Browsing by Subject "nest material"

Marine debris is a problem that also affects sea birds. Several bird species are known to utilise marine debris among their nest materials in different parts of the world. Debris in nests can cause entanglement and increase the risk of debris ingestion, and hazardous substances leaching from plastics can have negative effects on birds. There are also anecdotal observations of debris in the great cormorant (Phalacrocorax carbo sinensis) nests in the Gulf of Finland, however, systematic studies are lacking. In this Master’s thesis I examined the prevalence of debris in cormorant nests in the Gulf of Finland, focusing mainly on plastic debris. The study was carried out in four nesting islets, which were located in Kotka, Porvoo, Espoo and Kirkkonummi. The sampling took place in autumn 2021. 50 nests were randomly sampled on each nesting islet, and plastic debris in the nest was counted and classified according to their type, colour and origin. Plastic debris was further categorized in the laboratory according to their polymer type using Fourier Transform Infrared spectroscopy (FTIR). Debris from the nesting islets was also counted and classified according to their type, colour and origin. In total, 58% of the nests contained debris, but the prevalence of debris in the nests varied between the colonies; In Kirkkonummi debris was found in 92% of the nests while in Porvoo only 34% of the nests included debris. Plastics constituted great majority of nest debris (95%). Most common source for plastic debris was consumers, most common plastic type threadlike and polymer type polyethylene (PE). The number of debris in the nests was linked to the width and location of the nests: core nests contained more debris than periphery nests and the number of debris in the nest was positively correlated with the width of the nest. The amount of threadlike plastics in the nests was higher than that in the surrounding environment, indicating active selection by cormorants for threadlike debris types as nest material. Based on the results of this thesis, nest surveys could be a useful tool in evaluating the effectiveness of certain reduction measures aiming to tackle marine plastic pollution.