework to capture macroscale ecogeomorphological patterns of coastal ecosystems.Our results suggest the potential use of the fractal dimension o
Matteo ConvertinoAdam BockelieGregory A KikerRafael Munoz-CarpenaIgor Linkov
