Tagging birds
The tagging of birds on Stora Karlsö has been and still is
an important procedure, as the birds are also weighed, samples of
DNA taken and all information recorded. The declining weight of
the Guillemot chicks has been discovered through this annual procedure,
as has the number of adult birds found in fishing nets. Through
tagging the birds, we can also study the survival rate of the adult
bird, by counting the number of tagged birds that return to the
island each year.
Behavioural studies
The behaviour of birds can be a vital clue to the condition of the
environment they live in. We have studied how often and with what
the birds feed their young. The results have shown long-term changes
in their behaviour. By combining knowledge from other changes in
the ecosystem, we can gain a better understanding of the long-term
survival of the birds.
Inventories
The long-term development of the population is the key to the survival
rate of a species. Stora Karlsö is one of Sweden's most important
nesting sites for several seabirds and it is therefore of great
importance to follow up the progress of the seabird populations
on the island.
Monitoring
Our research has shown that by following these seabirds year after
year, we can discover long-term changes in the ecosystem. By studying
many species in different ecological niches and several parameters,
we can get a detailed and precise image of the ecosystem as a whole.
In swedish 
