Mute Swan - Cygnus olor

An adult Mute Swan, Cygnus olor, and a large "dirty gray" juvenile have been lingering in the first pond at Las Gallinas ponds, San Rafael, for a week or so. Mutes Swans are big birds indeed, a large male can rival the native Trumpeter Swan in size. Length of up to 63", wingspan to 94" and a weight of 25 pounds! This makes the Mute Swan one the largest birds capable of flight, up there is the American White Pelican.

Juvenile Mute Swan, Las Gallinas water treatment ponds

Mute Swan adult in a common swimming "display" - Ellis Creek, Petaluma 

The Mute Swan is a Eurasian Species, with 2/3's of the estimated population of 500,000 found in Russia (or what used to be the USSR). They are protected in some countries, eaten in others, and considered pests by some in many areas where they have been introduced, including northeast US and now California. Lots of people think their beauty outweighs the possible negatvie impacts. Good numbers of Mute Swans of can be seen in Sonoma (Shollenberger, Ellis Creek and Chileno Valley). Fortunately their numbers seem to have stabilized, wheras back east they increase by up to 10% per year. They are aggressive to other birds near their nesting sites, and to humans who get too close. The chicks, or cygnets, are gray, and remain gray through September, just now starting to get white plumage, as in the first photo. White gygnets are known to occur (photo, May 2013, Ellis Creek), presumably from a leucistic gene, and will become white juveniles.

The fully grown juvenile has a gray bill which lacks the knob seen on the adult. The bill here  (below) is starting to show some pink color, and will become orange by winter. Other swans native to our ABA area (Tundra and Trumpeter) have some yellow on the bill.

Taxonmy: 

Order: Anseriformes - Ducks, Geese, Swans, and Screamers

Family: Anatidae - Ducks, Geese Swans

Subfamily: Anseriinae - Swans and Geese

Tribe: Cygnini - Swans - Only 7 species in the world, in 3 genera. Our Tundra Swan (aka Whistling Swan) and Trumpeter Swan, along with the Whooper Swan, are in the genus Olor.The 3rd genus of swans is Coscoroba, with a single species, the Coscoroba Swan of southern South America.

Genus: Cygnus - 3 species, including the Black Swan of Australia/New Zealand, Black-necked Swan of southern South America and the Falkland Islands, and the Mute Swan.

Species: Cygnus olor - Mute Swan. From the above you will note that it is closer to the Black Swan than it is to the Tundra Swan.

Sources: Waterfowl, Madge and Burn, 1988, and Wiki-pedia.