Research
The Baltic Seabird Project has conducted research on Stora Karlsö since 1997, when the project began under the name “Seabirds in the Baltic Sea.” Much has happened since then, and from the menu above, you can read about the project’s background, our studies and staff, and have a look at our publications.
Studies
Fieldwork
The BSP’s fieldwork is carried out primarily on Stora Karlsö. Our fieldwork season begins at the end of April and ends around the 18th of July, and we have ongoing studies from the 1st of May to the 15th of July. We conduct both long-term studies (repeated annually) and shorter term studies that last for just one or a few seasons. The number of people manning the field station changes with the intensity of our fieldwork efforts, from two people in the low season to 10-12 people during the ringing of the guillemot chicks.
Ringing
Over the years, bird ringing has been, and continues to be, an important means of answering questions about population trends and the Baltic ecosystem at large. Ringing efforts have demonstrated weight loss trends in guillemot chicks, as well as detected the large number of adult birds drowning in fishing nets. By ringing the guillemots as chicks, we can study adult survival rate by observing how many of the ringed birds return each year.
Number of ringed Common Guillemots on Stora Karlsö, 1913 – 2015, a total of approximately 75,230 birds. © BSP/Aron Hejdström
Average weight of ringed Common Guillemot chicks on Stora Karlsö 1992 – 2015. © BSP/Aron Hejdström
Behavioural studies
Studying bird behaviour can provide important information about the conditions under which they live. For example, we have studies how often and with which species adults feed their young, and found long-term changes in this behaviour. When combined with knowledge of other changed in the ecosystem, this can lead to a better understanding of the conditions needed for long-term survival of the species.
Inventories
The long term health and survival of fish populations is what determines the health and survival of many other associated species. Stora Karlsö is the most important breeding area for several seabird species; thus, monitoring their population trends on the island is of great importance. Within the project, we follow the development of Common Guillemots, Razorbills, Lesser Black-backed Gulls and Herring Gulls each year. Inventory methods vary by species. In the auk species (guillemots and razorbills), we count breeding individuals in a set number of reference areas to determine general trends. For the gull species, we count the number of active nests.
Number of active nests belonging to Herring Gulls and Lesser Black-backed Gulls on Stora Karlsö, 2005 – 2015. © BSP/Aron Hejdström
Monitoring
The BSP has shown that by using the same methods year after year, the study of seabirds can detect long-term changes in the ecosystem. This method is called monitoring. By using many species occupying different ecological niches and increasing the number of study parameters, a clear and detailed picture of the ecosystem can be formed. One of the monitoring studies conducted by the BSP is the breeding success of Common Guillemots. In the study, 150-200 breeding pair of guillemots are followed from egg-laying in early May to when the hatched young reaches 15 days of age on the ledge, and is considered fully ready to leave the ledge.
Breeding success (percentage) of Common Guillemots on Stora Karlsö, 1996-2015. © BSP/Aron Hejdström
Collection of samples
By collecting and storing samples of blood, feathers, abandoned food, eggs, or even whole dead birds, we can complement our field studies with studies at the molecular level. For example, we can measure toxicity levels or nutrient content, and perhaps get a clue as to why the “hop weight” of guillemot chicks jumping from the ledge changes, despite the fact that they are receiving the same amount of food as before. Samples collected over a long period of time can also prove to be a valuable resource in the future. Developments in molecular research are advancing rapidly, and it is impossible to say what kind of data we may be able to obtain from old samples, other than that these new data will likely provide additional pieces of the puzzle in understanding the ecosystem in which these birds live.
Development of methods
Research is as much about HOW to collect or generate data as it is the type of data being collected or how it is analysed and interpreted. An important part of the research is to constantly question existing practices and consider whether it is possible to improve or find new ways to get answers to one’s questions. Within the BSP, we are actively developing methods on several fronts – from a small scale, such as how or where to best capture a bird to have a minimal amount of interference and provide the most accurate data, to a large scale, which may deal with which parameters, technicians and actors generate the best data for the system analysis of something as big as the entire Baltic Sea ecosystem.