Literal translation
When the gulls come to land, mark of bad weather.
Meaning
when gulls come ashore, bad weather is coming
Explanation
This weather-forecasting saying rests on an observable animal behaviour: gabian, gulls, take refuge along the coast and inland when a storm or heavy sea disturbance is coming, moving away from the open water where they normally feed. Marco, from the verb marca, to mark or to indicate, introduces this movement as a reliable sign, almost an omen, of coming bad weather. This kind of observation belongs to a very old and widely shared tradition of folk meteorology based on the behaviour of birds, insects, or plants, particularly developed in coastal regions where the sea heavily shapes daily activity: fishing, sailing, coastal farm work. The saying belongs to the same family as the one about the hazy moon foretelling rain or wind. It is used in ordinary register, often said by those living near the sea, right at the moment the birds' behaviour is observed, to announce an imminent change in the weather.