Entanglement rates and their effects on the population
In order to be able to estimate the consequences for population development, individuals entangled by artificial nesting material in the nature reserve "Lummenfelsen" are to be recorded throughout the year between November 2018 and June 2020. Gannets and guillemots become entangled in the artificial nesting material and in most cases die because they cannot free themselves from the plastic residues. Several times during the summer months, surveys of the entangled seabirds have already been carried out sporadically by the Institute for Bird Research "Vogelwarte Helgoland" and regularly since 2014 by the FTZ as part of two F&E projects financed by the "Umweltbundesamt" (2014-2016: "Coherent monitoring of the pollution of German marine and coastal waters with human waste and the ecological consequences with further focus on in-depth identification of the sources", UFOPLAN 2014; 2017-2021: "Follow-up assessment and establishment of long-term monitoring of the pollution of various marine areas and biota by marine waste (marine litter)", UFOPLAN 2017) in the Heligoland colony. The existing data material is to be reviewed and supplemented by the above-mentioned surveys. Guillemots visit the breeding rocks irregularly from the end of October. At this time, the gannet nests are not occupied, so that the birds come even closer to the gannet nests, thus increasing the risk of entanglement. Every winter, a relatively high number of gannets die in this way, but quantitative data on this are still completely lacking.
Little is known about the effects of plastic waste as nesting material on seabird populations. For this reason, the recorded entanglement rates are to be incorporated in a population model to be developed in this research project, in order to see what effect the entanglement has on the population or will have in the future if the entanglement increases.