Juan A. Amat

To make many sites accessible, humans have constructed roads. New layers of different materials (pipeclay, gravel, etc.) are added to the original soil for the construction of unpaved roads, which in marshy areas are readily used as nesting sites by ground‐nesting waterbirds. On the other hand, the disposal of dredged materials has been used as a s...

Migratory waterbirds are experiencing severe declines worldwide due to habitat loss. Their life cycles often span different countries and continents, highlighting the need for safeguarding wetland networks along migratory flyways. However, there are gaps in understanding how changes in specific sites can impact species at the biogeographical scale....

Fernandez-Duque et al. (Evol Ecol 37:859-869, 2023) reported instances where fledglings, able to move freely, were found in the nests of others of the same species containing chicks that were too young to fly. Interestingly, the foster parents fed these intruder fledglings. The researchers identified this as a novel behavior and termed it “Nest Int...

Variations in habitat quality in space and time prompt birds to track these changes to optimise their fitness. We investigated movements of Greater Flamingos Phoenicopterus roseus between long-established North Mediterranean breeding colonies and a new, fairly unpredictable, intermittently suitable South Mediterranean breeding colony (Ezzemoul, Alg...

One of the most southern breeding sites of the Northern Pintail Anas acuta in the SW Palearctic is in the Guadalquivir marshes (southwest Spain), part of which includes Doñana National Park. Breeding was recorded in 45.7% out of 46 years and was more frequent in those seasons in which the preceding autumn/winter was rainy, suggesting that the speci...

A comprehensive review of the natural history of the Ferruginous duck Aythya nyroca in Spain

The White-headed Duck is a stifftail with a highly fragmented distribution in the central and southwestern Palearctic, from south of Lake Baikal in the east, to northwestern Africa and the Iberian Peninsula in the west. Populations in north-central Asia are migratory, and spend the winter in the Middle East, Türkiye, and southeastern Europe. There...

After breeding, black-necked grebes (Podiceps nigricollis) perform a moult-migration to autumn hypersaline staging sites, where they moult the flight feathers and forage on superabundant brine shrimp (Artemia spp.) before leaving for wintering areas. During the stay in moulting sites, the grebes experience changes in organs and muscle size (atrophy...

Studies on brood desertion in birds have been mainly conducted on species with biparental care, and less often on uniparental species. Females of many duck species remain with their ducklings, unassisted by males, during variable periods of time before the chicks can fledge. In this paper, we examined factors that influence brood desertion by femal...

The increase of the tourism and urbanization of vast areas of dunes and beaches has been accompanied by an increase in the level of disturbances to many shorebirds, especially on those species which depend on such habitats to breed. The European Kentish plover (Charadrius alexandrinus) population is declining, also in the Canarian archipelago, one...

It has been proposed that carotenoid-based pigmentation should indicate the ability of individuals to acquire food and that this should be reflected in their body condition. In this study we examined whether the body condition of Greater Flamingos Phoenicopterus roseus was related to plumage coloration and the interaction of both variables with sex...

Coastal wetlands are valuable aquatic ecosystems with high biological productivity, which provide services such as a reduction in nitrogen loading into coastal waters and storage of organic carbon acting as carbon dioxide sinks. The predicted rise of sea level or freshwater extractions, particularly in the arid Mediterranean biome, will salinize ma...

Greater flamingos use cosmetic coloration by spreading uropygial secretions pigmented with carotenoids over their feathers, which makes the plumage redder. Because flamingos inhabit open environments that receive direct solar radiation during daytime, and carotenoids bleach when exposed to solar radiation, we expected that the plumage color would f...

Quail eggs have been widely used in field experiments, mainly to study factors associated with the risk of nest predation. Some shortcomings of using quail eggs in this type of study have been previously addressed (e.g., these eggs might be too big for some predators of eggs of small birds). Here, we show experimental evidence of another shortcomin...

Elevated concentrations of trace elements represent a major concern to wetland ecosystems, since river estuaries are geochemical endpoints that accumulate pollution. Although the negative impact of environmental exposure of highly toxic elements such as Pb and Hg has received substantial attention, we still lack a comprehensive understanding of the...

Abstract. Coastal wetlands are valuable ecosystems with high biological productivity and diversity, which provide ecosystem services such as a reduction in the inputs of nitrogen into coastal waters, and storage of organic carbon, thus, acting as net carbon sinks. The rise of sea level as a consequence of climatic warming will salinize many coastal...

Many studies addressing the use of nest materials by animals have focused on only one factor to explain its function. However, the consideration of more than one factor could explain the apparently maladaptive choice of nest materials that makes the nests conspicuous to predators. We experimentally tested whether there is a trade-off in the use of...

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...

European populations of black-necked grebes (Podiceps nigricollis) congregate every year to moult at the salt ponds of the Odiel Marshes (SW Spain). However, the Odiel Marshes are part of one of the most metal-polluted coastal estuaries in the world, which may pose risks to wildlife. We assessed the exposure of grebes to metal pollution during the...

Camouflage is a widespread strategy to avoid predation and is of particular importance for animals with reduced mobility or those in exposed habitats. Camouflage often relies on matching the visual appearance of the background, and selecting fine-scale backgrounds that complement an individual’s appearance is an effective means of optimising camouf...

Colourful plumage is typical of males in species with conventional sex roles, in which females care for offspring and males compete for females, as well as in many monogamous species in which both sexes care for offspring. Reversed sexual dichromatism—more colourful females than males—is predominant in species with sex role reversal. In the latter...

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 thermoreg...

Salinization is having a major impact on wetlands and its biota worldwide. Specifically, many migratory animals that rely on wetlands are increasingly exposed to elevated salinity on their nonbreeding grounds. Experimental evidence suggests that physiological challenges associated with increasing salinity may disrupt self-maintenance processes in t...

Studies of risk-taking by breeding birds have frequently addressed the effect of brood value on the decisions taken by incubating birds when predators approach their nests. However, leaving eggs unattended during predator disturbance may expose embryos to other potentially harmful factors, to which parent birds should respond when making decisions...

Aim Parental care improves offspring survival and therefore has a major impact on reproductive success. Whilst the influence of ambient environment on parental care is increasingly recognised, the impacts of environmental fluctuations remain largely unexplored. Assessing the impacts of environmental stochasticity, however, is essential for understa...

Background Selective pressure from pathogens is thought to shape the allelic diversity of major histocompatibility complex (MHC) genes in vertebrates. In particular, both local adaptation to pathogens and gene flow are thought to explain a large part of the intraspecific variation observed in MHC allelic diversity. To date, however, evidence that a...

Environmental trace element composition can have an important impact on ecosystem and population health as well individual fitness. Therefore, carefully assessing bioaccumulation of trace elements is central to studies investigating the ecological impact of pollution. Colonial birds are important bioindicators since non‐invasive sampling can easily...

Adults of all six flamingo species have rosy plumages. The flamingos acquire the carotenoid pigments that tinge their plumage from their diets, and are also able of metabolizing those pigments into others. Habitat characteristics may have affected which types of carotenoids are more commonly used by every species. The main function of coloration in...

Ardeola is the scientific journal of the Spanish Ornithological Society. We analyse historical changes in citation, topics and foreign authorship of articles published in Ardeola from its first publication in 1954 up to last year, 2015, to test to what extent the persistence of the journal during the last 61 years has been due to support of authors...

In ground-nesting birds egg colour and appearance may have evolved due to opposite selection pressures. Pigmentation and spottiness make the eggs darker and have been suggested to improve camouflage. However darker and more spotted eggs may reach higher temperatures when not attended by adults and receiving direct sunlight, which may be lethal for...

The unusually high quality of census data for large waterbirds in Europe facilitates the study of how population change varies across a broad geographical range and relates to global change. The wintering population of the greylag goose Anser anser in the Atlantic flyway spanning between Sweden and Spain has increased from 120 000 to 610 000 indivi...

We tested if Black-necked Grebe, a species in which both sexes undertake moult-migration, have an unbiased sex ratio at a moulting site in Europe, as previously found in North America and as was expected for a species with biparental care. For this we used a unique long-term dataset of 5821 grebes captured for ringing throughout the moulting season...

In sexually dimorphic species, the parental effort of the smaller sex may be reduced due to competitive exclusion in the feeding areas by the larger sex, or physiological constraints. However, to determine gender effects on provisioning patterns other intrinsic and extrinsic factors affecting parental effort should be accounted for. Greater flaming...

From August to December, thousands of Black‐necked Grebes Podiceps nigricollis concentrate during the flightless moult period in salt ponds in the Odiel Marshes, southern Spain, where they feed on the brine shrimp Artemia parthenogenetica. We predicted that because Black‐necked Grebes moulted in a food‐rich, predator‐free environment, there would b...

Predicted (a) total incubation and (b) female share of incubation in relation to ambient temperature over 12 time periods of the day in different plover populations (see Table 3). Number of nests observed in each time period are given in the legend. (PDF)

Mean (and standard deviation) in % total incubation, % female share and ambient temperature, number of nests, number of two-hour records and the years of data collection are shown for each population. In total, the study includes 1628 records from 285 plover nests. (DOC)

Social behaviours are highly variable between species, populations and individuals. However, it is contentious whether behavioural variations are primarily moulded by the environment, caused by genetic differences, or a combination of both. Here we establish that biparental care, a complex social behaviour that involves rearing of young by both par...

To reach the final host (greater flamingos), the cestode Flamingolepis liguloides alters the behaviour of its intermediate host, the brine shrimp, Artemia parthenogenetica, causing it to spend more time close to the water surface. During summer 2010, we showed that the prevalence of this cestode was consistently higher at the top of the water colum...

Gene flow promotes genetic homogeneity of species in time and space. Gene flow can be modulated by sex-biased dispersal that links population genetics to mating systems. We investigated the phylogeography of the widely distributed Kentish plover Charadrius alexandrinus. This small shorebird has a large breeding range spanning from Western Europe to...

After being fed by their parents, Greater Flamingo chicks store food in their crops, which protrude outwards. We allocated the crop profiles of chicks to four categories to assess the relationship between body mass and crop profile variation, and so determine whether crop size can be used as an accurate index of the amount of food ingested, and to...

The conservation of many species depends on sustainable economic activities that shape their habitats. The economic use of these anthropogenic habitats may change quickly owing to world trade globalization, market reorientations, price volatility or shifts in subsidy policies. The recent financial crisis has produced a global impact on the world ec...

Many bird species take recesses during incubation, and while the nests are unattended, the eggs may both be vulnerable to predation and reach suboptimal temperatures for embryo development. Perhaps to avoid these negative possibilities, some birds cover their eggs with materials when they depart from nests. We examined experimentally, using the gro...

Desde 1986 se anillan flamencos en las colonias de cría andaluzas, en Fuente Piedra, Doñana y las marismas del Odiel. Una investigación que ayuda a conocer, entre otros datos, su tasa de crecimiento, su distribución, su reproducción o cómo les afecta la transformación de humedales.

In the Mediterranean basin, Greater Flamingos Phoenicopterus roseus constitute a metapopulation with natal and breeding dispersal among colonies. However, the rate of exchange between European and North African colonies remains poorly known. In this paper, we document the wintering and breeding of European flamingos in Algeria and provide the first...

Capital breeding refers to a strategy in which birds use body stores for egg formation, whereas income breeders obtain all resources for egg formation at breeding sites. Capital breeding should occur more in large-bodied species because the relative cost of carrying stores for egg formation becomes smaller with increasing body size. Based on a comp...

We examined how availability of brine shrimps, Artemia parthenogenetica, influenced temporal aspects of foraging behaviour and population dynamics of moulting black-necked grebes, Podiceps nigricollis, from late August to early December in four salt ponds in the Odiel marshes, southern Spain, in 2008 and 2009. The moulting grebe population was high...

It was long thought that the colour of bird feathers does not change after plumage moult. However, there is increasing evidence that the colour of feathers may change due to abrasion, photochemical change and staining, either accidental or deliberate. The coloration of plumage due to deliberate staining, i.e. with cosmetic purposes, may help indivi...

We give examples of how waterbirds can be valuable indicators of changes in aquatic systems. Eutrophication is a widespread problem that can increase the food supply for some birds and hence increase their population size (e.g. great-crested grebes). Many birds are sensitive to changes in water depth, and some can decline due to siltation of shallo...

1. Contrary to the generally high level of natal philopatry (i.e. likelihood that individuals breed at their natal colony) found in first‐breeding colonial birds, little is known of natal philopatry later in life. Most hypotheses advanced to explain natal philopatry are valid at all ages. However, for young and inexperienced birds, the benefits of...

En especies de aves con cuidado biparental, cada sexo puede tener sus propios requerimientos de energía y/o esquema de tiempo para la alimentación, lo cual podría conducir a diferencias en las estrategias de alimentación entre ambos sexos. En los estuarios, las especies de playeros como Charadrius alexandrinus pueden forrajear en fangos intermareal...

We measured the hematocrit from greater flamingo chicks Phoenicopterus roseus over 4years to test whether this blood parameter was related to the nutritional condition of chicks, as there are controversial results on whether hematocrit may be used as an index of body condition. We also tested whether hematocrit increased with chick age, as there wo...

During nesting, many temperate and tropical shorebirds are exposed to direct solar radiation and face heat stress. The aim of our study was to determine whether belly-soaking (wetting of ventral plumage) contributes to reducing excess body heat in Kentish plovers Charadrius alexandrinus. We captured incubating plovers on sunny days at their exposed...

Monitoring programs for the Greater Flamingo Phoenicopterus roseus have been implemented in several colonies of the Mediterranean basin and northwest Africa. Methodologies used to obtain estimates of population sizes, breeding success, and demographic parameters may substantially differ among localities. It is important to attain a consensus on met...

We collected wing cover feathers from Greater Flamingo Phoenicopterus roseus chicks at the colonies of Ebro Delta (NE Spain), Fuente de Piedra (S Spain), Garaet Ezzemoul (NE Algeria) and Macchiareddu (Sardinia, Italy) to know whether diet quality (as determined using stable isotopes of N and C) is affected by colony size. Isotopic values of N and C...

The breeding population of Greater Flamingo in Spain during 2007 is 18,876- 19,076 pairs, which produced 3,601 chicks. Breeding success was only verified in three wetlands: Fuente de Piedra (15,076 breeding pairs (79.03%) and 2,658 chicks fledged); the Guadalquivir marshes (2,000 breeding pairs (10.48%) and just 52 chicks fledged); and the Ebro del...

Red-knobbed coot, Fulica cristata, was formerly distributed across several countries in the south-west Palaearctic. Remnant populations are now located in Morocco and Spain. In the latter, the red-knobbed coot is considered critically endangered, and its decline is attributed to changes in agricultural practices in the basins of wetlands, which hav...

Macronutrient (protein, lipids, and carbohydrates) assimilation efficiencies of wild birds have rarely been studied, but they may be particularly important for estimating the optimal diet. We assessed experimentally the energy and macronutrient assimilation efficiencies of captive Snowy Plover (Charadrius alexandrinus) feeding on the polychaete rag...

The red-knobbed coot Fulica cristata experienced a dramatic population decline in Spain, where the common coot F. atra does not face conservation problems. This is puzzling because both species have similar ecologies. It has been suggested that habitat alterations affected the quality of food plants, and this impacted differentially both coots. To...

In herbivorous birds the processing rate of food is constrained by gizzard capacity. To enhance digestive processes, many species ingest grit to grind the food. Grit ingestion, however, may further limit the capacity of the gizzard. Graylag Geese (Anser anser) wintering in SW Spain fed mainly on Alkali Bulrush (Scirpus maritimus) tubers, showing a...

Allocation trade-offs of carotenoids between their use in the immune system and production of sexual ornaments have been suggested as a proximate mechanism maintaining honesty of sexual signals. To test this idea, we experimentally examined whether carotenoid availability in the diet was related to variation in antibody response to novel antigens i...

We tested whether belly-soaking (i.e. wetting of ventral plumage) in incubating Kentish Plovers Charadrius alexandrinus in a hot environment serves to cool overheated eggs, or whether belly-soaking would mainly serve for adult thermoregulation, and egg wetting would be a mere consequence of the ventral feathers of incubating adults being wet. When...

Greater flamingos in southern Spain foraged in areas distant from a breeding site, spending 4-6 days in foraging areas between successive visits to the colony to feed their chicks. During four years, we took blood samples from chicks to ascertain whether there were interannual variations in several blood parameters, indicative of food quality and f...

Metapopulation conservation should rely on a flyway approach aiming at assessing the spatial range of metapopulations by estimating the level of exchanges among local populations. In the western Mediterranean, Greater Flamingos have been shown to constitute a metapopulation with natal and breeding dispersal among colonies. In this paper, we examine...

It is assumed that there is a trade-off between the costs allocated to mounting an immune defence and those allocated to costly functions such as breeding and moulting. The physiological basis for this is that mounting an immune response to pathogen challenge has energetic and/or nutrient costs which may interfere with metabolic processes of the ch...

Pairing of northern hemisphere dabbling ducks normally occurs in wintering sites. Mate choice occurs when some individuals congregate in courtship parties, in which females mainly choose mates according to male behavioural dominance. The sex ratio of some species is more male-biased at northern than at southern wintering sites, and the age ratio is...

Whether theoretical or empirical, traditional approaches to the study of ecological dynamics have focused almost exclusively on the asymptotic, long-term behaviour of real systems. Here, we explore the existence of transient (non-asymptotic) abrupt shifts in the dynamics of the Spanish population of White-headed duck, and relate this changes to var...

Connectivity among habitat patches has mainly been studied in relation to species-specific behaviours. However, the movements of animals among patches may have different functions, and tolerance to gaps between habitat patches may vary between these functions. We tracked the movements of greater flamingos during the breeding and post-breeding perio...

A small percentage (4.5%) of females Kentish plovers (Charadrius alexandrinus) observed breeding in southern Spain expressed a plumage trait characteristic of males: the forecrown (frontal) black bar. The expression of this male trait may be age-related, and reversible, i.e., within individuals it may be present in some years but not in other years...

1. A statistical model is developed for the globally threatened white-headed duck during its regional expansion throughout Spain from 1980 to 2000; the model estimates the relative intrinsic, climatic and stochastic effects on population fluctuations and spatial expansion on several time-scales. Facing the current lack of knowledge on the nature an...