One can frequently see large flocks of swans in front of the mouths of the Isonzo and in the lagoons. Until 30 years ago, it was not so easy to see a swan at liberty; the first natural reproduction took place in the lagoon of Marano only in 1981 following the release of some individuals from captivity. The current population is estimated at 1,500 individuals of which a hundred are breeding pairs. The swan is vegetarian, grazing by preference on seagrasses. Some young are born already white via a mutation called immutabilis, thus debunking the story of the ugly duckling: one can therefore come across cygnets following their parents that are both grey and white.