As the previous poster stated, there is no way of ascertaining gender based upon color.

Mute swans are by latin species name, Cygnus olor. Therefore, they are known as Mute swans scientifically. However, for swan keepers, they are know as either Royal Mutes (cyngets are taupe in color with black legs and feet, adults have black legs and black feet with reddish/orange beaks) or Polish Mutes(cygnets are white in color with buff feet, adults have orange beaks and buff colored legs and feet).

Polish Mutes were derived centuries ago when someone in Poland, Hungaria, etc., tried to interbreed swans to produce an albino coloring. They did not succeed and only produced what is called the leucistic coloring known as the Polish Mute. Basically, through genetics and copious inbreeding, the color became paler, but no albinism (meaning no color)was rendered.

Usually, not always, the male swan (cob) has a larger knob on his bill and is bigger than the female (pen). Incidentally, the cob's name actually came from the old German word for Knopf meaning Knob and the pen from the old English word for pennae, the way she carries her wings back.

Still body size and cob size are not necessarily indicative of gender. In some cases, we have seen the knob being larger on a female and even the female was actually larger. This may be due to food resources, genetics, stress, etc., which makes some birds smaller than others.

Venting is still not the most precise way of ascertaining gender. It is correct about half the time because either someone does not know what they are doing or the birds are too young and the genitals have not formed. Usually, venting should be done past the 1st year of age as all body organs have fully developed.

The most precise and correct form of ascertaining gender is through DNA Sequencing. This is where blood or a feather is sampled for DNA and the gender chromosomes are seen and recorded. The Regal Swan