Diet of the critically endangered blackchin guitarfish Glaucostegus cemiculus revealed using DNA metabarcoding.

We present the first assessment of the diet of the blackchin guitarfish Glaucostegus cemiculus (Geoffroy Saint-Hilaire, 1817) for West Africa using DNA metabarcoding on stomach contents of individuals captured in the Bijagós Archipelago, Guinea-Bissau. The diet was dominated by crustaceans, particularly caramote prawn Penaeus kerathurus (frequency of occurrence [FO] = 74%, numerical frequency [NF] = 54%) and fiddler crab Afruca tangeri (FO = 74%, NF = 12%). Bony fishes were present in 30% of the stomachs. We highlight the importance of conservation action for intertidal habitats and their associated benthic invertebrates for the survival of the critically endangered blackchin guitarfish.

Geographical variation in pace-of-life in a long-distance migratory bird: implications for population management.

Life-history theory predicts that animals should develop adaptive trade-offs between survival and reproduction to maximize their fitness. This results in a continuum of life-history strategies among species, ranging from slow to fast paces-of-life. The optimal pace-of-life has been shown to vary within environmental gradients, with a commonly observed pattern of a slow-to-fast continuum from the tropics to the poles. Within species, pace-of-life variability has however received much less attention. In this study, we investigated whether or not the pace-of-life of populations within a species follows the expected slow-fast continuum associated with latitude. We analysed the variability of life-history strategies among populations of the European roller Coracias garrulus, a long-distance migratory species, comparing breeding parameters and adult survival between populations across a latitudinal gradient. The findings showed a negative correlation between survival and clutch size in roller populations, with a slower pace-of-life in the northern populations and a faster pace-of-life in the southern populations: a reverse gradient to what might be expected from inter-specific studies. These results suggest that northern populations would benefit from measures enhancing adult survival probability, such as reduction in harvesting rates, while southern populations would respond better to actions favouring reproductive success, such as nesting site provisioning. This study highlights that life-history traits can vary substantially between populations of a single species with a large latitudinal breeding range, and pinpoint how knowledge about this variability may be key in anticipating different populations' responses to threats as well as to conservation strategies.

Low migratory connectivity and similar migratory strategies in a shorebird with contrasting wintering population trends in Europe and West Africa.

Migratory shorebird populations are declining worldwide, showing an apparent inability to respond to the interplaying challenges emerging along their flyways. Within the East Atlantic Flyway, non-breeding populations show moderate to strong declines in Sub-Saharan Africa, contrasting with stable or increasing trends in Europe. Local factors are insufficient to explain the opposite tendencies and, therefore, investigating migratory strategies and connectivity of these populations may help identifying the drivers of their demography. We followed the migratory journeys of 20 grey plovers (Pluvialis squatarola) from their wintering grounds in Guinea-Bissau (West Africa), Portugal and France (Europe) using tracking devices. Grey plovers wintering in Africa and Europe were found to share breeding grounds at European Russia and Western Siberia, revealing low migratory connectivity in the Eastern Atlantic population. All individuals followed a "skipping" migratory strategy, flying mostly mid-distance bouts, and using an unexpected large network of stopover sites to re-fuel usually for short periods. We identified 66 different stopover sites along the West African, European and Russian/Siberian coasts. All birds stopped at the Wadden Sea in both migratory periods, highlighting the importance of this region and the risk for a potential bottleneck. Low migratory connectivity and similar migratory strategies shared by grey plovers wintering in Europe and West Africa do not support their contrasting population trends.

Trace elements in relation to trophic ecology of long-distance migratory shorebirds and seabirds in West Africa.

Shorebirds and seabirds are abundant predators in coastal habitats worldwide, relying upon a high diversity of benthic invertebrates and fish, respectively. While occupying different trophic guilds, they are differently exposed to element contamination entering the coastal food web. Therefore, these birds have been used as bioindicators of environmental contamination in marine ecosystems. We analysed the concentration of trace elements in blood samples of 16 shorebird and seabird migratory species in a major non-breeding site, the Bijagós Archipelago, in regard to their trophic ecology. Overall, our study shows low exposure of this bird community to toxic elements, except for Hg. Most species presented Hg burdens within the moderate toxicity threshold, but one species (Dunlin) presented values at a potential high Hg toxicity risk. We found a positive relationship between Se and Ni concentrations and δ15N values (a proxy for trophic level). In addition, a positive relationship was found between δ13C (a proxy for habitat characteristics) and Hg, Fe, Cu and Mn, while the opposite pattern was recorded for As. Differences were also shown for several trace elements between the two studied trophic guilds: concentrations of As, Pb and Se were higher in pelagic fish consumers (seabirds), whereas Cr, Fe and Sr burdens were higher in benthic invertebrate consumers (shorebirds). Although previous studies in the same site revealed very high concentrations of Cd and Pb in some of the prey species of shorebirds and seabirds (bivalves and fishes), values found in birds for these two elements suggest no toxicological risk. Thus, exposure to toxic elements is not currently a threat to coastal bird populations, namely those facing apparent local declines in Guinea-Bissau, one of the most important non-breeding quarters for of West Africa. Still, Hg burdens were high in some species, deserving further monitoring.

Global changes in coastal wetlands of importance for non-breeding shorebirds.

Shorebird declines are occurring worldwide but the causes are not fully understood. Recent literature suggests that the deterioration of habitat quality at their non-breeding areas, mostly located in temperate and tropical coastal wetlands, might be a major contributing factor. However, most studies carried out so far tend to be restricted to a few regions. Remote sensing can help correct such geographical bias on knowledge by providing a standardized approach on how shorebird habitats have been changing over the last few decades at a global scale. Here we analyzed time series of remote sensing classifications of tidal flats and land cover to quantify worldwide habitat changes in coastal Important Bird and Biodiversity Areas (IBAs) relevant for non-breeding shorebirds over the last two decades. Globally, supratidal areas (used as roosting habitat) have changed more significantly than tidal flats (used as feeding habitat). Yet, we found striking losses of tidal flats in IBAs distributed in several regions of the East Asian - Australasian Flyway. At supratidal areas, there was a general expansion of marshland, grassland and urban areas, contrasting with a decline of barren land, woodland and cropland. The expansion of marshland occurred in IBAs of most regions of the world. Urban areas also expanded consistently in supratidal areas within the most populated regions of the world. The loss of barren land is particularly concerning as it may translate into a loss of high-quality roosts and it was highly frequent in IBAs of all migratory flyways. Overall, our results confirm the large losses of shorebird habitat in the East Asian - Australasian Flyway reported in the literature, and highlight unreported generalized changes in supratidal habitats, such as the expansion of marshland and the loss of barren land, that may have negative implications for shorebirds, deserving further research and consideration in conservation programs.

Global assessment of marine plastic exposure risk for oceanic birds.

Plastic pollution is distributed patchily around the world's oceans. Likewise, marine organisms that are vulnerable to plastic ingestion or entanglement have uneven distributions. Understanding where wildlife encounters plastic is crucial for targeting research and mitigation. Oceanic seabirds, particularly petrels, frequently ingest plastic, are highly threatened, and cover vast distances during foraging and migration. However, the spatial overlap between petrels and plastics is poorly understood. Here we combine marine plastic density estimates with individual movement data for 7137 birds of 77 petrel species to estimate relative exposure risk. We identify high exposure risk areas in the Mediterranean and Black seas, and the northeast Pacific, northwest Pacific, South Atlantic and southwest Indian oceans. Plastic exposure risk varies greatly among species and populations, and between breeding and non-breeding seasons. Exposure risk is disproportionately high for Threatened species. Outside the Mediterranean and Black seas, exposure risk is highest in the high seas and Exclusive Economic Zones (EEZs) of the USA, Japan, and the UK. Birds generally had higher plastic exposure risk outside the EEZ of the country where they breed. We identify conservation and research priorities, and highlight that international collaboration is key to addressing the impacts of marine plastic on wide-ranging species.

Linking trophic ecology with element concentrations in a coastal fish community of the Bijagós Archipelago, West Africa.

We report the concentration of 13 elements in the muscle and liver of 17 coastal fish species of the Bijagós Archipelago, Guinea-Bissau, and link element concentrations to trophic ecology as assessed by carbon (δ13C) and nitrogen (δ15N) stable isotopes. We found higher concentrations of Hg, Fe, Mn, Cu, Zn, Se and As in liver as compared to muscle tissue, and the opposite pattern for Sr and Ca in all fish species. The concentration of Hg and Se in muscle samples increased significantly with δ15N, suggesting a biomagnification of these elements in this food chain. The concentrations of Ca and Sr, Fe and Cr, Ca and Mn, and Fe and Mn were positively correlated to each other in more than 50% of the studied species. Fish constitute the most important animal protein source for people in Guinea-Bissau, and thus assessing the concentrations of potentially toxic elements is relevant for human health.

Stopover use of a large estuarine wetland by dunlins during spring and autumn migrations: Linking local refuelling conditions to migratory strategies.

Migratory strategies dictate stopover ecology, particularly concerning decisions of when, where and how long to stop, and what to do at stationary periods. In birds, individuals stop primarily to replenish energy stores, although the functions of stopover events vary among and within species, particularly between pre- and post-breeding seasons. Here, we combined plasma metabolite levels and haematological parameters to compare refuelling rates and physiological state within (early, mid, late) and between (spring, autumn) migratory periods, aiming to identify potentially different migratory strategies in a shorebird, the dunlin Calidris alpina, using a key stopover site in Iberia. Plasma triglycerides and ß-hydroxybutyrate concentrations did not differ between seasons, and small differences were found in haematological profiles (higher haemoglobin and hematocrit levels in spring). Similar refuelling rates and physiological status suggests a single migratory strategy in spring and autumn. During both seasons, dunlins arrive at the Tagus estuary with medium-to-high fuel loads, indicating they do not engage in prolonged fuelling. This agrees with a skipping migratory strategy, where birds fly short-to-medium distances while fuelling at moderate rates along a network of sites. Although we may expect late spring migrants to experience stronger pressures to optimally schedule migratory events, we found no significant differences in physiological profiles among early, mid and late migrants. Unexpectedly, such differences were found in autumn: early birds showed the highest triglycerides and haemoglobin levels and lowest ß-hydroxybutyrate concentrations. These results denote enhanced refuelling rates and blood oxygen-carrying capacity in early autumn migrants, which is typical of jumpers, i.e., birds travelling with larger fuel loads and performing fewer stops. Our study adds substantially to previous knowledge of stopover ecology in migratory shorebirds in the East Atlantic Flyway. Importantly, it indicates that the Tagus estuary is a high-quality stopover site for intermediate fuelling. Yet, understanding non-fuelling stopping functions is needed to ultimately inform conservation planning.

Spatial and seasonal variation in macrozoobenthic density, biomass and community composition in a major tropical intertidal area, the Bijagós Archipelago, West-Africa.

The coastal intertidal ecosystem of the Bijagós Archipelago, Guinea-Bissau, one of the largest and most important in West Africa, sustains a considerable proportion of the migratory shorebird populations of the East Atlantic Flyway and operates as a nursery area for benthic fish in the region. The macrozoobenthos in these mudflats constitute the main food source for both groups so that spatial and temporal variation in their abundance and community composition is likely to influence the abundance and distribution of fish and birds. In this study we described the spatial and temporal dynamics in the density, biomass, and community composition of macrozoobenthos across six intertidal flats in three islands of the Bijagós Archipelago. Overall, the Bijagós Archipelago was characterised by a highly species-rich macrozoobenthic community, with ca. 88 taxa identified across all sites, reaching a mean density of 1871 ± 58.3 ind.m-2 (mean ± SE) and mean biomass of 5.65 ± 0.41 g of AFDM.m-2 (ash-free dry mass per m2), values much lower than what was described for nearby intertidal areas, namely the Band d'Arguin, Mauritania. Density and biomass of major macrozoobenthos classes (Bivalvia, Polychaeta, Malacostraca and Gastropoda) differed across sites and months, displaying an overall increase in density towards the final months of the dry season (March and April). Similarly, community composition also differed significantly between sites and throughout the season. The site with most distinct community composition (Adonga) supported low diversity and high abundance of a few bivalve species, whilst other two sites that hosted the most diverse communities, were also the most similar between them (Anrumai and Abu). These spatial and temporal patterns constitute an important baseline to improve knowledge of this intertidal ecosystem and will contribute towards a better understanding of the spatial and temporal distribution patterns of their consumers.

Assessing the contribution of mangrove carbon and of other basal sources to intertidal flats adjacent to one of the largest West African mangrove forests.

Mangrove forests are productive habitats and major potential exporters of organic matter and nutrients to adjacent habitats. Here we examine the extent to which mangrove carbon is transferred to adjacent intertidal food webs in the second largest mangrove-covered area in Africa, in Guinea-Bissau. Applying stable isotope analysis and mixing models, we made comparisons at two spatial scales: (1) a large scale, comparing intertidal flats with (mangrove sites) and without (control sites) adjacent mangrove forests regarding the carbon isotopic signature of macrozoobenthos and sediment organic matter (SOM), and the relative importance of potential primary food sources in sustaining macrozoobenthos, and (2) a fine scale, performing stable carbon isotope measurements along 200 m transects from the coastline out to open intertidal flats, to trace mangrove carbon in macrozoobenthos and in the SOM. We found no evidence that mangrove carbon sustains intertidal food webs, despite SOM being significantly more depleted in 13C in mangrove sites. Mangrove leaves had the lowest relative contribution to the diet of macrozoobenthos, while macroalgae, benthic microalgae and POM showed variable but overall relevant contributions. Yet, at a smaller scale, mangrove carbon was detectable in SOM and in most macrozoobenthos, being strongest within 50 m of the mangrove edge and quickly fading with increasing distance. Our results suggest that there is only a marginal input of mangrove carbon into the food webs of unvegetated intertidal flats. Still, this leaves open the possibility of mangrove forests acting as sources of dissolved inorganic carbon and processed nitrogen, which can be assimilated by the algae and subsequently fuel adjacent food webs.

Elemental composition of whole body soft tissues in bivalves from the Bijagós Archipelago, Guinea-Bissau.

Marine bivalves are bioindicators of coastal environmental pollution, integrating monitoring programs worldwide. Nonetheless, the choice of particular species as an indicator requires validation, achieved by understanding the differences in element concentrations among and within species. The present study compares the chemical composition of whole body soft tissues of four common bivalve species from the Bijagós Archipelago, a pristine region of West Africa. Significant differences were recorded in the concentrations of various elements among studied species, which likely arise from species-specific uptake and bioaccumulation processes. Overall, there was a segregation between a group including the bloody cockle Senilia senilis and oyster Crassostrea tulipa (with high Cd and Zn concentrations) versus the two other species, Austromacoma nymphalis (with low Cu and high Mn, Se, Hg, Pb concentrations) and Diplodonta spp. (with high values of Cu, Al, Fe, V, Cr, Hg, Pb). C. tulipa was sampled in two different substrates (rock beds and mangrove roots), and the two groups revealed different chemical profiles, with significantly higher concentrations of P, Si, Zn and Cr and lower Cu in specimens fixed in mangrove roots. These results strongly suggest the influence of small-scale environmental variability on the accumulation of particular elements. We found extremely high Cd concentrations in S. senilis (27.1 ± 7.53 µg g-1 DW) and identified C. tulipa as another high Cd-accumulating species (ca. 10 µg g-1 DW). Our results suggest a detoxifying mechanism linked with the presence of Se to reduce the potential toxic effects of Cd in these two species. Cadmium concentrations reported for some bivalve species in this area largely exceed the maximum values proposed by the European Union, emphasizing the need for a regular contamination assessment.

Major, minor, trace and rare earth elements in sediments of the Bijagós archipelago, Guinea-Bissau.

Sixty sediment samples from four sites in the Bijagós archipelago were characterized for fine fraction, loss on ignition, major, minor and trace elemental composition (Al, Fe, Ca, Mg, Ti, P, Zr, Mn, Cr, Sr, Ba, B, V, Li, Zn, Ni, Pb, As, Co, U, Cu, Cs and Cd), and the elements of the La-Lu series. Element concentrations were largely explained by the Al content and the proportion of fine fraction content, with the exception of Ca and Sr. Sediments showed enhanced Ti, U, Cr, As and Cd concentrations with respect to estimated upper crust values, most likely mirroring a regional signature. Rare earth elements were in deficit relatively to the North American Shale Composite (NASC), mainly in coarser material. No pronounced Ce-anomaly was observed, while Eu-anomalies were positive in most analyzed sediments.

Plastic and other microfibers in sediments, macroinvertebrates and shorebirds from three intertidal wetlands of southern Europe and west Africa.

Microplastics are widespread in aquatic environments and can be ingested by a wide range of organisms. They can also be transferred along food webs. Estuaries and other tidal wetlands may be particularly prone to this type of pollution due to their particular hydrological characteristics and sewage input, but few studies have compared wetlands with different anthropogenic pressure. Furthermore, there is no information on microplastic transfer to secondary intertidal consumers such as shorebirds. We analysed intertidal sediments, macroinvertebrates and shorebirds, from three important wetlands along the Eastern Atlantic (Tejo estuary, Portugal; Banc d'Arguin, Mauritania and Bijagós archipelago, Guinea-Bissau), in order to evaluate the prevalence and transfer of microplastics along the intertidal food web. We further investigated variables that could explain the distribution of microplastics within the intertidal areas of the Tejo estuary. Microfibers were recorded in a large proportion of sediment samples (91%), macroinvertebrates (60%) and shorebird faeces (49%). µ-FTIR analysis indicated only 52% of these microfibers were composed of synthetic polymers (i.e. plastics). Microfiber concentrations were generally higher in the Tejo and lower in the Bijagós, with intermediate values for Banc d'Arguin, thus following a latitudinal gradient. Heavier anthropogenic pressure in the Tejo explains this pattern, but the relatively high concentrations in a pristine site like the Banc d'Arguin demonstrate the spread of pollution in the oceans. Similar microfiber concentrations in faeces of shorebirds with different foraging behaviour and similar composition of fibres collected from invertebrate and faeces suggest shorebirds mainly ingest microfibers through their prey, confirming microfiber transfer along intertidal food webs. Within the Tejo estuary, concentration of microfibers in the sediment and bivalves were positively related with the percentage of fine sediments and with the population size of the closest township, suggesting that hydrodynamics and local domestic sewage are the main factors influencing the distribution of microfibers.

Evidence for contrasting accumulation pattern of cadmium in relation to other elements in Senilia senilis and Tagelus adansoni from the Bijagós archipelago, Guinea-Bissau.

Shellfish harvesting in intertidal areas is a widespread and economically important activity in many countries across West Africa. However, in some areas, there is virtually no information concerning the levels of contaminants (and other elements related to nutritional aspects) in the harvested species. We collected sediments and several individuals of the West African bloody cockle Senilia senilis and of the razor clam Tagelus adansoni during the dry season of 2015 nearby three islands in the Bijagós archipelago, Guinea-Bissau. Aluminium, Ca, Fe, Mg, As, Cd, Co, Cr, Cu, Mn, Ni, Pb and Zn were determined in sediments and whole soft tissues of the two bivalves. Sediments showed uniformly low trace element concentrations, pointing to an ecosystem with low levels of trace element contamination. T. adansoni presented higher concentrations of most elements than S. senilis, with the exception of Cd that showed up to 40 times higher values in S. senilis than in T. adansoni from the same sites. Furthermore, Cd concentrations (25±8.7 mg kg-1, dw) in S. senilis are clearly above the maximum level established for human consumption. Future studies should clarify whether biological factors are the major responsible for this unusual situation.

Influence of age and sex on winter site fidelity of sanderlings Calidris alba.

Many migratory bird species show high levels of site fidelity to their wintering sites, which confers advantages due to prior knowledge, but may also limit the ability of the individual to move away from degrading sites or to detect alternative foraging opportunities. Winter site fidelity often varies among age groups, but sexual differences have seldom been recorded in birds. We studied a population of individually colour-marked sanderlings wintering in and around the Tejo estuary, a large estuarine wetland on the western coast of Portugal. For 160 individuals, sighted a total of 1,249 times between November 2009 and March 2013, we calculated the probability that they moved among five distinct wintering sites and how this probability is affected by distance between them. To compare site fidelity among age classes and sexes, as well as within the same winter and over multiple winters, we used a Site Fidelity Index (SFI). Birds were sexed using a discriminant function based on biometrics of a large set of molecularly sexed sanderlings (n = 990). The vast majority of birds were observed at one site only, and the probability of the few detected movements between sites was negatively correlated with the distance among each pair of sites. Hardly any movements were recorded over more than 15 km, suggesting small home ranges. SFI values indicated that juveniles were less site-faithful than adults which may reflect the accumulated knowledge and/or dominance of older animals. Among adults, females were significantly less site faithful than males. A sexual difference in winter site fidelity is unusual in shorebirds. SFI values show site-faithfulness is lower when multiple winters were considered, and most birds seem to chose a wintering site early in the season and use that site throughout the winter. Sanderlings show a very limited tendency to explore alternative wintering options, which might have implications for their survival when facing habitat change or loss (e.g., like severe beach erosion as can be the case at one of the study sites).

Seasonal variations in the diet and foraging behaviour of dunlins Calidris alpina in a south European estuary: improved feeding conditions for northward migrants.

During the annual cycle, migratory waders may face strikingly different feeding conditions as they move between breeding areas and wintering grounds. Thus, it is of crucial importance that they rapidly adjust their behaviour and diet to benefit from peaks of prey abundance, in particular during migration, when they need to accumulate energy at a fast pace. In this study, we compared foraging behaviour and diet of wintering and northward migrating dunlins in the Tagus estuary, Portugal, by video-recording foraging birds and analysing their droppings. We also estimated energy intake rates and analysed variations in prey availability, including those that were active at the sediment surface. Wintering and northward migrating dunlins showed clearly different foraging behaviour and diet. In winter, birds predominantly adopted a tactile foraging technique (probing), mainly used to search for small buried bivalves, with some visual surface pecking to collect gastropods and crop bivalve siphons. Contrastingly, in spring dunlins generally used a visual foraging strategy, mostly to consume worms, but also bivalve siphons and shrimps. From winter to spring, we found a marked increase both in the biomass of invertebrate prey in the sediment and in the surface activity of worms and siphons. The combination of these two factors, together with the availability of shrimps in spring, most likely explains the changes in the diet and foraging behaviour of dunlins. Northward migrating birds took advantage from the improved feeding conditions in spring, achieving 65% higher energy intake rates as compared with wintering birds. Building on these results and on known daily activity budgets for this species, our results suggest that Tagus estuary provides high-quality feeding conditions for birds during their stopovers, enabling high fattening rates. These findings show that this large wetland plays a key role as a stopover site for migratory waders within the East Atlantic Flyway.

Sex promotes spatial and dietary segregation in a migratory shorebird during the non-breeding season.

Several expressions of sexual segregation have been described in animals, especially in those exhibiting conspicuous dimorphism. Outside the breeding season, segregation has been mostly attributed to size or age-mediated dominance or to trophic niche divergence. Regardless of the recognized implications for population dynamics, the ecological causes and consequences of sexual segregation are still poorly understood. We investigate the foraging habits of a shorebird showing reversed sexual dimorphism, the black-tailed godwit Limosa limosa, during the winter season, and found extensive segregation between sexes in spatial distribution, microhabitat use and dietary composition. Males and females exhibited high site-fidelity but differed in their distributions at estuary-scale. Male godwits (shorter-billed) foraged more frequently in exposed mudflats than in patches with higher water levels, and consumed more bivalves and gastropods and fewer polychaetes than females. Females tended to be more frequently involved and to win more aggressive interactions than males. However, the number of aggressions recorded was low, suggesting that sexual dominance plays a lesser role in segregation, although its importance cannot be ruled out. Dimorphism in the feeding apparatus has been used to explain sex differences in foraging ecology and behaviour of many avian species, but few studies confirmed that morphologic characteristics drive individual differences within each sex. We found a relationship between resource use and bill size when pooling data from males and females. However, this relationship did not hold for either sex separately, suggesting that differences in foraging habits of godwits are primarily a function of sex, rather than bill size. Hence, the exact mechanisms through which this segregation operates are still unknown. The recorded differences in spatial distribution and resource use might expose male and female to distinct threats, thus affecting population dynamics through differential mortality. Therefore, population models and effective conservation strategies should increasingly take sex-specific requirements into consideration.

Mosaic-level inference of the impact of land cover changes in agricultural landscapes on biodiversity: a case-study with a threatened grassland bird.

Changes in land use/land cover are a major driver of biodiversity change in the Mediterranean region. Understanding how animal populations respond to these landscape changes often requires using landscape mosaics as the unit of investigation, but few previous studies have measured both response and explanatory variables at the land mosaic level. Here, we used a "whole-landscape" approach to assess the influence of regional variation in the land cover composition of 81 farmland mosaics (mean area of 2900 ha) on the population density of a threatened bird, the little bustard (Tetrax tetrax), in southern Portugal. Results showed that ca. 50% of the regional variability in the density of little bustards could be explained by three variables summarising the land cover composition and diversity in the studied mosaics. Little bustard breeding males attained higher population density in land mosaics with a low land cover diversity, with less forests, and dominated by grasslands. Land mosaic composition gradients showed that agricultural intensification was not reflected in a loss of land cover diversity, as in many other regions of Europe. On the contrary, it led to the introduction of new land cover types in homogenous farmland, which increased land cover diversity but reduced overall landscape suitability for the species. Based on these results, the impact of recent land cover changes in Europe on the little bustard populations is evaluated.