Black-headed gull

At the beginning of the 1990's attention was drawn to the fact that the Black-headed Gull population declined in all of Sweden, a national project was initiated to investigate the causes and Kvismare Bird Observatory participated in a study in Rysjön’s colony. The production of juveniles was measured, nestling weight at different ages and predation was studied. It was found that too few young birds survived and these results were applied to more places around Sweden. Unfortunately the cause couldn’t be safely identified, but probably has nutritional basis for Black-headed Gull diminished, it is speculated that better waste management and a more mechanized farming is behind that. Today, the production of young is still monitored in the black-headed gull colony in Rysjön.