Swans need certain basic requirements for nesting. It has been found that swans like to nest on a site similar to the one from which they were hatched. In other words, if they hatched out on an island, the (cobb) male who builds the nest will search for an island. If the site had been onshore at the base of a tree, generally they will search out such a place. They like as much privacy as possible and will often select out of the way places to nest. The nest will be from one to two feet high and four to six feet across. They will readily accept contributions of nesting material, especially when they nest on grounds that are highly maintained where green debris is not available.
Swans prefer nesting material composed of compost, reeds, cattails, sedges, and grasses. Hay can substitute as a nesting material, but can be slippery to the birds. Swans in Florida will begin nesting in late January, February, and March. They usually lay an egg every other day until a completed clutch comprises from 3 to 8 eggs. The incubation period is 40-45 days. The downy cygnets weigh about one-half pound at hatching with proper feeding grow very rapidly reaching 15 pounds within three months. At this time, they are feathered out and look like their parents except for their lighter bill color and grayish color around the head and neck region.
During times of nesting, especially in urban environments, swans should be penned. Pens provide protection from the urban setting, dogs, humans, and such. Pens also offer protection to curious humans that might be considered a threat to the nest and the pen (female) by the cobb. Swans become very territorial, especially during mating and nesting season. Pens should be large enough to accommodate an entire swan family. A minimum of 300 sq. ft. should suffice. Half of the pen should be on the lake bank and half of the pen should be in the water. Be aware of changing water levels in the pen during the nesting season.