Black Swan

I've seen this bird at Brookfield Zoo just west of Chicago, Illinois in a big pond with a number of other exotic waterfowl in the 1950's into the 1980's; then they did not seem to have them. For one summer season, someone in a camping park had two swimming in the Brandywine Creek near Downingtown, PA in 2012. Carousel Park that is southwest of Wilmington, Delaware had a couple in their Blue Lagoon that I saw in December 2016.

Although introduced from Australia in the 1860s, the Black Swan also reached New Zealand naturally at the same time. It prefers permanent fresh or brackish water for breeding. Their diet is mainly leaves and shoots of aquatic plants. Only about one in five nest in any one year. They heap plant material in piles to make their nests. Usually 6 eggs are laid and hatched five weeks later - incubation is by both parents. Cygnets are led to water within 24 hours of hatching. The fledging period varies between 95 to more than 140 days. For most of their pre breeding life they frequent marine or estuarine habitats. Most return to breed where they were born. Some live for up to twenty years.

These birds can be found living year-round (or close to year-round) in Lafreniere Park in Kenner, LA, a suburb of New Orleans. Regular white ones live there too, but the black ones are the stars of the lake. Sorry I can't give more info on the behavior of this swan compared to other swans, but I'll assume it's quite similar.