Kentish Plover Charadrius Alexandrinus Research Articles

Nest attendance of the Kentish Plover Charadrius alexandrinus in relation to temperature and incubation stage

ABSTRACT Nest attendance of Kentish Plovers Charadrius alexandrinus at an undisturbed site increased from approximately 70% in the initial days of incubation to 90–95% after day 10. During the day, nest attendance was negatively associated with ambient temperature, indicating that warm weather allowed parent birds to spend more time off the nest. At night, nest attendance was constant. Our results provide a baseline for nest attendance against which the effects of disturbance can be investigated.

Variations in the Reproductive Strategies of Different Charadrius alexandrinus Populations in Xinjiang, China.

Due to the influence of bio-geographical and environmental factors, as well as anthropogenic landscape features, organisms show different reproductive strategies among different populations. There is a lack of detailed information on the reproductive biology of Kentish plover Charadrius alexandrinus in arid lands in Central Asia. In this study, we summarized the characteristics of the reproductive biology of three geographically distinct plover populations in Aibi Lake in northwestern Xinjiang, Taitema Lake in southern Xinjiang and artificial reservoirs around Urumqi City in northern Xinjiang, based on 440 eggs from 158 nests observed and analyzed from April to July of 2019 and 2020. We found that there was no significant difference in clutch size among the three populations. However, the egg size of the Taitema Lake population was significantly larger than those of the other two populations, whilst the egg volume and clutch volume of the artificial reservoirs' populations were significantly larger than that of Aibi Lake. With the postponement of laying dates, the northern and northwestern populations showed the characteristics of a small clutch size and a relatively small egg size, respectively, and a decrease in reproductive output. The heavier female plovers in Taitema Lake laid eggs earlier, and there was a significantly positive correlation between female body mass and clutch size and egg size. The tarsometatarsus length of the female plovers was significantly positively correlated with the reproductive output in all three populations. The model selection results show that female body size and ambient temperature restrict the egg size and reproductive output of Kentish plovers, which is consistent with the upper limit hypothesis of the maternal condition and maternal constraint. Our data support the hypothesis that Kentish plovers show distinct flexibility in their breeding strategies to cope with the harsh natural environment in the arid lands of Xinjiang, China. The results of a relatively high average clutch size and average egg size imply that the saline wetlands of Western China are important breeding habitats for Kentish plovers.

Systematic revision of the ‘diminutive’ Kentish Plover (Charadriidae: Charadrius) with the resurrection of Charadrius seebohmi based on phenotypic and genetic analyses

The Kentish Plover Charadrius alexandrinus Linnaeus 1758 is a common shorebird in Eurasia and North Africa that breeds in a variety of habitats, exhibits different extents of migratory behaviour and is an emerging model species of breeding system evolution. Here we focus on the resident population found across the southern tip of India and Sri Lanka, and re‐evaluate its systematic status based on phenotypic and genetic distinctiveness from a sympatric migrant, Charadrius alexandrinus sensu stricto, and the recently elevated closely related Charadrius dealbatus in East Asia. We show that the Sri Lankan and South Indian (South Asian) population differs in body size, moulting pattern and plumage coloration from C. alexandrinus and C. dealbatus. Furthermore, based on two mitochondrial, two sex‐linked and 11 autosomal microsatellite markers from 378 individuals, we show that these three taxa have moderate genetic differentiation (Fst 0.078–0.096). The South Asian taxon is sister to the clade of C. alexandrinus sensu stricto and C. dealbatus with an estimated divergence time of 1.19 million years ago. We also examined ornithological records of major museum collections in Asia, Europe and North America for the south Asian taxon to evaluate its biogeographical and taxonomic status. Based on differences in genotype, phenotype, allochronic migratory pattern and breeding range, we resurrect the most suitable synonym, Charadrius alexandrinus seebohmi Hartert and Jackson, 1915, and elevate the nomen to the species level with the proposed English name ‘Hanuman Plover’.

Distribution of breeding waterbirds in relation to wetland characteristics in the Oued Righ valley in the Algerian Sahara

Abstract In the framework of this study 14 breeding species were identified in the wetland complex of the Oued Righ valley in the Algerian Sahara. Six species of breeding Anatidae were reported, two of which are classified as vulnerable and threatened, namely, the ferruginous duck Aythya nyroca and the marbled teal Marmaronetta angustirostris. For shorebirds, we noted reproduction of the pied avocet Recurvirostra avosetta, the black-winged stilt Himantopus Himantopus, and the Kentish plover Charadrius alexandrinus in most of the wetlands studied. We report for the first time nesting of the slender-billed gull Chroicocephalus genei at Chott Merouane with 72 pairs recorded during the breeding season 2018. This colony was associated with the larger colony of greater flamingo Phoenicopterus roseus composed of 640 pairs. Principal component analysis (PCA), gathering 69.74% of the information, showed a significant correlation between the distribution of different bird species and the main environmental factors, that is, vegetation, water surface area, water depth, and salinity, and a strong correlation between the species of Annatidae and Rallidae, which are associated with less-saline environments rich in vegetation and deep water, with the exception of shelducks, which prefer large surface areas with less-dense vegetation and more holomorphic water. For the shorebirds such as R. avosetta and H. himantopus, there was a clear preference for large wetlands with shallow water and relatively high salinity. A remarkable correlation was also noted for P. roseus, where a strong distribution of breeding populations was observed in areas with the highest salinity levels and a vast surface area.

Landscape and climatic predictors of Kentish Plover (Charadrius alexandrinus) distributions throughout Kazakhstan

Worldwide populations of shorebirds are declining, associated with a complex interplay of climate change, predation, human disturbance and habitat degradation. Comprehensive information on the distribution and breeding ecology of shorebird populations is crucial to understand and mitigate these threats. Kazakhstan, the largest country in Central Asia, comprises multiple flyways and breeding habitats for shorebird species, including the Kentish Plover Charadrius alexandrinus, but information on the population size and breeding distribution of shorebird species in the region is highly limited. We conducted a wide‐scale survey of Kentish Plover across Kazakhstan during the breeding season and utilize species distribution modelling to outline key anthropogenic and environmental variables that determine Kentish Plover presence. Our results reveal widespread distribution of Kentish Plovers across Kazakhstan but indicate that breeding densities are generally low. Our distribution modelling stresses the primary importance of proximity to water bodies and climate as the main predictors of Kentish Plover presence, but reveals a weak association with indicators of human disturbance. We utilize our distribution modelling to provide the first quantitative estimate of the breeding population size of Kentish Plover in Kazakhstan, which indicates a modest number of individuals given the size of the country (between 12 000 and 32 000 individuals). Our results indicate the key routes via which climate change may impact on population‐level distributions of Kentish Plover and provide a platform for future studies investigating species distributions across similarly vast and inaccessible regions.

Distribution, abundance and bio-characteristics of the Kentish plover (<i>Charadrius alexandrinus</i> L., 1758) in Tuva

The paper considers the distribution and elements of breeding bio-characteristics and abundance of the Kentish plover (Charadrius alexandrinus L.) on the basis of literary and the authors materials. The necessity of the species state revision is connected with the all-round decrease of its number and its inclusion in the last edition of the Red List of Threatened Animals and Plants of the Russian Federation. Optimal breeding habitats of the Kentish plover are located in a very limited area on the coasts of the steppe lakes of the Ulug-Khem and the Ubsu-Nur basins. The Kentish plover nests regularly in Tuva but its numbers are subject to considerable fluctuations depending mainly on hydrological conditions of the season. The total number of plovers within the studied area does not exceed 4050 pairs. The Kentish plover is more numerous and occurs more widely on migration. The main features of nesting bio-characteristics are similar in other areal parts but late nesting dates were recorded. Some deviations in oological characteristics were also fixed (totally 29 eggs from 9 egg clutches were described). Anthropogenic factors such as cattle grazing along the coasts as well as intensive recreational impact have a great influence on the condition of the local nesting population of the Kentish plover. The authors recommend including the Kentish plover species in the Red List of Threatened Animals and Plants of Tuva Republic due to their low numbers during their nesting and its extreme stenotopicity.

Status, distribution and conservation of Kentish plover <em>Charadrius alexandrinus</em> (Aves, Charadriiformes) in Sicily

The Kentish Plover Charadrius alexandrinus is a sensitive species whose national breeding population has been undergoing a sharp decrease, up to 50%, in 2010 compared to the previous decade. Due to the lack of updated data and fragmented knowledge about its current status and distribution in Sicily, a specific and accurate monitoring of this species was carried out during the years 2018 and 2019. About 230 km of coastline and 64 UTM squares 10x10 km were investigated during the breeding seasons, and a total of 205-287 pairs have been estimated for the whole region, distributed in 41 UTM squares (including the island of Favignana). Pairs are mainly concentrated in the complex of “Saline di Trapani and Stagnone di Marsala” and along the sandy coast of Gulf of Gela, with a higher abundance along the southeast coast of the region. Breeding population showed a decrease of 18-28% in number of pairs in comparison to the last estimation of 250-400 pairs reported for the years 2009-2010. After the investigation of 108 km of coastline and 46 UTM squares, the Sicilian wintering population has been estimated at 376- 563 ind., with wintering flocks mainly concentrated in the wetlands of “Mazara del Vallo” and along the coasts of Syracuse and the Gulf of Gela. These updated estimates place Sicily as the second most important Italian region for the wintering of this species, just after Sardinia. For the first time, the data collected have made it possible to draw up qualitative-quantitative maps of C. alexandrinus distribution in Sicily, providing an important instrument for the management and planning of specific conservation actions, which should be based on habitat protection and implementation of appropriate artificial ecological niches.

The allocation between egg size and clutch size depends on local nest survival rate in a mean of bet-hedging in a shorebird

BackgroundThe 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.MethodsWe 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.ResultsAlthough 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.ConclusionsOur 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.

Four‐legged foes: dogs disturb nesting plovers more than people do on tourist beaches

Recreational activities in nature have increased considerably in recent decades. Human disturbance may trigger similar trade‐offs in birds that the natural risk of predation generates on productivity through parental investment decisions. To estimate how the impact of human presence affects breeding birds on Mediterranean beaches, the behaviour of incubating Kentish Plovers Charadrius alexandrinus was studied in relation to the approach of people, vehicles and dogs. Observational data were collected and control experiments were performed with a standardized stimulus. The response variability of birds in the decision to flush from the nest was studied depending on the type of beach user, the location of the disturbance event and thermal stress. Walkers, when accompanied by dogs, flushed plovers 93.8% of the time when walking through dunes and 80.0% of the time when walking on paths, whereas pedestrians alone flushed plovers 47.6% of the time when in dunes and only 12.9% of the time when on paths. Lone dogs triggered a flushing response 100% of the time when they roamed the dunes and 50% on the shore. The number of users in each disturbance event did not affect the flushing behaviour. Nest return times were shorter on disturbed beaches, suggesting habituation to the human disturbance stimulus. The ambient temperature for the nests in which plovers flushed was lower and nest return time decreased proportionally with ambient temperature, both suggesting that habituation to the human disturbance stimulus encourages relaxation of the trade‐off between escape behaviour to avoid predation risk and the effects of thermal stress on unattended eggs. Females flushed more frequently (57.1%) than males (32.0%), suggesting that they may perceive risk differently. Establishing buffers between nesting areas and people may help birds habituate to the predictable and non‐lethal stimulus of human presence, facilitating coexistence between conservation and recreation.

Population divergence and gene flow in two East Asian shorebirds on the verge of speciation

Genetic isolation of populations over evolutionary time leads to the formation of independent species. We examined a pair of shorebirds – the Kentish Plover Charadrius alexandrinus and the enigmatic White-faced Plover C. dealbatus – which display strong plumage differentiation, yet show minimal genetic divergence based on previous mitochondrial and microsatellite work. Two scenarios may lead to this situation: (1) they represent clinal or poorly diverged populations with limited genomic differentiation despite substantial plumage variation, or (2) they are diverging taxa at the cusp of speciation, with ongoing limited gene flow obliterating signals of differentiation in traditional genetic markers. We compared the genotypes of 98 plovers (59 Kentish Plovers, 35 White-faced Plovers and 4 genomic hybrids) sampled in eastern Asia and Europe using ddRADSeq to harvest over 8000 genome-wide SNPs. In contrast to previous studies, our analyses revealed two well defined genomic clusters, with limited hybridization and a narrow contact zone. We also uncovered significant differences in bill length and further sex-specific differences in size, which may signal differences in mate choice between Kentish and White-faced Plovers. Our results support the hypothesis that this shorebird duo is on the verge of speciation.

Accumulation of trace elements in feathers of the Kentish plover Charadrius alexandrinus

A non-invasive study of trace element accumulation in tail feathers of the Kentish plover (Charadrius alexandrinus) was performed along the coastline of the northern littoral strip of the Venice Lagoon, with the aim to verify whether contamination may be a factor affecting conservation status of Kentish plover populations.Body burdens in feathers of 11 trace elements including toxic metals/metalloids and essential elements (As, Cd, Co, Cr, Cu, Hg, Ni, Pb, Se, V, Zn) were quantified by ICP-MS, then concentrations were normalized to feather's age calculated using ptilochronology in order to obtain daily deposition rates.Mercury emerged as a major threat to the conservation of the species, since average feather concentration was clearly above the adverse-effect threshold associated with impairment in the reproductive success in a number of bird species. Also Cd and Se occurred at levels that may impact on the conservation status of the studied species at local scale, even if to a lesser extent than Hg.Gender-related differences in trace element accumulation emerged only for As, although for this element the risks associated to environmental exposure seem to be negligible.

Offspring sex ratio is unrelated to parental quality and time of breeding in a multiple-breeding shorebird

Sex ratio is a fundamental concept in evolutional biology, and theory predicts that parents should invest in sons and daughters according to the fitness returns they expect from them. The fitness returns may depend on the timing of breeding and on parental conditions leading to sex ratios that depend on breeding date and/or parental quality. Here, we investigate the offspring sex ratio in a small shorebird, the Kentish Plover Charadrius alexandrinus, in a large breeding population in Eastern China, and test whether the parents adjust their offspring’s sex in response to hatch date, brood age and their own body condition. Using 1264 chicks from 676 broods that were molecularly sexed, we show that hatchling sex ratio was not significantly different from unity. Hatchling sex ratios were not related to hatch date or to the body condition of parents. In addition, we sexed 138 eggs that were confiscated from illegal egg collectors and found that the mortality of female and male embryos was not significantly different. The latter result is important by suggesting that neither primary sex ratio (i.e., at conception) nor secondary sex ratio (i.e., at hatching) is biased. Taken together, the even offspring sex ratio in Chinese Kentish Plovers is consistent with recent analyses of six plover populations that found even sex ratios at hatching. Future works should investigate whether the even sex ratio persists into adulthood, or it may shift toward more males (or females) due to sex-biased mortalities of juveniles and/or adults.

The protoporphyrin content of Kentish Plover Charadrius alexandrinus eggshells is better predicted by the fractal dimension of spottiness than by colour

Quantifying the pigment content in avian eggshells is important for the validation of hypotheses on the functionality of eggshell coloration. The few studies that have analysed whether eggshell coloration and spottiness are related to pigment content have found contradictory results. In this study, we analysed whether the coloration and the degree of spottiness of Kentish Plover Charadrius alexandrinus eggshells are related to pigment concentrations (protoporphyrin and biliverdin). We also examined whether the concentrations of these pigments are related to the fractal dimension (FD) of spottiness. The FD of spottiness may be useful as a simple standardized method to quantify complex patterning. We found that protoporphyrin was more abundant than biliverdin in eggshells. Contrary to expectations, the content of protoporphyrin was not related to eggshell colour, probably due to a different allocation of pigments between the spots and the background of the eggshell, and/or to the different allocation of pigments among eggshell layers. However, we found a positive relationship between the FD of eggshell spottiness and the amount of protoporphyrin. It is likely that the FD of spottiness (indicative not only of spot size and the degree of spottiness, but also of how convoluted the outlines of spots are and how spots are distributed across an eggshell) may be related to the mechanical function of protoporphyrin (e.g. in strengthening eggshells, which may interfere with the fractal structure of potential fractures), and/or it may also improve egg camouflage. However, more studies in other avian species are needed to evaluate if the FD of spottiness is a good surrogate for protoporphyrin content in eggshells.

A test of the “Leave Early and Avoid Detection” (LEAD) hypothesis for passive nest defenders

Studies of avian escape behavior have mostly focused on nonbreeding birds, however the costs and benefits of escape behavior are predicted to vary depending on whether or not birds are breeding. Passive nest defenders may escape an approaching threat earlier than would otherwise be the case as an adaptation that helps conceal their cryptic eggs. Alternatively, the investment in the clutch may mean that birds delay escape. We tested these predictions on a population of passively defending Little Tern (Sterna albifrons) and Kentish Plover (Charadrius alexandrinus) within the Saemanguem reclamation area, South Korea. Incubating terns exhibited longer flight-initiation distances to approaching pedestrians than did non-incubating conspecifics, suggesting early escapes may function to help conceal the locality of the nest. No such effect was evident for Kentish Plover.

Breeding birds in the Narta Lagoon (SW Albania) in 2016

Abstract The Narta Lagoon (59 km2) is one of the largest and most important coastal wetlands for migratory and wintering waterbirds in Albania. However, the breeding bird fauna of the site is still poorly studied. The current work aims to broaden the knowledge on the list of breeding bird species, their numbers, distribution and threats in the zone (with a focus on waterbirds). Relevant information for spring migrants is also provided. The survey consisted of two field visits in April and May 2016. The entire wetland area was covered and all its habitats were visited. In total, 136 bird species were observed. The total number of breeding birds was estimated at 6,400 pairs of 85 species. The most abundant breeders were the Little Tern Sternula albifrons with 377 breeding pairs (bp), Avocet Recurvirostra avosetta with 121 bp, and Kentish Plover Charadrius alexandrinus with 96 bp. In total, 3,461 individuals belonging to 80 species were recorded as non-breeders. At the species level, the most numerous were Kentish Plover with 1,100 individuals (ind.), Marsh Sandpiper Tringa stagnatilis with 600 ind., Greater Flamingo Phoenicopterus roseus with 321 ind., Common Shelduck Tadorna tadorna with 130 ind., Spotted Redshank Tringa erythropus with 120 ind. and Dunlin Calidris alpina with 100 ind. Breeding birds assemblages within the main studied habitats (salinas, lagoon, pine forests, mixed farmland, rocky hills with olive trees, and grasslands with bushes near the coast) and threats (the most significant of which were illegal shooting, trapping and dangerous power grid) are also described. Recommendations for future bird-friendly management, appropriate conservation activities and eco-tourism in the area are made.

Latitudinal variation in biophysical characteristics of avian eggshells to cope with differential effects of solar radiation.

Solar radiation is an important driver of animal coloration, not only because of the effects of coloration on body temperature but also because coloration may protect from the deleterious effects of UV radiation. Indeed, dark coloration may protect from UV, but may increase the risk of overheating. In addition, the effect of coloration on thermoregulation should change with egg size, as smaller eggs have higher surface‐volume ratios and greater convective coefficients than larger eggs, so that small eggs can dissipate heat quickly. We tested whether the reflectance of eggshells, egg spottiness, and egg size of the ground‐nesting Kentish plover Charadrius alexandrinus is affected by maximum ambient temperature and solar radiation at breeding sites. We measured reflectance, both in the UV and human visible spectrum, spottiness, and egg size in photographs from a museum collection of plover eggshells. Eggshells of lower reflectance (darker) were found at higher latitudes. However, in southern localities where solar radiation is very high, eggshells are also of dark coloration. Eggshell coloration had no significant relationship with ambient temperature. Spotiness was site‐specific. Small eggs tended to be light‐colored. Thermal constraints may drive the observed spatial variation in eggshell coloration, which may be lighter in lower latitudes to diminish the risk of overheating as a result of higher levels of solar radiation. However, in southern localities with very high levels of UV radiation, eggshells are of dark coloration likely to protect embryos from more intense UV radiation. Egg size exhibited variation in relation to coloration, likely through the effect of surface area‐to‐volume ratios on overheating and cooling rates of eggs. Therefore, differential effects of solar radiation on functions of coloration and size of eggshells may shape latitudinal variations in egg appearance in the Kentish plover.

The mitochondrial genome of the Kentish Plover Charadrius alexandrinus (Charadriiformes: Charadriidae) and phylogenetic analysis of Charadrii.

The suborder Charadrii (Aves: Charadriiformes), one of the most species-rich radiations within shorebirds, which contains good source for studies of ecology, behaviour and evolution. The resources of mitogenome have rapidly accumulated in recent years due to the advanced genomic sequencing, while suborder Charadrii's mitogenome has not been well studied. The primary objective of this study was to determine the complete mitogenome sequence of Charadrius alexandrinus, and investigated the evolutionary relationship within Charadrii. The mitogenome of C. alexandrinus were generated by amplification of overlapping Polymerase Chain Reaction (PCR) fragments. In this study, we determined the complete mitogenome sequence of the Kentish Plover Charadrius alexandrinus, and comparative analysed 11 species to illustrate mitogenomes structure and investigated their evolutionary relationship within Charadrii. The Charadrii mitogenomes displayed moderate size variation, the mean size was 16,944bp (SD = 182, n = 11), and most of the size variation due to mutations in the control region (CR). Nucleotide composition was consistently biased towards AT rich, and the A+T content also varies for each protein-coding genes. The variation in ATP8 and COIII was the highest and lowest respectively. The GC skew was always negative, with the ATP8 had higher value than other regions. The average uncorrected pairwise distances revealed heterogeneity of evolutionary rate for each gene, the COIII, COI and COII have slow evolutionary rate, whereas the gene of ATP8 has the relative fast rate. The highest value of Ks and Ka were ND1 and ATP8, and the ratios of Ka/Ks are lower than 0.27, indicating that they were under purifying selection. Phylogenomic analysis based on the complete mitochondrial genomes strongly supported the monophyly of the suborder Charadrii. This study improves our understanding of mitogenome structure and evolution, and providing further insights into phylogeny and taxonomy in Charadrii. In future, sequencing more mitogenomes from various taxonomic levels will significantly improve our understanding of phylogenetic relationships within Charadrii.

<b>Ceylon Kentish Plover <I>Charadrius alexandrinus seebohmi</I> breeding in Vani Vilasa Sagara, Hiriyur Taluka, Karnataka, India</b>

We report the breeding of the Ceylon Kentish Plover Charadrius alexandrinus seebohmi in Vani Vilasa Sagara, Hiriyur Taluka in the state of Karnataka, India. This is the first breeding record of the sub-species from Karnataka and this shows a lack of ornithological explorations in the wetlands of central Karnataka.

Apparent Survival and Long-Term Population Growth Rate of The Kentish Plover Charadrius alexandrinus in Mallorca, Archipelago, Spain

During the last few decades, many breeding waders have been declining worldwide, probably due to the reduction of suitable coastal habitats. Diagnosis of population parameters has become increasingly important for the conservation of waders. We used capture-recapture information of 214 adult Kentish Plovers Charadrius alexandrinus, marked between 1977 and 2015 at two breeding areas in Mallorca, Spain, to assess any possible temporal trend in the survival probability. Mean adult survival probability was 0.756 ± 0.05 with no differences between the two areas. The sparseness of the data did not permit robust estimates of yearly survival. However, models with a temporal trend in survival probability were not retained. An age-structured population model including demographic stochasticity suggested a stable population (λ = 1.024 ± 0.09). Perturbation analyses indicated that a 10% increase in mean breeding success (from 0.44 to 0.63), by reducing habitat loss or nest predation, would be sufficient to obtain positive population trajectories. —Garcias, P.J. & Tavecchia, G. (2018). Apparent survival and long-term population growth rate of the Kentish Plover Charadrius alexandrinus in Mallorca, Balearic Archipelago, Spain. Ardeola, 65: 59–68.

Coastal saltpans are a good alternative breeding habitat for Kentish plover Charadrius alexandrinus when umbrella species are present

The loss and degradation of natural habitats in coastal areas worldwide has adversely affected many waterbird species, changing their breeding distribution and reducing their productivity. Anthropogenic habitats such as saltpans can provide alternative or complementary habitats for waterbirds and mitigate the increasing human impact on natural coastal habitats. Unvegetated linear paths between salt ponds are used by ground‐nesting waterbird species to breed but their linear structure may facilitate the detection of nests by predators. This negative effect may, however, be counterbalanced by the advantages of breeding in mixed colonies. To evaluate the importance and the risks of breeding in saltpans we used the Kentish plover Charadrius alexandrinus breeding in coastal saltpans of southern Portugal as a model species. Specifically, we assessed the role of nest‐site characteristics, predation and nesting proximity to species with aggressive antipredator behaviour (black‐winged stilt Himantopus himantopus) on their breeding success. Kentish plovers selected nest‐sites on the edges of paths, with about 20% of water around the nest, and a mean visibility of more than 72%; however nest‐site characteristics were not correlated with nesting success. Predation was the main cause of nest loss in saltpans (42%); carrion crows Corvus corone were responsible for most daylight nest predation (58%) and red fox (Vulpes vulpes; 73%) for night predation. An 8‐yr monitoring plan of a Kentish plover population showed a linear increase in their breeding success as their breeding season increasingly overlapped with that of the black‐winged stilt. An experiment with artificial nests showed a significant increase in the number of exposure days (7 to 12) when these nests were within close distance of black‐winged stilt nests. Overall, our results showed that saltpans are an important alternative breeding habitat for the Kentish plover, especially for the maintenance of mixed species colonies.