All Mute Swans are known scientifically as Cygnus olor or Mute Swans. Swankeepers and scientists refer to them as Royal or Polish Mute Swans.

Royal Mute Swans are the traditional color with the adult swans having black legs and feet with a reddish orange bill. Their cygnets (baby swans) are taupe in color at hatching with black legs and black feet. The cygnets will turn completely white with reddish orange bills once the reach approximately one year of age.

Polish Mute Swans is a coloration in which the adults have orange bills with taupe colored feet and legs. Their cygnets hatch as white swans and stay that color throughout their lives without having to turn white at one year of age. Their bills will turn orange at approximately one year of age.

Many centuries ago, someone in eastern Europe decided that they wanted to produce a "white" or albino swan with no coloration. They set about this goal by inbreeding until they produced a "white" swan, however, an albino swan was never produced. The swan they produced was whiter in color with the taupe legs and feet and orange bill. Many people thought that it was a new species of swan calling it cygnus immutabalis (the unchangeable swan). However, it was not a new species, only what is known as a genetic mutation known as leucism. The leucistic swan is now known as the Polish Mute Swan. So, in laymen's terms, your swans are carrying the genetic leucistic gene and one of the cygnets appears as a Polish Mute Swan while the other carries the normal coloration gene and is known as the Royal Mute Swan. The Regal Swan