Quantifying the impacts of predation by Great Black-backed Gulls Larus marinus on an Atlantic Puffin Fratercula arctica population: Implications for conservation management and impact assessments

The management of predator-prey conflicts can be a key aspect of species conservation. For management approaches to be effective, a robust understanding of the predator-prey relationship is needed, particularly when both predator and prey are species of conservation concern. On the Isle of May, Firth of Forth, Scotland, numbers of breeding Great Black-backed Gulls Larus marinus, a generalist predator, have been increasing since the 1980s, which has led to increasing numbers of sympatrically breeding Atlantic Puffins Fratercula arctica being predated during the breeding season. This may have consequences for species management on the Isle of May and impact assessments of offshore windfarms in the wider Firth of Forth area. We used population viability analysis to quantify under what predation pressure the Atlantic Puffin population may decline and become locally extinct over a three-generation period. The predation level empirically estimated in 2017 (1120 Puffins per year) was not sufficient to drive a decline in the Puffin population. Rather, an increase to approximately 3000 Puffins per year would be required to cause a population decline, and >4000 to drive the population to quasi-extinction within 66 years. We discuss the likelihood of such a scenario being reached on the Isle of May, and we recommend that where predator-prey conflicts occur, predation-driven mortality should be regularly quantified to inform conservation management and population viability analyses associated with impact assessments.

Tracking the impacts of COVID-19 pandemic-related debris on wildlife using digital platforms

Since the start of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2; COVID-19) pandemic in December 2019, there have been global surges of single-use plastic use. Due to the importance of personal protective equipment (PPE) and sanitation items in protecting against virus transmission and from testing, facemasks, respirators, disposable gloves and disposable wet wipes have become global staples in households and institutions. Widespread use and insufficient infrastructure, combined with improper waste management have resulted in an emerging category of litter. With widespread presence in the environment, such items pose a direct threat to wildlife as animals can interact with them in a series of ways. We examined the scope of COVID-19 pandemic-related debris, including PPE and sanitation items, on wildlife from April 2020 to December 2021. We document the geographic occurrence of incidents, debris types, and consequences of incidents that were obtained from social media searches, unpublished reports from colleagues, and reports available from the citizen science database "Birds and Debris". There were 114 unique sightings of wildlife interactions with pandemic-related debris (38 from 2020 and 76 from 2021). Within the context of this dataset, most incidents involved birds (83.3 %), while fewer affected mammals (10.5 %), invertebrates (3.5 %), fish (1.8 %), and sea turtles (0.9 %). Sightings originated in 23 countries, and consisted mostly of entanglements (42.1 %) and nest incorporations (40.4 %). We verified sightings by contacting the original observers and were able to identify replicated sightings and increase the resolution of the data collected compared with previously published results. Due to the complexities associated with global use and accessibility of digital platforms, we likely underestimate the number of animals harmed by debris. Overall, the global scope of this study demonstrates that online and social media platforms are a valuable way to collect biologically relevant citizen science data and track rapidly emerging environmental challenges.

A standardised method for estimating the level of visible debris in bird nests

Unlike records of plastic ingestion and entanglement in seabirds which date back to the 1960s, the literature regarding debris in bird nests is comparatively limited. It is important to identify standardised methods early so that data are collected in a consistent manner, ensuring that future studies can be comparable. Here, we outline a method that can be applied to photographs for estimating the proportion of visible debris at the surface of a nest. This method uses ImageJ software to superimpose a grid onto a photograph of a nest/s. The number of cells with and without debris are then counted. Our proposed method is repeatable, straightforward, and accessible. We optimised the method to estimate the level of visible debris in Northern Gannet (Morus bassanus) nests, however, with some modification (i.e., adjustment of grid cell size), it could be applied to other seabird species, and terrestrial birds, that incorporate debris within nests.

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.

Monitoring nest incorporation of anthropogenic debris by Northern Gannets across their range

Anthropogenic marine debris is a recognised global issue, which can impact a wide range of organisms. This has led to a rise in research focused on plastic ingestion, but quantitative data on entanglement are still limited, especially regarding seabirds, due to challenges associated with monitoring entanglement in the marine environment. However, for seabird species that build substantial surface nests there is the opportunity to monitor nest incorporation of debris that individuals collect as nesting material. Here, we monitored nest incorporation of anthropogenic marine debris by Northern Gannets (Morus bassanus) from 29 colonies across the species' range to determine a) the frequency of occurrence of incorporated debris and b) whether the Northern Gannet is a suitable indicator species for monitoring anthropogenic debris in the marine environment within their range. Using data obtained from visual observations, digital photography and published literature, we recorded incorporated debris in 46% of 7280 Northern Gannet nests, from all but one of 29 colonies monitored. Significant spatial variation was observed in the frequency of occurrence of debris incorporated into nests among colonies, partly attributed to when the colony was established and local fishing intensity. Threadlike plastics, most likely from fishing activities, was most frequently recorded in nests, being present in 45% of 5842 nests, in colonies where debris type was identified. Comparisons with local beach debris indicate a preference for threadlike plastics by Northern Gannets. Recording debris in gannet nests provides an efficient and non-invasive method for monitoring the effectiveness of actions introduced to reduce debris pollution from fishing activities in the marine environment.

Seabirds and marine plastic debris in the northeastern Atlantic: A synthesis and recommendations for monitoring and research

Marine plastic pollution is an increasing, and global, environmental issue. Numerous marine species are affected by plastic debris through entanglement, nest incorporation, and ingestion, which can lead to lethal and sub-lethal impacts. However, in the northeastern Atlantic Ocean, an area of international importance for seabirds, there has been little effort to date to assess information from studies of wildlife and plastic to better understand the spatiotemporal variation of how marine plastic affects different seabird species. To improve our understanding of seabirds and marine plastic in this region, we completed a synthesis of the published and grey literature to obtain information on all known documented cases of plastic ingestion and nest incorporation by this group. We found that of 69 seabird species that commonly occur in the northeastern Atlantic, 25 had evidence of ingesting plastic. However, data on plastic ingestion was available for only 49% of all species, with 74% of investigated species recorded ingesting plastic. We found only three published studies on nest incorporation, for the Northern Gannet (Morus bassanus) and Black-legged Kittiwake (Rissa tridactyla). For many species, sample sizes were small or not reported, and only 39% of studies were from the 21st century, whilst information from multiple countries and years was only available for 11 species. This indicates that we actually know very little about the current prevalence of plastic ingestion and nest incorporation for many species, several of them globally threatened. Furthermore, in the majority of studies, the metrics reported were inadequate to carry out robust comparisons among locations and species or perform meta-analyses. We recommend multi-jurisdictional collaboration to obtain a more comprehensive and current understanding of how marine plastic is affecting seabirds in the northeastern Atlantic Ocean.