Rice fields are increasingly vital habitats for waterbirds due to global wetland loss, but this is often in conflict with agricultural interests. Farmers generally see waterbirds as a source of crop damage, which fosters negative perceptions and leads to the adoption of dissuasion techniques aimed at deterring birds from their fields. Balancing agricultural productivity with conservation thus requires understanding these conflicts. This study examines rice farmers’ perceptions of waterbirds in Portugal, focusing on perceived positive and negative impacts for rice production, the effectiveness of dissuasion methods, and potential conflict mitigation strategies. Focusing on one of Portugal’s largest rice field areas, questionnaire-based interviews revealed that farmers perceive waterbirds unfavourably due to visible crop damage, overlooking their ecological benefits. Flamingos, storks, and ibises were regarded as the species causing the greatest crop damage during sowing and harvesting. Dissuasion techniques were seen as moderately effective but necessary. Perceptions varied by age and education: older farmers viewed waterbirds less negatively but were less willing to consider conflict mitigation strategies, while younger farmers held particularly negative perceptions. Farmers with higher formal education had especially positive perceptions and were open to solutions, while simultaneously viewing dissuasion as cost-effective. Despite these differences, most farmers favoured economic compensation for crop damages over other conflict mitigation approaches. This study underscores the need for a better understanding of perceived impacts alongside accurate data on crop damage and economic value of waterbirds’ ecosystem services. A multifaceted strategy – understanding farmers’ concerns and priorities, addressing knowledge gaps, involving farmers in decision-making, and implementing compensatory measures – can help balance biodiversity conservation with agricultural productivity, promoting coexistence between waterbirds and rice farmers.

In species exhibiting sexual size dimorphism (SSD) but no plumage dimorphism, morphometric sexing using linear discriminant analysis (LDA) may offer an efficient and economical alternative to molecular methods in field studies. Despite their importance, published discriminant functions remain scarce for many avian families, namely the Threskiornithidae, which includes ibises and spoonbills. In this study, Glossy Ibis ( (Plegadis falcinellus) were captured in rice fields in Portugal and sexed using molecular techniques. Morphometric measurements-wing length, culmen length, tarsus length, and body mass-were recorded, revealing significant male-biased SSD across all metrics. Males were, on average, 24% heavier and exhibited 19%, 18%, and 7% longer tarsus, culmen, and wing lengths, respectively. Univariate discriminant functions using wing or tarsus length alone correctly classified 96% of all measured individuals, while a multivariate function including wing, culmen and tarsus length achieved 100% of accuracy. Eleven equations with one or more variables correctly assigned 100% of the females to their sex-class while classification accuracy for males ranged between 93 and 100%. Our findings highlight the effectiveness of morphometric methods for reliable sexing Glossy Ibis and provide a practical tool for future ecological studies requiring sex determination. Received 6 Feb 2025, accepted 4 Jul 2025.

Summary Medium to small petrels that mostly nest in burrows or crevices represent a large fraction of the world’s seabirds, yet their population trends are largely unknown. This lack of knowledge, which has implications for conservation planning, results mostly from methodological difficulties and from the approaches that have been used for their monitoring. Here, we present the surveying scheme created to monitor Cory’s Shearwater Calonectris borealis breeding numbers at their largest known colony, Selvagem Grande (Portugal). We defined 60 circular plots at fixed locations on this 2.45 km 2 island and counted nests with eggs annually at the end of laying. Results show that the population increased at 1.45% (95% confidence interval [CI]: 0.72–2.01%) per year between 2009 and 2023. We estimate that the current population size is 38,830 pairs (95% quantile CIs = 34,373–43,713). To the best of our knowledge, this study provides the first systematic information (using fully repeatable methods and providing CIs for the estimates) on population trends of Cory’s Shearwaters, one of the most abundant seabirds in the warm temperate and subtropical North Atlantic and one of the most studied petrels globally. Monitoring using the approach detailed here requires two days of work (by 2–3 persons) per year. Our results and simulations indicate that this is a powerful methodology, with narrow confidence limits for estimated trends and an ability to detect small population changes over short time spans. We suggest that more monitoring protocols similar to this one (with necessary site-specific adaptations, particularly for potential colony expansion where suitable habitat exists) should be developed and implemented in a range of colonies with crevice and burrowing nesting petrels to improve our knowledge on the population status of a broad fraction of the world’s seabirds.

Aim: To identify the broad-scale oceanic migration routes ('marine flyways') used by multiple pelagic, long-distance migratory seabirds based on a global compilation of tracking data. Location: Global. Time Period: 1989-2023. Major Taxa Studied: Seabirds (Families: Phaethontidae, Hydrobatidae, Diomedeidae, Procellariidae, Laridae and Stercorariidae). Methods: We collated a comprehensive global tracking dataset that included the migratory routes of 48 pelagic and long-distance migrating seabird species across the Atlantic, Indian, Pacific and Southern Oceans. We grouped individuals that followed similar routes, independent of species or timings of migration, using a dynamic time warping clustering approach. We visualised the routes of each cluster using a line density analysis and used knowledge of seabird spatial ecology to combine the clusters to identify the broad-scale flyways followed by most pelagic migratory seabirds tracked to-date at an ocean-basin scale. Results: Six marine flyways were identified across the world's oceans: the Atlantic Ocean Flyway, North Indian Ocean Flyway, East Indian Ocean Flyway, West Pacific Ocean Flyway, Pacific Ocean Flyway and Southern Ocean Flyway. Generally, the flyways were used bidirectionally, and individuals either followed sections of a flyway, a complete flyway, or their movements linked two or more flyways. Transhemispheric figure-of-eight routes in the Atlantic and Pacific oceans, and a circumnavigation flyway in the Southern Ocean correspond with major wind-driven ocean currents. Main Conclusions: The marine flyways identified demonstrate that pelagic seabirds have similar and repeatable migration routes across ocean-basin scales. Our study highlights the need to account for connectivity in seabird conservation and provides a framework for international cooperation.

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 Bijagos 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.

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.

In a scenario of global wetland loss, rice fields are becoming vital habitats for waterbirds, often offering abundant and predictable food resources. However, the increasing presence of waterbirds in rice fields is exacerbating human-wildlife conflicts, as birds are seen as pests by farmers due to the damage they perceive the birds inflict to the crops. To tackle this situation, farmers use dissuasion methods like propane gas cannons, but its effectiveness in reducing damage is often not quantified. In this study we evaluate the cost-effectiveness of propane gas cannons in deterring waterbirds from rice fields and test if there is a correlation between bird abundance in a given field during rice growth and rice yield in the same field. Waterbird counts were conducted before and after dissuasion actions targeting Glossy ibis and White stork in a major rice production area in Portugal. To assess the potential magnitude of damage reduction gained through dissuasion, we estimated the time elapsed between dissuasion events and the reestablishment of bird numbers in the disturbed fields. The economic cost of dissuasion was compared with the estimated gains from reduced damage. Results showed that on average, waterbird numbers recovered ca. 30 min after dissuasion, leading to an estimated 0.78% reduction in crop damage. The final yield of rice production was modelled considering all gains and costs involved in dissuasion actions in relation to an increase in dissuasion efforts for 11 scenarios of potential waterbird damage (0-20%). For dissuasion to be cost-effective, waterbirds would need to destroy at least 17% of the crops, far more than any damage previously recorded in Europe. Also, we found that the abundance of waterbirds in a rice field does not affect rice yield. We suggest that efforts to reduce damage should shift to more cost-effective and environmentally friendly methods, such as diversionary fields or economic compensations to farmers. This can enhance the economies of rice-dependent countries and reduce conflicts, ultimately reconciling rice agriculture with biodiversity conservation.

This study aims to understand how the structure and functions of waterbird communities in rice fields compare to those in other habitats within an agricultural landscape encompassing five habitats: saltpans, lakes, intertidal areas, pastures and rice fields. Over 2 years, waterbird counts were conducted every 15 days in these habitats. Non-metric multidimensional scaling was used to compare the composition and functional structure of the waterbird communities. Differences in both metrics were found among habitats throughout the year. These appear to be driven by spatial (presence of permanent water cover) and temporal gradients (yearly seasonality). Rice fields occupy a central position within the gradients. The composition and functional structure of waterbird communities in rice fields undergo significant changes throughout the year associated with the annual rice production cycle. Other habitats maintain more consistent communities, reflecting their more stable environmental conditions. Rice fields play a complementary role to other habitats in the landscape, likely acting as a buffer, partially mitigating the loss of some waterbird species amid the global decline of natural wetlands.

We investigated the non-breeding movements and distribution of West African Crested terns (Thalasseus albididorsalis) breeding in one of the largest colonies of the species, in Guinea-Bissau. Through GPS tracking of six individuals, we show that half of the birds performed long-distance migrations to non-breeding sites located up to 5039 km south of the colony, mostly in Nigeria and Angola. The other half performed short-distance migrations to areas within 340 km of the breeding colony, mainly in Guinea. These results show high variability on the migratory strategies of the West African Crested Tern and suggest low migratory connectivity within the studied population. Regardless of their migratory strategy, all tracked birds visited at least one additional breeding colony both after and before the breeding season. This behaviour might be particularly relevant for species breeding in unstable environments, which is the case of the studied species, nesting in highly dynamic coastal sandbanks. During the non-breeding season West African Crested terns used coastal areas falling within 18 different jurisdictions, highlighting the need for concerted action between all coastal countries of Western Africa, from Senegal to Angola, for the conservation of this species.

Unsustainable fossil fuel emissions have prompted a global shift towards renewable energy sources, such as wind. This has led to a strong expansion of wind power generation infrastructures, often conflicting with biodiversity conservation. Relatively large flying animals, such as birds and bats, have frequently been reported to collide with wind turbines, resulting in casualties that can depress population size and lead to local extinctions. Migratory species that move across continents through their year-round displacements may be especially at risk. We comprehensively assessed wind turbine exposure for a colonial migratory raptor of European conservation interest, the lesser kestrel Falco naumanni , based on the distribution and size of >1800 colonies and a large GPStracking dataset ( >350 individuals) for three distinct biogeographical populations (from Iberian, Italian, and Balkan peninsulas). 26 % of the European population has at least one wind turbine within the foraging areas around colony sites, Italian colonies being most at risk. The main European network of protected areas, the Natura 2000 network, failed to mitigate the potential negative impact of wind turbines on breeding populations. GPS-tracking revealed that exposure was negligible in the African non -breeding areas (Sahel region), particularly high during migration, and lower during breeding for Iberian and Balkan individuals but not for Italian ones. Different countries should prioritize different measures to mitigate collision risk with wind power generation infrastructures. This case study can be leveraged by conservationists and renewable energy stakeholders to mitigate conflicts between biodiversity conservation and expected wind energy infrastructure development in the near future.

Assessing at-sea distributions and behaviour of seabirds to identify critical foraging sites and spatial overlap with potential threats is a major step for delineating conservation guidelines. The West African Crested Tern ( Thalasseus albididorsalis ) is the most abundant breeding tern in West Africa, nesting from Mauritania to Guinea. Its restricted breeding range and exclusive nesting at coastal low-lying areas, place this species at particular risk of losing suitable breeding and resting sites as a consequence of current global changes, namely, sea-level rise. The at-sea distribution of this species is mostly unknown, and therefore, the specific threats faced are still unidentified. Here, we characterize the foraging behaviour and distribution of West African Crested terns breeding at the world’s second-largest colony of the species, in Guinea-Bissau, by tracking 20 individuals. Overall, terns took an average of 2 trips per day, travelling on average 100 km per trip, but often reaching areas up to 120 km from the colony. Shallow waters, usually not exceeding 10 m in depth, and upwelling areas were mostly used as foraging sites. Nocturnal movements, rarely reported on terns, suggest active foraging at night. Key foraging and resting sites were identified, which altogether may regularly hold 2.5–23% of the global breeding population of the West African Crested Tern. These areas are only partly (ca. 50%) covered by the existing marine Important Bird and Biodiversity Area (IBA). Therefore, our results should be considered in any re-evaluation of the IBA borders.

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.

Animals often face a trade-off between food acquisition and predation/disturbance avoidance. Yet, the extent to which this trade-off is affected by modulating factors such as thermal risk and foraging opportunities has been largely overlooked.Here, we examined the influence of temporal and environmental gradients on the flight initiation distance (FID, the distance at which animals flee from an approaching human-simulated predator) and escape mode (flying/low risk versus running/low cost) in 16 species of shorebirds foraging on tidal flats of the Bijagos Archipelago, Guinea-Bissau. We measured escape responses throughout the low tide period during wet and dry seasons and simultaneously recorded microclimate variables and occurrence of heat-reduction behaviour (ptiloerection). Furthermore, we measured corticosterone metabolites (CORTm) from droppings in red knots Calidris canutus to assess whether ptiloerection is associated to a physiological stress response to hot conditions.Overall, birds tolerated a closer approach at higher environmental temperatures and when showing ptiloerection. They also had shorter FIDs during the dry season and towards the start/end of the low tide period. FIDs also increased with body mass and decreased in areas with more human presence. In red knots, individuals showing ptiloerection had higher levels of CORTm, demonstrating a link between physiological and behavioural stress coping responses to heat events.Our results suggest that heat-stressed shorebirds take greater risks, supporting the idea of a thermoregulation-predation risk trade-off. They also indicate that shorebirds adjust risk taking to tidal and seasonal cycles, generally reducing FIDs when the energetic costs of escape are expected to be large. Finally, they suggest that shorebirds habituate to non-lethal human presence and respond to perceived predation risk in accordance with the predictions of optimal escape theory.These results are relevant to many animals that face a tight window for foraging activity while being exposed to predation/disturbance and heat during the day. We discuss management implications of our results in the context of global change.

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.

Studies providing a detailed diet description of whole-bird communities are surprisingly scarce. Yet, these studies are pivotal to comprehend the mechanisms structuring communities and the persistence of each species in the ecosystem. We characterized the diet of a shorebird community in a key non-breeding area of the East Atlantic Flyway, the Bijagós Archipelago (West Africa), combining molecular and morphological prey identification based on 239 droppings from 15 species. Our results show that while relying upon a super-abundant prey (fiddler crab), shorebirds consumed a very high number of taxa. We stress the relevance of highly mobile prey (especially crustaceans but also fish), which typically appear to be of little importance in most shorebird studies. Our results suggest that by consuming a high diversity of prey, shorebirds may reduce competition. This may be critical in a site ranked as the second most important area in West Africa for migratory shorebirds but marked by low benthic invertebrate availability. We further compared the performance of DNA metabarcoding and morphological identification of prey. Overall, molecular and morphological methods combined delivered the most comprehensive results, although molecular methods largely surpassed morphological methods regarding taxonomic detail achieved and number of prey taxa found (4 times more). Taxonomic resolution in the identification of polychaetes and bivalves using the 16S primer was low (mostly to class), whereas this primer clearly performed better than mitochondrial cytochrome c oxidase in identifying more insects and fish. We emphasize the need to increase invertebrate representatives from West Africa in barcode databases, in order to enhance metabarcoding results.

Predation risk profoundly shapes how animals behave and is one of the main forces driving the formation or maintenance of groups. For some species, group living may be facultative, and individuals may live solitarily or aggregate with conspecifics or heterospecifics, but the advantages of each strategy are still poorly known. Here, we investigated whether a predominantly solitary breeding species, the European roller, Coracias garrulus, acquires antipredator benefits from nesting in mixed-species colonies dominated by lesser kestrels, Falco naumanni. We compared the risk-taking behaviour of solitary rollers and rollers breeding in colonies by conducting two experiments. First, we investigated rollers??? latency to resume incubation when presented with a novel object, and second assessed their latency to resume chick provisioning and their investment in mobbing behaviour towards a predator model. We additionally compared the breeding performance and nest predation rate of rollers in each social context (solitary versus colonial) using data from 300 breeding attempts across 6 years. We found that rollers breeding in colonies returned to their nests sooner during the presentation of both the novel object and the predator model and attacked the predator model less frequently than solitary rollers, suggesting they can use heterospecifics as cues in deciding whether it is safe to return to their nests. In addition, rollers in colonies suffered less nest predation than solitary ones, but this did not translate into a higher productivity. Future studies should investigate whether breeding in colonies provides other advantages to rollers, such as increased adult survival or fitness. ?? 2022 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.

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.

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 Impor-tant 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.

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 m 2 ), 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.