Ringed Plovers Research Articles

An allometric approach to seasonal changes in intake rates of migratory shorebirds in the Bijagós Archipelago, Guinea‐Bissau

Shorebirds migrating along the East Atlantic Flyway must travel long distances from their breeding sites in arctic and subarctic regions to wintering areas in Europe and Africa. Selecting a winter location is an important decision, as it can have both immediate and future consequences. Shorebirds must ensure they have enough resources to fulfil their energetic requirements during winter, as well as during the fuelling phase, when they must accumulate fat stores for the return migration. Migratory shorebirds are declining worldwide, with several populations wintering in tropical Africa facing steep declines, particularly when compared with their conspecifics wintering in temperate Europe. However, one of the most important wintering sites in Africa remains relatively unstudied, the Bijagós Archipelago, Guinea‐Bissau. In this study, we quantify intake rates of eight migratory shorebird species wintering in the Bijagós and explore how these vary throughout their stay in the archipelago. Given the uncertainties associated with measurements of field intake rates, an allometric validation of our approach confirmed a slope comparable to that predicted by theory and verified in many situations. Contrary to our expectations, we found no evidence for an increase in intake rates in the fuelling period; in fact, decreases were noticeable in a few species over the non‐breeding season. The allometric relationship across species also confirmed the seasonally decreasing daily energetic intakes, particularly by smaller species. The comparison between the intake rates in the Bijagós and those reported in other wintering sites along the flyway highlights the particularly low values for Ringed Plover Charadrius hiaticula, Curlew Sandpiper Calidris ferruginea and Bar‐tailed Godwit Limosa lapponica. Limitations in intake rates and the associated energetic intake suggest that some species may be energetically constrained in the Bijagós, particularly during fuelling.

Evolution of leapfrog migration: A test of competition-based hypotheses.

Leapfrog migration is a common migration pattern in birds where the breeding and wintering latitudes between populations are in reversed latitudinal sequence. Competition for wintering and breeding sites has been suggested to be an ultimate factor, and several competitor-based hypotheses have been proposed to explain this pattern. If wintering sites close to the breeding sites are favored, competitive exclusion could force subdominant individuals to winter further away. Competitive exclusion could be mediated either through body size or by prior occupancy. The alternative "spring predictability" hypothesis assumes competition for sufficiently close wintering areas, allowing the birds to use autocorrelated weather cues to optimally time spring migration departure. To test predictions and assumptions of these hypotheses, we combined morphometrics, migration, and weather data from four populations of common ringed plover breeding along a latitudinal (56-68° N) and climatic gradient (temperate to Arctic). Critical for our evaluation was that two populations were breeding on the same latitude in subarctic Sweden with the same distance to the closest potential wintering site, but differed in breeding phenology, and wintered in West Africa and Europe, respectively. Thus, while breeding on the same latitude, their winter distribution overlapped with that of an Arctic and temperate population. Body size was largest within the temperate population, but there was no size difference between the two subarctic populations. Populations wintering in Europe arrived there before populations wintering in Africa. The largest variation in the arrival of meteorological spring occurred at the temperate breeding site, while there was almost no difference among the other sites. In general, temperatures at the northernmost wintering area correlated well with each breeding site prior to breeding site-specific spring arrival. Based on these observations, we conclude that competitive exclusion through body-size-related dominance cannot explain leapfrog migration. Furthermore, the assumptions on which the "spring predictability" hypothesis is based did not match the observed wintering ranges either. However, we could not reject the hypothesis that competitive exclusion mediated by prior occupancy in the wintering area could lead to leapfrog migration, and therefore, this hypothesis should be retained as working hypothesis for further work.

A PRELIMINARY SURVEY ON DIVERSITY OF AVIFAUNA IN KATWA, PURBA BURDWAN, WEST BENGAL, INDIA

Birds are used as bio-indicator due to their sensitivity to minor environmental changes. A survey was done from July 2022 to February 2023 to study the avifaunal diversity of Katwa. A total of 67 bird species were recorded during the study period. The species were categorized in three namely common resident (CR), not common resident (NCR) and migratory (M) of which 40 are common resident, 24 are not common resident and 3 are migratory. The found common birds species were house crow, common myna, red vented bulbul, house sparrow, spotted dove, asian koel, little ringed plover etc. Among the not common resident avifauna were Long-legged Buzzard, Cotton teal, Pied-cuckoo, Grey Wagtail, yellow Wagtail, White Wagtail etc. and the three migratory birds were Common Pochard, Red-crested Pochard and Northern Pintail. Katwa and adjoining Ajay Baadh has wide variety of trees, wetland, grassland and agricultural land which is the major contributing factor for the rich avifaunal diversity found during the short study period. This is a preliminary effort for documentation of the avifauna, but more studies and suitable conservation strategies are required in the study area.

Seasonal patterns and processes of migration in a long-distance migratory bird: energy or time minimization?

Optimal migration theory prescribes adaptive strategies of energy, time or mortality minimization. To test alternative hypotheses of energy- and time-minimization migration we used multisensory data loggers that record time-resolved flight activity and light for positioning by geolocation in a long-distance migratory shorebird, the little ringed plover, Charadrius dubius. We could reject the hypothesis of energy minimization based on a relationship between stopover duration and subsequent flight time as predicted for a time minimizer. We found seasonally diverging slopes between stopover and flight durations in relation to the progress (time) of migration, which follows a time-minimizing policy if resource gradients along the migration route increase in autumn and decrease in spring. Total flight duration did not differ significantly between autumn and spring migration, although spring migration was 6% shorter. Overall duration of autumn migration was longer than that in spring, mainly owing to a mid-migration stop in most birds, when they likely initiated moult. Overall migration speed was significantly different between autumn and spring. Migratory flights often occurred as runs of two to seven nocturnal flights on adjacent days, which may be countering a time-minimization strategy. Other factors may influence a preference for nocturnal migration, such as avoiding flight in turbulent conditions, heat stress and diurnal predators.

Chewing lice (Phthiraptera, Amblycera, Ischnocera) from shorebirds (Aves, Charadriiformes) in the Kızılırmak Delta, Turkey

This study was carried out in the Kızılırmak Delta Cernek Bird Ringing Station, Central Black Sea Region, during August and September 2020, to survey the louse species found on shorebirds (Aves: Charadriiformes). A total of 241 birds belonging to 13 species were searched for chewing lice. Eleven species in six genera of the family Scolopacidae (Actitis hypoleucos, Arenaria interpres, Calidris alba, Calidris alpina, Calidris falcinellus, Calidris ferruginea, Calidris minuta, Gallinago gallinago, Tringa glareola, Tringa totanus, Xenus cinereus) and two species in one genus of the family Charadriidae (Charadrius dubius, Charadrius hiaticula) were examined. Birds were caught alive with mist-nets, ringed, searched for lice, and released. A total of 153 birds (63.49%) were infested with lice belonging to 16 species, five amblycerans: Actornithophilus bicolor, Actornithophilus ochraceus, Actornithophilus totani, Actornithophilus umbrinus, Austromenopon lutescens, and eleven ischnocerans: Carduiceps fulvofasciatus, Carduiceps meinertzhageni, Carduiceps zonarius, Lunaceps actophilus, Lunaceps falcinellus, Lunaceps schismatus, Quadraceps hiaticulae, Quadraceps obscurus, Quadraceps ravus, Quadraceps strepsilaris and Saemundssonia platygaster frater. These eight species are new records for Turkey: Ac. bicolor, Ac. ochraceus, Ca. fulvofasciatus, Lu. falcinellus, Lu. schismatus, Qu. ravus, Qu. strepsilaris and Sa. platygaster frater. In addition, Qudraceps hiaticulae was recorded from Little ringed plovers (Charadrius dubius)  for the first time in the world in this study. According the lice checklist of wild birds in Turkey, a total of 188 bird species examined and 122 of them were infested, and a total of 217 chewing lice species has been recorded.

Consequences of migratory distance, habitat distribution and season on the migratory process in a short distance migratory shorebird population

BackgroundThe migratory process in birds consists of alternating periods of flight and fueling. Individuals of some populations make few flights and long stopovers, while others make multiple flights between short stopovers. Shorebirds are known for executing marathon flights (jumps), but most populations studied are long distance migrants, often crossing major barriers and thus forced to make long-haul flights. The sub-division of migration in short/medium distance migratory populations, where the total migration distance is shorter than documented non-stop flight capacity and where routes offer more homogenous stopover landscape, is little explored.MethodsHere we combine data based on conventional light level geolocators and miniaturized multi sensor loggers, comprising acceleration and light sensors, to characterize the migratory routes and migration process for a short/medium distance (~ 1300 to 3000 km) migratory population of common ringed plover (Charadrius hiaticula) breeding in southern Sweden. We were specifically interested in the variation in number and duration (total and individual) of flights/stopovers between seasons and in relation to migration distance.ResultsMost stopovers were located along the European Atlantic coast. On average 4.5 flights were made during autumn migration irrespective of migration distance, but in spring the number of flights increased with distance. The equal number of flights in autumn was explained by that most individuals migrating farther performed one longer flight (all but one lasting > 20 h), likely including crossing of the Bay of Biscay. Median duration of single flights was 8.7 h in autumn and 5.5 h in spring, and median stopover duration was ~ 1 day in both seasons. There was a positive relationship between total flight duration and migration distance, but total flight duration was 36% lower in spring compared to autumn.ConclusionsOur results suggest that when suitable stopovers are abundant common ringed plovers prefer making shorter flights even if longer flights are within the capacity of the species. This behaviour is predicted under both time and energy minimizing strategies, although the variable flight distances suggest a policy of time selected migration. Even if populations using several stopovers seem to be more resilient for environmental change along the route, these results are informative for conservation efforts and for predicting responses to future environmental change.

Incubation behaviour of the Common Ringed Plover Charadrius hiaticula at different latitudes

In biparental Charadriinae plovers, male and female incubation duties often resemble daily routines, with males typically incubating at night and females incubating during the day. By analysing incubation behaviour in three Arctic populations of Common Ringed Plover Charadrius hiaticula, we show that these diel routines are lost in the 24-h sunlight of the Arctic. In contrast, a non-Arctic population in East Scotland exhibited significant daily routines, with males dominating incubation during the late afternoon and night, and females dominating incubation during the early morning and midday hours. These patterns suggest that clear light/dark cycles are necessary for daily incubation routines to form in the Common Ringed Plover, although further research is needed to understand the specific drivers of this behaviour.

Morphological characteristics influence the spatial mixing patterns of shorebirds at Shengjin Lake.

The coexistence of species with similar ecological niches is one of the core interests of community ecology research. However, how functional feeding traits, including bill size and leg length, determine the niche of mixed flocks of shorebird species has seldomly been studied, as well as, microhabitat variables affect the spatial patterns of availability and the quality of patches for wintering. From October 2016 to March 2017 at Shengjin Lake, Anhui Province, China, we recorded 226 scan samples from the different microhabitats and 93 focal animal videos of four common shorebird species: common greenshank, spotted redshank, Kentish plover, and little ringed plover. We found that the species participating in the mixed groups were different in each microhabitat. The results of the overlap index for microhabitats and foraging techniques between the species were consistent with the morphological characteristics of these species. Kentish and little ringed plovers had the highest Pianka's niche overlap index values of 0.95 and 0.98 for microhabitats and foraging techniques, respectively, whereas common greenshank and spotted redshank had values of 0.78 and 0.89, respectively. Common greenshank and spotted redshank used four foraging techniques: a single probe (PR), multiple probes (MPR), a single peck (PE), and multiple pecks (MPE). Kentish and little ringed plovers only used PE and MPE. The mean bill size, mean leg length, and mean foraging frequency were significantly associated with water depth. The mean bill size and mean leg length were both significantly correlated with the mean foraging frequency of shorebirds. The vegetated area was the most important variable for grouping among shorebirds. We concluded that the four species showed differences in their preferred microhabitats and foraging patterns. Interspecific morphological differences, including bill and leg lengths, resulted in niche differentiation. Thus, effective resource allocation by regional species was realized, and a dynamic balance was achieved by the mixed foraging species. The information on foraging behavior and habitat requirements could be useful in the management of water levels in natural areas and conservation of a diversity of wintering shorebirds.

The effects of river regulation on diet diversity, dietary niche overlap and foraging habitat preferences of two sympatric plover species

During migration waders use a variety of microhabitats and a wide range of prey to supply their nutritional requirements. Most of them form multispecies flocks, which may result in increased competition for resources. In this study, we compare the abundance of potential prey for Ringed and Little Ringed plovers at unregulated and regulated stretches of the Vistula River. We also observed plovers and assigned them to the habitat in which they foraged and compare the diet, dietary niche overlap and foraging habitat preferences of these two plover species. The larger species, the Ringed Plover, foraged more often in invertebrate abundant habitats, yet exclusively on the three most abundant prey species, while the smaller species expanded its diet to include invertebrate species of low abundance and in suboptimal habitats. In the regulated river section, below the dam, the diet of the Little Ringed Plover was more diverse, and the dissimilarity of both plovers’ diets was much higher than in the regulated section. The unregulated river section offered richer foraging grounds and both species showed similar proportions of primary prey items in their diets here resulting in greater dietary niche overlap and weaker resource partitioning. Our study shows that river regulation increases competition for food resources due to a lower abundance of potential prey and has an influence on diet diversity and foraging habitat preferences of smaller, less competitive plover species.

Synchronous Declines of Wintering Waders and High-Tide Roost Area in a Temperate Estuary: Results of a 10-Year Monitoring Programme

Migratory wader populations are declining across all major flyways, mostly due to habitat loss and human disturbance. Portuguese wetlands act as key wintering and stop-over sites for many waders due to their strategic location in the East Atlantic Flyway. Despite their importance, there are major knowledge gaps in some areas, such as the Sado Estuary. The main goal of this study was to identify the phenological patterns and wintering trends of the most abundant wader species in this wetland, and to compare the results with the population trends found at regional and flyway scales. A comprehensive dataset of count data collected monthly in high-tide roosts under a set monitoring programme (2010–2019) was used. The results revealed strong declines in the overall number of waders and of three of the most abundant species—Avocet (Recurvisostra avosetta), Dunlin (Calidris alpina), and Common Ringed Plover (Charadrius hiaticula)—associated with a 21% reduction of the suitable high-tide roosts across the study area. These trends are similar to those compiled from winter counts for the entire Sado Estuary, and at regional (Tagus Estuary) and flyway levels. Our results highlight the need to maintain suitable high-tide roosts to contribute towards reverting current declines in wader populations.

Sharing habitat: Effects of migratory barnacle geese density on meadow breeding waders

1.Following targeted conservation actions most goose populations have increased. The growing goose populations caused an increase in human-wildlife conflicts and have the potential to affect nature values. As meadow birds, including meadow-breeding waders, were declining throughout Western Europe, the possible negative effect of rising numbers of foraging barnacle geese on their breeding success has been questioned.2.We used GPS-transmitter data to measure the density of foraging barnacle geese during daylight hours. Using dynamic Brownian Bridge Movement Models (dBBMM), we investigated the effect of barnacle goose density on the territory distribution of five wader species, and on nest success of the locally common Northern lapwing. We used model selection methods to identify the importance of barnacle goose density related to other environmental factors.3.Our results showed an insignificant positive association between barnacle goose density and nest territory density of the Northern lapwing and common redshank. Barnacle goose density had no influence on territory selection of godwit, oystercatcher and ringed plover. We did, however, find a negative correlation between barnacle geese density and the nest success of the Northern Lapwing.4.We infer that either barnacle goose foraging leads to improved territory conditions for some wader species, or that both barnacle geese and waders prefer the same type of habitat for foraging and nesting. Higher barnacle goose density was correlated with fewer Northern lapwing nests being successful.5.Synthesis and application: Experimental research is needed to disentangle the causal chain, but based on our observational findings, we suggest to increase water logging that may attract both barnacle geese and wader species. Further investigation on the effects of barnacle geese on wader species is necessary to identify the cause of the negative correlation between barnacle geese density and nest success of lapwings; nest protection experiments could give further insight.

Survival fluctuation is linked to precipitation variation during staging in a migratory shorebird

Understanding how weather conditions affect animal populations is essential to foresee population changes in times of global climate shifts. However, assessing year-round weather impacts on demographic parameters is hampered in migratory animals due to often unknown occurrence in space and time. We addressed this by coupling tracking and weather data to explain extensive variation in apparent survival across 19 years in a northern European population of little ringed plovers (Charadrius dubius). Over 90% (n = 21) of tracked individuals followed migration routes along the Indo-European flyway to south India. Building on capture–recapture histories of nearly 1400 individuals, we found that between-year variation in precipitation during post-breeding staging in northern South Asia explained 47% of variation in apparent adult survival. Overall, the intensity of the monsoon in South Asia explained 31–33% of variability in apparent survival. In contrast, weather conditions in breeding, final non-breeding and pre-breeding quarters appeared less important in this species. The integration of multi-source data seems essential for identifying key regions and periods limiting population growth, for forecasting future changes and targeting conservation efforts.

Complete mitochondrial genome of little ringed plover Charadrius dubius (Charadriiformes, Charadriidae)

This study encoded the complete mitochondrial genomic sequence of the little ringed plover Charadrius dubius. The mitochondrial genome has a total length of 16,864 bp, consisting of 13 protein-coding genes, 22 tRNA genes, two rRNA genes, and a control region. The nucleotide composition was 23.8% T, 31.6% A, 30.8% C, and 13.8% G. This study provides the basic information on the mitogenome of C. dubius and supports the understanding of mitogenomic information and its phylogenetic relationship within Charadriiformes.

Modelling important areas for breeding waders as a tool to target conservation and minimise conflicts with land use change

Breeding waders are high profile species of conservation concern because of their declining populations. Their future depends on the outcomes of land-use policy and local management decisions. However, the low spatial resolution of extensive data on wader occurrence is poorly suited to directing conservation initiatives or to minimising detrimental impacts arising from land-use changes such as forest expansion. We used statistical models to produce high-resolution maps of predicted wader abundance in Britain and tested whether these were sufficiently accurate to be used for decision making. Random forest regression trees were developed using Bird Atlas data modelled with a range of environmental data sets to predict the relative abundances of ten species of breeding wader across Britain at 1-km square resolution. Similar analytical frameworks could usefully be applied in other geographical areas.Correlations with Bird Atlas metrics and other independent data indicate that these predictive models worked best for Curlew Numenius arquata and Oystercatcher Haematopus ostralegus. Model performance was poorer for species with more restricted distributions and/or habitat requirements, such as Greenshank Tringa nebularia and Ringed Plover Charadrius hiaticula. The precision of model predictions was also limited by the rescaling of data to 1-km square resolution.To facilitate practical and consistent interpretation by stakeholders influencing the status of breeding waders, model outputs were categorised into five discrete strata of relative abundance. These strata were used to produce sensitivity maps (available at https://app.bto.org/wader-map/), primarily to inform high-level policy decisions. The model outputs were also used to investigate broad-scale associations of breeding wader distribution with landscapes and land uses. These show that high proportions of populations (relative to their extent) are supported by areas with comparatively low predation risk (e.g. islands and grouse moors) and also by nature reserves. At more local scales, the sensitivity maps can be used to help decide on the levels of scrutiny required to assess development proposals (e.g. for establishment of new tree planting).

Impact of Water Fluctuation from a Dam on the Mekong River on the Hatching Success of Two Sandbar-Nesting Birds: A Case Study from Bueng Kan Province, Thailand

Dam construction for the provision of hydropower and a stable water supply poses a major threat to freshwater biodiversity. Water fluctuation due to dam management has adverse effects on local people and biodiversity in downstream areas, including sandbar-nesting birds. The aim of this research was to determine the effect of water levels controlled by upstream dams on the breeding success of two sandbar-nesting birds, the little ringed plover, Charadrius dubius, and little pratincole, Glareola lacteal, along the Mekong River in Bueng Kan Province, Thailand. During January–May 2018, we found 160 active nests of only two species, the little ringed plover (n = 26 nests, 288 exposure days) and the little pratincole (n = 134 nests, 890 exposure days). Their nest success rates were 19.49 ± 7.52% and 5.54 ± 1.61%, respectively. Predation was a major cause of nest failure for both species (n = 82), followed by flooding (n = 44). We found a significantly increased probability of nest flooding when the water level was higher than when the nest was initiated for those located closer to the water, particularly during March and April, when water levels fluctuated. Our results indicate that dams threaten sandbar-nesting species.

Predation‐mediated edge effects reduce survival of wader nests at a wet grassland‐forest edge

AbstractEdge effects occur when the matrix has adverse impacts on the patches of remnant habitat. A widely explored example of this is the hypothesis of a higher predation pressure on bird nests closer to the habitat edge. In parallel with the recent loss of open habitats through afforestation as a climate change mitigation measure, an interest in the impact of forest on species dependent on open habitats has re‐emerged. We follow wader nest survival to study the issue of an edge effect in a system of wet grasslands fragmented by forests in a region where it has not been tested before, focussing mainly on northern lapwing (Vanellus vanellus), common ringed plover (Charadrius hiaticula), common redshank (Tringa totanus) and southern dunlin (Calidris alpina schinzii). To record nest survival, we monitored 753 nests of 10 wader species on coastal grasslands in Estonia for 3 consecutive years. A subset (n = 85) of these nests was equipped with camera traps to record nest predation events and predator association with forest edge. The distance to nearest trees and forest and a forest cover within a 1‐km buffer around each nest was measured. We recorded extremely low daily nest survival rates (0.903–0.922 for different species), with most nests lost to predation. We showed that nest survival is lower closer to the forest edge and negatively affected by the proportion of forest within a 1‐km buffer around each nest. Based on camera trap recordings, we suggest that the edge effect is caused by elevated nest predation rates by the most common predator, the red fox (Vulpes vulpes), closer to the forest edge. Future afforestation plans of open habitats need to acknowledge that the resulting fragmentation has a negative impact on nest survival of ground‐breeding birds. On the other hand, our results imply that restoration efforts aimed at removal of most damaging forest plantations could benefit breeding waders.

Initial biological development of a newly established side channel at the Lower Rhine

AbstractWithin the EU LIFE‐Nature project ‘River and floodplain revitalisation Emmericher Ward’, three small temporary waters and a former gravel pit were connected by a side channel running parallel to the river Rhine through former groyne fields. The initial status of macrozoobenthos, fish, avifauna, flora, vegetation, and habitats before and their development after implementation of the project's measures were recorded and compared. The monitoring years 2018 and 2019 were exceptionally dry and accompanied by an extremely low runoff in the Rhine and the side channel. These conditions likely affected the development of habitats and species populations in the new side channel. The new side channel showed intensive morphodynamic development and differentiation of its structures. While the more complex vegetation and habitat types appeared as mostly species‐poor initial stages, short‐lived species‐rich pioneer habitats such as annual mud banks in the water exchange area were already established. Two years after the implementation, the benthic invertebrate fauna was still predominantly species‐poor and dominated by neozoans. Occasionally, representatives of the more sensitive EPT fauna (Ephemeroptera, Plecoptera, Trichoptera) were already detected but were, in general, strongly underrepresented in the main stream. Low colonisation potential, nonpermanent flow, and lack of river wood limit the development of the macrozoobenthos community. The relative abundance of rheophilic fish species increased in the project area and high juvenile fish densities proved the function as a nursery habitat. As pioneer species of riverine landscapes, sand martins and little ringed plovers colonised the new structures already in the first year. The initial state of the side channel represented a typical dynamic pioneer habitat pattern of a sandy lowland river, which was almost absent in the Lower Rhine area. The new habitats were quickly colonised by pioneer flora and fauna, but the potential for more demanding and complex communities was restricted by the poor structural and biological states of the Lower Rhine.

Population specific annual cycles and migration strategies in a leap-frog migrant

A common migratory pattern in birds is that northerly breeding populations migrate to more southerly non-breeding sites compared to southerly breeding populations (leap-frog migration). Not only do populations experience differences in migration distances, but also different environmental conditions, which may vary spatiotemporally within their annual cycles, creating distinctive selective pressures and migratory strategies. Information about such adaptations is important to understand migratory drivers and evolution of migration patterns. We use light-level geolocators and citizen science data on regional spring arrivals to compare two populations of common ringed plover Charadrius hiaticula breeding at different latitudes. We (1) describe and characterize the annual cycles and (2) test predictions regarding speed and timing of migration. The northern breeding population (NBP) wintered in Africa and the southern (SBP) mainly in Europe. The annual cycles were shifted temporally so that the NBP was always later in all stages. The SBP spent more than twice as long time in the breeding area, but there was no difference in winter. The NBP spent more time on migration in general. Spring migration speed was lower in the SBP compared to autumn speed of both populations, and there was no difference in autumn and spring speed in the NBP. We also found a larger variation in spring arrival times across years in the SBP. This suggests that a complex interaction of population specific timing and variation of breeding onset, length of breeding season, and proximity to the breeding area shape the annual cycle and migratory strategies.Significance statementMigration distance, climate, and the resulting composition of the annual cycle are expected to influence migration strategies and timing in birds. Testing theories regarding migration behaviours are challenging, and intraspecific comparisons over the full annual cycle are still rare. Here we compare the spatiotemporal distributions of two latitudinally separated populations of common ringed plovers using light-level geolocators. We found that there was a larger long-term variation in first arrival dates and that migration speed was slower only in spring in a temperate, short-distance migratory population, compared to an Arctic, long-distance migratory population. This suggests that a complex interaction of population specific timing and variation of breeding onset, length of breeding season and proximity to the breeding area shape the annual cycle and migratory behaviours.

Regional models of the influence of human disturbance and habitat quality on the distribution of breeding territories of common ringed plover Charadrius hiaticula and Eurasian oystercatcher Haematopus ostralegus

We estimated the influence of human disturbance and environmental factors on territory establishment in common ringed plovers Charadrius hiaticula and Eurasian oystercatchers Haematopus ostralegus, to inform the conservation of these species. We examined a 212 km stretch of coastline in the United Kingdom in 2003, mapping all breeding pairs of both study species, as well as the environmental characteristics of beaches and locations of visitors on the beach, the latter measured by filming from a light aircraft. Of the 1,003 200m sections of beach surveyed, 183 contained ringed plover territories (267 breeding pairs) and 117 contained oystercatcher territories (226 breeding pairs). 38,634 human visitors to the beach were mapped from three flights. Population densities of both ringed plovers and oystercatchers were lower in locations with high visitor numbers, even when accounting for the influence of the environmental characteristics of the beach. The two bird species showed similar rates of territory establishment at very low visitor rates, but oystercatchers showed a stronger negative response when visitor rates reached higher levels. Binary logistic regression models were used to identify areas where the birds would benefit most from reductions in the number of visitors and we illustrate how this information could be used to inform management around sites otherwise favourable for territory establishment.

The 45thAnnual Report of the California Bird Records Committee: 2019 Records

From its last report through 2019, the California Bird Records Committee reached decisions on 204 records involving 225 individuals of 62 species and one species group, endorsing 176 records of 197 individuals. These include the first accepted state record of the Yellow-browed Warbler (Phylloscopus inornatus), bringing California’s total list of accepted species to 676, of which 13 represent established introductions. Other especially notable records detailed in this report include the state’s third Common Eider (Somateria mollissima), third Common Ringed Plover (Charadrius hiaticula), fourth and fifth Red-flanked Bluetail (Tarsiger cyanurus), a significant incursion of Cassin’s Sparrows (Peucaea cassinii) into the eastern Mojave Desert, and the first Spotted Redshank (Tringa erythropus) in 30 years.