Confidence intervals and sample size for estimating the prevalence of plastic debris in seabird nests

Prevalence of plastic debris in nests of two cormorant species in Peru

The guanay cormorant (Leucocarbo bougainvilliorum) and red-legged cormorant (Poikilocarbo gaimardi) are known for their prolific nest-building behavior, utilizing a diverse array of materials, including anthropogenic debris, thereby serving as valuable indicators of ocean plastic pollution. To elucidate inter-specific variations in nest plastic occurrence between these two cormorant species, we conducted a comprehensive examination of nests at 12 colonies along the Peruvian coast in 2018-2019. Our findings revealed a significantly higher occurrence of plastic in red-legged cormorant nests (mean 50 ± 27 %, N = 100 nests in 7 colonies) compared to guanay cormorant nests (mean 10 ± 20 %, 3497 nests in 8 colonies). Furthermore, the prevalence of plastic waste varied across colonies within both species. Off-white/clear plastic bags were the predominant color and type of debris found in both cormorant nests. This study is a baseline of plastic marine pollution occurrence along the Peruvian coast.

Toxic metals in rice among Asian countries: A review of occurrence and potential human health risks

Heavy metals such as cadmium (Cd), arsenic (As), and lead (Pb) pose significant health risks, particularly in Asia, where rice is a staple for nearly three billion people. Despite their known dangers and environmental prevalence, studies addressing their concentrations in rice across different regions and the associated health implications remain insufficient. This review systematically examines the occurrence and impact of these toxic elements, filling a critical gap in the literature. Data from seven countries indicate mean concentrations in the order of Pb > As>Cd, with values of 0.255 ± 0.013, 0.236 ± 0.317, and 0.136 ± 0.150 mg/kg, respectively. Uncertainty analysis shows extensive variability, especially for Cd, with a 95% confidence interval range from 0.220 to 0.992 mg/kg. The typical daily intake of heavy metals through rice consumption, in the order of As>Cd > Pb, frequently exceeds safe limits. Generally, data obtained from various studies showed that children were more prone to heavy metal contamination through rice consumption than adults. This review is fundamental for ongoing monitoring, future research, and management strategies to reduce heavy metal contamination in rice.

Nesting material adaptation of native bird species with anthropogenic litter along an urbanization gradient in Pakistan

Rapid urbanization and associated waste generation have become a mounting ecological concern for wildlife, especially avian communities. Research has primarily focused on investigating the impacts of human activities on marine birds with comparatively less focus on terrestrial species that live in far more anthropized environments and are at significant risk. Our study has explored the abundance and characteristics of anthropogenic litter in 70 nests of four generalist bird species: Bank Myna (Acridotheres ginginianus), Common Myna (Acridotheres tristis), Black Kite (Milvus migrans) and House Crow (Corvus splendens), within the city of Lahore (Pakistan) and its surroundings, by determining and following an urbanization gradient. The overall frequency of litter occurrence (FLO%) for all the sampled nests was 89%. Over 80% of the recorded litter items consisted of plastic materials, primarily dominated by sheet-like plastics. There was a strong association between fabric and Black Kite nests, and metal and House Crow nests. Litter incorporation increased across the gradient from rural to urban habitats. The highest FLO% was found in nests sampled from waste dumping sites and urban sites (95%-100%), where anthropogenic influence was more intense. The high level of litter incorporation is potentially indicative of a species' adaptive response to urbanization, associated with the decline in natural nesting material and availability of anthropogenic litter. These findings highlight the need for strengthening the existing global database for terrestrial litter and its effect on wildlife and devising policy actions for better waste management and conservation of natural ecosystem balance.

Gulls as potential sentinels for urban litter: combining nest and GPS-tracking information

The production of urban waste has increased in the past decades leading to its mishandling. The effects on public health, economy, and wildlife that waste mismanagement can have are forcing governments to increase their efforts in detecting and mitigating the presence of waste. Identifying and monitoring sentinel species to assess the presence of urban litter could be a cost-effective option. Thus, analyzing the nest composition of yellow-legged gulls from an urban population inhabiting a very high populated city (Barcelona, Spain), and combining this information with accurate GPS tracking data, provides a potential tool to monitor the presence of marine and terrestrial litter over time. The results revealed the highest presence of debris in the nests of a seabird ever recorded. All the nests examined contained anthropogenic waste, with plastic items present in all of them. Crossing the nest composition with GPS tracking movements confirmed that the waste to build the nests was collected in the urban area and not in other environments surrounding the city. Then, the nest waste composition may be a good indicator of waste mismanagement and advise the municipalities to improve waste management and recycling strategies for the different types of litter. Using gulls breeding in cities as sentinel species and, in particular, the study of their nest composition, may provide essential data to decision-making stakeholders to adopt a One Health approach and help improve not only the environment's health but also the health of those who live in it.

Seabirds pecking polystyrene items in offshore Adriatic Sea waters

A number of seabird species have been known to peck, displace, and ingest various plastic items including expanded polystyrene, for reasons that remain largely conjectural. Ingestion of polystyrene parts potentially causes lethal or sublethal effects on birds. Pecking can also result in the damage of polystyrene items, resulting in increased market turnover and environmental build-up, or economic consequences for stakeholders. In January and February, 2022, fishers in a portion of the western Adriatic Sea coast reported pecking damage caused by gulls (Laridae) to polystyrene buoys used to float, signal, and retrieve static fishing nets and traps. We investigated the magnitude of this phenomenon in four fishing harbours of Italy by scoring damage to 470 buoys and interviewing 29 fishers (encompassing 42% of the relevant fleet). Information was complemented by opportunistic observations at sea. Our preliminary assessment suggests that offshore polystyrene pecking increases in winter months, and it occurs sporadically among years. The overall economic damage to the static net fishery appeared generally modest (approximately 3-4 Euro to replace one buoy), with wide variations in the extent of reported damage. We reviewed the hypotheses behind polystyrene pecking, but none of them provide a clear explanation for the observed behaviour. Finally, we discuss potential effects on seabirds and advocate monitoring to investigate causal factors and mitigate damage to seabirds, fisheries, and marine environment.

Anthropogenic debris in Kelp Gull and other seabird nests in northern Patagonia, Argentina

Anthropogenic debris is used as nesting material by many seabirds and may result in negative impacts. We assessed the frequency of occurrence of debris (>5 mm) in Kelp Gull (Larus dominicanus) nests at six locations along 2400 km of the Argentine coast, at different distances from urban centres, and in nests of other seven seabird species nesting syntopically. Frequencies in Kelp Gull nests were in general relatively low, ranging between 3.3 and 37.5%, and differed significantly among colonies. No relationship was found between frequency and distance to urban centres. Debris were recorded with frequencies of less than 19.2% in nests of Olrog's Gulls (L. atlanticus), Dolphin Gulls (L. scoresbii), Imperial Cormorants (Leucocarbo atriceps) and Magellanic Penguins (Spheniscus magellanicus), but not in nests of Neotropical Cormorants (Nannopterum brasilianus), Rock Shags (Leucocarbo magellanicus) and Southern Skuas (Catharacta antarctica). This information obtained along a wide coastal sector provides a baseline for future monitoring.

Comparing photography and collection methods to sample litter in seabird nests in a coastal archipelago in the Southwest Atlantic

Different methods are used to quantify and classify litter in seabird nests, such as the collection method (CM) and the photography method (PM). We compared the CM and PM in 195 brown booby (Sula leucogaster) nests breeding in a coastal archipelago in the state of Rio de Janeiro, Brazil. Photographs recorded 109 litter items in 44 nests (23% of nests), compared to 416 litter items in 82 nests (42%) by the CM. Pairwise comparison showed a significant difference in the variety and amount of litter items per nest, which was greater for CM (2.1 ± 1.1 categories, 2.13 ± 4.8 items) than for PM (1.5 ± 0.8 categories; 0.56 ± 1.6 items), in addition to a significant difference in the overall litter composition. The CM has been the most often used method to date. Although PM underestimates the amount and frequency of litter, we encourage its use when litter is abundant in nests and for threatened species.

Measuring nest incorporation of anthropogenic debris by seabirds: An opportunistic approach increases geographic scope and reduces costs

Data on the prevalence of anthropogenic debris in seabird nests can be collected alongside other research or through community science initiatives to increase the temporal and spatial scale of data collection. To assess the usefulness of this approach, we collated data on nest incorporation of debris for 14 seabird species from 84 colonies across five countries in northwest Europe. Of 10,274 nests monitored 12% contained debris, however, there was large variation in the proportion of nests containing debris among species and colonies. For several species, the prevalence of debris in nests was significantly related to the mean Human Footprint Index (HFI), a proxy for human impact on the environment, within 100 km of the colony. Collecting opportunistic data on nest incorporation of debris by seabirds provides a cost-effective method of detecting changes in the prevalence of debris in the marine environment across a large geographic scale.

Human waste used as nesting material affects nest cooling in the clay-colored thrush

The internal temperature of nests largely depends on the materials used in their construction because the characteristics of each material affect the isolation of nest walls. In urban environments, the availability of natural materials for nest building decreases, while the availability of artificial materials increases. Therefore, many urban bird species use more artificial materials for nest building inside cities, which may affect the thermal properties of the nest. We conducted an experiment to measure the effect of artificial materials included as part of the nest structure, on nest thermoregulation. We used as a model, nests of the clay-colored thrush (Turdus grayi), an urban bird species that have been reported using artificial nest materials. In our experiment, we measured how variation in artificial materials mass affects the nest cooling rate in a climate-controlled room. We found that artificial materials increased the cooling rate of clay-colored thrush nests, compared with nests with only natural materials. This result is especially relevant because showed a negative direct effect of the use of artificial material for nest building in birds. Considering that the availability of artificial material is increasing in urban areas, while natural material is decreasing, it is expected that the negative effect of using artificital material for nest construction would increase in the clay-colored thrush and other city bird species.

The long-term legacy of plastic mass production

Mismanaged plastic waste is transported via rivers or city drains into the ocean where it accumulates in coastal sediments, ocean gyres and the deep ocean. Plastic harms marine biota and may ultimately return to humans via the food chain. Private initiatives proposing to collect plastic from the sea and rivers have gained widespread attention, especially in the media. However, few of these methods are proven concepts and it remains unclear how effective they are. Here we estimate the amount of plastic in the global surface ocean to assess the long-term legacy of plastic mass production, calculate the time required to clean up the oceans with river barriers and clean up devices, and explore the fate of collected plastic waste. We find that the projected impact of both single and multiple clean up devices is very modest. A significant reduction of plastic debris in the ocean can be only achieved with collection at rivers or with a combination of river barriers and clean up devices. We also show that the incineration and production of plastic has a significant long-term effect on the global atmospheric carbon budget. We conclude that a combination of reduced plastic emissions and reinforced collection is the only way to rid the ocean of plastic waste.

The use of anthropogenic debris as nesting material by the greater thornbird, an inland-wetland-associated bird of South America

Plastic pollution has become a globally pressing environmental issue. In birds, plastic may cause harm by entangling or ingestion when used for nesting. The use of anthropogenic nesting material has so far been mostly studied in birds of terrestrial or marine habitats, but there are yet very few reports for inland water-associated birds. The aim of this study is to better understand the extension and magnitude of the use of anthropogenic debris as nesting material by the greater thornbird (Phacellodomus ruber), a bird species preferably nesting in river floodplain wetlands in South America. We found that P. ruber uses disproportionally large quantities of plastic debris as nesting material (more than 90% of some nest chambers is plastic). This occurred even if ample vegetation (commonly used as soft material) was available. Most of the artificial nesting material was derived from wrapping material released into the environment. We suggest that this species has the potential to indicate vulnerable areas to plastic pollution associated with urban waste mismanagement.

Density and composition of surface and buried plastic debris in beaches of Senegal

Debris poses a series of problems to marine life and human well-being. However, estimates of density and characteristics of debris found on beach surfaces and buried in the sand are patchy on a global scale and absent for West Africa. Here we investigate the density of surface and buried debris accumulated in two beaches with contrasting levels of urbanisation in Senegal, West Africa. We also describe type, colour, weight, size, and possible source of the 1766 items collected. The average density of debris buried at a depth of 10 cm (48.75 items/m²) was 25 times higher than that observed at the surface (1.92 items/m²). Plastics accounted for 97.62% of the items. Plastic bags and clothing plastic were the most common types, whereas white and transparent were the most common colours. Most items originated from mixed sources, i.e. beach users and land-based sources (51.30%). Debris density in the urbanised site was 20 times higher than that in the non-urbanised site. Debris density can, therefore, be largely underestimated when sampling only on the beach surface. Our study provides the first findings for future research on beach debris in Senegal.

Characterization of anthropogenic materials on yellow-legged gull (Larus michahellis) nests breeding in natural and urban sites along the coast of Portugal

Anthropogenic materials are a persistent pressure on ecosystems, affecting many species. Seabirds can collect these materials to construct their nests, which may modify nest characteristics and cause entanglement of chicks and adults, with possible consequences on breeding success. The incorporation of anthropogenic materials in nests of seabird species that breed in both natural and urban environments, such as gulls, is poorly known. Here, we characterize and compare anthropogenic materials incorporated in yellow-legged gull (Larus michahellis) nests from two natural and two urban breeding sites across their Portuguese breeding range and during 2 consecutive years. Anthropogenic materials were found in 2.6% and 15.4% of gull nests from natural locations and in 47.6% and 95.7% of nests from urban breeding sites. No differences were found on hatching success between urban and natural breeding colonies. A significantly higher number of anthropogenic materials were found in the largest and more populated urban breeding colony, which on average included items of a greater mass but smaller size than items from the other three colonies. The higher incorporation of anthropogenic materials in urban locations could be a consequence of a lower access to natural nest construction materials and higher availability of anthropogenic debris. The quantity and diversity of anthropogenic materials incorporated in gull nests from urban locations indicate a need for improved debris management in urban settlements.

Using photographs to record plastic in seabird nests

The incidence of plastic in seabird nests can be used to track changes in the amounts of marine debris, but large sample sizes are needed for accurate estimates. Surveys of active nests cause disturbance to breeding birds, so we need an efficient way to sample nest plastics. Photographs of brown noddy Anous stolidus nests at Ducie Atoll, southeast Pacific Ocean, allowed rapid characterisation of plastic use with limited disturbance, and showed selection for blue-green items. Plastic was more prevalent in noddy nests at Ducie Atoll (97%) than at Inaccessible Island, South Atlantic Ocean (41%), despite lower debris densities at Ducie. Differences in nesting habitat and the resultant availability of natural nesting material drive this difference in plastic loads. Using photographs to record plastic in seabird nests reduces disturbance to breeding birds and might decrease the risk of missing cryptic debris items. Photographs also provide a permanent record of pollution levels.