Indigo-dyed cellulose fibers and synthetic polymers in surface-feeding seabird chick regurgitates from the Gulf of Alaska

We provide evidence of anthropogenic materials ingestion in seabirds from a remote oceanic area, using regurgitates obtained from black-legged kittiwake (Rissa tridactyla) chicks from Middleton Island (Gulf of Alaska, USA). By means of GPS tracking of breeding adults, we identified foraging grounds where anthropogenic materials were most likely ingested. They were mainly located within the continental shelf of the Gulf of Alaska and near the Alaskan coastline. Anthropogenic cellulose fibers showed a high prevalence (85 % occurrence), whereas synthetic polymers (in the micro- and mesoplastics dimensional range) were less frequent (20 %). Most fibers (60 %) were blue and we confirmed the presence of indigo-dyed cellulosic fibers, characteristic of denim fabrics. In terms of mass, contamination levels were 0.077 μg g-1 wet weight and 0.009 μg g-1 wet weight for anthropogenic microfibers and synthetic polymers, respectively. These results represent the only recent report of contamination by anthropogenic fibers in seabirds from the Gulf of Alaska.

Use of anthropogenic-related nest material and nest parasite prevalence have increased over the past two centuries in Australian birds

Global plastic production has increased exponentially since the 1940s, resulting in the increased presence of anthropogenic debris in the environment. Recent studies have shown that birds incorporate anthropogenic debris into their nests, which can reduce nest ectoparasite loads. However, we know little about the long-term history of interactions among birds, anthropogenic debris, and ectoparasites. Our study took a unique approach to address this issue by determining the prevalence of anthropogenic debris and ectoparasitic nest flies (Protocalliphora and Passeromyia spp.) in 893 bird nests from 224 species between 1832 and 2018, which were sourced from Australian museum collections. The prevalence of anthropogenic material increased from approximately 4% in 1832 to almost 30% in 2018. This change was driven by an increase in the incorporation of synthetic rather than biodegradable anthropogenic debris (by 2018 ~ 25% of all nests contained synthetics), with the first synthetic item being found in a nest from 1956 in the city of Melbourne. Nest parasite prevalence increased over time but contrary to other studies, there was no relationship between habitat type or anthropogenic material and parasite presence. Our study is the first to use museum specimens to quantify temporal and spatial impacts of anthropogenic material on birds, the results of which justifies contemporary concerns regarding the ubiquitous nature of human impacts on terrestrial wildlife.